# Solar charging solution. Thoughts?



## mdocod (May 8, 2015)

I'm thinking about pulling the trigger on a ...

_SUNKINGDOM™ 5W 5V Portable Ultra-thin Solar Panel Charger USB_

...from amazon for $22.99, fulfilled by amazon prime.

This seems like a really nice back-country charging solution for phones/GPS and 18650's (paired with an Xtar MC1 Plus). At only ~4oz and about 9" X 8" this is lighter, smaller, and less expensive than many options. The size/shape of this thing would strap unobtrusively to the "top" of my Xenith 88 without overhanging. This almost seems too good to be true, so I can't help but think I must be "missing" the catch. It even "appears" to be of a durable design. Am I missing something here? Is this $23 4oz solar panel really potentially this good? It seems like most other options with similar power claims are heavier, larger, and often more expensive. 

Has anyone here had any experience using a relatively compact "portable" solar panel like this to charge phones and/or 18650's? I'd love to hear any constructive thoughts on the issue, especially from anyone who has used this or similar products.

Thanks,


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## KITROBASKIN (May 8, 2015)

If you are using your flashlight quite a bit at night, I do not think that charger will replenish your batteries- especially if you are not getting that much sun. Seems like you could try it and let us know. It is not expensive. I use a 15 watt solar panel in the high altitude New Mexico sun and one can only get so much juice out of small systems.


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## WalkIntoTheLight (May 8, 2015)

5 watts isn't very much power. And I usually de-rate it a bit, because manufacturers tend to exaggerate, and also most of the time the sun isn't perfect to get that full rating.

Can you even charge a cell phone on such little power?


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## ChrisGarrett (May 8, 2015)

This is how I did it a few years back:

http://www.candlepowerforums.com/vb/showthread.php?342073-Portable-solar-charging-setup-I-just-built













While it's not going into my back pocket, it's sufficient (along with the mother batteries) to charge all of my NiMH and li-ion needs.

Chris


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## Timothybil (May 8, 2015)

There have been several solar charging threads over the last year or so. Use the search option at the top of the page to find them. Happy hunting!

PS: I too believe the unit you referenced is way too small to do you any good. My personal setup would be 15w folding solar panels -> power bank -> USB to 12v boost circuit -> i4 v2 charger. Just waiting on money for solar panels - will document when completed.


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## mdocod (May 8, 2015)

KITROBASKIN said:


> If you are using your flashlight quite a bit at night, I do not think that charger will replenish your batteries- especially if you are not getting that much sun. Seems like you could try it and let us know. It is not expensive. I use a 15 watt solar panel in the high altitude New Mexico sun and one can only get so much juice out of small systems.



I figure on a combined 2-8 hours of usage per night between 2X wizard pro V2 headlamps (wife and I). Mostly on firefly 3 and main mode 1, which have runtimes of ~1 week and 25 hours respectively. Some sporadic bursts at higher output for fun, or for investigation of "noises" should be factored in, but even the regular "high" mode on these headlamps run for 4.5 hours. In the dark woods I really prefer to avoid using bright lights except when I get unsettled by noises and need feel it necessary to investigate, otherwise, I want to see the stars and sit by flickering coals of campfire. 

Worst case scenario, I expect an 18650 to last 4+ nights in a headlamp. I don't expect to run down the batteries in our handheld spotting light at all on a trip, as it would only be used for short spotting and backup. 

I honestly don't expect to need to do a lot of charging if any on most trips. (I've made do with far less in the past) I just like the premise of having a system that is "sustaining-as-needed" rather than limited to however many cells I carry. I have 12 brand spanking new NCR18650B's (got em for $5 each on a recent "deal" on amazon), but it occurs to me that I could strike a balance, carrying a few less cells would "pay" for the weight of the solar panel (only 4 oz), which could perhaps prove useful for topping up a cell phone that is being purposed as a make-shift GPS, keeping in mind, that it would normally be OFF. We use physical Nat-Geo trail maps most of the time, but I'm not the best at orienteering, and it would be helpful in some places to be able to "identify" our position on a GPS to then translate that to the physical map. 

If I could charge up a single near-depleted NCR18650B in a full day, I'd be very happy with the system, as that would keep up just fine. I'd estimate that to require ~15WH after losses are considered. Do you think a panel rated 5W could muster up 15WH in a full day?

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WalkIntoTheLight said:


> 5 watts isn't very much power. And I usually de-rate it a bit, because manufacturers tend to exaggerate, and also most of the time the sun isn't perfect to get that full rating.
> 
> Can you even charge a cell phone on such little power?



My phone has a 3.7V 2.1AH battery.. If the panel could manage to get an 18650 topped up in a day, it should be able to top up a cell phone in a day as well. (keep in mind, the phone would not be ON except intermittently for use as a GPS once and awhile). 

5 watts isn't very much power, but if I could average 2 watts out of it for ~8 hours a day, or 3W for 5 hours, or something like that after regulation losses are considered, that would be very functional for me. Do you think that is an unreasonable expectation? 

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Timothybil said:


> There have been several solar charging threads over the last year or so. Use the search option at the top of the page to find them. Happy hunting!



I searched and skimmed dozens of threads before posting this. I did not see any discussion about any panels like the one I am referring to in this thread being used for back-packing. Most of the search results were over 3 years old, so aren't necessarily even relevant depending on what products and tech are available now. Most of the threads are regarding large systems like the one posted by ChristGarret above that have no place on my back 14 miles in. 

If you know of a thread that I missed. I'm all ears. 



> PS: I too believe the unit you referenced is way too small to do you any good. My personal setup would be 15w folding solar panels -> power bank -> USB to 12v boost circuit -> i4 v2 charger. Just waiting on money for solar panels - will document when completed.



Based on your experience with your 15W panel, do you think it is reasonable to assume that I could charge an 18650 cell or a turned-off cell phone (even less stored energy) in a day on a panel "rated" 5W?


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## KITROBASKIN (May 8, 2015)

Hopefully you will give it a go. I am probably not able to fully charge a nearly depleted 18650B with my 15 watt Goal Zero panel. I charge well before near-depletion whenever possible. We all appreciate your earnest inquiry and studied responses. By-the-way, I am primarily using an Xtar MC1 single bay, simple charger off of a USB connection, as my NiteCore i2 would not function with the panel. The larger Xtar chargers that I have are equipped with digital displays, and I do not wish to use electrons towards monitoring.


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## keithy (May 8, 2015)

Not sure what happened to my previous post, so I'll try again - 

I use a few solar panels when hiking, but haven't used them for charging 18650 or 14500 cells yet. I use them for charging camera, NiMH AAs for my GPS, UV water filter and flashlights. 

I looked a some of these 5W panels a while back (I can't remember the brand, but it looked similar to the Sunkingdom one) and found that it was lacking in output current. The 5W panel I tested was outputting less than 0.5A, and the AA charger I was using didn't like the lower current. It did manage to trickle charge a USB li-ion battery pack though. 

I now have 2 Goal Zero Nomad 7W panels, an Instapark Mercury 10W panel, and a Goal Zero Nomad 13W panel. The 13W panel is a bit too big and heavy to take backpacking. I use the Instapark Mercury 10W as a middle ground, as it can output a higher current than the 7W panels. The Instapark is meant to output a max of 2A, but I haven't been able to achieve that in direct Australian sun, with the devices I've plugged in. My USB AA chargers only accept an input of 0.5A, but using a tablet that can take 2A, I have tested the Instapark panel at up to 1.5A. The Goal Zero Nomad 7W panels output less - between 0.8A - 1A. 

One of the issues you might face is what happens when you get cloud cover or are in shade while it is strapped to your pack. I've noticed some panels stop charging devices after cloud cover, not sure whether the controller is shutting it off, or the device isn't accepting the reduced current. 

I haven't heard of the Sunkingdom brand but be aware of the cheaper solar panels out there. A mate bought a 13W panel that looked extremely similar to the Goal Zero Nomad 13 panel from a seller on eBay. It came from China, and size wise it measured up and looked like the Goal Zero. When we tested it out in the same conditions charging the same model of phone, it was clear that the Chinese copy wasn't up to scratch. It would only output around 0.5A, while the GZ 13W would output around 1.3-1.5A.

I haven't tried hooking up my Nitecore I4 to the solar panel via the 12V input though. I should give that a test and see whether it works. The Nitecore I4's input is 12V 1A, so I'm wondering if the current drops will it stop charging all together until the current goes back over 1A.

I'm using a device like this http://www.adafruit.com/products/1852 to check the current outputs from the solar panel. I previously used a spliced USB cable and my multimeter, but this is a bit neater and easier (although the red display can be hard to read in direct sunlight).


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## StorminMatt (May 8, 2015)

KITROBASKIN said:


> Hopefully you will give it a go. I am probably not able to fully charge a nearly depleted 18650B with my 15 watt Goal Zero panel. I charge well before near-depletion whenever possible. We all appreciate your earnest inquiry and studied responses. By-the-way, I am primarily using an Xtar MC1 single bay, simple charger off of a USB connection, as my NiteCore i2 would not function with the panel. The larger Xtar chargers that I have are equipped with digital displays, and I do not wish to use electrons towards monitoring.



The biggest bottleneck here is the half amp charging rate of the MC1. Even if you have a solar panel that can actually pump 2A through USB, you won't be able to charge the battery at more than half an amp. This is where the MC1 Plus comes in. But beware of the Goal Zero panels. Not sure about your 15W. But lots of them will only put out full power through a proprietary connector and maybe half an amp to one amp through USB. If you want a small folding panel that can put out lots of current through USB, you may want to look elsewhere.


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## Bullzeyebill (May 8, 2015)

keithy said:


> Not sure what happened to my previous post, so I'll try again -



Your other post had not been approved. I approved this one as it has more info.

Bill


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## TEEJ (May 8, 2015)

My favorite solar charging solution is Cottonpicker's folding solar chargers. He's on the forum, and makes them by hand to order. They far outperform the commercial stuff that's out there, and are extremely well built. He sets them up with built in ports for your ipod, computers, phones, batteries, battery packs, etc....whatever you need.


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## Timothybil (May 8, 2015)

mdocod said:


> Based on your experience with your 15W panel, do you think it is reasonable to assume that I could charge an 18650 cell or a turned-off cell phone (even less stored energy) in a day on a panel "rated" 5W?


First off, if you look closely you will see that I said the solar panel was waiting on money, so I don't have it yet. Now, since this discussion, I was doing some research and found out that the price dropped $20, so I went ahead and ordered it - it is scheduled for mid-week next week. If you can wait that long I will give a quick report as soon as it arrives.

Second, I think you should plan to put a power bank between the solar panel and whatever else. As you may have seen on the other threads, one of the problems with direct charging is the variable output of the solar panel(s). By using a power bank, it will accept whatever output is available and store it away. Then, in the evening or over night, the power bank can be used to charge whatever, even if it takes all night. I personally really like the Maxboost Electron banks. Mine is the 15,000mAh, but they also make one at 10,000mAh. One really nice feature is that they have a digital % of remaining charge display.

And last, but definitely not least, I think you would be much happier with this panel: *Anker® 14W Dual-Port Solar Charger with PowerIQ™ Technology*. It is about twice the cost, but produces almost three times the output, and is made by a recognized name in portable solar power. It is the one I have ordered so we will see how it does next week.

PS: I am not a camper or hiker, so that does influence my choices somewhat. I am more preparing for the power failures I expect to see in the next couple of years caused by failures in the regional power grids.


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## Timothybil (May 8, 2015)

TEEJ said:


> My favorite solar charging solution is Cottonpicker's folding solar chargers. He's on the forum, and makes them by hand to order. They far outperform the commercial stuff that's out there, and are extremely well built. He sets them up with built in ports for your ipod, computers, phones, batteries, battery packs, etc....whatever you need.


The last I heard, he wasn't in that business any longer, which is a pity because I would have liked to get a couple of his products.


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## scot (May 8, 2015)

I've played with cheap panels, and that's just what they are, CHEAP. I'll never buy a cheap one again. My two favorite are the Goal Zero and Suntactics. I once went for six months charging my IPhone from only the GZ panels and AA batteries that comes with them. Not once did I plug into the wall outlet.
Never have charged a 18650 from one though. Maybe I should try and report back. 
Big difference between just the 5 watt and the 8 watt, yet not much difference in size.
Love my solar panels, play with them all the time.


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## mdocod (May 9, 2015)

KITROBASKIN said:


> Hopefully you will give it a go. I am probably not able to fully charge a nearly depleted 18650B with my 15 watt Goal Zero panel. I charge well before near-depletion whenever possible. We all appreciate your earnest inquiry and studied responses. By-the-way, I am primarily using an Xtar MC1 single bay, simple charger off of a USB connection, as my NiteCore i2 would not function with the panel. The larger Xtar chargers that I have are equipped with digital displays, and I do not wish to use electrons towards monitoring.



Thanks for sharing your experience. 

I'm very tempted to give it a try despite the discouraging responses thus far. 

If a "15W" panel that costs >$100+ can't even charge a single NCR18650B in a day, then something seems out of whack. Highway robbery much? Something seems amiss there. Li-Ion charging is a pretty efficient process. A 12WH cell should only need ~15-16WH (all charging losses included) to charge (on a poor efficiency charger design). You're saying, you don't think the goalzero 15W panel could average 2W output over 8 hours in the sun?

In your experience, would you say the MC1 is "tolerant" of low input power? IE: will charge anyway, just at a reduced rate?

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keithy said:


> Not sure what happened to my previous post, so I'll try again -
> 
> I use a few solar panels when hiking, but haven't used them for charging 18650 or 14500 cells yet. I use them for charging camera, NiMH AAs for my GPS, UV water filter and flashlights.
> 
> I looked a some of these 5W panels a while back (I can't remember the brand, but it looked similar to the Sunkingdom one) and found that it was lacking in output current. The 5W panel I tested was outputting less than 0.5A, and the AA charger I was using didn't like the lower current. It did manage to trickle charge a USB li-ion battery pack though.



Thank you very much for sharing your experience, and taking the time to re-post a lost-post. This helps me "frame up" what I am up against here. Less than 0.5A may not be a deal breaker, depends on the behavior of the charger. 




> I now have 2 Goal Zero Nomad 7W panels, an Instapark Mercury 10W panel, and a Goal Zero Nomad 13W panel. The 13W panel is a bit too big and heavy to take backpacking. I use the Instapark Mercury 10W as a middle ground, as it can output a higher current than the 7W panels. The Instapark is meant to output a max of 2A, but I haven't been able to achieve that in direct Australian sun, with the devices I've plugged in. My USB AA chargers only accept an input of 0.5A, but using a tablet that can take 2A, I have tested the Instapark panel at up to 1.5A. The Goal Zero Nomad 7W panels output less - between 0.8A - 1A.



Sounds like that instapark panel isn't too bad of a deal (good power output for ~$50). Unfortunately, at a weight of about 1 lb, that doesn't really "pay" for itself very well. I could carry 8XNCR18650B's for the weight of that panel, which is more than I would ever anticipate needing in any single trip. By my figuring, the weight of the solar charging system would have to be less than 8oz to meet a comfortable "break-even" point for me, where I opt to leave behind 4 spare cells (only carry 2 spares instead of 6), and bring up to an 8 oz solar charging system along. The beauty of that 4oz panel I found on there, is that it would actually make my pack lighter. I'd leave behind 8 oz of spare cells, and bring along a total of about 5oz of charging gear instead (panel+mc1). 3oz is 3oz, and in backpacking, those ounces add up, everything has to be scrutinized, limits have to be imposed, especially since we also pack fishing gear (have that down to ~1lb per person). 



> One of the issues you might face is what happens when you get cloud cover or are in shade while it is strapped to your pack. I've noticed some panels stop charging devices after cloud cover, not sure whether the controller is shutting it off, or the device isn't accepting the reduced current.



Yea, need to figure out more details about this.. My understanding though, is that the MC1 is a good device for a solar setup because it won't allow any reverse "bleed-down," as could be the case with some solar panels when in the shade/dark when connected to some devices. 



> I haven't heard of the Sunkingdom brand but be aware of the cheaper solar panels out there. A mate bought a 13W panel that looked extremely similar to the Goal Zero Nomad 13 panel from a seller on eBay. It came from China, and size wise it measured up and looked like the Goal Zero. When we tested it out in the same conditions charging the same model of phone, it was clear that the Chinese copy wasn't up to scratch. It would only output around 0.5A, while the GZ 13W would output around 1.3-1.5A.



Makes me wonder if KITROBASKIN's GZ is a counterfeit, based on his reported experience with it... hmmm...



> I'm using a device like this http://www.adafruit.com/products/1852 to check the current outputs from the solar panel. I previously used a spliced USB cable and my multimeter, but this is a bit neater and easier (although the red display can be hard to read in direct sunlight).



I was planning to pick up Xtars version of the same type of device to test with if I do decide to buy something, but based on the feedback so far, nobody seems to think that 4oz panel will do anything useful, so I may not even be bothering. 

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TEEJ said:


> My favorite solar charging solution is Cottonpicker's folding solar chargers. He's on the forum, and makes them by hand to order. They far outperform the commercial stuff that's out there, and are extremely well built. He sets them up with built in ports for your ipod, computers, phones, batteries, battery packs, etc....whatever you need.




Thanks for the heads up, I'm trying to locate a recent sales thread but not having any luck. Sounds like he isn't doing this anymore. Though, a DIY isn't necessarily out of the question for me, but I'd prefer to buy a ready-made product. The market appears to have enough options and competition to more or less ensure that any DIY attempt would be more for the novelty of DIY than for any value-add. 

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Timothybil said:


> First off, if you look closely you will see that I said the solar panel was waiting on money, so I don't have it yet. Now, since this discussion, I was doing some research and found out that the price dropped $20, so I went ahead and ordered it - it is scheduled for mid-week next week. If you can wait that long I will give a quick report as soon as it arrives.
> 
> Second, I think you should plan to put a power bank between the solar panel and whatever else. As you may have seen on the other threads, one of the problems with direct charging is the variable output of the solar panel(s). By using a power bank, it will accept whatever output is available and store it away. Then, in the evening or over night, the power bank can be used to charge whatever, even if it takes all night. I personally really like the Maxboost Electron banks. Mine is the 15,000mAh, but they also make one at 10,000mAh. One really nice feature is that they have a digital % of remaining charge display.
> 
> And last, but definitely not least, I think you would be much happier with this panel: Anker® 14W Dual-Port Solar Charger with PowerIQ™ Technology. It is about twice the cost, but produces almost three times the output, and is made by a recognized name in portable solar power. It is the one I have ordered so we will see how it does next week.



Sorry I did read your previous reply incorrectly. I think I got it mixed up with someone else's response. 

I appreciate your thoughts on the matter. Unfortunately, I don't see any way for a 28oz solar panel and a 10oz redundant power bank to break even on weight vs just carrying more charged cells. For that much weight I could just carry an additional ~20 X NCR18650B's (on top of the 2 or so spares that would come along regardless plus those that would already be in the headlamps and handhelds). From a back-packing perspective within the context of the type of trips we will be able to take, the break-even point is going to be if a functional panel + 1 cell charger weighs as much or less than bringing 4 more spare 18650's (about 8oz). 20 spare cells (26 total including a "baseline" of 2 spares and 1 cell already loaded in each headlamp and hand-held) would be ~3 months worth of use, maybe more. A 3 month expedition isn't happening, our schedules don't allow for that, so it doesn't make sense for our power system (solar or not) to weigh as much as a 3 month supply of batteries. 




> PS: I am not a camper or hiker, so that does influence my choices somewhat. I am more preparing for the power failures I expect to see in the next couple of years caused by failures in the regional power grids.



Back-packing requires careful attention to weight. I'm not as "serious" about the weight reductions as many back-packers, (we bring a good camera, fishing gear, comfortable sleeping pads, roomy tent, etc), but it is important to me to be careful how I am "spending" the ounces in my pack. I'll carry more weight if it provides me with a creature comfort or benefit or activity that I consider to be with the "cost" in weight. In this case, I'm actually looking for something small, low power, and light weight. I expect the performance to be low, but don't need much to create a sustainable and be beneficial system. One way or another, I will likely have enough cells on any trip to make it through rain or shine anyway. With so many modes on these headlamps, there's really no reason not to be able to stretch out a single 18650 for a week or more if necessary (Which is about as long as any of our trips would ever be anyway). I mean, the runtime in firefly 3 mode (~9 lumens, which is plenty for most camp/kitchen stuff) is basically an entire week on an 18650 anyway. Yes, one could theoretically leave on 1 week trip and leave the headlamp on the entire week at ~9 lumens the entire time, without swapping the battery the entire trip). Point being, I'm not trying to power a search and rescue operation or or a portable guitar hero session or something. 

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scot said:


> I've played with cheap panels, and that's just what they are, CHEAP. I'll never buy a cheap one again. My two favorite are the Goal Zero and Suntactics. I once went for six months charging my IPhone from only the GZ panels and AA batteries that comes with them. Not once did I plug into the wall outlet.
> Never have charged a 18650 from one though. Maybe I should try and report back.
> Big difference between just the 5 watt and the 8 watt, yet not much difference in size.
> Love my solar panels, play with them all the time.



Thank you for sharing your experience.

I see that suntactics has a 6" X 11" folding panel that weighs 8 oz, that is a "true" 5W panel, for $130. (made in USA). That looks like a very high quality panel. When paired with a charger it would be borderline in terms of weigh to benefit ratio, and potentially overkill, as I really don't need a "true" 5 W panel to achieve sustainability, but I'm going to bookmark that one. 

Based on your experience with cheap panels, do you think they might deliver even half of their rated output in full sun? Reason I ask is that, I'd actually rather have a 2-3W panel (even if it claims 5W on the box) that weighs 4oz, than a true 5W panel that weighs 8oz for this application.

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*Thanks everyone for your participation, feedback, ideas, and interest in the topic. This is great stuff. 

If I may be so bold to try to steer the conversation away from any panel that weighs over ~8 ounces or is larger than ~100 sq inches. It doesn't matter if it could power a whole zoo, it doesn't do me any good to be larger or heavier than this as I could just carry more cells at that point. I'd love to hear more experiences and/or thoughts about small (weak) light weight panels, specifically if anyone has used them with an MC1 charger. 

Regards,*


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## StorminMatt (May 9, 2015)

mdocod said:


> I see that suntactics has a 6" X 11" folding panel that weighs 8 oz, that is a "true" 5W panel, for $130. (made in USA). That looks like a very high quality panel. When paired with a charger it would be borderline in terms of weigh to benefit ratio, and potentially overkill, as I really don't need a "true" 5 W panel to achieve sustainability, but I'm going to bookmark that one.



Although the Suntactics sCharger 5 is a REAL 5W charger, it is NOT a good choice for charging cylindrical Li-Ion batteries. The problem with that charger is that the USB output features Suntactics' patented auto retry system. Auto retry periodically (every three minutes, I think) cuts power for a second before reconnecting. The reason for this is that devices like iPhones will stop the charge if power is low (like from intermittent shading of the panel), and not resume once power is increased. Charging will only resume if power is disconnected and reconnected. However, this same feature is detrimental when it comes to charging bare Li-Ion cells. Xtar chargers will not charge a battery that is stuck in a charger with over 4V. The same thing happens if the charger is charging a battery and power is disconnected and reconnected when the battery has over 4V. So with auto retry, the best you can get is a 4V charge. Also, Xtar chargers charge at a low rate when the charge is started before stepping up to a higher rate. This will happen every few minutes with auto retry, drastically slowing the charging rate. So avoid the sCharger 5.

However, Suntactics also sells the sCharger 8. This charger has both an auto retry port AND a normal, 'constantly on' port (unlike the sCharger 5). It's only a little bigger than the sCharger 5. But it produces 8 watts vs 5. It also only costs about $20 more (for almost twice the power!). I actually have the sCharger 8. And it works GREAT. It will even charge my iPad Air, albeit not at wall charger speeds. But I can charge either my iPhone or a couple of UR14500p cells (in an MC2) every bit as quickly as with a wall charger (it will do both simultaneously, but more slowly - keep the MC2 off the auto retry port!). It should also fully charge a completely drained 18650 in just a few hours with an MC1 Plus.


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## keithy (May 9, 2015)

mdocod said:


> Thank you very much for sharing your experience, and taking the time to re-post a lost-post. This helps me "frame up" what I am up against here. Less than 0.5A may not be a deal breaker, depends on the behavior of the charger.
> Sounds like that instapark panel isn't too bad of a deal (good power output for ~$50). Unfortunately, at a weight of about 1 lb, that doesn't really "pay" for itself very well. I could carry 8XNCR18650B's for the weight of that panel, which is more than I would ever anticipate needing in any single trip. By my figuring, the weight of the solar charging system would have to be less than 8oz to meet a comfortable "break-even" point...



No problems. I tried hooking up my panels to my nitecore i4 by 12V input but relatively cloudy today without direct sunlight the charger didn't turn on at all. The current output was well less than 0.3A.

I know what you mean by weight. I just bought a new pack to save 2.2pounds and a newer lighter sleeping bag and I'm looking at some lighter tent solutions now as well. I've been looking for a new AA USB charger to pair up with my solar panels and came across Sunjack on Amazon.

They have a 7w panel that looks like the goal zero and is cheaper on amazon. http://www.sunjack.com/product/sunjack-7w-solar-charger/ but the panel alone weighs 0.8lbs. I'm keen to know how the xtar works with a solar panel.


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## KITROBASKIN (May 9, 2015)

The half amp limit on the Xtar MC1 charger may be limiting the capabilities of my panel. I have one of Xtar's USB volt/amp analyzers and will check it out. 

Typically I will recharge 18650's when they go down to less than 3.85 volts or so. They do charge up, but an almost completely drained 18650 will take a lot more time. One should also consider the quality of the USB cord and connections involved in the process.

If a person regularly adjusts the orientation of the solar panel to constantly face the sun on a cloudless day, all day, it may perform as the advertised specs claim. That is my guess.

Your discussion motivated me to read up some more about this subject last night. Thanks for that. My solar panel is possibly for motorized transportation camping, and emergency use primarily, when grid power goes down. Your requirement for a lightweight panel makes sense, as well as a low price to justify the purchase because your use will probably not be that often. Carrying more batteries might be the more practical thing to do, but having the capability to charge from the sun is very appealing from an emergency scenario point-of-view. And based on your words, it is hoped you will post your experiences if/when you take the plunge.


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## mdocod (May 9, 2015)

StorminMatt said:


> ...The problem with that charger is that the USB output features Suntactics' patented auto retry system.... Xtar chargers will not charge a battery that is stuck in a charger with over 4V. .....So avoid the sCharger 5.



My experience with Xtar chargers, is that some of them won't initiate a charge on a cell >~4V that is INSERTED into a charger that is powered up, but when power to the charger is "cycled" with the cell already in the charger, it almost always re-initiates charging regardless of cell voltage. I'm not sure how the MC1 behaves, but my experience with other xtar chargers leaves me to believe that the "auto-retry" function of that panel would not be a problem. If anything, it would likely result in achieving higher charge saturation, as it would "re-initiate" the charge after termination over and over again. 



> However, Suntactics also sells the sCharger 8....



Looks nice, now, if they would just make a version called the sCharger 3 at <5 ounces and <$50  I'd be very interested.  I just can't rationalize a 14oz panel.

Perspective: 
My favorite back-packing saw, is actually made by fiskars and sold at walmart in the garden department for ~$8-13 (depending on time of the year). It's a 13" long pull-saw blade with a composite handle. The whole thing weighs only 7oz with the blade guard. It offers equal or better cutting performance per oz than anything I'm aware of at 2-10X the price, and arguably offers a lot more useful utility and/or survival value per oz than a 14oz solar panel.

I love those "gems" we find in the most unlikely places, and would really like to believe there's a "gem" of a 4oz solar panel out there that could charge an 18650 or top up a cell phone in a day without costing an arm, leg, and left testicle. 

------------



KITROBASKIN said:


> The half amp limit on the Xtar MC1 charger may be limiting the capabilities of my panel. I have one of Xtar's USB volt/amp analyzers and will check it out. Typically I will recharge 18650's when they go down to less than 3.85 volts or so. They do charge up, but an almost completely drained 18650 will take a lot more time. One should also consider the quality of the USB cord and connections involved in the process.



I figure it should take an MC1 (at 500mA rate) ~5-7 hours to charge up a mostly depleted 18650 in ideal conditions (normal USB power or USB power adapter) anyway, so yea, my idea was to look for a panel that would more or less "match" this charge rate. I was optimistically thinking I'd get the "plus" version and see if it would allow me to make the "best" use of available power in excess of 500mA in ideal conditions, but I guess that would depend on the charger's behavior. I figured with solar being intermittent it would be all day to top up a mostly depleted 18650 with a "500mA" charger, which would be perfectly fine by me, as even that would be double my anticipated consumption rate of about 1 cell depletion per 2 nights between 2 people (I expect at minimum ~4 nights from an 18650, per headlamp/person). 

If you have that analyzer and MC1, maybe you could do me a huge favor...

I'd like to get a "feel" for how the MC1 behaves when the available current drops below 500mA... like, will it keep charging with less? I was thinking, if you could hook it up to the solar panel, and gradually "shade" the panel to see how low the current has to drop before the charger quits attempting to charge at all, that would be a massive help for me. If the MC1 can basically behave as a "variable" rate charger below 500mA, then it should make a fantastic charger for solar, truly eliminating the need for a "buffer" battery to make decent use of available power. The behavior of the charger is gong to have a large impact on how much panel is required to make it functional. 



> If a person regularly adjusts the orientation of the solar panel to constantly face the sun on a cloudless day, all day, it may perform as the advertised specs claim. That is my guess.



Even if I could only get 2-3W from a 5W panel in "ideal" conditions I'd be pretty happy with a 4oz $23 panel (The MC1 charges at~2W). Keep in mind, we don't just go packing for the sake of packing. We are more "destination/recreation" oriented back-packers, Unlike many packers, who are more "achievement" oriented (mountain-summits and trail-miles). For every 10-15 miles covered on the trail, we're probably going to try to spend a day at a "destination" somewhere along that trail, likely a mountain lake, or cluster of lakes, to fish, take nature/landscape photos, and sit by the fire until late, then, when the fire calms to a glimmer, enjoy the stars. On these "recreation" days, I'd have plenty of opportunity to manipulate the panel into ideal positions for sun, and would even consider the "chore" a "fun" part of my recreation, as I enjoy that sort of tinkering. 



> Your discussion motivated me to read up some more about this subject last night. Thanks for that. My solar panel is possibly for motorized transportation camping, and emergency use primarily, when grid power goes down. Your requirement for a lightweight panel makes sense, as well as a low price to justify the purchase because your use will probably not be that often. Carrying more batteries might be the more practical thing to do, but having the capability to charge from the sun is very appealing from an emergency scenario point-of-view. And based on your words, it is hoped you will post your experiences if/when you take the plunge.



If I do take the plunge on one of these panels I'll certainly do plenty of testing and share my findings with the community. 

----------

This guy on youtube seems pretty happy with the larger 8W version of the same panel I'm looking at... Getting to "see" the panel in the video, and the way it is indeed what I was hoping, sort of a semi-flexible but durable looking piece of plastic with the solar cells laminated between layers. Seems a lot more durable/KISS to me than a lot of the other panel designs I've seen, many which are both heavier and more expensive. 



Granted, he is in a position to monetize sales of these panels, so I'm not sure how credible he is. From my understanding he is a real wildland firefighter and homesteader so must have some idea of how to spot junk, but on the other hand it's also likely he may not have any reference to know what good is in the first place. That silly LED bulb is also really not useful for back-country work or recreation IMO, so maybe he doesn't know jack.


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## StorminMatt (May 10, 2015)

I can actually see ALOT of value in a smaller, lighter version of the Suntactics panels. After all, if your main concern is charging flashlight batteries, you really don't need too much power to do it. To put things into perspective, sometimes when I go day (or should I say night) hiking, all I carry is an SC52w. It may not have the brightness of my 18650 or 26650 lights. But 50 or 108 lumens is fine for most uses. And it will do this for at least 3hr or 7.5hr (respectively) on a Sanyo UR14500p (which can be charged in an MC0 rather than an MC1 to save even more weight). With about 2W of power, you can fully charge a fully drained UR14500p in less than two hours (1:45-1:50, to be precise). But I'm not sure Suntactics would make such a charger. After all, most potential customers don't charge cylindrical Li-Ion batteries. Most people want such a charger for smartphones. And a 3W charger would hardly be up to the job.


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## mdocod (May 10, 2015)

A "true" 3W panel in direct sunlight would theoretically charge my smart phone in about 3-4 hours. (Assuming the charge controller in it is more or less a linear regulator, nothing fancy; lossy, like the MC1). 

The way I see it, a "true, few-watt" panel should be plenty for just about anything on a backpacking trip for a group of 1-4. I mean, the phones should be OFF most of the time anyway back there. It's largely useless turned on, unless you are using it as a GPS while bushwacking or something, which isn't really our focus/style. We may go off-trail around lakes/rivers for fishing, but really don't need a GPS to find our way around a lake 

--------

I'm biting the bullet and giving that _SUNKINGDOM™ 5W 5V_ panel a try. For $23 it's worth the risk. If it doesn't come anywhere close to being functional/useful it's not much of a loss, or I could simply return it. 

If nothing else, I'll be able to report some measurements to the CPF community.


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## KITROBASKIN (May 10, 2015)

mdocod said:


> I'm biting the bullet and giving that _SUNKINGDOM™ 5W 5V_ panel a try. For $23 it's worth the risk. If it doesn't come anywhere close to being functional/useful it's not much of a loss, or I could simply return it.
> 
> If nothing else, I'll be able to report some measurements to the CPF community.



Great. Perhaps you can give us some 'real world' observations. Curious to know if it might be rain resistant.

Yesterday, the temperature was way above freezing but we got a bit of snow on-and-off during the blustery, mostly cloudy day. I get concerned about the wind causing damage to my rigid panel. But I did hook up an ML102(?) charger, purchased perhaps last summer, to grid power. As CPF member HKJ reported, after the green 'charged' indicator went on, the charger kept on sending amperage to the cell. The Xtar USB Detector showed 0.02A, briefly going to 0.01A then back to 0.02A. And while it did indicate 0.8A charge initially with a Kinoko 18650 starting at about 3.7V, one perhaps should not leave a battery in that charger for very long after the green indicator lights up. I left mine on more than a half hour after 'green' and it was still getting the 0.02A. However, the voltage on the Kinoko was about 4.17, when I pulled it and it is in pretty good shape.

We have a lot of sun today. I will try to check out the charging behavior of the MC1.


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## kosPap (May 10, 2015)

mdocod, nice to see stumble in a post by you again...

A guy in a local forum stumbled to the same dilemma.
But hsi probmlem was that he needed to charge AA&AAAs from a 5v/USB panel.
If you are to ever require this in the future I would eurge you to find a 12V one.


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## KITROBASKIN (May 10, 2015)

I just spent maybe a half hour writing a thread about solar experiments this morning, and the CPF 'token expired' with no sight of what I wrote.

Xtar MC1 did well, both in partial obstruction of panel (with forearm and hand about 18 inches away), and the use of 50% (maybe more) shade cloth.


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## StorminMatt (May 10, 2015)

Speaking of lower power (<5W) solar panels, Goal Zero actually makes a 3.5W panel, the Nomad 3.5. Unfortunately, they bundle it with one of their pricey power banks. So you end up having to pay around $100 for the thing. Portapow also makes a 3W panel. Like the Sunkingdom panel (and unlike the Goal Zero), it is a nonfolding design. And it's actually fairly cheap at just under $20. Not sure how good it is, or whether it hits the numbers. But it might be worth looking into.


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## SemiMan (May 10, 2015)

-----


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## SemiMan (May 10, 2015)

Ooops .....


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## keithy (May 10, 2015)

mdocod said:


> I'm biting the bullet and giving that _SUNKINGDOM™ 5W 5V_ panel a try. For $23 it's worth the risk. If it doesn't come anywhere close to being functional/useful it's not much of a loss, or I could simply return it.
> 
> If nothing else, I'll be able to report some measurements to the CPF community.


It would be good to get an update and how it works with the Xtar. I might have to pick up an MC1 to use with my panels. I see the MC2 needs input current of 1A, so that might rule it out for me given my panels can fluctuate under 1A. Sunday was a rainy day in Oz, so I didn't get a chance to test my I4 with the panel again via 12V. 



SemiMan said:


> If you are planning to charge while actually hiking with the panel on your back, especially in the summer, then cut any expectations way down. Panel orientation is likely to be far from ideal if not the wrong direction from the sun, and depending on where you hike, shade will be common. Best location for a small panel, would likely be on the top of your head .... no really. A small panel on the top of a Tilley would likely collect more sun than something several times its size hanging on your back.
> 
> Solar works good when stationary when it can be oriented in the right direction and not be shaded.


This can be true, but from my experience, it works well in the right conditions when hiking. I took both my GZ 7W and the Mercury 10W to Nepal for a month long trekking trip, and both functioned great. The 7W panel was on a hiking partner's pack, while the 10W was on mine. If we were walking into the sun, the panel was strapped to the front like a bib. The most optimum solar orientation is to get the sun about 90 degrees to the panel, but even when it wasn't, both panels still managed to work well enough to charge AAs via USB, or trickle charge a USB battery pack, or direct charge a digital camera. For example my 7W panel charged a 900mAh Sony camera battery directly from empty to full in about 2 or so hours in strong Nepal sunlight, but there was a lot of reflection from the snow as well. Charging up a 5000mAh battery pack took about 2 days, and 4xAAs took about a day as well. 

And then there are times that solar didn't work. I took the panels on a hike through Borneo, and it was not much use. The rainforest canopy cover meant direct sunlight was very low while walking, and when we got to camp it was usually overcast or raining...



kosPap said:


> A guy in a local forum stumbled to the same dilemma.
> But hsi probmlem was that he needed to charge AA&AAAs from a 5v/USB panel.
> If you are to ever require this in the future I would eurge you to find a 12V one.



I do this, charging AAs/AAAs from 5V with both solar panels via USB. The chargers I use I mentioned in this other post: http://www.candlepowerforums.com/vb...-of-Eneloops&p=4651131&viewfull=1#post4651131

The ones I use are currently not perfect, but I might order that Sunjack charger from Amazon. It says it has independent charging channels and is a smart charger so might suit my needs.


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## KITROBASKIN (May 10, 2015)

Turns out that even though I could charge my old "feature" phone straight off the Goal Zero 15 watt, the Moto E smart phone did not. I used an ML102 charger from the solar panel, and as a battery bank, for the Moto E. That worked but the shade test did not go well for the ML102, and when the light turns green, indicating the battery is charged, it was still taking a little amperage when I was testing it on the grid power.


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## StorminMatt (May 11, 2015)

SemiMan said:


> The odds of this being 5W I would say are pretty close to 0. Looking at the actual solar panel area, that would put it 18%+ ... which is unlikely for an assembled unit of this quality.
> 
> The issue with solar is not whether you "can" charge it in a day, but whether you will be able to. You can't predict the sun and if you are planning to charge while hiking, then multiply that many times over. An overcast day could cut the amount of sun down 5-10x from a sunny day, and ignore all the marketing BS about how good some panels are in shade/overcast ... the best ones are still only collecting maybe 1/5 to 1/10 of a bright sun day.



While I don't think this panel will produce 5W, I think it will do ALOT better than 18% of that (.9W). Judging by the size, I think that 3W is probably right on the money (provided the regulation is not too inefficient). As far as shade, it is definitely true that shading is VERY detrimental to the output of photovoltaic panels. Even a very small amount of shading on a panel can greatly reduce output. But not everybody lives (and especially hikes) in gloomy places. In places like the Sierra (here in California), sunlight is flat-out INTENSE. And cloudy days are rather rare. The same is true about many other places in the Southwestern US. Granted, the same cannot be said about the Northeastern US or the UK. But in places (like California, Arizona, or Colorado) that receive sunlight in abundance, using a solar charger is kind of a no-brainer. Especially since alot of people in these places hike.


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## mdocod (May 11, 2015)

KITROBASKIN,

Thank you for taking the time to do some experiments and share your results. I appreciate it  I also loose posts on here a lot. Usually happens when I work on a post over the course of many hours as I have time to do so, and make the mistake of clicking one of the "buttons" in the reply controls (like insert image, or remove formatting, etc). I feel your pain 



KITROBASKIN said:


> Great. Perhaps you can give us some 'real world' observations. Curious to know if it might be rain resistant.



If you watch that video I embedded above, you can sort of get a feel for the construction of the panel. It appears to me to be a plastic lamination of sorts, and would, IMO, be very weather/rain resistant based on the looks of it in that video. This is one of the things that draws me to it so much. Seems like so many other panels, even "nice" panels do not actually have the electronics or solar cells in a "sealed" container, rather, they almost seem to be in like flat polyester pouches with clear plastic windows.

------

StorminMatt

I think Semiman means that the panel would have to be 18% efficient to achieve ~5W for its size. Interestingly enough, the specifications for the unit actually do claim "15%-18.5%" efficiency, though I think that is optimistic given the price point. 

----------



SemiMan said:


> The odds of this being 5W I would say are pretty close to 0. Looking at the actual solar panel area, that would put it 18%+ ... which is unlikely for an assembled unit of this quality.



Like I've said a bunch of times in this thread, if it does 2-3W in ideal conditions I think it would be a fantastic panel for my intended use. 



> The issue with solar is not whether you "can" charge it in a day, but whether you will be able to. You can't predict the sun and if you are planning to charge while hiking, then multiply that many times over. An overcast day could cut the amount of sun down 5-10x from a sunny day, and ignore all the marketing BS about how good some panels are in shade/overcast ... the best ones are still only collecting maybe 1/5 to 1/10 of a bright sun day.



I have zero expectation of any useful power output in shade or overcast. I will however, happily hike in the shade, or in overcast any time I can get it, in favor of being able to charge batteries, as that is much more comfortable.



> If you are planning to charge while actually hiking with the panel on your back, especially in the summer, then cut any expectations way down. Panel orientation is likely to be far from ideal if not the wrong direction from the sun, and depending on where you hike, shade will be common. Best location for a small panel, would likely be on the top of your head .... no really. A small panel on the top of a Tilley would likely collect more sun than something several times its size hanging on your back.



Great minds...






















FYI... the top of that pack, is basically the same height as the top of my head, give or take a few inches depending on how "full" the pack is. 

I had already considered the fact that a lager panel would actually wind up being mounted in a less than ideal position on the pack. A small panel in the sun beats a big panel in the shade. 



> Solar works good when stationary when it can be oriented in the right direction and not be shaded.



As I said in post #19 above, I will not only have time to baby-sit the panel on some days of the types of trips we go on, I'd also likely enjoy doing it, as it is a geeky toy for me to play with in the woods. 



> You already ordered ..... have fun with it, but set expectations low and bring the extra batteries the first few trips.



I believe my expectations are reasonable, and trust me, I always wind up packing too many batteries. 



> If weights an issue, you can always get a better pack  ..... which is likely why I switched to canoeing .... much less like exercise
> 
> Semiman



I'm not sure what you mean by getting a "better" pack. The Xenith 88 is supposed to be my new "better" pack for dealing with these loads. Just bought it this spring with REI dividends and 20% off coupon and can't wait to get it out this summer and give it a more thorough test run.


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## SemiMan (May 11, 2015)

StorminMatt said:


> While I don't think this panel will produce 5W, I think it will do ALOT better than 18% of that (.9W). Judging by the size, I think that 3W is probably right on the money (provided the regulation is not too inefficient). As far as shade, it is definitely true that shading is VERY detrimental to the output of photovoltaic panels. Even a very small amount of shading on a panel can greatly reduce output. But not everybody lives (and especially hikes) in gloomy places. In places like the Sierra (here in California), sunlight is flat-out INTENSE. And cloudy days are rather rare. The same is true about many other places in the Southwestern US. Granted, the same cannot be said about the Northeastern US or the UK. But in places (like California, Arizona, or Colorado) that receive sunlight in abundance, using a solar charger is kind of a no-brainer. Especially since alot of people in these places hike.



18% w.r.t. solar panel means efficiency of the panel as a solar collector, not efficiency w.r.t. a MFR claim.

The OP mentioned hiking around a lake. Most lakes (not all) are surrounded by significant vegetation. 

I have hiked a fair amount in California ... and have been both fried in the sun, and enjoyed shade the whole time. It all depends where you hike.


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## SemiMan (May 11, 2015)

mdocod said:


> I'm not sure what you mean by getting a "better" pack. The Xenith 88 is supposed to be my new "better" pack for dealing with these loads. Just bought it this spring with REI dividends and 20% off coupon and can't wait to get it out this summer and give it a more thorough test run.



Well then you have already made the best improvement you can! That pack looks really good and reviews well. Amazing what a difference a good pack can make.

Would be interesting to see an MPPT charger on one of these little solar unit. I am counting 10 cells on your pack, putting the open circuit voltage up near 7 and the MPPT voltage 6-6.5V. Starting with a depleted Li-Ion and a linear charger, the power waste could be (6.5-3.4)/6.5 * 100 = 47%. There are some chips out there targeted at Cell-Phones charging with solar.


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## KITROBASKIN (May 11, 2015)

After looking at the panel in question on Amazon, I am impressed. The next size up (7watts?) is much heavier. Based on mdocod's experience, I may go for it as well.


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## mdocod (May 11, 2015)

SemiMan said:


> Well then you have already made the best improvement you can! That pack looks really good and reviews well. Amazing what a difference a good pack can make.
> 
> Would be interesting to see an MPPT charger on one of these little solar unit. I am counting 10 cells on your pack, putting the open circuit voltage up near 7 and the MPPT voltage 6-6.5V. Starting with a depleted Li-Ion and a linear charger, the power waste could be (6.5-3.4)/6.5 * 100 = 47%. There are some chips out there targeted at Cell-Phones charging with solar.



The MPP for 10 solar cells in series should actually be pretty close to 5V? No?

Either way, it's anybodies guess as to what, if any regulation method is employed for the USB output on this thing. It would be nice if they employed some sort of semi-intelligently designed fixed switched buck (or boost if the panels are wired 5S2P) circuit that allows it to achieve something close to MPP at higher loads. It wouldn't have to be very sophisticated at all. In fact, trial and error with pre-existing compact USB regulators would probably achieve a decent result, and that's sort of what I expect to find in the little USB port/dongle on the back of these sunkingdom panels. I think the important "trick" there, would be to just get the "sizing" of the regulator correct for the panel (which on many of them, could be adjusted with a sense resistor), so that maximum power draw from the regulator lands near the MPP of the panel.

I wonder if true MPPT on a system of this size would really be all that useful anyway. I suspect that the added component cost and weight could more or less "pay" for a larger panel anyway. I'm of the thought process here that MPPT only pays dirt if the device that is being charged/powered can always absorb the maximum power available from the panel anyway. A USB output panel, is sort of expected to be a "lossy" system in order to provide broader functionality/compatibility, since not all devices would make use of the available power anyway. I think a simple fixed but "tuned" system is an acceptable compromise here.


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## SemiMan (May 11, 2015)

mdocod said:


> The MPP for 10 solar cells in series should actually be pretty close to 5V? No?



YES! .... sorry losing my mind. Likely MPP is close to 5.4-5.6V given typical mono crystalline cells of the last few years.

Simple buck or boost circuits and/or chargers don't work well with solar cells as input when coupled with typical outputs. Most typical circuits regulate to the output value (voltage or current), and will keep drawing more and more power from the input to achieve that as needed. With the I/V curve of the cell, that causes the input to collapse and you get nothing out. Some USB charger chips will regulate to say 100mA/500mA output, but not to "as much as they can pull"

There are some simple MPPT low cost controllers on the market. Temp comp them with an NTC/PTC and they work quite well.

MPPT cost may be a bit higher than adding a few watts of panel, but the size and weight will be a lot less which is nice for portable.


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## StorminMatt (May 12, 2015)

Then again, maximum power point tracking only really works well when you have a place where you can dump ALL of the maximum power output of a photovoltaic panel (like, say, the utility grid or a large battery bank). In the case of charging iPhones or Li-Ion batteries using USB chargers, you are dealing with devices that draw rather fixed levels of power. In this case, MPPT is neither required nor desirable. Unless, of course, you have a high capacity USB power bank that you can dump energy into.


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## mdocod (May 12, 2015)

Yea, as long as considerations are made to prevent the regulator from collapsing the panel-side circuit voltage to below the MPP of the panel, then a fairly basic regulator can work.. While a "tracking" system would be great, it really isn't required in a product whose output regulator is being designed into a system with a known panel. If you look at a graph of the MPP voltage for given panel across a usable range of sun conditions, the voltage range is actually fairly narrow. A fixed-function system can emulate behavior close enough to MPPT for 1 specific panel by simply choosing where on the range to optimize for and tuning that fixed-function system to achieve that desired outcome.


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## jorn (May 12, 2015)

Used 2 cottonpicker panels to charge a 10000 mAh powerbank yesterday. Under clouds and rain. So cottonpickers panels work. Even in the arctic, where the sun is rarely seen


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## SemiMan (May 12, 2015)

StorminMatt said:


> Then again, maximum power point tracking only really works well when you have a place where you can dump ALL of the maximum power output of a photovoltaic panel (like, say, the utility grid or a large battery bank). In the case of charging iPhones or Li-Ion batteries using USB chargers, you are dealing with devices that draw rather fixed levels of power. In this case, MPPT is neither required nor desirable. Unless, of course, you have a high capacity USB power bank that you can dump energy into.



This is completely wrong. MPPT give you more power always. Most of the time you are no where near peak power hence this would not be an issue most of the time. Most phones will take at least an amp off 5v or 5 watts so with a 5w panel I am never over. MPPT simply extracts as much as I can get out of the panel.


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## SemiMan (May 12, 2015)

mdocod said:


> Yea, as long as considerations are made to prevent the regulator from collapsing the panel-side circuit voltage to below the MPP of the panel, then a fairly basic regulator can work.. While a "tracking" system would be great, it really isn't required in a product whose output regulator is being designed into a system with a known panel. If you look at a graph of the MPP voltage for given panel across a usable range of sun conditions, the voltage range is actually fairly narrow. A fixed-function system can emulate behavior close enough to MPPT for 1 specific panel by simply choosing where on the range to optimize for and tuning that fixed-function system to achieve that desired outcome.



Except that does not take into account fairly large voltage swings from heat. LT has some chips like you describe. I have modified with temp comp and can get another 10-15% with little cost/complexity.


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## StorminMatt (May 12, 2015)

SemiMan said:


> This is completely wrong. MPPT give you more power always. Most of the time you are no where near peak power hence this would not be an issue most of the time. Most phones will take at least an amp off 5v or 5 watts so with a 5w panel I am never over. MPPT simply extracts as much as I can get out of the panel.



If you are not using the maximum amount of power the panel can deliver, then you can't be operating the panel at the maximum power point. All that power has to be going somewhere. The whole point of maximum power point tracking is to operate panels at the maximum power point so as to generate as much power as you can when you can sell it all to your local utility. Or charge a large battery bank to power your house overnight. Needless to say, I don't think you are going to find MPPT on a small USB panel. Maximum power point trackers are used for residential and utility scale photovoltaic systems.


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## ChrisGarrett (May 12, 2015)

I've read that on smaller loads the MPPT controllers might actually be a hinderance because they require more power to run than PWM controllers.

Chris


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## mdocod (May 12, 2015)

I did a little searching around. Found the " _SparkFun Sunny Buddy - MPPT Solar Charger_ " for $25. 

If this $23 sunking panel turns out to be a waste, I may go ahead and do a little project box cradle charger and USB "power brick" all-in-one. I'll just use the 18650s that I intend to charge anyway as the power "brick" in the system, thus, no wasted weight (I do not want a system that has a lipo pack acting as a middle-man for everything). 

Such a project box could prove useful, as I could put a little miniature digital voltage read-out on it to "test/monitor" battery SOC in the back country. And could even configure it with multiple slots for cells, to charge multiples in parallel, which would help maximize the use of the panel (stretch out the variable-CC stage as far as possible), and also achieve higher charge saturation (charge termination would be divided by the number of cells installed). I could even put PTC devices between the cell slots in parallel so that any accidental installation of severely mixed state cells would not result in a high-rate charge/discharge between cells. (I could probably do without that last one, but hey, why not). 

Lots of fun ideas... I wonder if there is anything like that MPPT charger controller for less than $25 that is equally good. The fact that it can be programmed to charge at up to 2A is neat. I'd probably go ahead and open that flood gate all the way so it would always charge at the best possible rate available from a relatively small panel. 

I also wonder if the sunking panel with its USB regulator removed would prove to be a "decent" 4W+ panel when tied into such a system. 

Bah.. I need to stop fantasizing about where this *could* go...


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## SemiMan (May 12, 2015)

StorminMatt said:


> If you are not using the maximum amount of power the panel can deliver, then you can't be operating the panel at the maximum power point. All that power has to be going somewhere. The whole point of maximum power point tracking is to operate panels at the maximum power point so as to generate as much power as you can when you can sell it all to your local utility. Or charge a large battery bank to power your house overnight. Needless to say, I don't think you are going to find MPPT on a small USB panel. Maximum power point trackers are used for residential and utility scale photovoltaic systems.




NO, that is not why MPPT was developed. MPPT was developed because it extracts the most possible power from the solar panel ALWAYS. Not just when it is at its maximum output, but at all outputs. Solar panels are rarely at their maximum output. With a fixed installation panel, they will rarely be at their maximum power. MPPT ensures you are getting all the power the panel can generate, not just the maximum current at some arbitrary output voltage.

I would not say you are not going to get MPPT on a small USB panel. It makes a lot of sense for a backpacking panel. Given there are no low costs chips to support it, It is just a matter of time.

FYI - many commercial solar lighting products use MPPT as well as again, it extracts the most power possible. When size of the panel matters (pole size, footing size, installation ease), then this becomes important even if panels are cheap.

Semiman


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## SemiMan (May 12, 2015)

ChrisGarrett said:


> I've read that on smaller loads the MPPT controllers might actually be a hinderance because they require more power to run than PWM controllers.
> 
> Chris



In an off the shelf, not designed for the application charger, that can certainly be true. A 25A, 24V (500W) charge controller I designed had a quiescent power draw of 0.25W when it was on and actively charging. From there and up, it was 95+% efficient. It also went into deep shutdown when not charging, waking up periodically to check the panel voltage to see if anything was there. Most PWM chargers I tested had 8-15mA quiescent, 24 hours a day, or about 100mW - 400mA (voltage dependent). Even with a few watts, my MPPT was better.

On the other hand, many commercial MPPT chargers in that size draw 25-75mA, just sitting there, 24 hours a day (housekeeping, displays, bad design), and may not hit 90% efficiency until 10+ watts. In a high sun environment, they are still better at a fairly small panel size. However, in a low sun environment, a PWM charger would be better.


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## KITROBASKIN (May 12, 2015)

I read years ago that an MPPT charger was useful in a DC well water pump situation where no batteries were involved; strictly 'pump it when you can' into a storage tank. Sounds like they are more sophisticated now.


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## mdocod (May 13, 2015)

Semiman,

I think you misunderstood the point that StorminMatt was trying to make, which, I'm pretty sure is a point we all agree on... 

I think that there may have been a semantic misunderstanding here: _"If you are not using the maximum amount of power the panel can deliver, then you can't be operating the panel at the maximum power point."_

In context, I believe the point being made is that an MPPT system is only significantly useful if we have someplace to put the extra harvested energy. The "maximum amount of power" in this context, does not mean "peak ideal-condition output," it means;"maximum power possible at any given time/conditions."

MPP is a moving target depending on variables, if our load is a constant, then MPPT is going to be of questionable benefit unless a middle-man power bank is added to the system, which adds weight and more efficiency losses itself. 

----------

The only way to really employ an MPPT system for backpacking in a "proper" manner from my perspective, would be if the power bank and the batteries we intend to charge for devices are one and the same. The MPP harvesting should be dumped directly to those cells which we intend to use in our devices. Any alternative is bringing along "wasted" or "dumb" weight that would arguably be better spent on simply having a larger panel in the first place. 

Now.. I just need a 18650 powered SLR camera and an 18650 powered smart phone or GPS. grrrr....


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## SemiMan (May 13, 2015)

I did not misinterpret Matt, his conclusion is wrong, especially when backpacking.

With a small panel, bad angles, shade, etc. It will be very rare to have more panel output than whatever you are charging could accept. Load is not going to be constant it is going to be panel dependent most of the time.

Hence it would be highly beneficial to get every bit you can out of the panel. Having MPPT is virtually equivalent to having said larger panel but with a smaller weight and size penalty.


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## Teobaldo (May 13, 2015)

My experience tells me that it is very difficult to properly charge a power bank with the help of a solar panel being in motion, since the change of position of the panel will greatly affect the charge. 












In the above photo, Brunton Solaris 6 over a backpack Maxpedition Vulture II connected to a Ruinovo 2x18650 power bank. I did not notice an increase in the charge level of my power bank (had only 25-50-75-100% charge indicators, so probably charged less than 25% I not have a multimeter to check the state of charge either). I used about 8 hours travel in the desert of Atacama, with clear sky, however, the many curves in the road and the movement of the sun prevented the proper functioning of the panel.

*Caution:* Most panels can deliver more than 12v. My Powerfilm and Brunton go up to 19V, so the use of a controller / regulator before reaching a battery is necessary. In the power bank almost is not necessary, since most come with USB charging.

Finally, It all depends on your needs. If you only intend to use a flashlight an hour a day in the middle/low mode, then would be necessary to take only a couple of 18650 spare. But my suggestion is that you take a solar panel and an external battery as backups also serve you to charge any device (GPS, cell phone, camcorder, etc). The only big problem with a setup like this is the time to charge the power bank, because with a smaller panel of 10 watts takes too long to finish the job. The larger the panel, the better, but that requires an increase in the size and weight of luggage.

I do not know the solar panel you mention (although I had seen on Amazon), but I do not see why should not work well.

My powerbanks:






My solar panels:






I think it might be better to opt for the use of USB only, as this can be achieved with less voltage higher amperage. From this point of view my Powerfilm was a waste of money, and it's a little awkward to carry in a backpack or bike luggage (I do not used on my trip last year for this reason and decided to use the two smaller).

Regards.


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## Timothybil (May 14, 2015)

Received my Anker 14w panel yesterday afternoon. After actually holding it in my hand, I have to agree that that is a significant amount of weight. It doesn't really affect me the way I am going to use it, but I can see your perspective better now. I didn't get a chance to really do any experimenting yesterday, and today is supposed to be rain all day, so I will see what I can do as conditions change. I did try one interesting test. I have a 1.2w USB LED light I us at night to see my way around when I get up in the middle of the night. I plugged that into one of the USB output ports, and grabbed by trusty Nitecore TM11 and used it to light up one panel on Turbo (roughly 2k lumens) from about one foot away. It was sufficient to light up the LED quite nicely, which kind of surprised me actually.
I have a seriously depleted power bank (Maxboost 15K mAh with digital percentage readout) ready to use as my power sink, and a USB voltage/ammeter unit to read the solar panel output. I have a whole set of tests planned whenever the sun decides to participate. I will post my results, hopefully in the next day or two.


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## IonicBond (May 14, 2015)

Anker is one of the good brands. I also have the smaller 8 watt versions stashed in various pockets in my vehicles just in case.

No joke though - the "IQ" 5v output circuitry works great with a variety of usb cabling. Back in the day, I was constantly making "charge only" cables to interface with bog-standard usb outputs for various solar projects. If I didn't, some devices would refuse to charge, or fall back to less than 500 milliamps charge, even though the panel was capable of much more. Anker's "IQ" has been a big convenience not having to homebrew custom cables for the best charge rate.


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## IonicBond (May 14, 2015)

Teobaldo said:


> I think it might be better to opt for the use of USB only, as this can be achieved with less voltage higher amperage. From this point of view my Powerfilm was a waste of money, and it's a little awkward to carry in a backpack or bike luggage (I do not used on my trip last year for this reason and decided to use the two smaller).



Hang on to the Powerfilm. You can drive some tent-stakes through each of the panels, and the only output you'll lose is the loss of what was poked out - the panel will still work perfectly. One reason the army uses them - bullet holes are not a problem. If you are charging small batteries like sealed agm's (Powersonic, Universal Battery, CSB, and the like), then recommend the "RA-9" charge controller. I'm glad you mentioned that. It is basically a Morningstar 4.5a Sunguard pwm with the powerfilm connectors already attached. Works great. But I do understand the convenience of just switching to usb charging for lithium packs...


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## StorminMatt (May 14, 2015)

SemiMan said:


> I did not misinterpret Matt, his conclusion is wrong, especially when backpacking.
> 
> With a small panel, bad angles, shade, etc. It will be very rare to have more panel output than whatever you are charging could accept. Load is not going to be constant it is going to be panel dependent most of the time.
> 
> Hence it would be highly beneficial to get every bit you can out of the panel. Having MPPT is virtually equivalent to having said larger panel but with a smaller weight and size penalty.



MPPT WOULD be beneficial if the panel CAN'T supply enough power for a given application. That way, it coukd just sit there and do its best. But you would need to be VERY careful here. Because if you are using MPPT in this sort of application and the panel suddenly gets enough irradiance to deliver more power than an application can handle, you've got problems. What would be needed here is a maximum power tracker with the ability to limit power output. And I've never actually heard of something like this being available. It would be something that would need to be built from scratch.


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## reppans (May 14, 2015)

FWIW, I use this GZ G10+ Adv kit and Powerfilm 4AA - clicky. They have about the same solar surface area, and I've tested them side-by-side under various conditions using a MHC9000 discharge function to measure capacity. 

This agrees with what you can find online - but the mono-crystalline paneled GZ is ~twice as efficient (~18%) as the thin-film PF (~9%), but only in perfect conditions (perpendicular and tracking to direct sunlight). Behind a window, angle to sun, cloudy, etc. then the thin-film pulls a head, but to put it perspective, if the GZ does 60mph in perfect sunlight, then the PF does 30; and in imperfect conditions, the PF does 15 and the GZ does 5.

The tree canopy in the East pretty much makes solar a stationary emergency-only thing for me, so I prefer to carry the PF as its ~ a quarter the size the weight (4oz) of the GZ. My back-up bench is consolidating gadgets around AA Eneloops so I cannibalize cells on priority, incl. a 2NiMH > iPhone charger. My primary light is a 16650, but it runs on an Eneloop or CR123 just fine too (or any cell, if in a pinch). I actually like 3V CRAA primaries as backup cells since they'll power my light to full output, and still feed all my other 2AA gadgets.


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## SemiMan (May 14, 2015)

StorminMatt said:


> MPPT WOULD be beneficial if the panel CAN'T supply enough power for a given application. That way, it coukd just sit there and do its best. But you would need to be VERY careful here. Because if you are using MPPT in this sort of application and the panel suddenly gets enough irradiance to deliver more power than an application can handle, you've got problems. What would be needed here is a maximum power tracker with the ability to limit power output. And I've never actually heard of something like this being available. It would be something that would need to be built from scratch.




99% of the time ... well maybe 95% of the time the panel WILL NOT be able to supply enough power for the given application we are discussing and/or able to supply as much power as the application could use. MPPT does not mean that it "forces" out power, it just means that it makes as much power available as can be taken out of the panel.

Unless you have an issue with quiescent power from the MPPT controller, MPPT is pretty much always better. It is pretty much exactly the same as having a panel that is 15-40% larger depending on the voltage mismatch between the panel and the load.

There is nothing to be careful with .... any downstream charging circuit will limit charge current the odd times there is more current available then needed .... which backpacking is likely to be almost never.

Semiman


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## SemiMan (May 14, 2015)

reppans said:


> This agrees with what you can find online - but the mono-crystalline paneled GZ is ~twice as efficient (~18%) as the thin-film PF (~9%), but only in perfect conditions (perpendicular and tracking to direct sunlight). Behind a window, angle to sun, cloudy, etc. then the thin-film pulls a head, but to put it perspective, if the GZ does 60mph in perfect sunlight, then the PF does 30; and in imperfect conditions, the PF does 15 and the GZ does 5.



I would tend to disagree with some of this.

Contrary to what all the thin film people tell you, angle makes every bit as much difference to thin film as it does to monocrystalline, especially modern mono cells. Even with clouds, the difference tends not to be that great unless the clouds are substantial ... to use your analogy, of 60:30 ... under heavy clouds, it may be 4:5 .... with both putting out little.

Sun angle is all about projected area ... thin film buys you nothing except a little lower efficiency lost at <10% sunlight and a bit of boost over older mono cells in clouds with higher blue light.

Under a tree canopy, its a whole different call game, at least with the some thin film units where the cells are long strips. The geometry makes them far less susceptible to shade.

Semiman


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## reppans (May 14, 2015)

SemiMan said:


> I would tend to disagree with some of this.
> 
> Contrary to what all the thin film people tell you, angle makes every bit as much difference to thin film as it does to monocrystalline, especially modern mono cells. Even with clouds, the difference tends not to be that great unless the clouds are substantial ... to use your analogy, of 60:30 ... under heavy clouds, it may be 4:5 .... with both putting out little.
> 
> ...



As said, I tested these side by side and used a C9000 discharge function to measure input capacity. I hung both in a window during the winter (w/ some tree branch shading) SE in the AM, SW in the PM and the PF consistently beat the GZ by a good margin (I recall doubling) - I was actually very disappointed in GZ until someone here explained the MC panel needed direct sunlight. I took both outside and tracked the sun and sure enough, the efficiency reversed with the GZ doubling the PF. However, it is correct that I did change multiple variables (glass, shade, angling) at once, so I cannot be certain which had the greatest effect on efficiency..


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## SemiMan (May 14, 2015)

reppans said:


> As said, I tested these side by side and used a C9000 discharge function to measure input capacity. I hung both in a window during the winter (w/ some tree branch shading) SE in the AM, SW in the PM and the PF consistently beat the GZ by a good margin (I recall doubling) - I was actually very disappointed in GZ until someone here explained the MC panel needed direct sunlight. I took both outside and tracked the sun and sure enough, the efficiency reversed with the GZ doubling the PF. However, it is correct that I did change multiple variables (glass, shade, angling) at once, so I cannot be certain which had the greatest effect on efficiency..



That tree branch shading in the window will change a lot with the GZ panel. You would likely find that simply rotating the panel can change efficiency.

Saying they need direct sunlight is not accurate though. They will do quite well down to fairly low levels of light. That said, if you are looking at purely current versus power, the thin film may hold up better.

In stationary solar installations, mono and poly cells regularly beat thin film cells, watt for watt. Those installations see bright sun, clouds, off angle, everything ... except shade. The mono and poly cells do every bit as good as the thin film watt for watt. i.e. a 100 watt mono/poly panel collects as much power as a 100 watt thin film.

Shade is a completely different animal and depending on the film film mfg methodology, they can be a lot better.

The other issue with a window will be that many windows are coated, and may be lopping off a good portion of the spectrum ... definitely UV, but also IR. If it takes out IR, that will generally have a more detrimental effect on mono\poly.

Semiman


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## mdocod (May 14, 2015)

The SunkingDom 5W panel came in the mail yesterday, under heavy storm clouds (of course) so I had to wait till today to try it out.

We went on a hike to a lake today for some fishing and exercise, and a chance to test out some new gear. 

I packed my Xenith 88 to 59lbs. Included was a multi-meter, a bunch of NCR18650's at different states of charge, the new MC1-Plus, Xtar USB analyzer, the Sunkingdom 5W panel, and numerous USB cords. 

The new pack was marvelous, the most comfortable I have been after 5 miles on the trail (~2.5 each way) at over 50lbs ever, by a long shot; but I was sort of expecting this. Osprey packs come with cubic price tags for a reason. There are some things in backpacking where there really isn't a "gem-in-the-rough" option, you either suffer with mediocrity or fork over some bucks for good stuff. I am very happy to have forked over the bucks for the Xenith 88, it changes my whole perspective on how comfortable ~60lbs can be.

------------

Luckily, not everything that is "backpacking" worthy has to be expensive, and I can now say with a reasonable amount of confidence, that there is no reason to spend cubic bucks, or carry cubic weight for a solar panel to charge phones and 18650s. This 4oz panel exceeded my "ideal conditions" expectations today, but here's the kicker: It did so in overcast. 

Today I observed everything from ~0A to ~0.7A charging rate at up to ~4.8V (at the analyzer)) with the 5W sunkingdom panel during varying amounts of cloud cover and overcast. I have yet to have a chance to test it in clear skies with direct sunlight. Peak "power" observed at the analyzer was ~3.3W under thin whispy overcast.

My phone (optimus G, 2100mAH) was plugged into the panel for 4 hours today. It was on the entire time, in the mountains, likely fighting for a signal much of the time, and charged from 31% to 95%.

Of those 4 hours it was plugged in, I would categorize conditions as follows:
1 hour of very thin wispy overcast (thin enough to feel spurts of radiant "heat" on your skin), charge rates observed at 0.5-0.7A. 
2 hours of overcast (thick enough to feel "shaded" from the sun), charged rates observed at 0.3-0.5A. 
1 hour of either heavy cloud cover or "canopy shade" while hiking under trees, charge rates observed at 0-0.3A. 

Based on what I have seen thus far, I think that in "ideal" conditions this thing would charge my phone in ~3 hours, and charge an NCR18650B in ~6 hours. 

$23, 4oz. Seems too good to be true but the darn thing works and IMO, works really well.


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## SemiMan (May 14, 2015)

mdocod said:


> The SunkingDom 5W panel came in the mail yesterday, under heavy storm clouds (of course) so I had to wait till today to try it out.
> 
> We went on a hike to a lake today for some fishing and exercise, and a chance to test out some new gear.
> 
> ...




Great reporting! Thin wispy clouds have less impact on total sun than you would expect. I can't remember where to find it now, but you can actually get hourly solar irradiation reports ... about a week after it happens if you ever want to compare your experience. They are done on 70 mile blocks though.

For $23 that works, that is great. I may pick up a couple. I am thinking of whipping up a micro-mppt controller and this would be good to try it with. It sounds like your phone has good circuitry for responding to the varying charge current available. Some of them will just bounce between 100mA, 500mA, 1A and not operate well in between.

Semiman


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## Timothybil (May 15, 2015)

Glad it worked out for you. Was this charging on the go or stationary? It sounds like on the go, and that makes it even better. Did you mount the panel on the top of your pack like you indicated? It looked like an ideal spot.
No sun at all today so no testing. Tomorrow is supposed to be the same but may try to see what happens with overcast skies. Sunday is supposed to be clear with partial clouds so hope to test a lot then.


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## KITROBASKIN (May 15, 2015)

Looking forward to results of full sun. Thanks for the report!


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## mdocod (May 15, 2015)

Hi Semiman,

I'm not sure what sort of charging circuitry is going on in my phone, but both my phone and the MC1-plus seem to allow for a pretty wide range of charging rate. In fact I've measured from 50mA to 970mA on these devices with the Xtar analyzer with no noticeable favoritism's along the way. (50mA connected to the solar panel, held up to a 60W light bulb / 0.97A connected to a "1.2A" USB transformer/regulator)

I have noticed, that very low charge rates don't work in the MC1-Plus when the battery being charged is at a very low state of charge. The cell needs to be above ~3.5V in order to get charging to initiate at very low rates. Based on observing the behavior of the charger when operating in conditions with a cell at <3.5V, my guess is that something along the chain is demanding a minimum of ~4V to function. The USB comes "online" and then the charger attempts to initiate the charge only to have the voltage then collapse out of spec, and this cycle repeats over and over with no progress. The more discharged the cell is that I'm trying to charge, the higher the "cut-in" power required to initiate charging is. Granted, even out in over-cast I had no problems initiating a charge on a "dead" li-ion cell (~3.0V); though, this behavior is something to keep in mind. I'll make a point not to do "full" discharge cycles with our 18650's, rather, swap them out and top them up more frequently. 

Even if the 0.7A maximum that I observed in "whispy overcast" is the best I'm going to get out of this thing, that's still going to be just fine, and better than I had hoped for. 

That said, I am now intrigued enough to consider doing an MPPT solution someday. Probably won't be this year, as I think we have our gear pretty well settled and I'd like to sort of "lock it in" for now. 

-----------

Timothy,

Most of the good gains on the cell phone charging test took place while the panel was stationary as we sat by the lake and fished. It was during this time of our trip today that the sun was the least obstructed by clouds. Of the 4 hours that the charging test was conducted, approximately 2 hours of that was hiking, and those "hiking" hours landed in conjunction with the most intense cloud cover during our trip (beginning and end). By my recollection and math, the phone gained ~20% charge in the 2 hours we were hiking in bad solar collection conditions (compounding negatives), and ~45% charge in the 2 hours it was stationary in better conditions.


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## KITROBASKIN (May 15, 2015)

With my home PV system (before I got married) the most amps I could draw were when the sky was partly cloudy and the sun was unobstructed by clouds. That is, the clouds were not so thick and full of moisture, but were lit up bright by the sun. Of course, when the sun was blocked by the clouds the amperage went way down. These events exceeded the rating on my panels and came close to exceeding the capacity of my charger controller. It would be interesting to see when this happens with a small panel.


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## mdocod (May 15, 2015)

This morning I hooked up the panel and observed 0.7-0.8A charging rate with cirrocumulus clouds between me and the sun while charging a nearly-depleted NCR18650B in the MC1-Plus. 

At that time, I did some additional experimentation with the MC1 and various batteries revealed that the charge rate tappers downward slightly with cells that are in a higher state of charge in more "ideal" sun conditions, even before any expectation of reaching the CV part of the charge. I suspect this is a consequence of the way the panel's USB "regulator" and the MC1-Plus are "bucking" the voltage down from the panel. To put some numbers on it, I observed a drop in charge rate from ~0.75A down to ~0.65A going from a ~3.0V cell up to a ~3.8V cell. 

I'll have to do some more testing, but I guess the take-away from this, is that if I want to put forth the effort I could manipulate how I use the panel to help maximize the available power under different conditions. Based on my observations thus far, it would be best to do "top-up" charging of cells and devices over 50% SOC in less than ideal conditions to maximize the time spent actually charging (minimize the "drop-out/collapse" effect), and then perform charging of heavily depleted devices and cells in ideal conditions to hit the highest peak current with no possibility of dropping below the cut-in point. All of this may prove strictly academic as in actual practice I don't think it will matter, the panel could be employed in a "dumb" manner to good effect for my intended application. 

------------

At around 2PM this afternoon, we had a short spurt of full clear sun with a few adjacent clouds much like the situation described by KITROBASKIN. I carefully manipulated the panel and tried to get a "peak" reading. While charging a mostly depleted NCR18650B, I observed a maximum 4.45V and 0.87A at the Xtar analyzer, or, very nearly 3.9W.

I think its safe to say that the panel _itself_ in this "system," is indeed capable of ~5W maximum; obviously, due to the lack of sophisticated power tracking electronics, it will never actually put 5W down the pipe as is. Of course, then I'm taking further losses with the MC1-Plus, which is likely nothing more than a linear regulator. The "5W maximum" panel, winds up charging at ~3W maximum at the target cell in this setup, which is still fine IMO.


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## KITROBASKIN (May 15, 2015)

Very interesting and much appreciated. During my tests last weekend, I obstructed a portion (maybe15-20%) of the 15 watt panel with my hand and forearm about 18 inches away, slowly pivoting from a vertical to a horizontal orientation. This did lower voltage and amps a lot of course but the MC1 recovered nicely. The same can not be said for the ML102 (blinking until complete disconnect) or the otherwise fine charger, Xtar VC2 (kept on trying to restart over and over again) I also used some shade cloth with the MC1 and saw good recovery again; Obstructed 3.79V and .2A, Shaded 3.9V and .12A, Full sun 4.91V .47A. This was charging a Kinoko 18650 starting at 3.64V.


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## StorminMatt (May 16, 2015)

I have to say that I'm impressed with this 5W Sunkingdom Panel. So much so that I bought one. We'll see how it works under the clear Northern California sky. Hopefully it will be able to charge iDevices, as there seem to be mixed reports about this in the reviews (this COULD be due to the fact that an iDevice will refuse to charge if current is insufficient, such as in cloudy weather, shade, and/or if the panel is improperly oriented). But at least I know it will charge Li-Ion batteries with Xtar chargers.


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## mdocod (May 17, 2015)

StorminMatt,

Note Kitrobaskin's experience with the VC2. Not all Xtar chargers are going to be solar friendly. I think the MC1, MC1-Plus, and MC2 are the chargers to have for this sort of setup as they employ basic linear buck regulators (current in=current out). I believe that the MC1-Plus and MC2 likely contain the same 4-channel charging circuit (the channels are in parallel in these chargers). The MC1 (non-plus) likely contains a stripped down version with only 2 channels in parallel. There may be other options out there, but almost anything with a more sophisticated power regulation method is likely going to require more fixed power input to function; tradeoffs! Obviously, the MC1 (non-plus) should probably be avoided simply because it will not be able to harness the maximum current output the sunkingdom panel is capable of. 

If I had a do-over, I may have opted for the MC2 instead of the MC1-Plus, both have the same maximum charge rate but the MC2 effectively divides that between 2 bays, which, would be a bit lower "maintenance" and may have made better use of available power by splitting the available power between 2 cells. Though I could more or less achieve the same result with a modification to the MC1-plus to charge a pair of cells (or more) in parallel.


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## StorminMatt (May 17, 2015)

From my experience, the XP1, MC0, MC1, and MC2 all seem to work quite well with my Suntactics panel. The only issue I have observed is that charging is sometimes only half an amp with two 14500s with the MC2. I haven't been able to do any testing on this since I got my Xtar power meters. But I suspect it's due to reduced voltage on warmer days (the Suntactics panel regulates down a ~6V output by linear converger rather than regulating down ~12V with a buck converter). Not sure how the Sunkingdom panel will fare, as it has been (and is forecast to be) unseasonably cool lately here in Northern California. In any case, it will be interesting to see how well this panel works with the MC2 while charging a couple of 14500s.


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## mdocod (May 18, 2015)

I was just bouncing around on amazon and other sites around the web, looking at some reviews and trying to get my head more firmly wrapped around the current "portable-solar" market (my interest is now "peaked" a bit, as seeing how well this little cheap panel works, I think its fair to say that solar has matured to a mainstream-ready stage). I noticed that this brand "sunkingdom" is actually claiming to use SunPower brand panels in many of their products. I don't believe that is what is in this particular 5W panel, but the premise inspires confidence. If those products indeed do have SunPower brand panels in them, then this Sunkingdom brand may indeed be a more legitimate, quality oriented brand than the "impression" we might get guessing from the sidelines. I'm also not the first person to have thrown a tester on a sunkingdom panel and come away impressed. 

I've spent quite a bit more time scouring the interwebs, and have yet to find anything in the ~"true 3W" class that weighs around the same or less, at ANY price, and everything I have found weighs and costs more, and most appear to be less durable. This "5W" (rated) sunkingdom panel appears to me to be in a class of its own, and firmly setting an impressive standard for what 4 ounces can do.


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## StorminMatt (May 18, 2015)

I noticed that they actually do have a Sunpower-based 5W panel, but it costs about $10 more than this one. And it is less square compared to the cheaper panel (which kind of makes it less packable). I'm not sure how well it compares, or whether it is a better panel. But I might eventually try buying one just for kicks. Regardless, the cheaper 5W panel seems to be selling like hotcakes! It's gone from 19 in stock when I bought mine to only FOUR right now. CPF members following this thread, maybe?


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## KITROBASKIN (May 18, 2015)

You think the Sunkingdom panel is reasonably durable? Are there any claims by the manufacturer of water resistence?


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## mellowman (May 18, 2015)

sunkingdom, poweradd...etc are not manufacturers they just have they name put on it and resell it.


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## mdocod (May 18, 2015)

StorminMatt said:


> I noticed that they actually do have a Sunpower-based 5W panel, but it costs about $10 more than this one. And it is less square compared to the cheaper panel (which kind of makes it less packable). I'm not sure how well it compares, or whether it is a better panel.



There seem to be nearly a half dozen variations of sunkingdom panel at any given "wattage" size. Some folding, some rigid, some with sunpower panels, some with other stuff. One particular 5W alternative appears to fold and weigh in at ~7oz and approximately 7" X 14" (unfolded). Another appears to be a fraction of an ounce lighter (still ~7oz), and ~8.5" X 11", but "rigid" (non-folding).

After looking at more offerings from sunkingdom, I can't help but wonder if they may share OEMs with Instapark or Anker. They offer a line of very similar looking rectangular folding panels as well.




> But I might eventually try buying one just for kicks. Regardless, the cheaper 5W panel seems to be selling like hotcakes! It's gone from 19 in stock when I bought mine to only FOUR right now. CPF members following this thread, maybe?



The price just jumped up to $30, lol. 

I'd be very interested to hear how the heavier, larger 5W panel with the sunpower cells compares (either the folding, or non-folding version). I suspect probably a stronger panel in terms of performance, just more appropriately rated. 

---------



KITROBASKIN said:


> You think the Sunkingdom panel is reasonably durable? Are there any claims by the manufacturer of water resistence?



Imagine thin solar cells laminated between plastic cutting boards. My impression is that this simple design should be very durable. 

The manufacture doesn't list anything specific about water-worthiness, but does have "water sports" listed as an application for the product on the packaging. I wouldn't want to dunk it, for fear of messing up the USB voltage regulator/controller, but I can't see any reason the panel shouldn't handle rain/sleet/snow and even small hail provided the USB dongle is facing down. 

I was sitting out back the other day taking measurements with the panel and a strong gust of wind came up, whipped up the panel and smacked it against a short garden fence. I retrieved the panel and proceeded to use heavy rocks to hold the corners in place.

---------



mellowman said:


> sunkingdom, poweradd...etc are not manufacturers they just have they name put on it and resell it.



No doubt. It's also obvious they have more than one OEM, so not all of their panels will necessarily offer the same value/performance.


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## SemiMan (May 18, 2015)

StorminMatt said:


> I noticed that they actually do have a Sunpower-based 5W panel, but it costs about $10 more than this one. And it is less square compared to the cheaper panel (which kind of makes it less packable). I'm not sure how well it compares, or whether it is a better panel. But I might eventually try buying one just for kicks. Regardless, the cheaper 5W panel seems to be selling like hotcakes! It's gone from 19 in stock when I bought mine to only FOUR right now. CPF members following this thread, maybe?



I would not expect much better performance with Sunpower cells, just smaller. They may do a bit better in low light depending on what standard cells are being used in the other panels. Sunpower cells were always good at low light. Using large cell pieces may make them a bit more fragile though.


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## ChrisGarrett (May 18, 2015)

They're up to $30 right now and so I'm looking at the 14w dual USB port folding 4 panel jobbie for $40 shipped. 700mA per panel, with 2.1A and 2.5A USB outputs when using one output at a time.

Folders have a problem with the durability of the panel connecting wires falling within the folds, this is why you don't see more than a 2-3 year warrant on the better ones. Just the nature of the beast--you bend metal wires enough and they'll break.

Still, for limited use, where I'm not backpacking anywhere, the 14w might be the better, faster play for my needs.

Chris


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## MrJino (May 18, 2015)

I recently got a 15 watt folding solar panel, it has 2 usb inputs, that automatically pair high and low charge devices, and paired it with a 15000 mah battery bank.
Both are ravpower, found on amazon as well.
I paid under 100 bucks for both.

As for use, it works very great. It's my first solar panel, but I've been eyeing them for years and waited for prices to final become reasonable.
I'm trying to figure out how to recharge my batteries through solar, as my chargers are direct plug in, not usb.


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## ChrisGarrett (May 18, 2015)

MrJino said:


> I recently got a 15 watt folding solar panel, it has 2 usb inputs, that automatically pair high and low charge devices, and paired it with a 15000 mah battery bank.
> Both are ravpower, found on amazon as well.
> I paid under 100 bucks for both.
> 
> ...



You need to get something like a Klarus CH1 USB NiMH/li-ion battery/cell charger and use it with your RavPower on a USB plug that puts out at least 1A @ 5v, which some of these 14w + panels can easily do.

There are other battery/cell chargers out there that will work, but not many that do both chemistries.

Chris


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## MrJino (May 18, 2015)

I believe 2.4 a


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## ChrisGarrett (May 18, 2015)

MrJino said:


> I believe 2.4 a



Knock yourself out:

http://www.lygte-info.dk/info/indexBatteriesAndChargers UK.html

There aren't a lot of quality 5v 1A multi-chemistry (NiMH/li-ion) chargers, so getting one of each, might be the way to go...at least that's the road I'm thinking of travelling.

The Klarus CH1 was hoped to be that charger, but its 1A charging rate is too high for AAAs and the smaller li-ions, like the 10440s, 16340s and 14500s, but if you don't care about that, give it a whirl, since they're only ~$10 US shipped.

Chris


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## MrJino (May 18, 2015)

Thanks for the suggestion !

My battered are mostly rcr123a, plan on getting a 18650 light and have a AAA keychain light in the mail.


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## ChrisGarrett (May 18, 2015)

MrJino said:


> Thanks for the suggestion !
> 
> My battered are mostly rcr123a, plan on getting a 18650 light and have a AAA keychain light in the mail.



I'm probably going to pull the trigger on an Xtar MC1-Plus for li-ion duties (or two) and call it a day. It has two charging rates 500mA/1A, so while not perfect for 16340s, it can charge them up without banging hard on them. Maybe I get the Klarus and just use that for the bigger li-ions and AA NiMH batteries only, I don't really know?

If I buy one of these Sun-TASTIC 5v solar charger doohickeys, with twin USB outputs, I can run both chargers at once. I already have a small 60w 'portable/non-backpackable' solar charging setup that runs on 12v and works with all of my NiMH/li-ion chargers, but something even smaller and easier to setup might be the way to go. 

Anyhow...

Chris


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## SemiMan (May 18, 2015)

Okay I am convinced, time to add another solar panel. These will be great for beach days, keeping the phones, bluetooth speakers topped up. Normally I just bring a 5000mA battery pack, but they get forgotten. I can leave the panel in the car. I don't like leaving the batteries in the car as the high temps degrade them too quick.


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## MrJino (May 18, 2015)

My ravpower 15w is usually on my dash while I'm at work, i keep the 15000 mah battery under my seat with the long usb cable so it doesn't heat too much.


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## StorminMatt (May 18, 2015)

ChrisGarrett said:


> I'm probably going to pull the trigger on an Xtar MC1-Plus for li-ion duties (or two) and call it a day. It has two charging rates 500mA/1A, so while not perfect for 16340s, it can charge them up without banging hard on them.



Well, the nice thing about these small Xtar chargers is that they don't break the bank. Why not get the MC1+ for larger batteries and the MC0 for smaller batteries like your 16340s? The MC0 is somewhat smaller and lighter. So if all you are using are 16340s, it's easier to take with you. Plus, you can manually choose between .25A and .5A. And if you get both, you've still only spent around $15-$16 on chargers.

If you like the MC0, there's also the XP1 to consider. It's only a little larger than the MC0. But in addition to all the capabilities of the MC0, it adds the ability to charge NiMH. Admittedly, at .5A, it will take a VERY long time to charge a single Eneloop. But in a pinch, it might work (and it would certainly work better for topping off than charging a fully depleted cell). Like the MC0, it costs around $6.


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## ChrisGarrett (May 18, 2015)

StorminMatt said:


> Well, the nice thing about these small Xtar chargers is that they don't break the bank. Why not get the MC1+ for larger batteries and the MC0 for smaller batteries like your 16340s? The MC0 is somewhat smaller and lighter. So if all you are using are 16340s, it's easier to take with you. Plus, you can manually choose between .25A and .5A. And if you get both, you've still only spent around $15-$16 on chargers.



Crap, for the last three hours, I've been looking at Xtar chargers on every freakin' place I can find and Xtar doesn't make it easy, lol.

I'm going to forego my disdain and desire for the need to have a USB 2.0 only charger while now considering one of those inexpensive Sun-Tastic (Kingdom) 14w 5v folding solar panels and just run whatever battery/cell charger I end up getting. This will be my lightweight solution for 'on the go.'

My 60w rigid system isn't something that I'm going to lug to the beach, bring on a short hike, or easily grab while running out the door.

Now, for the chargers: they all offer slight nits and imperfections, which I find amusing.

The Klarus CH1 is multi-chemistry, but due to its high charging rate, it's not suitable for AAAs (no real biggie,) 10440s (no biggie,) 16340s (deal breaker) and 14500s (deal breaker.) If I buy the Klarus, I buy it knowing that I'm only using it with my AAs, my 17670s (collecting dust in a 6P LED,) 18650s and maybe my 26650s if they even fit.

The Xtar MC0 has two of the lower rates--250mA/500mA, so the 10440s, 16340s and 14500s are all fine, but it's single bay, li-ion only and DOES NOT fit the 18650s, so that's a big deal breaker for me, since I run a lot of 18650 lights.

The Xtar MC1+ is nice and now has both the 500mA and 1A rates. It's single bay, but will do 18650s, even though the 500mA rate is maybe a touch too high for my 16340 cells. I don't care about my 10440s, so we're teetering on the edge here, but at about $10, one gets a bit faster charge for the bigger cells over the 500mA MC1 basic.

The Xtar MC2 is kind of a dual bay version of the of the MC1+ and has an auto sensing charging range of 250mA-1A, for two cells depending on the USB input current. It'll do 10440s up through 18670, but not my 26650s (no deal breaker.) 

We also the smaller Xtar VC2 and the NiteCore UM10 and UM20 to consider, but those three are also li-ion only and with their LCD displays, might not be the best thing for solar panels and higher charging rates?

The little Sanyo Eneloop USB AA/AAA charger that is now out of production, can be found on Ebay right now, but the guy wants $50 for it and well...he can get his money from somebody else, even though that would be a killer solution for the original price of ~$22.

The Panasonic version is vapor ware for me.

Here's what I'm leaning towards: the Xtar MC2 with optional AC wall wart for $15, the little Xtar VC 10 current/voltage meter for $5, the $10 Xtar MC1+ (just to replace my faulty MP1S,) the SunKingdom 14w dual USB folder for $40 shipped and then that damn $10 Klarus CH1 JUST to be able to charge up AAs with the 5v panel.

The hard part is trying to get everything from one guy, which ain't happening right now, so the next best thing is trying to mitigate extra shipping costs.

It's been a fun mental exercise, so far, lol. $40+$35+$10 for a total of $85 and 3 chargers and a solar panel.

Tell me where I'm going wrong?!? This is a 'covering all of one's bases' type of solution, so keep that in mind.

I have looked at the Goal Zero solo AA/AAA chargers, but they're $40 shipped for a new one and ehhh...even two Klarus CH1s are cheaper.

Chris


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## StorminMatt (May 18, 2015)

ChrisGarrett said:


> The Xtar MC2 is kind of a dual bay version of the of the MC1+ and has an auto sensing charging range of 250mA-1A, for two cells depending on the USB input current. It'll do 10440s up through 18670, but not my 26650s (no deal breaker.)



Although you say this isn't a dealbreaker, I just thought I would let you know that the MC2 actually CAN charge 26650s. It will only do one at a time, though. And only at .5A. In this way, it is the same as just using the old MC1.


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## Timothybil (May 18, 2015)

As promised, the first results of testing with my Anker 14w folding panel. Actually had sunlight today so was able to test some. Placed the Anker in the window of my apartment facing the setting sun this afternoon. Almost direct sunlight through 70s era double pane glass window (no tint, no film, no special gas [probably just nitrogen]) and was able to get one amp out of the USB port into my power bank. Sun is supposed to be out tomorrow with less wind so should be able to take outside and actually test in direct sunlight. Given that I was able to get one amp through the glass window, I am expecting no problems getting the full 10w in direct sun. [Anker sells as 14w panel, but fine print in website FAQ says due to voltage conversion and regulation losses, only 10w available at USB output. Oh well]


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## SemiMan (May 18, 2015)

ChrisGarrett said:


> Crap, for the last three hours, I've been looking at Xtar chargers on every freakin' place I can find and Xtar doesn't make it easy, lol.
> 
> ....
> 
> ...



I think this is why I go with AA-NiMh or 18650 LiCo only. I just got tired of the pain of the rest.

Let me know what you pick. I need a good AA-NiMh USB charger for traveling and the beach.

Semiman


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## SemiMan (May 18, 2015)

Timothybil said:


> As promised, the first results of testing with my Anker 14w folding panel. Actually had sunlight today so was able to test some. Placed the Anker in the window of my apartment facing the setting sun this afternoon. Almost direct sunlight through 70s era double pane glass window (no tint, no film, no special gas [probably just nitrogen]) and was able to get one amp out of the USB port into my power bank. Sun is supposed to be out tomorrow with less wind so should be able to take outside and actually test in direct sunlight. Given that I was able to get one amp through the glass window, I am expecting no problems getting the full 10w in direct sun. [Anker sells as 14w panel, but fine print in website FAQ says due to voltage conversion and regulation losses, only 10w available at USB output. Oh well]



In the real world, 14W would be a low percentage of the time, but at least it means you will get closer to 2A more often.


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## mdocod (May 18, 2015)

Just noticing, if you do a search for "sunpower" on amazon, there are indeed a bunch of "brands" selling these portable panels, at reasonable prices, with modern high efficiency cells, and the reviews are generally pretty good. I realize that amazon reviews are largely from folks with limited technical knowledge, however, tech knowledge or not, these panels must actually be doing what they claim to be able to do (charge portable devices at respectable rates) otherwise people wouldn't be impressed by them. Very cool stuff. I'm still scouring for other ultra-light panels to check out, but haven't really found much. There are indeed lots of options to choose from rated ~5-20W that are reasonably priced (~$30-60) and appear to actually be "decent" panels.


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## IonicBond (May 19, 2015)

mdocod said:


> That said, I am now intrigued enough to consider doing an MPPT solution someday. Probably won't be this year, as I think we have our gear pretty well settled and I'd like to sort of "lock it in" for now.



Forget it - mppt at these low power levels is only for marketers and engineers that over-engineer just for the sake of it. If you are running a system that is under 200 (two HUNDRED) watts, or live in the arctic with only 1 hour of solar insolation per day, just getting another (or larger) panel is the easiest thing to do.

MPPT is great when applied properly. However, in the cheap marketplace, you'll see weasel-words in marketing like "UP TO xx%" and so forth, which basically mean that their mppt algorithm is junk. Typically, mppt is best applied with high-voltage panels, such as grid-tie 24 volts or higher per panel. With our little 5/12v camping panels, mppt is sucker-bait.


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## IonicBond (May 19, 2015)

mdocod said:


> I realize that amazon reviews are largely from folks with limited technical knowledge, however, tech knowledge or not, these panels must actually be doing what they claim to be able to do (charge portable devices at respectable rates) otherwise people wouldn't be impressed by them.



Most consumers are not aware of the shoddy materials and construction practices the cheap panels are made out of, yet alone don't have the ability to PROVE what they got actually meets the sales specs. Grandma won't be pulling out a Fluke 87V and measure the ISC (short circuit current) of the panel. As long as the little red charging led lights on the phone, she won't know or care that the panel spec'ed to provide 1A output in good sun is only doing 100ma. 

Good time to bring up testing - obviously an inline 5v or 12v ammeter is a good thing. One thing to test is that each cell is actually functioning or wired properly. Since mono / polycrystalline panels reduce their output drastically when partially shaded (tiny wet leaf, shadow from tent rope across one cell etc) , this actually provdes a good way to test each cell!

Under good steady lighting conditions, measure the *current* output from the panel. Shade one of the cells with a piece of paper, two or three fingers over one of them, etc, and you should notice a drastic drop in current. If you don't, then that cell or wiring to it may be bad.

Contrast this to thin-film panels like Powerfilm. If you shade half the panel, the panel will only produce half it's rated output. A tiny leaf on a mono/poly panel will reduce the panel's entire output to near unusable. So, while thin-film is not as efficient, and is just a bit larger to acommodate (about 1/3 larger than mono panels), the baby-sit factor while you are camping means that slight shading will not waste your entire day with thin-film.

Something to think about - best thing is you can prove it to yourself and not rely on salesman or Amazon reviews. And oh yeah, if you are using a 5v output, make sure your device doesn't balk at your cabling - something which the Anker's IQ mechanism figures out for you. Otherwise, Grandma might end up having to make custom "charge only" usb cabling in the field.


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## Timothybil (May 19, 2015)

I went back and checked my setup after the sun went down. The two hours of sunlight I got in the above post was sufficient to charge my 15,000 mAh power back 6%, by the digital meter in the power bank. Not bad for thru-the-window sunlight. Will post more as I test.


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## mdocod (May 19, 2015)

IonicBond,

Thank you for sharing your thoughts on the matter. 

If you have a chance, please Google: "SparkFun Sunny Buddy - MPPT Solar Charger"

I can certainly see how "MPPT" within the scope of small portable panels could wind up being thrown around as a marketing buzzword, but I also see no technological reason that it could not be implemented for nearly any size power system. Keep in mind, that from my perspective, I'd rather have a 4oz panel that fits on "top" of a pack with a custom little 2.5oz MPPT charger that I could build out of that sunny buddy and a gutted 2-slot charger, (And even throw in a USB output regulator to charge a phone from), than an 8oz panel and a 0.7oz MC1-Plus. From a back-packing perspective, making a small light panel work better would indeed be superior to having a larger panel. 

----------

I did not see any reviews by a presumably ignorant grandma on amazon for these panels. While I appreciate the point you are trying to make, I think you're also perhaps trying to diminish a harsh truth; Based on the trending of reviews for this new "wave" of presumably "nice" cheap portable panels, and my own experience: Some of these modern cheap portable panels are offering better performance and functionality than expensive portable panels from a few years ago. If amazon reviews were entirely useless, then we would see 5 star ratings on all portable solar panels on there, yet, there are PLENTY of panels on there, with consistently poor reviews. If the "does grandmas charge light turn on" criteria were being used for all of these reviews, then we wouldn't be seeing panels with 1-3 star ratings on there. 

A lot of these reviews on amazon for these panels, include some basic measurements (usb analyzer), or how long it took to charge a known device from X to X. Lots of people reporting that their new little reasonably priced solar panel charges their device "just as fast" as their wall-wart or computer's USB port. Are these people electrical engineers? No. Do they need to be electrical engineers with oscilloscopes and true-rms fluke meters with recent calibration certificates to be able to observe and report charging performance for a common consumer electronic device? No. What we have here, is not grandma reporting in that the charge light on her flip phone came on when she plugged it in, but a diverse range of people, many of whom are well informed, intelligent, and have experience with other panels, and are including useful, tangible information in their reviews. 

It would be nice to see these portable panels all held to a "standard" for specification claims. No doubt, most will fall short simply because they do not incorporate regulation losses into the rating. If the panel delivers good true power per weight, size, and cost relative to competing options, then I would be hard pressed to fault them for sliding on that technicality, but a level playing field (like an ISO/ANSI standard) would be nice, even if it did turn out to be sort of gimmicky, at least it would be standardized. .


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## SemiMan (May 19, 2015)

IonicBond said:


> Forget it - mppt at these low power levels is only for marketers and engineers that over-engineer just for the sake of it. If you are running a system that is under 200 (two HUNDRED) watts, or live in the arctic with only 1 hour of solar insolation per day, just getting another (or larger) panel is the easiest thing to do.
> 
> MPPT is great when applied properly. However, in the cheap marketplace, you'll see weasel-words in marketing like "UP TO xx%" and so forth, which basically mean that their mppt algorithm is junk. Typically, mppt is best applied with high-voltage panels, such as grid-tie 24 volts or higher per panel. With our little 5/12v camping panels, mppt is sucker-bait.



Sorry but hand waving is not a valid engineering argument. MPPT is always a good technique done properly for the application at hand.

The fact they say up to xx% and not an exact number has nothing to do with accuracy of MPPT algorithms and everything to do with not knowing the exactly panel/load differential which varies with panel, load, light level and temperature.

MPPT without increasing area effectively gives you a bigger panel. That needs to be weighed against the cost of implementation and in this case weight as well and quiescent draw and conversion efficiency. Given weight and size is an issue for portable, MPPT purpose designed for the app would be a nice way to get more power without the weight / size penalty.

The voltage of the panel is meaningless, only the voltage mismatch between the panel and load. A 24v panel with a 24v battery system has no more mismatch than a 6v panel with a 3.7v battery system.


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## SemiMan (May 19, 2015)

IonicBond said:


> Most consumers are not aware of the shoddy materials and construction practices the cheap panels are made out of, yet alone don't have the ability to PROVE what they got actually meets the sales specs. Grandma won't be pulling out a Fluke 87V and measure the ISC (short circuit current) of the panel. As long as the little red charging led lights on the phone, she won't know or care that the panel spec'ed to provide 1A output in good sun is only doing 100ma.
> 
> Good time to bring up testing - obviously an inline 5v or 12v ammeter is a good thing. One thing to test is that each cell is actually functioning or wired properly. Since mono / polycrystalline panels reduce their output drastically when partially shaded (tiny wet leaf, shadow from tent rope across one cell etc) , this actually provdes a good way to test each cell!
> 
> ...



No the units made with sunpower cells have 2x the output of the powerfilm for the same area approximately, not 1/3 larger.

As well, to lower the output of a mono panel drastically it is not enough to simply throw some shade across it. The output of any given cell will still be roughly equal to the area that is illuminated. 2-3/fingers on small cells may be enough but the shade of a tent rope is likely to have not a large effect. Keep in mind its mainly the cell geometry of the powerfilm that improves shade performance. Hiking/camping in the woods the real world performance of powerfilm watt for watt will of course be superior and maybe by a lot.


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## SemiMan (May 19, 2015)

mdocod said:


> It would be nice to see these portable panels all held to a "standard" for specification claims. No doubt, most will fall short simply because they do not incorporate regulation losses into the rating. If the panel delivers good true power per weight, size, and cost relative to competing options, then I would be hard pressed to fault them for sliding on that technicality, but a level playing field (like an ISO/ANSI standard) would be nice, even if it did turn out to be sort of gimmicky, at least it would be standardized. .


'

But would you be willing to pay the added cost? .... not that a flash test would be difficult or expensive, but it will add cost and tell you nothing about reliability. I am not aware of any standards for testing the reliability of flexible panels so that is out.

I found the reviews fairly useful. They are like any other internet reviews .... some quality reviews, others not, and easy to pick the difference.


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## mdocod (May 19, 2015)

SemiMan said:


> 'But would you be willing to pay the added cost? .... not that a flash test would be difficult or expensive, but it will add cost and tell you nothing about reliability. I am not aware of any standards for testing the reliability of flexible panels so that is out.



I seem to recall you saying the following: _"The odds of this being 5W I would say are pretty close to 0. Looking at the actual solar panel area, that would put it 18%+ ... which is unlikely for an assembled unit of this quality."

_And you are certainly not the only one to have participated in this thread, and implied or flat out said that inexpensive panels fail to achieve their "specified" power. This seems to be a common "theme/complaint," thus, I offered that a standardized method of rating them could be beneficial. Your response to the idea phrased as a question to me, implies that you'd rather keep specifications non-standard and inflated if it means keeping prices low. 

Historically, cheap chinese solar panels probably had no incentive to disclose any sort of honest information about the true performance of their panel, as it would not have helped them sell their trash. Things have obviously changed, there are now functional, useful products, whose label specifications are just not well understood or standardized. From what I can tell, I think a lot of these panels are just using the panels maximum theoretical output as the "rating" rather than a "final system" rating. 

Like I said, any standards would likely wind up being somewhat "cheatable," and be sort of gimmicky unless the buyer understands what the standard actually means, but at least the buyer would have the option of learning what that standard means, and know what tests were performed, and how, to achieve a particular rating for performance, or durability, or whatever. 

We now have standards for flashlights that can tell us something useful about lumens, runtime, and peak beam intensity. These numbers don't tell us anything about tint, or spill beam profile, or the output-vs-time characteristic of a light, so its an imperfect system that can create some confusion for those who don't understand the limits of the standards. Would we be better off without them? I honestly do not know. 

Introducing a standard would certainly have an effect on _cost_, but not necessarily price. Standards don't typically find their way into an industry until the market and or liability for the a product is large enough to demand it. IE: When technology vs cost reaches critical mass in terms of viability for mainstream. If we are indeed at a point where $30-50 solar panels are charging phones, pads, and other portable devices pretty darn good, then we are arguably at a point in this technologies life-cycle that is ready to go mainstream. The added costs of performing standardized testing on a product that is actually mainstream viable is not going to be greater than the cost benefits of the sort-of volume this market is likely headed for.



> I found the reviews fairly useful. They are like any other internet reviews .... some quality reviews, others not, and easy to pick the difference.



There is a modern trend among enthusiast communities to dismiss and even despise "reviews" on mainstream websites like newegg, amazon, etc. I'm glad to hear I'm not the only one who is actually willing to read them and decide for myself on an individual basis whether they are useful, rather than paint the whole slew of them with a wide brush like so many of us "elitist's" often do (yes, I am an admitted "elitist snob" when it comes to consumer goods.)

Great example of this is in computer hardware reviews. Most people leaving reviews for these things aren't going to leave a very detail oriented performance review, but people WILL leave negative reviews for problems, or point out interesting or unexpected "issues". If the same problem pops up repeatedly for the same product, then we have a trend that is not limited to one reviewers incompetence or bad experience, rather, an actual product defect that is appearing across an entire batch. Being able to skim through and then do word searches through consumer reviews, can be extraordinarily helpful. People don't leave 5 star reviews for products that are built like trash and don't do what they expect them to.


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## ChrisGarrett (May 19, 2015)

I always read as many reviews as I can. Before I bought my SunKingdom 14w 5v panel last night, I read the reviews and sorted through the chaff. It's not hard to figure out who knows what they're talking about and who's just happy that the item 'turned on' right out of the box.

Anyhow, my 'folder' shipped today, from Cali, so along with the new Xtar XP1, MC1+ and volt/current meter, I'll fiddle with things next week and see what I see, as far as output goes. 

I also bought a Ruinovo 4x18650 (4xSanyo 2600s) power bank that HKJ reviews and I'll tie that into the portable equation, as well.

Chris


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## SemiMan (May 19, 2015)

Mdocod .... I find it interesting the calls for standards on solar panels but where is the indignation on batteries not meeting claims, USB chargers not hitting specs, etc. Why pick on one area.

People buy stereos and amps every day and the standards in that area and independent tests are?

What about standardized tests for battery life on cell phones?

Heck you can't even trust mileage ratings on cars and only through court action has it been fixed.

Big panels have testing standards as they are needed or there would never be financing for the long term ROI of solar installations.

The best you can hope for in this market is good old capitalist approach. Formal review sites that measure and the suppliers that want to be shown as superior and will actively ask to be tested. 

Is there enough money in the market to support the advertising model that would go with that? ... Solar simulators are not cheap.


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## mdocod (May 19, 2015)

Based on what I know now, if I were in the market to buy a larger 10W+ (claimed) panel for ~$50 from amazon, I think I'd probably be looking a the following panels pretty closely (at the time of posting these links, these are ~$50 each):

STIN SunPower ... 16 watt Solar Power Charger

SUNKINGDOMTM 13W 5V Sunpower Solar Panel ... (13W/Black)

CHOE High Efficiency 19W Dual-Port USB Portable Foldable Solar Panel.....

There are a lot of offerings in that popular folding ~14W "rated" size with more generic looking panels from sunkingdom/kingsolar/anker/x-dragon/instapark/poweradd/allpower/gerafus/ravpower. They sell for ~$40-50, and I'm sure some of them are perfectly functional, but it just seems to me like we'd get more for the money and size and weight with those devices constructed from sunpower panels listed above.


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## mdocod (May 19, 2015)

SemiMan said:


> Mdocod .... I find it interesting the calls for standards on solar panels but where is the indignation on batteries not meeting claims, USB chargers not hitting specs, etc. Why pick on one area....



In summery; if the standards aren't perfect, don't do them at all.

Just say what you want to say without the loaded questions. 

--------

I see now where I went wrong. I inadvertently have pressed a hot button issue with you that is rooted in politics.

I did not intend to come across "calling for" or "demanding" regulation/standards etc. When I said _"It would be nice to see these portable panels all held to a "standard" for specification claims."_ I mis-spoke. That should have been worded differently, and I realize now the error in not wording that more carefully, as I can see how that would be a hot ticket short fused sort of way to ignite a passionate fury under anyone with any sensitivity on the subject of politics. 

You should know, that we are likely on the same page, and this is just a misunderstanding brought about by me, not taking the time to proof read that post more carefully. I should have spotted how that statement would come across and dealt with it before, as such, that is not the case. The result of this misunderstanding, is that you feel compelled to discredit me with loaded questions in order to bury what you interpret as a threat.

If I could have a do-over. I would say that I think it would be useful for there to be a standard established, which these companies could optionally choose to participate in using to rate their portable panel charging "systems." Such a standard could actually be a business venture for a small company, as companies could collaborate and agree on standards, then petition them to be recognized by ISO or ANSI with designations (syntax?). The demand for a way to test panels without a huge investment in equipment would likely spur a small business venture to provide outsourced 3rd party testing for panels. 

----------

My belief is that an imperfect law is better than lawlessness. An imperfect standard is better than no standards. I already stated that I expect it to be gimmicky and misleading, I'd rather be able to compare products on a known bad standard than on a whim of mixed quality user reviews.


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## SemiMan (May 19, 2015)

mdocod said:


> In summery; if the standards aren't perfect, don't do them at all.
> 
> Just say what you want to say without the loaded questions.
> 
> ...




All good discussion! 

Is it about politics? Perhaps? .... Government regulation often adds cost without resulting benefit. Industry standards are good when followed. There is no mandated requirement on big solar panel testing, but you don't sell panels without them because banks will never finance. That same pressure does not exist on small panels .... or frankly almost anything.

All that is left is class-action lawsuits .... quite a messy way.

I do believe there should be stronger consumer protection laws, the issue is how do you police the sellers? Amazon and Ebay are still the wild west in many ways. Wild claims that cannot be true, product that is not legal to sell (i.e. without electrical approvals in jurisdictions that require it) being sold, etc.

Problem is, innocent till proven guilty works great when we are talking about individuals, but makes it too easy for companies to avoid doing whats right.

Semiman


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## IonicBond (May 19, 2015)

mdocod said:


> I can certainly see how "MPPT" within the scope of small portable panels could wind up being thrown around as a marketing buzzword, but I also see no technological reason that it could not be implemented for nearly any size power system.



Yes, it can be done, and technically is superior. But keep our low-power application in mind - a slightly larger panel, or even just 15 more minutes of sun exposure with a standard pwm charger can even the score. Marketing departments are counting on us forum fanatics to go gaga over specs, discounting real-world conditions, and do their marketing for them.


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## SemiMan (May 19, 2015)

IonicBond said:


> Yes, it can be done, and technically is superior. But keep our low-power application in mind - a slightly larger panel, or even just 15 more minutes of sun exposure with a standard pwm charger can even the score. Marketing departments are counting on us forum fanatics to go gaga over specs, discounting real-world conditions, and do their marketing for them.



When you are backpacking, weight counts and size counts and you don't have an extra 15 minutes ... you have what you have. 20-35% more output is not unreasonable and that is more than 15 minutes. That is also a 5 watt panel that behave more like a 6.5 ... or a 20 that behaves like a 25-27. What better place to use MPPT. MPPT is not just for high power, it is also for maximum efficiency. No one is going gaga. FYI, pretty much all the stuff we are looking at here is not PWM, but linear regulator (or none at all). PWM is for lead-acid primarily.


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## IonicBond (May 19, 2015)

SemiMan said:


> As well, to lower the output of a mono panel drastically it is not enough to simply throw some shade across it. The output of any given cell will still be roughly equal to the area that is illuminated. 2-3/fingers on small cells may be enough but the shade of a tent rope is likely to have not a large effect. Keep in mind its mainly the cell geometry of the powerfilm that improves shade performance. Hiking/camping in the woods the real world performance of powerfilm watt for watt will of course be superior and maybe by a lot.



While mono / poly-crystalline panels are more efficient per area, once you shade one of the cells, you put it into a reverse-bias condition. Now the output of the *entire panel* will suffer badly. In large panels, that can lead to burning up the cell(s). This is one reason why there are bypass-diodes (not to be confused with blocking diodes) to split the current of the panel in half, trying to protect the shaded / reverse biased cell. You'll be able to prove that to yourself easily enough.

With thin-film, there are no cells per-se, even though Powerfilm may look like it has a bunch of tiny ones. You can reverse-bias (shade) any portion of the panel, and will put out as much as is illuminated without having bypass diode protection. While it will survive, it is not a good idea to do this long-term, as in a permanently shaded area for a fixed installation. But for portable use, no sweat. You can purposely damage a thin-film - put a tent stake through it - cut it in half - whatever - what is left still works. Don't put a tent-stake through your mono panel. 

In the end we are just dealing with inexpensive stuff and not putting in a grid-tie or off-grid housing solar project. Having fun in the backyard is one thing. If you are on top of the Andes and trying to charge your team's sat-phone, yeah, better go with Powerfilm.


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## SemiMan (May 19, 2015)

IonicBond said:


> While mono / poly-crystalline panels are more efficient per area, once you shade one of the cells, you put it into a reverse-bias condition. Now the output of the *entire panel* will suffer badly. In large panels, that can lead to burning up the cell(s). This is one reason why there are bypass-diodes (not to be confused with blocking diodes) to split the current of the panel in half, trying to protect the shaded / reverse biased cell. You'll be able to prove that to yourself easily enough.
> 
> With thin-film, there are no cells per-se, even though Powerfilm may look like it has a bunch of tiny ones. You can reverse-bias (shade) any portion of the panel, and will put out as much as is illuminated without having bypass diode protection. While it will survive, it is not a good idea to do this long-term, as in a permanently shaded area for a fixed installation. But for portable use, no sweat. You can purposely damage a thin-film - put a tent stake through it - cut it in half - whatever - what is left still works. Don't put a tent-stake through your mono panel.
> 
> In the end we are just dealing with inexpensive stuff and not putting in a grid-tie or off-grid housing solar project. Having fun in the backyard is one thing. If you are on top of the Andes and trying to charge your team's sat-phone, yeah, better go with Powerfilm.




Stick to subjects you know and/or understand. Thin film panels ABSOLUTELY have cells. Those cells are really absolutely no different from the ones in mono/poly panels, though the junctions may be of different material. In all cases, they are semiconductor diode junctions, and many junctions are stacked to arrive at the desired voltage. They have have ITO conductors and be created with a different manufacturing process, but for all intents and purposes they are exactly the same. The ONLY reason why SOME thin film panels do much better in heavy shade is that the cell geometry is quite different from your typical mono/poly cell. They are usually (not always) long strips, as opposed to squares. As long strips, the odds of significantly shading a single cell are much lower than shading discrete squares. However, you will note that some of these small panels are actually a series/parallel combination and to that end, have some good natural resistance to shade.

As we are talking low voltage panels that are not stacked in series strings, reverse bias is not an issue as we don't have voltages enough to exceed the breakdown of the cell.

Thin film panels can and do have bypass diodes. It all depends on their construction.

In fact, PowerFilm specifically uses individual cell plates in the construction of many of their panels ... just like a mono/poly panel and if you shade one of their cells, you will drastically reduce the power. Many of the PowerFilm units do not have the advantages often assigned to thin film panels except in fairly low light where their higher fill factor results in better performance. Practically, it tends not to be a huge advantage.


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## keithy (May 22, 2015)

mdocod said:


> This morning I hooked up the panel and observed 0.7-0.8A charging rate with cirrocumulus clouds between me and the sun while charging a nearly-depleted NCR18650B in the MC1-Plus.


Thanks for the updates on the Sunpower panel. I'm quite impressed it can do what it says for the size.

And thanks for the link to the other larger panel http://www.amazon.com/dp/SUNKINGDOM/?tag=cpf0b6-20 I actually like this design as it incorporates a stand behind the panel so you can prop it up to face the sun. With my Instapark Mercury or GZ Nomad 7 panels, I have to pack a folding phone/tablet stand so I can angle it to the sun at campsites. I have these stands




that weigh about 22grams (1.2 oz) but it would be nice if it was already incorporated into the panel design.

And I'm always jealous of how quickly you guys in the US get Amazon deliveries. Unless I pay for the expensive expedited delivery (which can be more than the cost of the item), it is taking around 3 - 4 weeks to get orders delivered to Australia.


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## ChrisGarrett (May 22, 2015)

keithy said:


> And thanks for the link to the other larger panel http://www.amazon.com/dp/SUNKINGDOM/?tag=cpf0b6-20 I actually like this design as it incorporates a stand behind the panel so you can prop it up to face the sun. With my Instapark Mercury or GZ Nomad 7 panels, I have to pack a folding phone/tablet stand so I can angle it to the sun at campsites. I have these stands
> 
> 
> 
> ...



I just received my SunKingdom 14w dual USB foldable solar charger yesterday and had it out on my shaded patio trying to charge up my phone on a very 'jungle-esque' condo balcony.

There was a 14" wide segment of sunlight on the edge of the deck about at noon, poking through the clouds and I tilted the 4-panel charger up against a pot at 50* and the thing started charging lickety-split.

It's going to rain and so the clouds eventually covered the 'bright section' and the charger stopped charging the phone, but that's to be expected.

I have the Xtar current/volt meter coming today, or tomorrow and so on Monday, I'll be able to take everything downstairs and get better readings.

For the SK 14w panel, the panels are backed by a few layers and are fairly stiff. The unit weighs in at 1.87#, so not too light. It has two USB jacks 2.1A and 2.5A, so good enough for any portable USB device and a total power figure of 2.8A, as stated on the charger itself. 18.5% efficient and nicely done graphics on the outside, with a little storage pocket built in to the last section holding the USB module.

All for $39.99 shipped via Ebay.

Chris


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## StorminMatt (May 22, 2015)

I actually bought Sunkingdom's 6.5w Sunpower panel to give a try. This one is a little bigger than the 5w panel I have. But at half a pound, it's still fairly lightweight. And it's still a single panel rather than a folding charger, which makes it simpler and more rugged. Hopefully, the extra wattage should be enough of a boost to allow it to charge an iPhone or power an MC1+ with full speed


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## KITROBASKIN (May 22, 2015)

StorminMatt said:


> I actually bought Sunkingdom's 6.5w Sunpower panel to give a try. This one is a little bigger than the 5w panel I have. But at half a pound, it's still fairly lightweight. And it's still a single panel rather than a folding charger, which makes it simpler and more rugged. Hopefully, the extra wattage should be enough of a boost to allow it to charge an iPhone or power an MC1+ with full speed



This is the one I am looking at. Please give us an update.


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## mdocod (May 22, 2015)

There are multiple 6.5W panels from them, at least 3 or 4 different versions..

The one I am interested in is this: http://www.amazon.com/dp/SUNKINGDOM/?tag=cpf0b6-20

Weight isn't listed.


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## KITROBASKIN (May 22, 2015)

mdocod said:


> There are multiple 6.5W panels from them, at least 3 or 4 different versions..
> 
> The one I am interested in is this: http://www.amazon.com/dp/SUNKINGDOM/?tag=cpf0b6-20
> 
> Weight isn't listed.



That's the one.

This afternoon I used my 15 watt Goal Zero with the Xtar VP2 charger (12V) on an 18650. It did charge at the 1A level but did not confirm it with a meter. I have a clamp meter but have no place in the circuit where the pos. and neg. wires are separated.


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## mdocod (May 23, 2015)

Hey StorminMatt,

Which specific 6.5W panel did you pick up? I'm wondering if that one I linked above might be lighter, it appears to be constructed the same way mine is, and is technically the same "size" in terms of surface area (overall size). These "bare white" panels seem to be lighter weight than those with the black woven-nylon sleeves. 


------

Thanks for the update Kitrobaskin, 

Yea I would expect the large GZ panel to have no problems essentially running a ~4-5W load. Glad to hear it is working though. In good sun it should really have no problems running the VP2 with 2 cells running at 1A each, as long as the panel is under continuously ideal conditions.


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## StorminMatt (May 23, 2015)

The one I got actually has the nylon sleeve. Now that I think of it, maybe I should have gotten the bare white one. Oh well. In any case, it looks like the two panels (bare white and black) are EXACTLY the same electrically. So I would expect them to perform identically.


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## mdocod (May 23, 2015)

Just looked at that listing again for the "white" version. Estimated delivery isn't till June 18-July 7. Must be shipping from the other side of the world via row boat or something. Bummer... I think I'll hold out and see if they ever pop up here in the states and with a listing that shows the weight.


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## IonicBond (May 23, 2015)

Interesting - I took a look at the Sunkingdom folding panel, and it looks like there are no grid wires that usually lay atop mono / polycrystalline cells. It actually appears to be thin-film cut into strips to look like a large mono cell. That will actually be a good thing in the temporary shading situations.

If it is truly thin film, then there is the CIGS vs standard thin film debate and on and on......


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## SemiMan (May 23, 2015)

"Actually" being the key word. They are most definitely monocrystalline cells. They are back contact cells.

AND AGAIN .... If it was thin film it would have little/no advantage over mono for shading as that advantage is based on geometry and in this case no geometry advantage.


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## KITROBASKIN (May 23, 2015)

mdocod said:


> Just looked at that listing again for the "white" version. Estimated delivery isn't till June 18-July 7. Must be shipping from the other side of the world via row boat or something. Bummer... I think I'll hold out and see if they ever pop up here in the states and with a listing that shows the weight.



I did go ahead and order that white panel last night. This morning Amazon informed that Sunkingdom has shipped but the estimated delivery date is June 18 into July. But it is free shipping. This is similar to banggood, although I hope Sunkingdom is more accurate with their product description. Banggood sent me clips for a flashlight that was said to be titanium; one is magnetic though...

With our intense sun, anything black really heats up. That is why I like the white body of this panel. I also appreciate the caution Sunkingdom gives about leaving a device in the sun for a long time. Many years ago I had a flashlight with a solar panel on the side of the body. After a few times setting it inside the window sill, the plastic frame of the light 'melted' and warped, rendering it useless.

I looked closely at the Powerfilm products; had to pass.

Thanks to you guys (StorminMatt for one) I will be using the Goal Zero more efficiently in the future. Perhaps today I will test partial obstruction of the panel with the Xtar VP2 charger. Orbtronic (where I got the VP2) says they will be stocking the Xtar MC1+ soon, and they are already stocking the new 3500mAh 10Amp continuous, unprotected 18650. I'll be ordering from them.


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## KITROBASKIN (May 24, 2015)

Turns out the Xtar VP2 charger can be used effectively with a solar setup (at least with a Goal Zero 15 watt panel). The variable partly-cloudiness we have been having tested OK, maybe sometimes it seemed to terminate charge before reaching 4.2V but that was when it was quite cloudy and the batteries were over 4V (more experimentation advised). I did a partial obstruction test (forearm and hand about 20” above panel, beginning with a vertical orientation and slowly rotating the forearm to horizontal in relation to the panel) and I did need to pull the 18650's and reinsert to continue charging, but they were already about 4V, so needs more experimentation as well. Today I completed a 4.2V charge on the 5200mAh Orbtronic 26650 with occasional cloud cover, so that's good. 

Interestingly, while this Goal Zero setup will not charge a Moto E smartphone or an iPad2 straight from the USB output, I *AM* able to insert a (higher Amp 2 USB ports) 12V car adaptor into the female 12V car socket (that uses a Goal Zero plug to connect to the panel). So it looks like I do not have to have an intermediary pass-through battery bank, at least for reasonably sunny days.

I do question how much power is used up to drive the Xtar VP2 display panel on the charger. Still plan on getting an Xtar MC1+ charger. And while it seems prudent to use some kind of anchoring method (I use shock cord) for these smaller panels, to keep them from blowing away in the wind, it is a viable option. Definitely looking forward to the smaller Sunkingdom unit.


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## jorn (May 25, 2015)

hope this new tec is coming soon. 22,1% efficiency 
http://www.nanotech-now.com/news.cgi?story_id=51504


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## SemiMan (May 25, 2015)

Most of this tech is already in sunpower cells. They are higher efficiency already than this and have good shade response with good blue efficiency. They are n material.


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## IonicBond (May 25, 2015)

SemiMan said:


> Stick to subjects you know and/or understand.



I do. But with MUCH less hatred for those that don't know.



> As we are talking low voltage panels that are not stacked in series strings, reverse bias is not an issue as we don't have voltages enough to exceed the breakdown of the cell.



Short term yes, but long term, no.



> In fact, PowerFilm specifically uses individual cell plates in the construction of many of their panels ... just like a mono/poly panel and if you shade one of their cells, you will drastically reduce the power.



Ouch. Cover half of a thin-film like a powerfilm, and you get half the current, while the voltage stays nearly the same. Try covering half, or even a small subset of a mono panel, and compare notes about the current.

The guy in this video isn't me, but shows the difference in shading between the two. There's a lot of blather at the end of it, but it is a test that anyone can duplicate with their hand and an inline usb ammeter even:

https://www.youtube.com/watch?v=flvkYi753Js

Thing is, what I say is easily reproduced by those that own them, or do their own research on the matter - I'm sorry, but you are wrong - and there's nothing wrong with that. It is a learning opportunity. Unless this is just bait for a semantics slugfest. 

To lay the matter to rest, instead of speculating, why don't you actually purchase a thin-film panel, and prove it to yourself?


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## SemiMan (May 26, 2015)

Sorry but linking to YouTube does not give you any credibility.

I have developed commercial solar electronics and been involved in megawatts of solar installations. 

I have done large numbers of solar lighting both standard product and app specific for shelters and similar structures.

I have had in my hands over the years, Sunpower based (Jaiwei), Solarworld, CSI, Kyocera, Global Solar (cigs), FirstSolar (cdte), United Solar Ovanic (a-si like powerfilm) etc.

Most of the benefit of thin is purely geometry. That is real world, not YouTube. My shelter products were often under shade at times and for a given area, the sunpower would always outperform any thin film in real world testing.

Powerfilm is made up of cells .... Period. It does not look like a bunch of little cells ... Those are just the conductors which are needed over all the surface to collect charge. The powerfilm cells are actually quite non-ideal for shade tolerance. Long strips like First Solar are almost ideal from shade tolerance in real world conditions.


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## SemiMan (May 26, 2015)

Short term yes ... Long term no .... What are you blathering about. The panel can either generate enough voltage to generate reverse bias or not .... The ones we are talking about here don't... Period. They are diodes .... There is no long term failure mode this condition ... Exceed breakdown or don't.

Please get some real experience not just Wikipedia and YouTube.


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## SemiMan (May 26, 2015)

So all the video shows is that if you take a large geometry cell and a small geometry cell and shade them with an object as big as the small geometry unit that the small geometry unit will perform worse .... No kidding.

If this was done with a CSI panel with large cells the drop would have been far less.

The small panels we are discussing have small cells even for powerfilm and will be shade susceptible.

The small CSI panels with multiple series strings will do relatively well.


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## SemiMan (May 26, 2015)

No hatred, just no tolerance for wiki experts who really don't know what they are talking about leading others astray.


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## MrJino (May 28, 2015)

My ravpower 15 watt is fairly decent at charging the aw 18650 3400 mah, though it takes about a full day.


 Looking to get a foldable 30 watt.


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## StorminMatt (May 28, 2015)

MrJino said:


> My ravpower 15 watt is fairly decent at charging the aw 18650 3400 mah, though it takes about a full day.
> 
> 
> Looking to get a foldable 30 watt.



It takes a full day because you are using an MC1. The MC1 only charges at half an amp. Upgrade that to an MC1+, which can charge at one amp. That way, you can cut charging time by a half if your panel can support that kind of current (which 14W should).


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## MrJino (May 28, 2015)

Ah that's good to know. Think I'll update charger soon. Not that I use it often, only have 1 light at 18650


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## mdocod (May 28, 2015)

Yea even that dirt cheap little "5W" panel I picked up, (more like a 3W on average), can charge with the MC1+ at up to nearly 0.9A. A larger panel would have no problems running the full 1amp until CV stage kicks in.


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## MrJino (May 29, 2015)

mdocod said:


> Yea even that dirt cheap little "5W" panel I picked up, (more like a 3W on average), can charge with the MC1+ at up to nearly 0.9A. A larger panel would have no problems running the full 1amp until CV stage kicks in.



Is the mc1+ usb compatible?


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## ChrisGarrett (May 29, 2015)

MrJino said:


> Is the mc1+ usb compatible?



It's only a USB charger (and li-ion,) so no 12v input, or NiMH capability. It does require at least a 1A wall wart to yield the 1A charging rate.

Chris


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## MrJino (May 29, 2015)

Awesome. Will order it then.

I usually charge my stuff with a power bank that is 2.4 amp, but regulates to whatever is plugged in.


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## mdocod (May 31, 2015)

We're just wrapping up the wettest month since records began here where I live. Not a particularly good month to be trying to test out a solar panel...

Today it was sunny for *hours* on a day I actually had time to tinker. I set up the 5W Sunkingdom panel with the Xtar MC1-Plus at 3:30 in the afternoon propped up towards the sun in the back yard with a very new NCR18650B at 3.5V. 3 hours later I decided to end the test as the sun was setting behind clouds so the party was over. In that 3 hours, in which I manipulated the panel 3 times for position, (changing angle, and eventually re-locating to the front yard where the sun was not being blocked by houses), the charge rate averaged about 0.7A, (I checked it about a dozen times). Sometimes as high as 0.85A, sometimes as low as ~0.5A or less with occasional clouds passing over. When I "finished" the test, the cell was at 4.0V resting. 

0.7A for 3 hours should be about 2.1AH worth of charge, or about 60% of the cells capacity, and according to the results here: http://lygte-info.dk/info/BatteryChargePercent UK.html , from 3.5V to 4.0V represents almost exactly 60% of the cells capacity. 

This confirms for me that the Xtar analyzer tool is functionally accurate, and the panel can indeed deliver useful power continuously.

From my back-packing/fishing perspective, this is actually really useful. That 3 hours of catching rays, buys about 20 hours of ~60 lumen operation on a wizard pro (divided by 2 people, that's easily 3+ "nights" worth of charge from 3 hours of sunlight). . Another way to look at it, is that every hour of charging buys about an hour of runtime in high mode (~325 lumen by my estimate), which, I would not normally use, except when performing a task requiring much greater visual acuity... perhaps gutting a fish, for example. 

--------

In other experiments, I did manage to get the panel to produce ~4.5W output today, but only temporarily. I discovered that when the panel was positioned up close to the house both with the direct sunlight, and the reflected sunlight from the sliding glass door bearing down on it, the output "spiked" to [email protected] while charging an older protected 18650 that was ~3.75V "SOC." Within 10 minutes, this charge rate diminished to ~0.6A. The panel was very hot to the touch as a result of its positioning. Positioning it with direct sunlight, but no additional reflected light appears to produce the best results long term.

----------

[edit in]

More testing/tinkering this morning at around 11AM in good direct sunlight with "reflective clouds" conditions, I witnessed the highest charge "current" rate yet, 0.94A into a mostly depleted (3V resting) 18650 on the MC1+. It actually maintained >0.9A in these conditions for quite awhile... This is revealing, as it suggests that the USB voltage regulator on this device MUST be some sort of MPP tuned device, as the panel seems to be able to run at ~4W output in ideal conditions, continuous, regardless of whether that is at [email protected] or [email protected] I sort of doubt this could be improved on my margins significant enough to be worth bothering with.


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## KITROBASKIN (Jun 6, 2015)

I was informed that the Sunkingdom 6.5W panel was shipped the day after I ordered (5/22/2015) and picked it up today. So even though I was told the free shipping may take as long as mid July, it was less than two weeks. By the time I got it set up, we only had about 15 minutes of sunlight before it went over the mountain; but it did charge a little bit! (few hundredths of a volt)

It is light and appears well made though I can't directly connect the Xtar USB voltage/amperage detector to the panel because the USB output on the back is built to be very compact, thus not far enough away from the panel for the detector to fit. Used the Xtar MC1 charger today: Hope to use the Xtar VC2 charger tomorrow.

Wanted to say a big Thank You to mdocod for bringing this up. He and others (including Semiman) motivated me to remember to use my existing solar panel as well as getting this compact, lightweight unit.


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## mdocod (Jun 8, 2015)

That's awesome Kitrobaskin, 

I look forward to hearing more!

I use a short decent quality USB extension cable to run from the panel to the Xtar. I found one with 24GA power wires in it that seems to work pretty good.


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## StorminMatt (Jun 8, 2015)

I can tell you one thing. The 6.5W panel charges an iphone MUCH more quickly. It literally charges wall wart fast, just like the sCharger 8.


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## KITROBASKIN (Jun 8, 2015)

That panel is awesome. Bright sun; started charging Moto E cell phone at 76%, finished in less than an hour. Used the Xtar VC2 on a pair of 18650's. The charger indicated .5A going to each cell. I stopped them at about 4.1V and 4.15V so I could try charging an iPad 2. It seemed to charge at a similar rate as the Goal Zero off of the 12V connection (about 2 hours- 37% to 67%). Then I put on a pair of brand new Orbtonic 5200mAh 26650's that came with the factory voltage of ~3.65V; ran out of full sun before they charged but earlier I tried two of my best 115V wall transformer/power supplies and the VC2 indicated they were providing only .4A and .35A to each cell, while the Sunkingdom panel supplied an indicated .5A. Only the Ipad 2 power supply provides that to the VC2. 

mdocod: Once again you have something I would like to get. Where did you find that short USB to female USB cord? Also: when fashioning voltage leads for the Xtar USB detector; were you careful about which wires to use off the stripped USB cord, or can a person just try the wires to see what works without damaging the detector?

one caveat for the Sunkingdom used in conjunction with the Xtar VC2 charger: If a solid object obscures part of the panel, the Amps will go down drastically, and will not go back to normal after the obstruction has passed (no longer shading the panel) unless one pulls the cells and reinserts. This effect is significantly worse if the shade is blocking part of the panel along the shorter dimension of the rectangular 'array' than if the shade runs the other, longer dimension (but they're both terrible) I used the shade from just the narrow profile of my hand for the obstruction test, about 18 inches away, so the blocking only covered, I would say, less than 10% of the panel. I did not get to observe the effect of uniform cloud shade of varying degrees to see what affect that would have on charging.

Will hopefully use the Xtar MC1 charger tomorrow on the new Orbtronic 3500mAh protected 18650, that I took down to ~3.6V last night. Got to get one of those MC1+ chargers.

Sorry for the long explanation, but I was hoping to explain findings and encourage others to report their experience.


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## KITROBASKIN (Jun 8, 2015)

Well, turns out that occasional clouds will cause the Xtar VC2 to set to a lower charge current and not go back up when the sun becomes bright again. The Xtar MC1 does not have that issue.

I did spring for a USB extension cord (Radio Shack) so that I can use the Xtar detector with this Sunkingdom 6.5 watt 5 volt solar panel.


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## StorminMatt (Jun 8, 2015)

Beware of USB extensions. I have yet to find one (even 24AWG extensions) that DOESN'T significantly reduce current. Although I can't measure current, I can tell that my iPhone charges MUCH faster when I DON'T try to measure current.


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## KITROBASKIN (Jun 8, 2015)

Got that right. The USB extension (and the detector?) lowered the Amps available on the Xtar VC2 a lot.


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## Timothybil (Jun 8, 2015)

Two pieces of info: 1. Mediabridge uses 24 gauge wire in their cables - I asked. 2) USB A male to A female cables can be found as short as 6". I have one that length that I needed to be able to use my USB meter on my 14w fold-out panel.

And, yes, I would expect using a USB power meter would cut down on output - the power to run the meter has to come from somewhere. If I was really concerned about accuracy and losses I would find a meter that had it's own battery so it wouldn't load down the output being measured.


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## StorminMatt (Jun 8, 2015)

Timothybil said:


> And, yes, I would expect using a USB power meter would cut down on output - the power to run the meter has to come from somewhere. If I was really concerned about accuracy and losses I would find a meter that had it's own battery so it wouldn't load down the output being measured.



The USB power meter HAS to reduce the power available to the load. Not only does the meter use power to run it. There are also losses across the sense resistor. But from my experience, this is ALOT less than the losses through the USB extension (including the extra contact resistance).


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## Woods Walker (Jun 9, 2015)

Some of my solar stuff in action. 












I like longer cords for some applications shorter for others. Here the longer Micro and Mini USB cables allow the batteries to be placed out of direct exposure to sunlight.







The PIXO has many options. Notice the two pins in the center. Those are adjustable and can charge a bunch of things including camera/action cam battery packs etc etc etc. They're not kidding by claiming "universal charger".







But it can't do everything. For what's left I use this.







Between these two and the Guide 10 I can charge just about any smaller device or battery. The primary weakness of both chargers is an interruption in voltage will cause an error aka too many passing clouds so it needs to be watched. The Guide 10 is better in that regard however can only charge 4XAA or AAA and there MUST be 4 loaded. The PIXO can do a 1 or 2.

Just for goofing around powering a 350 lumen USB powered light and cell phone at the same time with indirect winter sunlight though a window. Heck some parts of the high efficiency 14 watt panel are shaded.











More inside testing. First my Amazon guide 10 review. Yea I just gotta talk to whoever will listen....




> I really wanted to give 3.5 stars but went with 4 rather than 3. This review is based on my initial testing and field use. My primary need was for backup power when hunting, fishing, camping or even my BOB. My GPS, headlamps,camera and radio use AAs. I needed a field charger for my phone with the ability to solar recharge more AAs than my older Powerfilm 2XAA (doesn't have a USB port) solar charger for storms like Sandy. I actually did have to recharge my phone using one of those smaller Solio chargers which was USB charged before we lost power for a week. Yes the need for backup power isn't limited to fantasy. Stuff can and does happen.
> 
> 
> First the pros:
> ...




Ok I think the Guide 10 has 2300 (or whatever mAh in the AAs) at 4.8 volts 11Wh. The Guide 10 pushed up my phone from 24% to 88%. Not sure if it was totally full as it's really hard to determine the capacity with a degree of certainty. The best I can get is an appropriate guess during use and charging. Fast flashing green LED good, solid better. Red not so much. LOL! Ok so it was now too empty for phone charging. Using the standard ALLPOWERS 18 Watt and higher efficiency ALLPOWERS 14 Watt.












After a few hours the Guide 10 was able to charge the phone from 83% to 100%. All this from sunlight inside the house. It probably had more power but didn't push this test farther. 


For some reason this never grows old. 







One interesting fact which has been noticed by others. The lower efficiency (17%) solar panels from ALLPOWERS, ANKER etc etc etc seem to operate at lower light than the 22-25% panels. The sun has moved on yet the light is still glowing. The higher efficiency panel can't do this but seems very good in stronger sun. In low light levels the charge is very very slow with the 17% panel. Still something is better than nothing so it's a bit of give and take on both types. You will find these two panel types sold in many panel chargers.


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## KITROBASKIN (Jun 9, 2015)

Having scrutinized forest pictures posted by Woods Walker, I'm guessing North Carolina/Virginia? With all the trees, etc. it must be a challenge to use solar. Sounds like panels that can handle that would be best. Thanks for the perspective. I am returning the 3 foot USB extension; way too much loss.


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## ChrisGarrett (Jun 9, 2015)

KITROBASKIN said:


> Having scrutinized forest pictures posted by Woods Walker, I'm guessing North Carolina/Virginia? With all the trees, etc. it must be a challenge to use solar. Sounds like panels that can handle that would be best. Thanks for the perspective. I am returning the 3 foot USB extension; way too much loss.



I have a cheap USB extension cord here and last week, I was playing with the Xtar meter and it and I went from my PC @ 5.08v to 4.99v with the cord inline. 

This is a fact of all wires, however. With big solar panels, we want to keep the runs as short as possible, between the panel, controller, battery and load.

Nothing new.

Chris


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## KITROBASKIN (Jun 9, 2015)

That USB extension was $18 from the shack of radio.


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## mdocod (Jun 10, 2015)

That's really exciting to hear that the 6.5W panel is pretty good. I'll keep it in mind if I ever need to order another panel....

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Of all the USB "extension" cords I have here and tested, the following seems to be the best: http://www.amazon.com/gp/product/B00ESZJEEG/?tag=cpf0b6-20

The unusual design which allows it to be inserted either direction likely contributes to reduced contact resistance, as the contact "plate" must bend to "fit." Unlike most USB plugs which we press in and they feel like they find a definite "home" position, this design just produces a very "tight" feeling connection that can't be driven all the way home. I have measured no difference in charge rates with or without this "in play." (I'm sure there is a difference, but the Xtar can't resolve it, even with 1/100th of an amp/volt precision.)

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I have in my shopping cart one of these: http://www.amazon.com/gp/product/B00NIGO3R4/?tag=cpf0b6-20

On hiking trips I'd like to be able to just plug in both the phone and MC1+ at the same time, so that if one or both is only performing a "top up" charge (CV), I'll have less wasted charging potential. I'll let yall know how it goes when it gets here. 

---------

Kitrobaskin, 

You asked about making the little USB test lead... By my understanding (quick google search), red and black are power on most USB cables. I didn't bother testing the particular cable I stripped down because the wire colors all matched a color diagram I found with a google search. If you find discrepancies, it would be a good idea to use a DMM and a USB pin diagram to trace the proper power wires.

You picked up the "white" laminated plastic 6.5W panel right? Do you have a way to weigh that thing? I'm really curious to know the weight, and how it compares to the 5W. Both panels are actually the same overall surface area (in terms of the actual full device, I'm sure the surface area of cells in the 5W is less). So I would expect them to weigh about the same unless the sunpower cells are significantly heavier.


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## KITROBASKIN (Jun 10, 2015)

mdocod said:


> You picked up the "white" laminated plastic 6.5W panel right? Do you have a way to weigh that thing? I'm really curious to know the weight, and how it compares to the 5W. Both panels are actually the same overall surface area (in terms of the actual full device, I'm sure the surface area of cells in the 5W is less). So I would expect them to weigh about the same unless the sunpower cells are significantly heavier.



Yes, the white one. It is 185 grams on my plastic Ohaus beam balance (about 6.5 oz)

12 inches by a little over 6 inches wide, about 2mm thick, not counting the USB port

Thanks for all your information; much appreciated.


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## Timothybil (Jun 10, 2015)

Since we have been having such an intense discussion of these and other panels, I thought I would pass this on. I recently became aware of Massdrop, a group buy sort of outfit. While looking at their current 'drops' today I ran across this one: Sunjack Solar Panel + Battery. If you are interested, the web page is www.massdrop.com.


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## ChrisGarrett (Jun 10, 2015)

Timothybil said:


> Since we have been having such an intense discussion of these and other panels, I thought I would pass this on. I recently became aware of Massdrop, a group buy sort of outfit. While looking at their current 'drops' today I ran across this one: Sunjack Solar Panel + Battery. If you are interested, the web page is www.massdrop.com.



Gotta register for that site to see it, so no thanks.

There are millions of cheap panels flooding the market, so one needs to really try and determine the level of quality and real world charging rates, one might get when actually using them out in the wild.

Remember the 6000mAh 18650s and 3000LM flashlights.

Chris


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## LetThereBeLight! (Jun 10, 2015)

Forgive me if I've said this before but suntactics.com & aspectsolar.com have some very high quality and durable solar chargers and panels.


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## TinderBox (UK) (Jun 11, 2015)

A solar panel that unfolds like a projector screen, not cheap at $7500

Can anybody see what wattage it is.

http://en.rocketnews24.com/2012/06/...-around-your-own-portable-solar-power-source/

John.


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## ChrisGarrett (Jun 11, 2015)

$7600, no output specs, no thanks.

Go get a PowerFilm 1200w/7.2A foldable panel for $1300 and buy some LiFePO4 mother batteries for another grand and spend the savings on hookers and blow.

Everybody wins.

Chris


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## TheShadowGuy (Jun 12, 2015)

Timothybil said:


> Since we have been having such an intense discussion of these and other panels, I thought I would pass this on. I recently became aware of Massdrop, a group buy sort of outfit. While looking at their current 'drops' today I ran across this one: Sunjack Solar Panel + Battery. If you are interested, the web page is www.massdrop.com.



I saw that one. Pretty expensive for what you get, I think ($99 +shipping for 8000mah battery+14w panel). I haven't heard of Sunjack either, but I do live under a rock.

I've been eyeing up a $30 (with Prime shipping) Anker 8W foldable panel to test out. I've used various other Anker products, including multiple power banks, mouse, keyboard, etc. and they have all been excellent quality and durable. If I do pull the trigger, I'll let you guys know how well it works.


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## Phlogiston (Jun 12, 2015)

I have an Anker IQ 14W foldable solar panel which I've been experimenting with. That's a much larger panel than the ones people have been discussing here, and I've been focusing mostly on indoor experiments, so I decided it would be best not to clutter this thread with a long post about that. 

If anyone's curious, I've posted some thoughts on the Anker panel in a new thread: 

http://www.candlepowerforums.com/vb...ghts-on-the-Anker-IQ-14W-foldable-solar-panel


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## keithy (Feb 24, 2016)

I got one of the Sunkingdom 6.5W high efficiency panels after reading about them here and I'm quite impressed so far. I got this one





http://www.amazon.com/dp/SUNKINGDOM/?tag=cpf0b6-20

I've also picked up a high efficiency 20W Blitzwolf panel to try out:

So far, the portable panels I still have are:


Goal Zero Nomad 7W 430g (15.2oz)
Instapark Mercury 10W 500g (17.5oz)
Goal Zero Nomad 13w 750g (26.5oz)
Blitzwolf 20W high efficiency panel 550g (19.4 oz)
Sunkingdom 6.5W high efficiency panel 250g (8.8 oz)

The Blitzwolf one is this one:





http://www.blitzwolf.com/BlitzWolf-...arger-with-power3S-for-iPhone-6s--6-p-21.html

I bought mine from Banggood.com with a discount code BW-L1 $6 off bringing it down to USD$43.99 But I noticed that on Amazon if you use the code BLITZ222 it brings the price from $58.90 to about the same $43.90. 

The Blitzwolf 20W is quite good. It is definitely a higher efficiency panel, that is much lighter than my 13W Goal Zero just a bit heavier than the Instapark Mercury 10W and outputs a higher current. I've not got devices that take a 3A output so can't test that, but have got my phones and tablet charging at around 2A. But is a bit bulky for shorter trips and I have some complaints about the design - the pouch opening should face the other way as I've found clipping it to a pack means that your gear might fall out through the velcro. 

But on to the Sunkingdom. 

I like the inclusion of an adjustable kickstand to angle the panel to the sun. Normally I take a small folding tablet stand like these to put behind the panel so it angles to better to the sun. :






I can't test the Sunkingdom 6.5W with any of my USB testers as the USB port is upside down and the screens on all my USB testers end up facing into the panel and it's quite tight so I can't bend it to have a look at the reading. I got rid of my old frankenspliced USB cable I previously used with a multimeter to test the current while charging, and my current extension cables are all crap and drop current/voltage. So I until I get a short USB extension or get a right angle USB adapter, I can only test the output by using it. 

So I tested it by plugging a few flat 5000mAh battery banks into the Sunkingdom - the 6.5W panel charged in about half a day (I didn't time them, but I'll do that when the packs go flat again). The same battery banks would take around 2 days charging (about 10 hours) with a Nomad 7w to charge to full or 5 hours with the Instapark Mercury 10W. Trying my phone (with a 2000mAh internal battery), it seemed to charge relatively quickly so I am guessing that it is pushing out at least 1.5A. 

The only thing I'm a bit concerned about is how well it will fare in my backpack on backcountry/hiking trips. All my other panels are folding ones, and the solar panels are protected, this one being a one piece leaves the solar panel exposed, so I'll have to look at getting something protective for the front. 

But thanks for the heads up on the Sunkingdom. It seems to be quite a good panel for its weight. 

About leaving stuff in the sun, when at home, I use one of these insulated boxes to put the devices I'm charging with the panels inside:




I have one that fits my phones and batteries, and one that fits my 7" tablet. Protects stuff from overheating in the sun. I've cut a little notch in the box so the cablet can slide through. 

When I'm hiking though I wrap some clothes or a jacket around my devices and put them in my pack so they don't overheat.


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## sidecross (Feb 24, 2016)

I am not sure if I posted these two links before, but I found the information useful. They are from mjlorton.

https://www.youtube.com/watch?v=MgRloFSeWoE

https://www.youtube.com/watch?v=nNnIZeAaaCk


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## ChrisGarrett (Feb 24, 2016)

keithy said:


> I got one of the Sunkingdom 6.5W high efficiency panels after reading about them here and I'm quite impressed so far. I got this one
> 
> 
> 
> ...



I can't use my Xtar volt/current meter on my 14w Sunkingdom folding panel, either, since the socket faces the wrong way against the flap.

I'm thinking of picking up one of these just to have:

http://www.ebay.com/itm/171960893133?_trksid=p2060353.m1438.l2649&ssPageName=STRK:MEBIDX:IT

HKJ reviews it here and he feels it's acceptable and accurate for current measurement purposes:

http://lygte-info.dk/review/USBmeter KCX-017 UK.html

The short flexible cable should allow for one to rotate the meter 180* and be able to be read it.

Chris


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## TinderBox (UK) (Feb 26, 2016)

I have the Cozypony 24W 4 panel folding, I have an Sunkingdom 5w white, I have an generic 5w folding 3 panel folding, I have an GoalZero 7w 2 panel folding.

Just wish we had more consistent sunshine in the UK, as i often think i have wasted my money, but i have survivalist addiction goes hand in hand with my many many flash-lights.

John.


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## keithy (Feb 27, 2016)

ChrisGarrett said:


> I'm thinking of picking up one of these just to have:
> 
> http://www.ebay.com/itm/171960893133?_trksid=p2060353.m1438.l2649&ssPageName=STRK:MEBIDX:IT
> 
> ...



That does look like it would work, but I have four different USB meters now, since my first post in this thread!

I ordered an "L" shaped USB adapter that I think might do the trick. 

I noticed a weird thing with my 6.5W Sunkingdom panel today. It was working well when I tested it last, but this morning I had it propped up at an angle for the morning sun from about 10am onwards. I had a 5000mAh power pack plugged in, and the light on the power pack was blinking showing it was charging when I checked, but the battery pack was only still on 1 bar (lowest charge) after 5 hours. 

So I'm not sure if it possibly got cloudy briefly, and it stops charging. I'll try a different cable tomorrow and I'll have to pay more attention to it to see if it is reliable enough to take on long hiking trips. 

And further testing of my Blitzwolf 20W panel - I plugged in a 16000mAh Xiaomi batterybank to it this afternoon on a cloudless day. The Xiaomi battery bank usually charges at around 1.8A with my AC USB chargers, but with the Blitzwolf facing the afternoon sun, my USB meters only showed it charging at 0.84A. Not sure why as the other day my phones were getting an output of around 1.8-2.0A plugged into the Blitzwolf. 

I'll have to give them more real world testing. 



TinderBox (UK) said:


> I have the Cozypony 24W 4 panel folding, ...



I'm curious about the CozyPony. The specs say it is around 1.3 pounds (590g) which would mean it is one of the lighter high efficiency panels. Does yours weigh that? or more?

The specs say that it has a "Built-in smart chip: It has unique automatic start function controlled by software.On cloudy days the solar energy stops working, when it become sunny, it does not need to plug any button, would automatically resume work controlled by software."

Have you tested that bit out? Some of my panels don't start up charging again at full rate when cloud briefly covers the panel. 



> but i have survivalist addiction goes hand in hand with my many many flash-lights



That sounds familiar. I have a whole stack of portable solar panels, and still have my first ones from my original foray into portable solar some 14 years ago - these iSun solar power panels which had a 2W output (http://www.pcmag.com/article2/0,2817,16182,00.asp). I got three of them to daisy chain together but they were quite useless in real life (bulky and underpowered).

Then I bought this Coleman Exponent Flex 5 http://www.amazon.com/dp/B00020BM3W/?tag=cpf0b6-20 back in 2005. And unfortunately it was also quite useless in real life. And this was even back before big smartphone batteries. 

It wasn't until I got the second gen Goal Zero Nomad 7W that I found these portable solar charging solutions to be useful. 

And these newer lighter weight "high efficiency" panels like that in my new Sunkingdom and Blitzwolf panels seem to be giving better output for weight.


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## TinderBox (UK) (Feb 27, 2016)

Hi

I just weighed it for you, it weighs 542g not certain what that is in lb/oz

Never really had a chance to try it out (UK weather), it`s most likely a re-brand, and 24w is more likely to be 20w, 5w a panel according to that guy on youtube, any special charging features are most likely marketing the regulator looks the same as other brands though i have not tested the claims.

John.



keithy said:


> I'm curious about the CozyPony. The specs say it is around 1.3 pounds (590g) which would mean it is one of the lighter high efficiency panels. Does yours weigh that? or more?
> 
> The specs say that it has a "Built-in smart chip: It has unique automatic start function controlled by software.On cloudy days the solar energy stops working, when it become sunny, it does not need to plug any button, would automatically resume work controlled by software."
> 
> Have you tested that bit out? Some of my panels don't start up charging again at full rate when cloud briefly covers the panel.


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## keithy (Feb 27, 2016)

TinderBox (UK) said:


> Hi
> 
> I just weighed it for you, it weighs 542g not certain what that is in lb/oz



Cheers John - That seems to be in line with my newer Blitzwolf 20W panel then, so I suspect it is uses the lighter high efficiency type panels. 

Compare that against the Goal Zero 20W panel which weighs over 1.1kg.


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## TinderBox (UK) (Feb 27, 2016)

Yeah, but your Blitzwolf 20W is most likely 15W not 20W, 5W per panel, manufactures exaggerate.

John.


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## keithy (Feb 27, 2016)

TinderBox (UK) said:


> Yeah, but your Blitzwolf 20W is most likely 15W not 20W, 5W per panel, manufactures exaggerate.



How do you figure 15W? The panels are about the same size as the 6.5W Sunkingdom one. The panels are taller than the panels in my Goal Zero 7 and Instapark Mercury 10. And taller than the 5W Sunkingdom panel as well. 

I was guessing that the Blitzwolf was closer to 19W. It advertises that it uses the Sunpower 21.5-23.5% efficiency panel that the Sunkingdom one does as well. So I meant the weight of yours was closer to these higher efficiency panels rather than the older panels like those used in my GZ 7W, Instapark Mercury and GZ 13W. 

I was going to order the Anker 21W http://www.amazon.com/dp/B012YUJJM8/?tag=cpf0b6-20 which appears shares the same design and dimensions and also as the Blitzwolf 20W one I ordered, but at the time I ordered, the Anker wouldn't ship to Australia. 

The Anker 21W has the same size and dimensions as my Blitzwolf panel and is also using the same SunPower solar array of 21.5-23.5% efficiency, but is somehow lighter at 420g - the individual 6.5W panels weighs 190g ea (from http://www.glorysolar.com/products_detail/&productId=94ba6638-defe-411b-a568-03b5695ab416.html) so I'm not sure how it could be that light for a 21W three panel array.


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## TinderBox (UK) (Feb 27, 2016)

Ok, I just mesured my Cozypony 24W panels are 242mm x 128mm Visible and have 11 section and look identical to yours, can you measure the Blitzwolf 20W panels.

John.


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## keithy (Feb 27, 2016)

TinderBox (UK) said:


> Ok, I just mesured my Cozypony 24W panels are 242mm x 128mm Visible and have 11 section and look identical to yours, can you measure the Blitzwolf 20W panels.



The Blitzwolf 20W is 240mm x 125mm and also with 11 sections. So similar to yours. I've only measured from visible panel end to end. 

The Sunkingdom 6.5w is actually a bit larger at 270mm x 125mm with 12 solar sections. The sunkingdom one has an edge boundary but I've only measured from visible panel end to end again. 

So I'm now thinking that the Blitzwolf is closer to 18W (using 3 x 6W panels). 

I wonder how the Anker 21W is so much lighter at 420g. I'll ask someone on Amazon who's bought it if theirs actually weighs that or more.


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## TinderBox (UK) (Feb 27, 2016)

Also it`s better to use your solar panel to charge a power bank, rather than directly to the phone/tablet in case of clouds ect break the charging cycle as some phone have to be reset to resume charging.

I have an Soshine E4S 2x18650 power bank, that has an UPS function meaning it can be charging from an solar panel at the same time it is charging your phone/tablet, I also buy the white version if available as black plastic can soak up the heat and melt, while white plastic reflects heat.

John.


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## ko4nrbs (Feb 28, 2016)

KITROBASKIN said:


> one caveat for the Sunkingdom used in conjunction with the Xtar VC2 charger: If a solid object obscures part of the panel, the Amps will go down drastically, and will not go back to normal after the obstruction has passed (no longer shading the panel) unless one pulls the cells and reinserts. This effect is significantly worse if the shade is blocking part of the panel along the shorter dimension of the rectangular 'array' than if the shade runs the other, longer dimension (but they're both terrible) I used the shade from just the narrow profile of my hand for the obstruction test, about 18 inches away, so the blocking only covered, I would say, less than 10% of the panel. I did not get to observe the effect of uniform cloud shade of varying degrees to see what affect that would have on charging.



Was this a function of the VC2 charger or the Solar Panel?
Bill


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## sidecross (Feb 28, 2016)

ko4nrbs said:


> Was this a function of the VC2 charger or the Solar Panel?
> Bill


As TinderBox(UK) wrote it is better to charge a powerbank; the XTAR chargers use too much current with a lighted screen and LED's


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## ko4nrbs (Feb 28, 2016)

sidecross said:


> As TinderBox(UK) wrote it is better to charge a powerbank; the XTAR chargers use too much current with a lighted screen and LED's


I would use the MC1 Plus with a 5 volt 8 watt panel. 

My application is as follows. I intend to use the charger as not only a charger but also as a cell holder. The cells will be left in the charger to provide external power to a digital camera. The cells will be connected in parallel with the camera. I am expecting the charger to keep the cells charged up as sunshine permits. Everything will be installed in a waterproof case. This will be left in the woods to capture photographs of animals as they wander by.
Thank you,
Bill


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## sidecross (Feb 28, 2016)

ko4nrbs said:


> I would use the MC1 Plus with a 5 volt 8 watt panel.
> 
> My application is as follows. I intend to use the charger as not only a charger but also as a cell holder. The cells will be left in the charger to provide external power to a digital camera. The cells will be connected in parallel with the camera. I am expecting the charger to keep the cells charged up as sunshine permits. Everything will be installed in a waterproof case. This will be left in the woods to capture photographs of animals as they wander by.
> Thank you,
> Bill


Sounds like a good solution for your use. :thumbsup:


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## KITROBASKIN (Feb 28, 2016)

ko4nrbs said:


> Was this a function of the VC2 charger or the Solar Panel?
> Bill



I believe this was a function of the charger, in response to the significant drop in power from the panel. Sorry to say I have not been using the portable solar panels in quite some time, and now that we have a new puppy, it will be some time before I can trust her not to do major damage to them. That, or figure out how to place them beyond her reach.


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