I have a 12v 30w solar panel. I don't mind charging one 14500 cell at a time if I have to since this is for camping where you have plenty of time for such things. If such a device that can accept solar power already exists, please let me know, but my search efforts are exhausted for naught. I thought about just connecting my xtar charger straight to the panel since it accepts 12v at 2 amps but the concern of over voltage and lack of power made me rethink. isn't there some sort of cheap regulator or something that doesn't steal all my power?
Solar charging 14500 Li-Ion batteries. Best option?
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Timothybil
Flashlight Enthusiast
Does your solar panel have the option of outputting at USB levels? If it does, there are several very good chargers like the Xtar VC4 that run off of USB ports. If I remember correctly, the Nitecore I4 charger has a 12v input so that is an option. But I don't know how it would behave with a varying input voltage.
Does your solar panel have a regulator to output the 12v, or does it really put out like 18v and depend on a charge controller to do the regulation?
ChrisGarrett
Flashlight Enthusiast
With anything over 20w, you really need a 12v digital charge controller, like my Morningstar SS-10-L, that charges/powers a battery and/or a 12vdc load.
I have an older Xtar WP2 II 12vdc charger that does 500mA and 1A, so that works with my 12v solar panels (2x30w). Personally, I'd look for a Anker PowerPort 21w USB folder and something like an Xtar Hummingbird XP-1 NiMH/li-ion single bay charger for <$10 and go that route. It doesn't accept anything larger than an AA/14500, but it has two rates of 250mA and 500mA, so it's good for the smaller cells.
Chris
IonicBond
Enlightened
Chris has it right. For camping purposes, a smaller Morningstar 4.5a Sunguard controller would do fine with your 30 watt panel, especially because it is all sealed and potted. No adjustments.
Grab a small agm, like 5 to 7ah size as your intermediary load to charge, and at the same time use a 12v li-ion charger attached to that.
Like most controllers, attach the battery to the controller first, and the panel last. This allows the controller to get it's brain together first. If you attach the panel first, and the battery last, many controllers not knowing the difference between a dead 0 volt battery, and one that is missing entirely as you put the system together may either refuse to charge, or go into a float-only safe mode. So batt first, panel last. And of course attach your li-ion charger to the agm battery once that's all together.
Now you have a stable source of power for the charger. When clouds or other obstructions pass over the panel, the li-ion charger doesn't know any difference.
If the 14500's are LiFeP04 chemistry (3.2v nominal, not the 3.6v nominal of other types), a smaller setup like a folding panel with a 5v usb output to a SunJack AA/lifepo4 charger works too. BUT, you have to babysit the charger, since any obstruction to direct sunlight may make the charger reset, and in some cases stop charging altogether and error-out, requiring a reinsertion of the batteries. Make note of the beveled side of the micro-usb jack - it's not too apparent and if you push it in the wrong way, you can damage the jack. On mine, the smaller beveled side of the jack is facing down.
I charge 14500 lifepo4's as a goof this way. Not a serious setup, but it works. And, the low 300ma output per cell (if you're lucky) is just too slow for most AA nimh, but I guess if you have no other option ....
Grab a small agm, like 5 to 7ah size as your intermediary load to charge, and at the same time use a 12v li-ion charger attached to that.
Like most controllers, attach the battery to the controller first, and the panel last. This allows the controller to get it's brain together first. If you attach the panel first, and the battery last, many controllers not knowing the difference between a dead 0 volt battery, and one that is missing entirely as you put the system together may either refuse to charge, or go into a float-only safe mode. So batt first, panel last. And of course attach your li-ion charger to the agm battery once that's all together.
Now you have a stable source of power for the charger. When clouds or other obstructions pass over the panel, the li-ion charger doesn't know any difference.
If the 14500's are LiFeP04 chemistry (3.2v nominal, not the 3.6v nominal of other types), a smaller setup like a folding panel with a 5v usb output to a SunJack AA/lifepo4 charger works too. BUT, you have to babysit the charger, since any obstruction to direct sunlight may make the charger reset, and in some cases stop charging altogether and error-out, requiring a reinsertion of the batteries. Make note of the beveled side of the micro-usb jack - it's not too apparent and if you push it in the wrong way, you can damage the jack. On mine, the smaller beveled side of the jack is facing down.
I charge 14500 lifepo4's as a goof this way. Not a serious setup, but it works. And, the low 300ma output per cell (if you're lucky) is just too slow for most AA nimh, but I guess if you have no other option ....
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ChrisGarrett
Flashlight Enthusiast
IonicBond
Enlightened
Thanks - I learned most of my li-ion stuff from CPF'ers, so we're even! 
Just to be complete without turning it into a lead-acid thread - with the Morningstar Sunguard, it run a very conservative absorb voltage of 14.1v, which is ok for a sealed gel, but not really for a sealed agm. To do agm right, it needs to see 14.4 to 14.7v absorb.
So in this case the small sealed AGM with the Sunguard is kind of sacrificial. It won't last as long as it would on the SunSaver with it's voltage jumpers. "Sealed", on the Sunsaver is also conservative, designed for gel, and not agm. If the longest life is desired for a true agm, then remove the jumper on the Sunsaver, and run with the "flooded" voltage, which is about 14.4v.
So just a tip for lurkers not to blindly use the silk-screen jumpers without checking the actual voltages used first, and use what is actually appropriate.
The other tip is that despite how fast we may want to charge lead-acid, it takes 8-16 hours of float to *truly* recharge that last 1 percent of an agm. There is no way to hurry that up for most people. A luxury we don't have with most solar setups since the sun doesn't stay up that long. So be sure to give the batt plenty of float time, even though it may be a ridiculously low amount of current compared to overall panel output. Hard to do in a daily cyclic-discharge scenario, but just try your best.
It's really funny how too long a time spent getting that last 1 percent of li-ion recharged to full is actually detrimental, whereas with lead-acid agm's, it is beneficial to give the batt a long period of float charge to get that last 1 percent in - otherwise you walk it down in capacity from sulfation over the long run.
I always found that difference fascinating.
Just to be complete without turning it into a lead-acid thread - with the Morningstar Sunguard, it run a very conservative absorb voltage of 14.1v, which is ok for a sealed gel, but not really for a sealed agm. To do agm right, it needs to see 14.4 to 14.7v absorb.
So in this case the small sealed AGM with the Sunguard is kind of sacrificial. It won't last as long as it would on the SunSaver with it's voltage jumpers. "Sealed", on the Sunsaver is also conservative, designed for gel, and not agm. If the longest life is desired for a true agm, then remove the jumper on the Sunsaver, and run with the "flooded" voltage, which is about 14.4v.
So just a tip for lurkers not to blindly use the silk-screen jumpers without checking the actual voltages used first, and use what is actually appropriate.
The other tip is that despite how fast we may want to charge lead-acid, it takes 8-16 hours of float to *truly* recharge that last 1 percent of an agm. There is no way to hurry that up for most people. A luxury we don't have with most solar setups since the sun doesn't stay up that long. So be sure to give the batt plenty of float time, even though it may be a ridiculously low amount of current compared to overall panel output. Hard to do in a daily cyclic-discharge scenario, but just try your best.
It's really funny how too long a time spent getting that last 1 percent of li-ion recharged to full is actually detrimental, whereas with lead-acid agm's, it is beneficial to give the batt a long period of float charge to get that last 1 percent in - otherwise you walk it down in capacity from sulfation over the long run.
I always found that difference fascinating.
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There are many radical differences due to the very different chemistries. Another major difference is that you don't gain much using shallow cycles for lead-acid, but for Li-ion you can get 10x or more equivalent full cycles (or lifetime total Ah), e.g. see this post for some graphs.
There are many radical differences due to the very different chemistries. Another major difference is that you don't gain much using shallow cycles for lead-acid, but for Li-ion you can get 10x or more equivalent full cycles (or total lifetime Ah), e.g. see this post for some graphs (see esp, the dramatic Wohler curves at the end of that post).
IonicBond
Enlightened
As a total goof, I'm going to try a LiitoKala charger with a 5v usb input and see how that goes. Supposedly handles the typical fold-out portable panels. For nimh, 3.2v and 3.6v nominal li-ion chemistries too.
We'll see how well that goes when I walk in front of the panel.
Yep - shallow cycling is bad for lead-acid too. Unless one draws at least 5 - 10 percent of the capacity, the natural sulfation process during discharge is not spread out evenly and hot-spots develop.
Nice charts - the takeaway from that is to center your usage for best longevity, rather than keep cells full and shallow cycle from 100%.
The problem for me was that with total over the board care of my huge LiFep04's, I outlived the cycle-life. That is, after about 8 years, they aged faster than I could cycle them.
We'll see how well that goes when I walk in front of the panel.
Yep - shallow cycling is bad for lead-acid too. Unless one draws at least 5 - 10 percent of the capacity, the natural sulfation process during discharge is not spread out evenly and hot-spots develop.
Nice charts - the takeaway from that is to center your usage for best longevity, rather than keep cells full and shallow cycle from 100%.
The problem for me was that with total over the board care of my huge LiFep04's, I outlived the cycle-life. That is, after about 8 years, they aged faster than I could cycle them.
The linked graphs show that shallower cycles do improve total lifetime Ah for the lead-acid batteries tested there, but the gains are very small: max 20% (vs. 420% for Li-ion, and up to 1700% in the 2nd study).
IonicBond
Enlightened
** CAUTION ***
One thing I forgot to mention when using an intermediary lead-acid battery when using these charger is to be mindful of the tolerance rating of the 12v input to the charger.
Many devices have a 15% + / - tolerance in regards to their 12v input. IF the charger is truly designed for 12v, and not a typical mobile voltage of 13.8v you may end up cooking the charger when the lead-acid enters the CV phase.
That is, the typical "absorb" or CV phase of a solar charger is set to something to anywhere from 14.1v to the more common 14.4 - 14.6v.
If the charger truly wants to see 12v at the input, then a 15% higher rating means it will accept up to 13.8v max. Most of the time this is just on the highest edge. However, if that solar controller has an absorb voltage setting of 14.4v, and eventually enters that phase, then you may go over-voltage on the li-ion charger.
If the dc "12v input" of the charger is TRULY designed for 13.8v, then you have some leeway to almost 15.87v for the charger input, and it will not be damaged when / if the panel does actually reach the higher 14.x absorb voltages.
This problem can sneak up on you if you always have a very discharged lead-acid, and a high-current load from a full bay of discharged li-ions. But given enough time, or a large enough panel, along with a charger that is truly designed for 12v, then you may smoke the charger with over-voltage eventually.
Soo .. if one absolutely must do this, and cannot verify if the li-ion charger is designed for 12v or 13.8v initially, then set the solar charge controller to a low absorb voltage, like 14.1v. Even better would be to set it for "float only", and although you won't efficiently charge the lead-acid, you'll be pretty sure of protecting the voltage input of the li-ion charger.
Just things to be mindful of when shoe-horning two products together via solar. It can be done, but don't be caught off guard by a "gotcha".
One thing I forgot to mention when using an intermediary lead-acid battery when using these charger is to be mindful of the tolerance rating of the 12v input to the charger.
Many devices have a 15% + / - tolerance in regards to their 12v input. IF the charger is truly designed for 12v, and not a typical mobile voltage of 13.8v you may end up cooking the charger when the lead-acid enters the CV phase.
That is, the typical "absorb" or CV phase of a solar charger is set to something to anywhere from 14.1v to the more common 14.4 - 14.6v.
If the charger truly wants to see 12v at the input, then a 15% higher rating means it will accept up to 13.8v max. Most of the time this is just on the highest edge. However, if that solar controller has an absorb voltage setting of 14.4v, and eventually enters that phase, then you may go over-voltage on the li-ion charger.
If the dc "12v input" of the charger is TRULY designed for 13.8v, then you have some leeway to almost 15.87v for the charger input, and it will not be damaged when / if the panel does actually reach the higher 14.x absorb voltages.
This problem can sneak up on you if you always have a very discharged lead-acid, and a high-current load from a full bay of discharged li-ions. But given enough time, or a large enough panel, along with a charger that is truly designed for 12v, then you may smoke the charger with over-voltage eventually.
Soo .. if one absolutely must do this, and cannot verify if the li-ion charger is designed for 12v or 13.8v initially, then set the solar charge controller to a low absorb voltage, like 14.1v. Even better would be to set it for "float only", and although you won't efficiently charge the lead-acid, you'll be pretty sure of protecting the voltage input of the li-ion charger.
Just things to be mindful of when shoe-horning two products together via solar. It can be done, but don't be caught off guard by a "gotcha".
StorminMatt
Flashlight Enthusiast
Power banks are notoriously inefficient. You maybe get out 60-70% of what you put into them. This isn't a problem when you are using mains power. But these kinds of losses become VERY significant with a portable solar charger (ie charging a 600mah 14500 becomes a whole lot more like charging a 1000mah cell). Therefore, power banks should only be used when absolutely necessary or as a means of storing excess charge for nighttime use. In any case, you can get DC-DC converters of various types VERY cheaply these days. You shouldn't have any problems finding something that will give you a steady 12V output for a few dollars. You can also get USB power supplies that accept varying input voltages up to around 20-25V for maybe $2 or less. You can then use this to power a USB charger.
In any case, 14500s are actually REALLY easy to charge with a small solar panel. From my experience, a small panel capable of around 1A and a small, simple USB charger (like the XTAR MC2) is all you really need. With this simple combination, you can completely charge two completely drained 14500s in less than two hours (provided you have good sun). This combination can also be quite lightweight, and is good for backpacking.
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mjgillen
Newly Enlightened
I don't mean to steal this thread so just let me know if I should start my own however my questions are pretty much in line so here goes:
I want to create a Solar setup that I can charge my batteries with energy harvested from the sun. I have no equipment right now and have never done solar however this is what I am thinking:
With that setup I am hoping to be able to use the deep cycle battery to power my battery charger, amateur radio setup, etc., all using "free" energy from the Solar panel.
Thoughts appreciated.
Michael
I want to create a Solar setup that I can charge my batteries with energy harvested from the sun. I have no equipment right now and have never done solar however this is what I am thinking:
- 30w 12v solar panel (recommendations appreciated - have no clue which brand, is 30w enough? etc.)
- charge controller (recommendations appreciated)
- deep cycle battery - was thinking about a Gel Cell 100AH however also looking for recommendations
- battery charger: was thinking about the SkyRC MC3000 charger connected to the deep cycle battery to charge my various rechargeable batteries (all round cells), a couple of power banks (for the cell phones) etc.
With that setup I am hoping to be able to use the deep cycle battery to power my battery charger, amateur radio setup, etc., all using "free" energy from the Solar panel.
Thoughts appreciated.
Michael
once you get 12v output you can buy 12v USB car adapters that can take 12-24v input. I've seen people saying that some can take 28v input. You can then use any USB device including a lithium ion/nimh charger. I bought 2 of these online for $10 on sale that support QC3.0 fast charging also a $3 circuit board that supports QC3.0 with on board USB port.
