# What's the best 2 or 4 AA mobile USB charger?



## computerpro3 (Feb 13, 2010)

I'm looking something mainly to keep my usb gadgets running in case of an extended power outage or backpacking trip, so it must be reliable. I tried the duracell "My pocket charger" but it's a piece of junk as it requires a total voltage of 2.8V to turn on, meaning it doesn't work with even slightly depleted eneloops. 

I need something that is reliable, takes 2 or 4 AA's (small size is nice for EDC), and that works with nimh rechargables/alkalines/L91 lithium primaries.

What are you guys using?


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## SnowplowTortoise (Feb 13, 2010)

This thread has a bunch of links to various chargers and some discussion:
https://www.candlepowerforums.com/threads/185952

I started a thread about an 18650 version a while ago. I believe there are some links to AA versions in there as well.
https://www.candlepowerforums.com/threads/252259


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## keeftea (Feb 13, 2010)

Tekkeon m1500 and it was only 20 from adorama b/m.


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## Magic Matt (Feb 13, 2010)

computerpro3 said:


> What are you guys using?



A solar panel array, that I made for a grand total of about £2.
http://www.videojug.com/film/how-to-make-a-solar-powered-usb-charger

Using batteries to charge batteries seemed pretty pointless to me, since the circuitry is usually very inefficient.


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## TranceAddict (Feb 14, 2010)

Sanyo Eneloop USB mobile booster or charger, 2 AA


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## NutSAK (Feb 15, 2010)

keeftea said:


> Tekkeon m1500 and it was only 20 from adorama b/m.



I believe you mean MP1550.


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## keeftea (Feb 15, 2010)

NutSAK said:


> I believe you mean MP1550.



Thanks, yep that's the one.


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## computerpro3 (Feb 18, 2010)

I order the eneloop mobile booster. It looks like it's the most reputable option.

I tried using my L91's in the duracell my pocket charger while waiting for the mobile booster to come in, and the batteries got REALLY hot - why does this happen? Will I be able to use L91's in the incoming Sanyo booster?


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## NutSAK (Feb 20, 2010)

Magic Matt said:


> Using batteries to charge batteries seemed pretty pointless to me, since the circuitry is usually very inefficient.



A solar panel charger seems pointless to me when it's dark. In that situation, I'll take the inefficient AA charger over the inoperative solar one.


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## andrewnewman (Feb 20, 2010)

computerpro3 said:


> I order the eneloop mobile booster. It looks like it's the most reputable option.
> 
> I tried using my L91's in the duracell my pocket charger while waiting for the mobile booster to come in, and the batteries got REALLY hot - why does this happen? Will I be able to use L91's in the incoming Sanyo booster?



Ack! I believe you are trying to recharge lithium primaries (L91 batteries). Do not EVER place these in ANY recharger. Seriously. They will heat and vent both flame and toxic fumes. Please PLEASE read up on this. These batteries CANNOT be recharged. Sorry to sound so alarmed but we've had a few too many fires, explosions and "near misses" on CPF of late!!!


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## computerpro3 (Feb 20, 2010)

andrewnewman said:


> Ack! I believe you are trying to recharge lithium primaries (L91 batteries). Do not EVER place these in ANY recharger. Seriously. They will heat and vent both flame and toxic fumes. Please PLEASE read up on this. These batteries CANNOT be recharged. Sorry to sound so alarmed but we've had a few too many fires, explosions and "near misses" on CPF of late!!!



:laughing:

Thanks for your concern, but I'm not that dumb! I'm not trying to charge the batteries, I'm trying to use the L91's in a device designed to put out USB current from AA batteries to charge a cell phone.


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## Mr Happy (Feb 20, 2010)

computerpro3 said:


> Thanks for your concern, but I'm not that dumb! I'm not trying to charge the batteries, I'm trying to use the L91's in a device designed to put out USB current from AA batteries to charge a cell phone.


The USB mobile chargers put a heavy load on AA cells and L91's have a relatively high internal resistance. This causes them to warm up when subjected to sustained high currents.


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## computerpro3 (Feb 20, 2010)

Thanks, that makes sense. Now I ordered the Tekkeon Mp1550 too as I'm concerned about the Sanyo's ability to reliably charge my phone (which sometimes draws MORE than the USB 500ma) with only 2 batteries.

I hate this forum...  So much money gone!


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## JollyRoger (Feb 20, 2010)

http://www.amazon.com/dp/B000XSBVK2/?tag=cpf0b6-20

you can find it cheaper (closer to $20 or $25) sometimes.

It puts out clean USB power. No problems charging my Palm Pre.

I like how it also charges AA and AAA's and has 4 independent charging channels.

a bit bulky, but all-in-one solution. there is a flip out ac prong on the back. you can plug it into the wall and use it to charge the AA or AAA's or use it as a wall USB power source, too.


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## computerpro3 (Feb 22, 2010)

Got my tekkeon, and it appears to work great with eneloops. 

One thing though - it gets wicked hot when charging my phone. Is this normal? It is almost painful to the touch near the usb port.


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## keeftea (Feb 22, 2010)

Mine def does not get wicked hot but warm and i think thats normal.


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## NutSAK (Feb 22, 2010)

Mine also does not get hot, but the temp would probably be dependent on the current draw of the unit you're charging.

I like my Tekkeon MP1550 but, IMO, it should only be used to charge AA batteries in an emergency situation, and with depleted cells.


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## Lynx_Arc (Feb 23, 2010)

JollyRoger said:


> http://www.amazon.com/dp/B000XSBVK2/?tag=cpf0b6-20
> 
> you can find it cheaper (closer to $20 or $25) sometimes.
> 
> ...


I have one of these, the AC plug can be removed completely I use a wallwart on mine instead so it sits flatter and I removed the cover as I don't see a use for it sitting flat on a table.


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## Bones (Feb 23, 2010)

JollyRoger said:


> .
> http://www.amazon.com/Duracell-Charger ... CEF23DX2
> 
> You can find it cheaper (closer to $20 or $25) sometimes.
> ...



Here's a link to the version of the mobile charger that includes 4 pre-charged cells (2xAA & 2xAAA) and the auto-adapter. Prices are currently starting at about 18.00. I found it by searching for CEF23, which is the designation for the base model, and then looking for the DX4N extension (CEF23DX4N):

http://www.amazon.com/Duracell-Charger ... CEF23DX4N



Lynx_Arc said:


> I have one of these, the AC plug can be removed completely I use a wallwart on mine instead so it sits flatter and I removed the cover as I don't see a use for it sitting flat on a table.



For what it's worth, there are indications that chargers that come with covers may actually rely on them to terminate properly:

http://www.candlepowerforums.com ... post3286742

http://www.candlepowerforums.com ... post3070129
.


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## Lynx_Arc (Feb 23, 2010)

Bones said:


> For what it's worth, there are indications that chargers that come with covers may actually rely on them to terminate properly:


I haven't had any problems with termination charging rayovac hybrids and some generic 1600mah nimh cells with the cover off they stay cooler. I read those two threads some and the chargers mentioned were the duracell power gauge and a sanyo charger not the duracell mobile charger. It is possible the charge rates (ma/hr) is different on the chargers maybe lower on the others causing them to charge slower and heat up less.


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## robb01 (Feb 23, 2010)

Bones said:


> Here's a link to the version of the mobile charger that includes 4 pre-charged cells (2xAA & 2xAAA) and the auto-adapter. Prices are currently starting at about 18.00. I found it by searching for CEF23, which is the designation for the base model, and then looking for the DX4N extension (CEF23DX4N):
> 
> http://www.amazon.com/Duracell-Charger ... CEF23DX4N
> 
> ...



Thats the one ive been using, very happy with it


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## MarioJP (Feb 26, 2010)

I wonder if Ni-Zn would benefit. Higher voltage means better efficiency??


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## newbie66 (Jul 7, 2014)

My local dealer just started selling the "Fujitsu Portable Smart Charger" which can:-

- Recharge "Fujitsu Rechargeable" AA and AAA batteries.
- Charge Smartphone & portable devices anytime, anywhere.

Here is the link to the website (scroll down to the 2nd half of the page): http://www.fdk.com/cyber-e/pi_bt_fujitsunimh.html

Has anyone tried it and will 4 high capacity Fujitsu/eneloops (4 X 2450mAh) be able to charge a phone with a 4000mAh Li-Ion cell?


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## AnAppleSnail (Jul 7, 2014)

MarioJP said:


> I wonder if Ni-Zn would benefit. Higher voltage means better efficiency??



Maybe. I can't keep my NiZns healthy. It doesn't help that the factory is closed and all the cells I can find are 'new-in-box' old stock. After several charge cycles, especially if I ever once, for even one night, forget to immediately recharge them, the charger blinks angry red at me. Failed cell again!

In the meantime, I have Eneloops that have been in regular use since about 2008 (With my first real flashlight). I can't tell which ones are the old ones compared to the new ones - Not much change after five years!


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## HKJ (Jul 7, 2014)

AnAppleSnail said:


> Maybe. I can't keep my NiZns healthy. It doesn't help that the factory is closed and all the cells I can find are 'new-in-box' old stock. After several charge cycles, especially if I ever once, for even one night, forget to immediately recharge them, the charger blinks angry red at me. Failed cell again!



Looking in the datasheet for the NiZn cells, I wonder if the problem is over discharge. At lower current they only discharge to 1.3 volt!


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## AnAppleSnail (Jul 7, 2014)

HKJ said:


> Looking in the datasheet for the NiZn cells, I wonder if the problem is over discharge. At lower current they only discharge to 1.3 volt!



That alone would make a stock driver circuit risky!

I have some Duracell-branded thing that holds 4 AA Alkaleak or NiMHs. It puts out 500 mAh for 4 hours, which is decent. I want a way to turn off its obnoxious green LEDs, and it cannot charge its batteries from any source. But it is fairly compact for large, changeable capacity.


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## digiowl (Sep 16, 2014)

newbie66 said:


> My local dealer just started selling the "Fujitsu Portable Smart Charger" which can:-
> 
> - Recharge "Fujitsu Rechargeable" AA and AAA batteries.
> - Charge Smartphone & portable devices anytime, anywhere.
> ...


Looks interesting. Usb charge and discharge. Proper lid. Can even handle alkalines by the looks of it. Now to find a european seller.


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## newbie66 (Sep 19, 2014)

Good luck trying to get it. 

Anyway I got one myself. Charging is a bit slow though for my phone with a 4000mAh battery. I don't have the means to measure the charging voltage or whatnot.


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## newbie66 (Sep 19, 2014)

It can only charge and be charged when all 4 batteries are in it.


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## BloodLust (Sep 19, 2014)

I use a Goal Zero Guide 10 Plus.
You can use the solar panels, 12V or USB to charge it.
Comes with LSD batteries and works with Eneloops.

www.candlepowerforums.com/vb/showthread.php?357771-Goal-Zero-Guide-10-Plus-Adventure-Kit-REVIEW


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## digiowl (Sep 19, 2014)

newbie66 said:


> It can only charge and be charged when all 4 batteries are in it.


I expected the charge limitation, but i thought their site said it had independent channels.


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## newbie66 (Sep 19, 2014)

digiowl said:


> I expected the charge limitation, but i thought their site said it had independent channels.



Ooops sorry. I made a mistake. That is the folly of not properly reading the manual...

Only when used to charge devices it requires 4 batteries. 

When charging batteries it is different. Taken from the manual itself: "This charger can charge 2 or 4 AA rechargeable batteries. When charging only two batteries, place batteries next to each other starting from the right or left charging slot."
The manual also states: "This charger can charge 2AA and 2AAA batteries simultaneously."


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## newbie66 (Sep 19, 2014)

BloodLust said:


> I use a Goal Zero Guide 10 Plus.
> You can use the solar panels, 12V or USB to charge it.
> Comes with LSD batteries and works with Eneloops.
> 
> www.candlepowerforums.com/vb/showthread.php?357771-Goal-Zero-Guide-10-Plus-Adventure-Kit-REVIEW



Cool, but really expensive though...


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## kreisl (Nov 15, 2014)

newbie66 said:


> Ooops sorry. I made a mistake. That is the folly of not properly reading the manual...
> 
> Only when used to charge devices it requires 4 batteries.
> 
> ...



Are you talking about the Fujitsu Portable Smart Charger 4×AA?
Let's be clear and call the 4 battery slots from left to right S1, S2, S3, and S4:



When i want to charge four AA batteries in it, i must insert them in S1&S2&S3&S4. 
When i want to charge two AA batteries in it, i must insert them in either S1&S2 or in S3&S4. Any other configuration (S1&S3, S1&S4, S2&S3, S2&S4) will not work. 
When i want to charge one AA battery in it, it is not possible. For some unknown reason, one must pair up the battery with another one and resort to the situation described in [2]. 
When i want to charge three AA batteries in it, it is not possible. For some unknown reason. 
When i want to use the device as powerbank (for powering/charging my Galaxy smartphone, iPod, iPad), i must insert four AA/AAA batteries at the same time, in S1&S2&S3&S4. As soon as 1 battery is removed and only 3 slots are left occupied, the powerbank will stop working. 
 
Is this description correct and complete?

Then [5.] would indicate that the powerbanking mode makes use of the 4 batteries in some sort of a direct/indirect serial configuration.

Information on the Fujitsu lemme call them PSC-4A and PSC-2A is hard to come by on the WWW. Very hard. From my understanding of the circled percentages and i don't know any Chinese, the PSC-4A provides ~double the amount of capacity than its PSC-2A counterpart. For the output mode, in the PSC-2A the two batteries are linked internally in a serial configuration. Since the PSC-4A can charge "139%" of an iPhone 5 whereas the PSC-2A can charge only "55%", it is a fair assumption that PSC-4A is basically a device with doubled internals of PSC-2A (2s1p), that is two PSC-2A's in parallel if you will, =2s2p. In either device the electronics would boost from 2.4V (=2*1.2V) to the spec'ed 5V.
According to specs, max output current of PSC-2A is 0.5A and max output current of PSC-4A is 1.0A. Sounds logical for 2x(PSC-2A) connected in parallel . Alternatively, the four batteries of the PSC-4A output mode could be connected in series (=4s1p) and all the info from the two Chinese product webpages would still make sense i guess, wouldn't it? If the PSC-4A powerbank doesn't work with 3 batteries at all, then it is likely that the electronics tries to boost from 4.8V (=4*1.2V) to the spec'ed 5V, which would explain the higher efficiency: 139% is more than the double of 55%! 

For the end user, the main decision maker is not the double capacity which the PSC-4A provides but the half amperage which the PSC-2A supplies. The typical modern smartphone draws much more than 0.5A from the USB cable to get charged up. My Galaxy Note3 for example draws ~1.45A current when its LiIon battery is fully depleted. Clearly, the PSC-2A would not be compatible with the Note3: when connected to the depleted Note3, the PSC-2A would do nothing, no charging!

Same applies now to the PSC-4A. No matter if its powerbank internals are linked in a 2s2p or a 4s1p configuration. What matters is the 1.0A max amperage output limitation. 1.0A is still lower than what my Note3 requires/demands at 3% charge level (fully depleted Samsung cell). As long as my Note3 is fully depleted, the PSC-4A would not be able to charge up the smartphone, or i would at least run into some issues with the PSC-4A and or the Note3. Incompatible!

If the above is all true and correct, then I am not wondering, why in practice/RL, AA-powered powerbanks never became long-lasting successful bestsellers. I've been talking to various AA-powerbank manufacturers and they admit that these old technology products (~2010 invented and a short-lived success back then) don't play a role anymore on today's market for various reasons, for example the low/limited amperage they supply, which makes them more and more incompatible with the latest handheld 3.8V devices such as iPad, tablet PC's, bigger smartphones, etc.

(...)

Having said that, i still know an AA-powered powerbank (uses serial configuration 3s1p) which is capable of supplying 1.45A+ at 5V, model name begins with MC and ends with 3000


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## newbie66 (Nov 16, 2014)

kreisl said:


> Are you talking about the Fujitsu Portable Smart Charger 4×AA?
> Let's be clear and call the 4 battery slots from left to right S1, S2, S3, and S4:
> 
> 
> ...




I did try to charge my Lenovo P780(4000mAh battery capacity) with the 4xAA Fujitsu and it does charge although slow compared to the 2.0A wall charger that came with the phone. Haven't tried with alkalines though.


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## digiowl (Nov 16, 2014)

The Fujitsu is rated for 1A, and that depends on them getting the charging spec right. If you don't have a USB voltmeter handy, try installing Battery Monitor Widget from 3c and see what it says about the charger performance.


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## kreisl (Nov 17, 2014)

newbie66 said:


> I did try to charge my Lenovo P780(4000mAh battery capacity) with the 4xAA Fujitsu and it does charge although slow compared to the 2.0A wall charger that came with the phone.


Wow, nice smartphone! Thanks for the info. I did read amazon customer reviews of other 4xAA power banks and they reported problems or issues with devices which _try _to draw higher currents than the output spec/rating, that's how i claimed that the Fujitsu wouldn't be compatible with a (fully depleted) Note3 or Note4.

Btw, there is a primitive quick method of determining the max capacity which a battery pack (input) could possibly supply to your smartphone battery (output), namely through the conservation of energy (or an energy balance):

If you have four AA batteries, then it shall not matter too much if they are connected in 1s4p, 2s2p or 4s1p, their total energy stays the same: four batteries are four batteries. If you know the capacity of one AA battery (e.g. 2000mAh for 1 Eneloop), then you could guesstimate its energy as P=U*I*t=1.2V*2.0A*1h=2.4Wh. Four AA batteries contain 4*2.4Wh=9.6Wh energy. This energy gets transferred to your smartphone battery at 5 or 5.5V:

9.6Wh / 5V = 1.92Ah = 1920mAh

So the very max one could possibly charge up a smartphone battery with is 1920mAh capacity. There are energy losses thru heat dissipation, boost conversion efficiency losses, energy conversion losses in the smartphone battery, etc, and this primitive calculation is a rough thing from the very start. It would be an empirical exercise to find out by how many mAh's (exact number) 4 Eneloop AA's do charge up a 3.8V liion battery within a Samsung Galaxy. After all the losses, it could be 1200, 1400 or 1600mAh, who knows?

Problem is that it is too difficult to measure the capacity of the Samsung battery before and after the energy transfer. The smartphone only shows a percentage number of the battery level, e.g. "3%" for fully depleted, "100%" for fully charged.

Anyway, it is good knowledge that 4 standard Eneloop AA's could not provide more capacity than ~1920mAh to a USB device (iPad, iPod, iPhone).

The Chinese PSC-4A webpage states (i don't know Chinese so i might be wrong hh) that it can charge the Kindle Fire HD 7 (rated: 4400mah) to 43%, the iPad Mini (rated: 4440mAh) to 47%, and the iPhone 5 (rated: 1440mAh) to 139%. When you do your maths (4400*.43, 4440*.47, and 1440*1.39), you're getting an average of ~2000mAh, which is not too far away from my estimated 1920mAh.

Bingo! :thumbsup:


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## newbie66 (Nov 17, 2014)

kreisl said:


> Wow, nice smartphone! Thanks for the info. I did read amazon customer reviews of other 4xAA power banks and they reported problems or issues with devices which _try _to draw higher currents than the output spec/rating, that's how i claimed that the Fujitsu wouldn't be compatible with a (fully depleted) Note3 or Note4.
> 
> Btw, there is a primitive quick method of determining the max capacity which a battery pack (input) could possibly supply to your smartphone battery (output), namely through the conservation of energy (or an energy balance):
> 
> ...



Thanks! Your explanation is quite technical indeed. I am a bit loss but somehow able to understand a bit on the capacity part.


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## kreisl (Nov 18, 2014)

thx too!

Commercial *2 AA* mobile USB chargers must be a rarity (outside of Japan, ChibiM ) but they do exist, for example the PSC-2A by Fujitsu and the Powerchimp Lite by Powertraveller Ltd. For the product designer the limiting design guideline has to be the typical current which he/she wants to drive through each AA battery, it should be as high as possible but still a reasonable number because AA batteries do not sustain nor maintain high amperage, say 2 or 3 amps, too well, apart from the heat production in the cells. Eneloop/Fujitsu-FDK AA 2000mAh don't have a problem with constant 1 amp, though. So no matter if the batteries are in series (2s1p) or in parallel (1s2p) configuration, the designer would not want to drive over 1 amp through each cell. In a direct parallel configuration, you'd basically have 1 single battery with 1.2V/4000mAh driven at 2 amps; in a direct serial configuration, you'd basically have 1 single battery with 2.4V/2000mAh driven at 1 amp. Doing the maths, both configurations provide the same power: P(parallel) = 1.2V*2.0A = P(serial) = 2.4V*1.0A = 2.4W. And since the output voltage is fixed by spec, namely 5 volts, the output amperage stays the same, namely I(out) = 2.4W/5V = 0.48A = 480mA. If the designer uses Eneloop Pro/XX in the 2 AA mobile USB charger and dares to drive 1.5A through each cell, then the output amperage can't be over 720mA (=2.4V*1.5A/5V). With these simple thoughts, it is safe to claim that you won't find a commercial 2 AA mobile USB charger which provides over 720mA output amperage and that most models will most likely be at ~0.5A, because 0.5A output spec translates to 1.0A current draw from each one of the 2 AA batteries, and 1 amp current draw is a reasonable figure.

See also the FAQs-tab of Powerchimp Lite:







The PSC-2A uses a 2s1p serial configuration afaik (boosts from 2.4V to 5 volts), whereas the Powerchimp Lite uses a 1s2p parallel configuration afaik (boosts from 1.2V to 5 volts). As we have learned in theory, the battery configuration doesn't matter much : output power, output energy, output amperage, output capacity are all directly dependent on the number of AA batteries and not on their configuration. Why? Because output voltage (=5 volts) and AA cell current (=1 amp) can be regarded as design constants in both configurations.

So how much capacity can a 2 AA mobile USB charger provide?

Similar calculation as in my previous post, 1 Eneloop battery has 2000mAh capacity or about 2.4Wh energy, 2 Eneloop batteries then have 4.8Wh, this energy is output at 5 volts, so the output capacity is 960mAh (=4.8Wh/5V) or less, which isn't much at all!

Summary:
2 full Eneloops could provide no more than 960mAh at the USB port, no matter their configuration.
3 full Eneloops could provide no more than 1440mAh at the USB port, no matter their configuration.
4 full Eneloops could provide no more than 1920mAh at the USB port, no matter their configuration.

With these low numbers and restrictions it should be obvious, without further explanations, why it would be practically a technical §$%&/"# to devise a smart 4 AA powerbank which tries to treat each AA cell as individually contributing energy source (e.g.: M1:1.1V, M2:1.3V, M3:1.2V, M4:1.4V, all offline voltages btw) in order to take into account their individual capacity levels and to take advantage of them by boosting from their total set of capacities&voltages and or smartly drawing energy simultaneously from this and that battery, maybe like sort of a "NiMH balance powerbank" hehe; point is, no smart device is smart enough to actually know the exact individual capacity levels beforehand! Clearly, when powerbanking from 4 AA cells, all 4 cells should/must have the identical condition (voltage, remaining capacity) to make any technical sense, no matter whether they are arranged in a 4s1p or 1s4p configuration. And if that so, then the 4s1p configuration (as seen in most/all 4 AA powerbanks on the market!) is the natural preferred solution because of the lower driver current (otherwise 4 amps lol) and better boost conversion efficiency.

Having said that, while the IFA 2014 ad for MC3000 states "Power Bank Function (Li-Ion Battery Only)" and makes it sound like a restriction, in the end it isn't: Whoever has a bunch of fully charged Eneloops and can't employ but them for powerbanking/charging his smartphone, could still use them in the MC3000 with ease for this not recommended task.

Q. May i ask, what is the "not recommended task" please? Sollie, i didn't pay attention. My bad.
A. "Not recommended" is taking 2, 3 or 4 AA batteries as power source for charging or powerbanking your external USB device.

Q. Sorry for bothering, but why again is this not recommended? No maths, just 1 clear sentence, please. TIA
A. In most commercial AA powerbanks the output amperage doesn't suffice for bigger smartphones or tablet-PC's, moreover the output capacity is limited to 2000mAh with 4 Eneloop AA's. Impractical, don't you a?

Q. Well yes i do. S*cks. And what is a bigger smartphone, how big is "bigger"?
A. A USB 5V gadget which tries to draw over 1.0 amp from the USB port..

Q. Any commercial 4 AA powerbank out there which provides 1.5 or 2.0 amps output as drawn from the connected USB device?
A. Hellya the MC3000, with only 3 AA's. However the output capacity limitation still applies due to the law of physics. As i said, it's a not recommended task, no matter how you turn it.

Q. So, give up and move on?
A. I didn't say that. In emergency situations, rugged 2 AA or 4 AA powerbanks could still play a life-saving role. Better than not having any powerbank in da house or on the road!

Q. Could you do a review of an established AA powerbank with empirical tests and data?
A. Lemme get my hands on a good one, first. …

EDIT:
I have 4x Samsung SDI ICR18650-32A (date code 2D92, manufactured Sep-2013) at 3.500V offline voltage. I had used mc3k -0.50A DISCHARGE program with -0.01A D.REDUCE option to produce these cells. I put 2 of the them into two defined slots of TOMO V8-4 powerbank. I filled the Powerchimp with 4x Eneloop AA (BK-3MCCE, Made in Japan) hot off the mc3k charger and connected the TOMO with it and a USB doctor in between.
powerchimp: The process started off with "0.79A" and over "5.50V" (USB doctor). That current seemed to stabilized at "0.74A" at "5.01V".
generic: The process started off with "0.77A" and over "4.97V" (USB doctor). That current seemed to stabilized at "0.74A" at "5.01V".

After some time (d*mn i should have timed it!) the Powerchimp ran out of juice and shut down operation. (The Eneloops were depleted to some low voltage 1.0000V and low energy, but who cares.) The offline voltage of the 2 Samsung cells were X.XXXV and X.XXXV. I discharged both cells in mc3k, again with -0.50A DISCHARGE program with -0.01A D.REDUCE option down to 3.500V, and got XXXXmAh X.XXXWh and XXXXmAh X.XXXWh.

Woah, after ~"1500mAh" transferred, the USB doctor measures "0.22A" (dropping still) and 4.00V, while the Powerchimp indicates a RED LED. I kept the process going in order to queeze all energy possible out of the system, even though the Powerchimp circuitry obviously had dropped out of proper regulation (hence its RED LED!). At this point the TOMO display showed weird behaviour .. because of the low USB-in supply voltage, apparently.

powerchimp: At "3.94V" the USB doctor jumped from "0.05A" to "0.00A", while the Powerchimp-LED and TOMO-display were still showing energy transfer. Since the USB doctor seemingly stopped counting capacity, i removed it from the USB line, at "1562mAh" transferred. This (not very accurate) value we will use for comparison.

( generic: At "3.91V" the USB doctor displayed "0.00A", while the RED LED was off and the TOMO-display was still showing energy transfer. Since the USB doctor seemingly stopped counting capacity, i removed it from the USB line, at "1352mAh" transferred.
Both Samsung had 3.782V offline. )



At "3.87V" the TOMO display stopped the animation.
Both Samsung batteries had 3.792V offline.

powerchimp:
Samsung #1: 742mAh 2.687Wh
Samsung #2: 749mAh 2.717Wh
sum: 1491mAh 5.404Wh (out of "1562mAh" transferred)

generic:
Samsung #1: 639mAh 2.305Wh
Samsung #2: 646mAh 2.333Wh
sum: 1285mAh 4.638Wh (out of "1352mAh" transferred)


next test: 1x Sanyo NCR18650GA (in TOMO) powering the charging of 4x Eneloop AA (in Powerchimp)
"1450mAh" transferred at "0.95A" (USB doctor), then TOMO shuts down because too high current draw from 18650..
total "1580mAh" transferred at "0.30A" USB level, just charging 1x Eneloop AA in Powerchimp. Then Lii-100 shuts down. Sanyo at 3.05V offline voltage.

Eneloop #1: 314mAh 0.383Wh
Eneloop #2: 315mAh 0.380Wh
Eneloop #3: 316mAh 0.384Wh
Eneloop #4: 383mAh 0.470Wh
sum: 1328mAh 1.617Wh

next test: 1x Sanyo NCR18650GA (in Lii500) powering the charging of 1x Eneloop AA (in Powerchimp)
charges with "0.30A" (USB line)
total "1920+9+1mAh" transferred at "0.30A" USB level, just charging 1x Eneloop AA in Powerchimp. Then Lii-100 shuts down. Sanyo at 3.05V offline voltage.
Eneloop #5: 1526mAh 1.913Wh

next test: 1x Sanyo NCR18650GA (in Lii500) powering the charging of 1x Samsung 18650 3.500V (in TOMO)
charges with "0.41A" (USB line) initially
total "1920+9+1mAh" transferred at "0.40A" USB level, just charging 1x Samsung 18650 in TOMO. Then TOMO shuts down.
Sanyo at 3.10V offline voltage, which makes sense.
Samsung #1: 1767mAh 6.538Wh

next test: 1x Sanyo NCR18650GA (in TOMO) powering the charging of 1x Samsung 18650 3.500V (in Lii-500)
charges with ~"0.50A" (USB line) initially
total "1661+1mAh" transferred at ~"0.50A" USB level, just charging 1x Samsung 18650 in Lii-500. Then TOMO shuts down.
Sanyo at 3.25V offline voltage.
Samsung #2: 1586mAh 5.832Wh

next test: 4x Eneloop AA (in Powerchimp) powering the charging of 1x Samsung 18650 3.500V (in Lii-500)
charges with ~"0.50A" (USB line) initially
total "1613mAh" transferred at ~"0.50A" USB level, just charging 1x Samsung 18650 in Lii-500. Then Powerchimp LED goes from green (most of the time) to red (critical level Eneloop near the end) back to green ("0.00A").
Eneloops at <1.10V offline voltage, depleted!
Samsung #3: 1522mAh 5.585Wh

next test: 4x Eneloop AA (in Generic) powering the charging of 1x Samsung 18650 3.500V (in Lii-500)
charges with ~"0.50A" (USB line) initially
total "1542mAh" transferred at ~"0.50A" USB level, just charging 1x Samsung 18650 in Lii-500. Then Liitokala shows 4 LED's ("0.00A").
Eneloops at <0.95V offline voltage, depleted!
Samsung #4: 1452mAh 5.333Wh

next test: BlitzWolf USB 2.4A powering the charging of 4x Eneloop AA (in Powerchimp)powering the charging of 1x Samsung 18650 3.500V (in Lii-500)powering the charging of 1x Samsung 18650 3.500V (in Lii-500)fgfpowering the charging of 1x Samsung 18650 3.500V (in Lii-500)powering the charging of 1x Samsung 18650 3.500V (in Lii-500)powering the charging of 1x Samsung 18650 3.500V (in Lii-500)powering the charging of 1x Samsung 18650 3.500V (in Lii-500)
charges with ~"0.50A" (USB line) initially
charges with ~"1.04A" (USB line) initially
charges with ~"1.01A" (USB line) initially, start 16:19oclock

charges with ~"1.04A" (USB line) initiallycharges with ~"1.04A" (USB line) initially
charges with ~"1.04A" (USB line) initially
"0.16A" current draw after LEDs have turned green (trickle charge?), Eneloop have 1.44xxV
charges with ~"1.00A" (USB line) initially
1.00A 4red0green
0.80A 3red1green
0.75A 3red0green
0.??A 2red1green
0.54A 2red0green
0.32A 1red1green
0.30A 1red0green
0.07A 1green
0.00A 0green
"7801mAh" from BlitzWolf to Powerchimp
Eneloop #1: 1772mAh 2.229Wh
Eneloop #2: 1787mAh 2.238Wh
Eneloop #3: 1785mAh 2.246Wh
Eneloop #4: 1801mAh 2.264Wh
sum: 7145mAh 8.977Wh


next test: 4x Eneloop AA (in Powerchimp) powering the charging of 1x Samsung 18650 3.500V (in TOMO)
charges with "0.42A" (USB line) initially
total "1635mAh" transferred at ~"0.39A" USB level, just charging 1x Samsung 18650 in TOMO. Then Powerchimp LED goes from green (most of the time) to red (critical level Eneloop near the end, "0.05A 4.06V") to blinking red(!, "4.03V") and back to green ("0.00A").
Eneloops at <0.90V offline voltage, i.e. depleted!
Samsung #1: 1506mAh 5.520Wh (starting from 3.916V)


next test: 4x Eneloop AA (in Generic) powering the charging of 1x Samsung 18650 3.500V (in TOMO)
charges with ~"0.40A" (USB line) initially
total "1620mAh" transferred at ~"0.39A" USB level, just charging 1x Samsung 18650 in TOMO. Then Generic's red LED turns off (at ~"1600mAh") and drops out of regulation ("0.00A" at ~"1620mAh") but there is still current draw and TOMO is still on.
Eneloops at 0.87xxV, 0.87xxV, 0.0V, 0.0V offline voltage, crazily depleted! => "2.60V" is where USB doctor shuts off (dark display, gone dead). Samsung had 3.917V.
Eneloops 0.9xV when USB doctor dropped to "0.00A".
Samsung #2: 1486mAh 5.470Wh

next test: 4x NCR18650GA (in TOMO) powering the charging of 4x Eneloop AA (in Powerchimp)
charges with "0.96A" initially
at the end the TOMO shuts down everything, offline voltage 4x 3.148V.
"7290mAh+5+2+1"
Eneloop #1: 1698mAh 2.151Wh (reference value since discharged with -0.10A, not -0.50A)
Eneloop #2: 1633mAh 2.075Wh
Eneloop #3: 1697mAh 2.153Wh
Eneloop #4: 1690mAh 2.149Whsum: 6718mAh 8.528Wh

next test: 4x NCR18650B (in Omni) powering the charging of 4x Samsung 18650 (in TOMO)
charges with "1.53A" (USB doctor) initially, current decreases gradually but stays over "1.40A". total transferred "8400mAh" after 5h54min. Samsung at 4x4.040V.
Samsung #1: 1992mAh 7.417Wh + 35mAh 0.125Wh
Samsung #2: 2038mAh 7.611Wh + 37mAh 0.130Wh
Samsung #3: 1979mAh 7.388Wh + 41mAh 0.144Wh
Samsung #4: 1980mAh 7.367Wh + 34mAh 0.121Wh
sum: mAh Wh

next test: 4x NCR18650B (in Omni, after 7+ days in storage) powering the charging of 4x Samsung 18650 (in TOMO)
charges with "1.50A" (USB doctor) initially, current decreases gradually but stays over "1.37A". total transferred "7849mAh" after xhxxmin. Samsung started at 4x3.500V and ended at 4x3.977V.
Samsung #1: 1823mAh 6.747Wh + mAh Wh
Samsung #2: 1816mAh 6.722Wh + mAh Wh
Samsung #3: 1885mAh 6.960Wh + mAh Wh
Samsung #4: 1856mAh 6.880Wh + mAh Wh
sum: mAh Wh

test1.01: next test: 4x Samsung (in TOMO) being discharged with logging USB Gold at '1.000A', then 'Continue' with '0.20A/0.10A/0.05A'. TOMO lowest acceptable current draw is 0.04A. Then the four cells (4x ~3.098V hot off TOMO) were discharged with D.REDUCE -0.01A to 3.00V CUT VOLT.
Gold measurements: 6561mAh 32.05Wh
D.Reduce mc3k measurements: 5mAh 0.015Wh + 5mAh 0.017Wh + 4mAh 0.014Wh + 19mAh 0.059Wh
mc3k full discharge: 4.20V to 3.00V, also with -0.01A D.REDUCE: (2799+2790+2788+2797)mAh (10.463+10.405+10.422+10.421)Wh = 11174mAh 41.711Wh

test1.02: next test: 4x NCR-GA (in TOMO) being discharged with logging USB Gold at '1.000A', then 'Continue' with '0.05A'. TOMO lowest acceptable current draw is 0.04A. Then the four cells (4x ~3.10V hot off TOMO) were discharged with D.REDUCE -0.01A to 3.00V CUT VOLT.
Gold measurements of TOMO output total: mAh Wh
then D.Reduce mc3k measurements: 76mAh 0.230Wh + 79mAh 0.239Wh + 78mAh 0.235Wh + 77mAh 0.231Wh = 310mAh 0.935Wh
mc3k full discharge: 4.20V to 3.00V, also with -0.01A D.REDUCE: ((3244mAh 11.924Wh + 3236mAh 11.899Wh + 3255mAh 11.969Wh + 3239mAh 11.912Wh = *12974mAh 47.704Wh*))
mc3k full charge was: 3.00V to 4.20V, with 0.01A TERMINATION: ((3263.4mAh 12.632Wh + 3258.1mAh 12.625Wh + 3228.3mAh 12.481Wh + 3256.7mAh 12.615Wh = 13006.5mAh 50.353Wh; 13011mAh 49.892Wh))

test1.03: next test: 4x Samsung (in TOMO) being discharged with logging USB Gold at '2.000A', then 'Continue' with '0.05A'. TOMO lowest acceptable current draw is 0.04A. Then the four cells (4x ~3.098V hot off TOMO) were discharged with D.REDUCE -0.01A to 3.00V CUT VOLT.
Gold measurements: mAh Wh
D.Reduce mc3k measurements:
mc3k full discharge: 4.20V to 3.00V, also with -0.01A D.REDUCE: 2799mAh 10.463Wh + 2790mAh 10.405Wh + 2788mAh 10.422Wh + 2797mAh 10.421Wh = 11163mAh 41.681Wh
(mc3k full charge was: (2830+2837+2744+2806)mAh (11.437+11.469+11.078+11.338)Wh)
(mc3k full charge was: (2800+2809+2734+2794)mAh (11.335+11.334+11.027+11.321)Wh)

test1.04: next test: 4x Samsung (in TOMO) being discharged with logging USB Gold at '2.000A', with no 'Continue'. Then the four cells (4x ~3.590V hot off TOMO) were discharged with D.REDUCE -0.01A to 3.00V CUT VOLT.
Gold measurements: 4903mAh [4903.33333333333] 23.79Wh [23.7927486834731]
D.Reduce mc3k measurements: (483+474+481+447)mAh (1.604+1.584+1.607+1.488)Wh = 1885mAh 6.283Wh
mc3k old full discharge: (2799+2790+2788+2797)mAh (10.463+10.405+10.422+10.421)Wh = 11174mAh 41.711Wh (actual capacity is lower)
capacitive efficiency ≥ 4903/(11174-1885) = 52.8%
power efficiency ≥ 23.79/(41.711-6.283) = 67.15%

test1.05: next test: 4x NCR-GA (in TOMO) being discharged with logging USB Gold at '2.000A', with automatic restarts but no 'Continue'. Then the four cells (4x ~3.3V hot off TOMO) were discharged with D.REDUCE -0.01A to 3.00V CUT VOLT.
Gold measurements: 6248mAh [6248.95347222286] ????Wh [29.0020123290283]
D.Reduce mc3k measurements: (245+273+256+269)mAh (0.753+0.844+0.790+0.830)Wh = 1043mAh 3.217Wh
mc3k new full discharge: (3233+3233+3252+3231)mAh (11.899+11.900+11.969+11.895)Wh = *12949mAh 47.663Wh*
(mc3k full charge: 3268+3271+3223+3258mAh 12.517+12.540+12.332+12.488Wh)
capacitive efficiency = 6248/(12949-1043) = 52.5%
power efficiency = 29.00/(47.663-3.217) = 65.2%


test1.06: next test: 4x NCR-GA (in TOMO) being discharged with logging USB Gold at '2.000A', without automatic restarts and no 'Continue'. Then the four cells (4x ~3.569V hot off TOMO) were discharged with D.REDUCE -0.01A to 3.00V CUT VOLT.
Gold measurements: 4786mAh [4786.111111] 23.30Wh [23.2970944162507]
D.Reduce mc3k measurements: (1035+1031+1019+1054)mAh (3.459+3.445+3.399+3.526)Wh = 4139mAh 13.829Wh
capacitive efficiency = 4786/((12949+12931)/2-4139) = 54.4%
power efficiency = 23.30/((47.663+47.624)/2-13.829) = 68.9%



test1.07: next test: 4x Samsung (in TOMO) being discharged with logging USB Gold at '1.500A', with 'Continue' at 0.50A. 
Gold measurements: mAh Wh

test1.08: next test: 4x NCR-GA (in TOMO) being discharged with logging USB Gold at '0.500A', without automatic restarts and no 'Continue'. Then the four cells (4x ~3.2V cold off TOMO) were discharged with D.REDUCE -0.01A to 3.00V CUT VOLT.
Gold measurements: 7492mAh [7489.16666666667] 38.12Wh [38.11553533]
D.Reduce mc3k measurements: (134+135+138+130)mAh (0.406+0.407+0.417+0.394)Wh = 537mAh 1.624Wh
mc3k new full discharge: (3214+3232+3252+3233)mAh (11.834+11.906+11.974+11.910)Wh = *12931mAh 47.624Wh*
capacitive efficiency: 7492/((12949+12931)/2-537) = 60.4%
power efficiency: 38.12/((47.663+47.624)/2-1.624) = 82.8%

test1.09: next test: 4x NCR-GA (in TOMO) being discharged with logging USB Gold at '1.500A', without automatic restarts and no 'Continue'. Then the four cells (4x ~3.2V cold off TOMO) were discharged with D.REDUCE -0.01A to 3.00V CUT VOLT.
Gold measurements: 6805mAh [6804.1666666666] 33.83Wh [33.8231162037495]
D.Reduce mc3k measurements: (197+191+185+200)mAh (0.601+0.581+0.562+0.610)Wh = 773mAh 2.354Wh
capacitive efficiency: 6805/(12931-773) = 56.0%
power efficiency: 33.83/(47.624-2.354) = 74.7%

test1.10: next test: 4x NCR-GA (in TOMO) being discharged with logging USB Gold at '1.000A', without automatic restarts and no 'Continue'. Then the four cells (4x ~3.2V cold off TOMO) were discharged with D.REDUCE -0.01A to 3.00V CUT VOLT.
Gold measurements: 7205mAh [7205.82361111198] 35.91Wh [35.9063912308317]
D.Reduce mc3k measurements: (171+177+170+168)mAh (0.521+0.537+0.517+0.513)Wh = 686mAh 2.088Wh
capacitive efficiency: 7205/((12931+12899)/2-686) = 58.9%
power efficiency: 35.91/((47.624+47.479)/2-2.088) = 79.0%
mc3k new full discharge: (3221+3223+3242+3213)mAh (11.855+11.866+11.931+11.827)Wh = *12899mAh 47.479Wh*

test1.11: next test: 4x NCR-GA (in TOMO) being discharged with logging USB Gold at '1.750A', without automatic restarts and no 'Continue'. Then the four cells (4x ~3.25V cold off TOMO) were discharged with D.REDUCE -0.01A to 3.00V CUT VOLT.
Gold measurements: 6537mAh [6537.04486111191] 32.20Wh [32.1982975752789]
D.Reduce mc3k measurements: (199+226+226+218)mAh (0.609+0.693+0.696+0.669)Wh = 869mAh 2.667Wh
capacitive efficiency: 6537/(12899-869) = 54.3%
power efficiency: 32.20/(47.479-2.667) = 71.9%

test1.12: next test: 4x NCR-GA (in TOMO) being discharged with logging USB Gold at '2.100A', with automatic restarts and manual 'Continue'. Then the four cells (4x ~3.6V cold off TOMO) were discharged with D.REDUCE -0.01A to 3.00V CUT VOLT.
Gold measurements (corrected): [4430.16027778]mAh [21.3592405754]Wh
D.Reduce mc3k measurements: (1143+1139+1146+1105)mAh (3.841+3.828+3.853+3.709)Wh = 4533mAh 15.231Wh
capacitive efficiency: 4430/((12899+12882)/2-4533) = 53.0%
power efficiency: 21.36/((47.479+47.448)/2-15.231) = 66.3%
mc3k new full discharge: (3210+3212+3237+3223)mAh (11.819+11.837+11.918+11.874)Wh = *12882mAh 47.448Wh*

test1.13: next test: 4x Samsung (in TOMO) being discharged with logging USB Gold at '0.500A', with no 'Continue'. Then the four cells (4x ~3.???V cold off TOMO) were discharged with D.REDUCE -0.01A to 3.00V CUT VOLT.
Gold measurements: 6509mAh [6507.46527777496] 32.97Wh [32.9623039926457]
D.Reduce mc3k measurements: (151+139+133+134)mAh (0.458+0.421+0.405+0.407)Wh = 557mAh 1.691Wh
mc3k old full discharge: (2752+2768+2740+2756)mAh (10.254+10.334+10.229+10.258)Wh = 11016mAh 41.075Wh (actual capacity is higher)
capacitive efficiency: <= 6509/(11016-557) = 62.2%
power efficiency: <= 32.97/(41.075-1.691) = 83.7%

test1.14: next test: 4x NCR-GA (in TOMO) being discharged with logging USB Gold at '0.200A'. Then the four cells (4x ~3.16V cold off TOMO) were discharged with D.REDUCE -0.01A to 3.00V CUT VOLT. COLD ENVIRONMENT.
Gold measurements (corrected): 7214mAh [7214.69333334227] 36.94Wh [36.9323830505564]
D.Reduce mc3k measurements: (109+112+110+106)mAh (0.329+0.337+0.331+0.319)Wh = 437mAh 1.316Wh
capacitive efficiency: 7214/((12840+12882)/2-437) = 58.1%
power efficiency: 36.94/((47.266+47.448)/2-1.316) = 80.2%
mc3k new full discharge: (3200+3209+3218+3213)mAh (11.771+11.820+11.845+11.830)Wh = 12840mAh 47.266Wh

test1.15: next test: 4x NCR-GA (in TOMO) being discharged with logging USB Gold at '0.350A'. Then the four cells (4x ~3.19V cold off TOMO) were discharged with D.REDUCE -0.01A to 3.00V CUT VOLT. COLD ENVIRONMENT.
Gold measurements: 7391mAh [7388.2472222191] 37.63Wh [37.6052995594571]
D.Reduce mc3k measurements: (126+131+128+124)mAh (0.383+0.398+0.390+0.377)Wh = 509mAh 1.548Wh
capacitive efficiency: 7391/(12840-509) = 59.9%
power efficiency: 37.63/(47.266-1.548) = 82.3%
mc3k new full discharge: 

For NCR-GA in TOMO without automatic restarts and no 'Continue' we have:
for capacitive efficiency: {{0.2,58.1},{0.35,59.9},{0.5,60.4},{1.0,58.9},{1.5,56.0},{1.75,54.3},{2.0,54.4},{2.1,53.0}}
for power efficiency: {{0.2,80.2},{0.35,82.3},{0.5,82.8},{1.0,79.0},{1.5,74.7},{1.75,71.9},{2.0,68.9},{2.1,66.3}}fs

test5.02: next test: 4x NCR-GA (in VP4PLUS) being discharged with logging USB Gold at '1.000A'. Then the four cells (4x ~3.0V hot off VP4PLUS) were discharged with D.REDUCE -0.01A to 3.00V CUT VOLT. WARM ENVIRONMENT.
Gold measurements: 7142mAh 35.79Wh 
D.Reduce mc3k measurements: (51+26+32+40)mAh (0.154+0.078+0.097+0.122)Wh = 149mAh 0.451Wh
capacitive efficiency: 7142/((12840+12867)/2-149) = 56.2
power efficiency: 35.79/((47.266+47.353)/2-0.451) = 76.4
mc3k new full discharge: skipped, not done.

test5.03: next test: 4x NCR-GA (in VP4PLUS) being discharged with logging USB Gold at '2.400A'. Then the four cells (4x ~3.1V hot off VP4PLUS) were discharged with D.REDUCE -0.01A to 3.00V CUT VOLT. WARM ENVIRONMENT.
Gold measurements: 6610mAh 32.16Wh 
D.Reduce mc3k measurements: (107+99+254+153)mAh (0.324+0.300+0.784+0.465)Wh = 613mAh 1.873Wh
capacitive efficiency: 6610/((12840+12867)/2-613) = 54.0%
power efficiency: 32.16/((47.266+47.353)/2-1.873) = 70.8%
mc3k new full discharge (ordered): (3208+3229+3215+3215)mAh (11.810+11.884+11.830+11.829)Wh = 12867mAh 47.353Wh

test5.04: next test: 4x NCR-GA (in VP4PLUS) charging XIAOMI, then being discharged with logging USB Gold at '1.000A'. Then the four cells (4x ~3.0V "hot" off VP4PLUS) were discharged with D.REDUCE -0.01A to 3.00V CUT VOLT. WARM ENVIRONMENT.
Gold measurements: 
D.Reduce mc3k measurements: (21+40+14+27)mAh (0.063+0.122+0.043+0.081)Wh = 102mAh 0.309Wh
capacitive efficiency:
power efficiency: 
mc3k new full discharge (ordered):

test5.05: next test: 4x NCR-GA (in VP4PLUS) being discharged with logging USB Gold at '0.500A'. Then the four cells (4x ~3.0V cold off VP4PLUS) were discharged with D.REDUCE -0.01A to 3.00V CUT VOLT. WARM ENVIRONMENT.
Gold measurements: 
D.Reduce mc3k measurements: (14+10+13+10)mAh (0.043+0.031+0.041+0.032)Wh = 47mAh 0.147Wh
capacitive efficiency: 
power efficiency: 
mc3k new full discharge: skipped, not done.

test5.06: next test: 4x NCR-GA (in VP4PLUS) being discharged with logging USB Gold at '1.500A'. Then the four cells (4x ~3.1V cold off VP4PLUS) were discharged with D.REDUCE -0.01A to 3.00V CUT VOLT. WARM ENVIRONMENT.
Gold measurements: 7093mAh 35.12Wh
D.Reduce mc3k measurements: (35+56+68+26)mAh (0.107+0.168+0.205+0.078)Wh
capacitive efficiency: 
power efficiency: 
mc3k new full discharge: skipped, not done.

test5.07: next test: 4x NCR-GA (in VP4PLUS) being discharged with logging USB Gold at '0.750A'. Then the four cells (4x ~3.1V cold off VP4PLUS) were discharged with D.REDUCE -0.01A to 3.00V CUT VOLT. WARM ENVIRONMENT.
Gold measurements: 7038mAh 35.46Wh
D.Reduce mc3k measurements: (21+12+10+17)mAh (0.065+0.036+0.032+0.053)Wh
capacitive efficiency: 
power efficiency: 
mc3k new full discharge: skipped, not done.

test5.08: next test: 4x NCR-GA (in VP4PLUS) being discharged with logging USB Gold at '0.500A'. Then the four cells (4x ~3.1V cold off VP4PLUS) were discharged with D.REDUCE -0.01A to 3.00V CUT VOLT. WARM ENVIRONMENT.
Gold measurements: 6725mAh 34.04Wh
D.Reduce mc3k measurements: (6+10+11+6)mAh (0.020+0.031+0.034+0.018)Wh = 33mAh 0.103Wh
capacitive efficiency: 
power efficiency: 
mc3k new full discharge (ordered after cell no. not slot no.): (3210+3199+3198+3185)mAh (11.826+11.790+11.791+11.730)Wh = *12792mAh 47.137Wh

*test5.09: next test: 4x NCR-GA (in VP4PLUS) being discharged with logging USB Gold at '2.000A'. Then the four cells (4x ~3.2V cold off VP4PLUS) were discharged with D.REDUCE -0.01A to 3.00V CUT VOLT. WARM ENVIRONMENT.
Gold measurements: 
D.Reduce mc3k measurements: (81+62+25+31)mAh (0.247+0.187+0.077+0.094)Wh = 199mAh 0.605Wh
capacitive efficiency: 
power efficiency: 
mc3k new full discharge: skipped, not done.

test5.10: next test: 4x NCR-GA (in VP4PLUS) being discharged with logging USB Gold at '1.250A'. Then the four cells (4x ~3.1V cold off VP4PLUS) were discharged with D.REDUCE -0.01A to 3.00V CUT VOLT. WARM ENVIRONMENT.
Gold measurements: 7134mAh 35.46Wh
D.Reduce mc3k measurements: (46+35+19+23)mAh (0.140+0.106+0.057+0.071)Wh = 123mAh 0.374Wh
capacitive efficiency: 
power efficiency: 
mc3k new full discharge: skipped, not done.

test5.11: next test: 4x NCR-GA (in VP4PLUS) being discharged with logging USB Gold at '1.750A'. Then the four cells (4x ~3.1V cold off VP4PLUS) were discharged with D.REDUCE -0.01A to 3.00V CUT VOLT. WARM ENVIRONMENT.
Gold measurements: 7013mAh 34.51Wh
D.Reduce mc3k measurements: (75+59+27+34)mAh (0.228+0.179+0.081+0.105)Wh = 195mAh 0.593Wh
capacitive efficiency: 
power efficiency: 
mc3k new full discharge: skipped, not done.


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## newbie66 (Nov 20, 2014)

Wow! Another detailed explanation. Thanks again! I plan to only use the AA powerbank for emergencies only since as you explained it can't provide much capacity to the phone. It is nice tp have options.


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## MarioJP (Nov 20, 2014)

This is a interesting thread. I use AA powerbanks to charge my phone. Sure I could of switch to li-ion bank, but just find AA's are too convenient. Also li-ion degrade quite quickly after heavy use, and they cut off point gets shorter. Thats just my opinion.


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