Using 4 rechargable Li-po AA batteries

[Ganreizu]

9200 mAh...

[Spleen21]

Haha.

They were cheap ebay jobbies just for testing. Doubt they're anywhere near that much. In fact, i can't even get them to charge past 4.050v.

Since it all seems to be working, i'm now on the lookout for some decent quality ones.

[SidSilver]

Interesting and very nice

[smoki86]

@spleen21
Wow, that looks great and pretty much what I was going for.
What is your guess on safety if you randomly reorder/replace single cells?
I want to join the pack together at the bottom so it can only be replaced at once.

[Spleen21]

Im pretty new to using and charging batteries in this way but i have been doing some reading.
It seems to me that adafruits warning to never ever charge lithium batteries in parallel is perhaps aimed more at "the lowest common denominator". It's their disclaimer. The people who would take no precautions when using a type of battery tthat is well known to be fickel.
Other reads suggest that taking precautions and using common sense shouldnt be a problem.
I personally would never swap out a single li-ion battery from this arrangement for another. Get 4 batteries, preferably from the same batch, charge each one on its own until full then keep those same 4 together for good. Soldering/welding them together solves that problem! If you need to swap 1 battery......swap all 4 for a whole other group of matched 4. Never mix them once matched.
Im certainly going to be paying close attention to mine. Ill be monitoring temperature and charge of each battery, for the first few charges in particular.
Im going to treat them like theyre trying to burn my house down until i grow some confidence in them. Especially for a grand total of $4 from china!

[day]

not sure which/where you bought, but got these :
http://www.ebay.fr/itm/361370008315
waiting to receive them and see what to do with them.
how do u evaluate your setup in terms of risk ?
also, how did you change the arrangement from series to parallel ? thanks for any help/advices

[Spleen21]

Those are the same batteries i got. Don't expect wonders from them though. You get what you pay for. I only bought them to prove my setup would work. Once i'm finished ill look for some decent ones.

I cut the battery terminals in half and soldered the positives and negatives in 2's. All negatives along the bottom, all positives along the top. Then all the positives are connected together and all the negatives are connected. One negative wire and one positive wire each go to the protection circuit. You can see this in the photos i posted.

Other than the normal risks associated with Lithium batteries, the only risk i see is if you were to lend it to your 8 yr old cousin and the batteries went flat and he tried to put some normal alkalines in it without knowing. So long as its only you using it and you keep the batteries balanced i can't see it being a problem. Don't forget though, I'm no expert. Just going off what i've read on the interwebs.

If anyone out there who knows about this stuff has any suggestions, please.......I'm all ears!

[day]

thanks for the details, the pictures and everything
appreciate it !

I would have a protection board to it to prevent overcharging
and I also plan on having a battery level indicator anyway
but being able to use the batteries without soldering them is a relief.

have you tried to see how many mAh can they deliver ? I am asking because you are saying "don't except wonders from them".

also, when you say "keeping them balanced", how would you do that ? by always charging them together to full ?

[Spleen21]

Although the sticker says 2300 mAh each, even once fully charged the powerboost starts showing low battery as soon as the pi is under load. I'm using Popcorns battery monitor script which automatically shuts down the pi.
I have no problems when using a 2000 mAh pack from adafruit. It lasts a good 1.5 - 2 hrs before any low batt indication which is what i would expect.

[jeffy1021]

Most of the 14500 batteries I've looked at are rated between 750 and 900 mah. Some even have protection circuits built into the individual cells themselves. But if you are connecting 4 in parallel, it probably makes more sense to use a single protection circuit for the group.

http://www.batteryjunction.com/14500-category.html