max amps to charge a123s?

[t-maxxracer32]

hey just wondering if i can charge my a123s at 10 amps?

if i do will it get the same 4600 mah everytime?

thanks!

[johnrobholmes]

They are pretty resilient cells, so yes you can charge them at 10 amps. They do need to be slow charged every few cycles to keep them in balance too.

[Serum]

people have charged them with 20-40A and they seem to like it.

[BrianG]

Hmm. 7 minutes to charge a 1p pack at 20A. That sounds nice. Just don't expect ANY balancer to do its job at those charge rates as there is no way imbalanced cells can equalize in that time frame...

[johnrobholmes]

I have heard of guys plugging 3s packs into a 12v battery to charge them. Let the heat hit around 150F and they are done. Takes 10min or less.

[Serum]

Look up the HY 5020 E.

There is a movie on youtube of the beast charging A123 cells. It's an intelligent 'power supply'

http://www.youtube.com/watch?v=q-1fb9_V2II

This is it.

Youtube is currently not working at this side of the sea though..

[BrianG]

Originally Posted by johnrobholmes

I have heard of guys plugging 3s packs into a 12v battery to charge them. Let the heat hit around 150F and they are done. Takes 10min or less.

Yeah, I've heard of that too. If it's the same thing I'm thinking of, they rely on the resistance of a long piece of wire to limit the current somewhat. A VERY poor way to do this. Far too unreliable if someone uses a battery or 12v supply that is higher or lower in voltage, or uses different size packs. It would be easy (and safer IMO) to make a simple and proper 10-20A constant-current circuit and just use a temp probe to stop the charge at a certain temp.