Charging 12v Nihm

[Packhorse]

I am thinking of building another battery pack for my Mag light head using 20 or 30 A size Nihm 2500ma batterys to get 5000ma or 7500ma at 12v
How would I charge this? I asume a SLA charger is not the best.
I have a multi voltage charger for my Panasonic drill that charges its battery packs in 20-30 min. But I think it has a temp sensor in the battery pack.
Any problems using so many batterys?
I could use 10 C batterys but 30 A batterys give me more current and are cheaper.

 

[bradshsi]

I'm thinking that having 2 or 3 stacks of cells in parallel isn't too good an idea. NiMH are already hard to charge as it is. With multiple stacks you are likely to get mismatch in the charging. Plus you should use a temp sensor when charging, so which stack would you attach it to ?

A look at batteryspace, gives me a price of $51 for 20 A cells @2100 mAh which you'll need to assemble yourself. However for $30 you can buy 10 C cells @5000 mAh (again self assembly).

Alternatively you can get a prebuilt 14.4 volt pack (to overvolt your light) for $49. (I use this pack in my light).

So in summary I'm not sure that A cells are cheaper or as practical.

Hope this helps