Does anyone know who builds battery packs? I have a couple A123
Nano phosphate battery packs that i want to get the cells out and have made for my Slash... Any advice out there on that ?

Also are there generic chargers that will charge any Nano batteries ???

about 1/2 of all lithum chargers out there will do LiFe(a123) batts

buy a 40+watt IRON and some battery bars and make your own pack

Do I have to balance the cells or anything ?

What kind of charger would i use?

Its a little more involved than that. The cells are constructed diff - the pos is the full metal end and the end with the blue insulator is neg. They make special bars for these (I've only seen them in a plane shop out of Japan) due to the way the cell ends are made, but most use soldering braid. The cells do need to be balanced - the Dewalt pacs I harvested had a balancer builtin to the pac.

Most modern chargers will charge a123s - they usually call it LiFePO4 or LiFe - its the same thing.

http://www.youtube.com/watch?v=qMGu6y6RCGA