Where to Get a Welder for Batteries?

There is one here that may be suitable.

http://www.powerstream.com/

I presume you mean weld nickle tabs on to coin cells and or stacks of cells??. Try pin welding manufacturers.

You could make your own easily with low voltage capacitive discharge circuit designed for the power range required.

We are a small company locate in Richmond Hill, Ontario, Canada that do battery pack, may be we could help. Please send us the info.

www.comparcorporation.com

Guest, I don't know where you are located, but in california there is a company called Calfornia Lasers located in Simi Vally who will custom designs laser welding solutions. The email is Arthur@californialasers.com. Good Luck