Balancing while charging multiple batts is the problem. Its possible to have a short through a balance connector rigged for multiple batteries. I don't know of any balancer that comes setup to do multiple batts - chargers - yes, but not a separate standalone balancer.

Series charging of multiple batts is also an option and it requires a serial type balance connector.This is a good reference on charging in parallel and has a pretty clear breadboard type multiple balance connector shown.



http://www.rchelicopterfun.com/paral...-charging.html