How to charge/balance two TrakPower's

[BrianG]

Basically, you hook up a balancer to each pack, and then the inputs to the balancers are tied in parallel and then to the charger. Like FP said, you have to make SURE that each pack is at the same charge level, has seen the same number of cycles, etc. This is because if there is ANY difference in voltage between the two pack, you're gonna get a high current spark until they equalize to each other.

So, it would be MUCH better IMO to make a Y adaptor to charge both packs in series using a single 4s+ balancer.