I need to know how to wire up the balance ports when charging series. The batteries will be 2 X 2s with a single bullet connector for balancing, like seen here: (the deans connector is what I use to hook to my charger)





Wiring the main leads is easy, positive from my charger to positive on battery 1, negative from my charger to the negative on battery 2, and a jumper between the negative battery 1 and positive battery 2. Wiring the balance leads is what I don't understand, as one wire from my charge cable goes to a bullet connector on the battery, and the other just goes to the positive cable. When I remove the small white connector that currently connects to the balance board I will need to connect them to a 4s balance connector, but where on the 4s balance connector will they wire to? Also, I'll have 6 wires, seems like too many?

Serial charging is a little tricky. At best only worthwhile with packs at very similar charge states and capacities. Generally parallel charging is safer and frequently faster. To make best use of either requires a suitably powered charger. What charger do you have?

But here are some diagrams that may help. One balance wire is redundant. Suggest double checking everything with a voltmeter, don't assume!



This is for 3S packs but shows the trend:

It's a Passport charger. It'll charge a 4s at 10 amps, and we are currently charging a 7200mah at 10 amps, so I'd like to cut the time in half by charging two of those at the same time, since the charger will still do 10 amps on 4s.

I guess the biggest confusion is that I don't know which wires are redundant or where they would all go on the new balance connector. Currently only one comes from the battery via a dedicated wire (the small bullet in the pic) and the one comes from each of the battery's main power connections.

When I remove the balance connector I will have

White from balance port
red from main positive
black from main negative

and two sets of those since it is two batteries