2 batts charing on one charger. Wire diagram?

[BrianG]

To charge two packs in series, just use the same type of Y adaptor you'd use to hook two packs to an ESC.

If you do charge two packs in series, they should be the same type, capacity, age, and amount of use. Otherwise, some cells may get a better charge than others and you may actually end up overcharging or undercharging some of them. The same goes for pretty much any battery really. If you use two packs at once, I would treat them as one single pack. Use the both together when running and charging, or charge/use them seperately.