What is the white plug for on lipo batterys ? My other ? Is will a airtronics caliper 3pls am radio work with a new castel creations speed control. Please help me. I new to this new tecnology

The white plug is a balance lead, you need a lipo charger with a balance board to charge them so no damage is done, if a lipo is under or overcharged bad things can happen. Balancing the cells is the best safe way to charge a battery and keep it in good health

Make sure your radio has a lipo cutoff alarm if you run lipo batteries in it.

If the battery is for a car, make sure you set the low voltage cuttoff in the esc.