Dont do this at home. I just bought a board to charge multi batteries at the same time. I loaded in 2 2200 3 s batteries and I went to stick in the balancer wires and boom they exploded and caught fire inside my condo. i was lucky to escape injury and damage by pulling the batteries out of the charger, although they were still burning until i put them in the sink. I partially melted the batteries and the balancing board. i was pissed at the store for selling me a shorted out board, but when he looked at it, he pointed out that i put the balance wires in the 4 s slot instead of the 3 s slot. the burnt board was the evidence he was right. We were able to save the board but he hot glued shut all the other non 3 s sockets so i could not do that again and only can insert the 3s wires in a 3 s socket. the board works great by the way. He even saved the batteries but cut off the balance wires. The damaged batteries were chargeable but i did not trust them so i retired them. i even looked at a video about resoldering the balance wires on to the batteries after exposing the guts, No thanks, i retired the batteries and bought 2 2800 zippy and a multistar 4000 and still have 3 2200 left. all batteries perform well in single battery flight and flying twin batteries in the 2200 and 2800 and single only in the 4000. incredible flight times as u can see in another post. in summary, be very careful with the lipos in charging and storing and around any hot or harp objects. i would never leave them or a baby in a hot car.in fact treat them like a new born baby. not too hot or cold, keep away from anything sharp, and obviously keep them away from me.