One question. Are you in need of a one plug, bms type of battery as opposed to the rc LiPo using a charger with a balance plug? The rc type would be several batteries connected together in series to add their voltage. You do have to separate them and charge individually. You may know this, it is one or the other. I use cad and 3d printing to make battery holders for ebike use. If you can run 75v fully charged you would need three 6s batteries. Let me know if this might work for you.