My 17s battery pack is not charging above 69v I have series 13s and 4s bms There is a bit of unbalance in the cells about ± 0.05 volts Also the bms cuts the power at only at 61 volts about 3.56 per cell Please 🙏 tell me the reason so I can repair it (About two times the positive and negative terminal also get short fow a few second with bms installed)