Dmethvin, Yes you are understanding wrong (although your post immediately above this one suggests you are understanding now?) The video you link to is excellent (and recommended viewing for anyone trying to understand why we need a BMS). As shown in that video. BMS does not charge cells it discharges them ( or more accurately with our BMS prevents them taking any more charge. Also, in that video, all charging is done via the discharge lines, there is no seperate charge lines