Simple BMS Circuit and Charger for a Li-Ion Battery Pack 12 V

A simple reliable BMS circuit and also a charger were designed for a battery pack containing 3 Li-ion cells connected in series (ca. 12 V / 9 Ah). The charger is based on a DC/DC converter with transformer (fly-back converter). The pulse transformer of the converter ensures the galvanic separation of the charged battery pack from the mains. The control circuits of the charger co-operate with the BMS circuit to avoid an overvoltage of any cell during the charging. Technical parameters of the battery pack, BMS and charger are mentioned. Detailed schematics of BMS circuit and also charger are included. Also the operation of both circuits is briefly explained. Some important waveforms of the charger power circuit are presented.