Built-In Upgraded BMS:ESUN Rechargeable deep cycle 12V Lifepo4 Battery Has built-in BMS (Battery Management System) to Protect the Battery Cells From Overcharge, Over-discharge, Over-current, Short circuit, Over-heating, and Low-temperature Charging Damage while also Balancing Battery Cells, as well as Low and High Temperature for increased performance and longer life. If the Battery Temperature Exceeds (-10°C) or (50°C), Our BMS Will Automatically Shut it Down.