Victron Energy BatteryProtect 12/24V 100A

The BatteryProtect disconnects the battery from non-essential loads before it is completely discharged, which would damage the battery, or before it has insufficient power left to crank the engine. The BatteryProtect is a uni-directional device, meaning it can only handle current in one direction—either to a load or from a charger, but not both simultaneously. Additionally, current can only flow from the Battery terminal to the Load terminal. When used with a load, the battery connects to the Battery terminal, and when used with a charger, the charger connects to the Battery terminal.