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Smart BatteryProtect 12/24V

Smart BatteryProtect in a lithium battery system with external BMS

The image below shows a Smart BatteryProtect in a lithium battery system with external BMS. The external BMS (Victron Lynx Smart BMS in this example) has an ATD (allowed to discharge) and ATC (allowed to charge) output. Designed as a dry contact, ATD and ATC function as a switch that directly controls the SBP via its remote terminal.

For this, the Smart BatteryProtect must be programmed to Li-ion mode.

The dry contact is wired between the L and H connectors of the remote terminal.

If, for example, ATD opens in the event of a lithium battery cell undervoltage, the SBP will immediately disconnect the load without delay.

The SBP will remain disengaged for 30 seconds, even if ATD closes within this period. After this 30 seconds, it responds immediately and connects the load to the battery.

Please note that the under voltage thresholds and alarm output of the SBP are inactive in this mode.


If you have a lithium battery with internal BMS (so-called drop-ins) that does not have an output for controlling loads or chargers, the SBP must be programmed in mode A or B. Mode C is not applicable in this case.


Smart BatteryProtect in Li-ion mode controlled by ATD from a Lynx Smart BMS