Cyrix Lithium BMS Battery Coupler

The Cyrix battery coupler is a high performance microprocessor controlled relay which can be used to protect Victron LiFePO4 batteries.

AllVictron LiFePO4 batteries have an integrated cell equalization functionto prevent cell undervoltage, overvoltage and overtemperature. This regulates the differences between the cells internally and tells the external BMS whether it should switch charging or discharging on or off.


- Switching off the load in the event of an imminent cell undervoltage and
- Switching off or reducing the charging current in the event of an imminent cell overvoltage, a high temperature (>50°C) or a low temperature (<0°C).

The core of this protective measure is the VE.Bus BMS or the Small BMS, but the VE.Bus BMS can only directly tell VE.Bus devices to interrupt charging or discharging. Other loads or chargers must be controlled externally. This is also the case with the Small BMS, which cannot control VE.Bus devices.

Several Cyrix switches that can be controlled by the BMS are available to switch off such loads or chargers.

The models differ in:

System voltage, load strength and whether a load or a charge is to be controlled.

Load is used to control the load and Charge to control the charge.

Please contact us, for more complex systems it often makes sense to consult us.