Victron Cyrix-Li-charge 24/48V-120A intelligent charge relay

The Cyrix-Li-Charge 24/48V-120A from Victron Energy is an essential accessory for 12V and 24V LiFePO4 battery systems. With its capacity to handle currents of up to 120A, it serves as the perfect addition to the VE.Bus BMS by acting as a battery switch for loads that cannot be switched directly through the VE.Bus BMS.

General function of the Cyrix battery coupler:

The device, a powerful microprocessor-controlled relay, automates the parallel connection of batteries when a specific voltage level is reached, indicating the state of charge, and disconnects them as soon as the voltage falls below a critical value, indicating discharge. The Cyrix battery coupler effectively replaces isolation diodes by operating without any voltage loss, which means that no adjustment of the output voltage of generators or chargers is necessary.

Operation of the Cyrix-Li-Charge 24/48V 120A:

The Cyrix-Li-Charge is activated to connect a battery charger under the following conditions:

• The "Charge Disconnect" output of the VE.Bus BMS is active,
• A voltage of at least 13.7 V (or 27.4 V or 54.8 V) is measured at the battery charger connection,
• A voltage of 2 V or more is detected at the battery connection (remains inactive if not connected to the battery).
• The device immediately disconnects the connection if the control output switches to the "free floating" state or if overvoltage or overheating of the cells is detected. After the charging process has been stopped and the cell overvoltage alarm has been reset, the Cyrix reconnects. After two reconnection attempts within 3 seconds, the delay switches to 10 minutes. The Cyrix switches off if the battery voltage falls below 13.5 V, with a delay time of one hour.

Important notes:

If there is no or only minimal discharge current, the Cyrix remains inactive because the battery voltage exceeds the threshold of 13.5 V. If the voltage of the battery charger immediately reaches 13.7 V or higher again after a disconnection, the Cyrix reactivates the connection after a short delay of 3 seconds.