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Cyrix-Li-ct 12/24V-120A intelligent Li-ion battery combiner

$116.96 (inc. GST)

The Cyrix-Li-ct 12/24V-120A intelligent Li-ion battery combiner is a type of relay designed to combine the power from two lithium batteries to power a single electrical load. It is compatible with both 12V and 24V electrical systems and is capable of handling loads up to 120 amps.

SKU: CYR010120412 Categories: ,

Victron Cyrix Li-ct combiner:

The first line of protection is cell balancing. All Victron LiFePO4 batteries have integrated cell balancing. The second line of protection consists of:

-shut down of the load in case of imminent cell under voltage, and

-shut down or reduction of the charging current in case of imminent cell over voltage, high temperature (>50°C) or low temperature (<0°C).

The VE.Bus BMS is the core of the second protection line. However, not all loads or chargers can be controlled directly by the VE.Bus BMS. In order to shut down such loads or chargers several VE.Bus BMS controllable Cyrix switches are available.


Cyrix-Li-load- The Cyrix-Li-load will disengage when its control input becomes free floating. If the battery voltage recovers after disconnecting (which will happen when no other loads are connected to the battery), the output of the BMS will become high and the Cyrix will reengage after 30 seconds. After 3 attempts to reengage, the Cyrix will remain disengaged until battery voltage has increased to more than 13V (resp. 26V or 52V) during at least 30 seconds (which is a sign that the battery is being recharged). Alternatively, a BatteryProtect can be used (advantage: very low power consumption).


Cyrix-Li-Charge- The Cyrix-Li-Charge will connect a battery charger with 3 seconds delay:

-if the Charge Disconnect output of the VE.Bus BMS is high, and

-if it senses 13,7V (resp. 27,4V or 54,8V) or more on its battery charger connection terminal, and

-if it senses 2V or more on its battery terminal (the Cyrix will remain open, if not connect to the battery).

The Cyrix-Li-Charge will disengage immediately whenever its control input becomes free floating, signalling cell over voltage or cell over temperature. In general a cell over voltage alarm will reset shortly after charging has been stopped. The Cyrix will then reconnect the charger after a delay of 3 seconds. After two attempts to reengage with 3 seconds delay, the delay increases to 10 minutes. Whenever battery voltage is less than 13,5V (resp. 27V or 54V), the Cyrix will disengage with a delay of 1 hour.

Note 1: In case of zero discharge current, or a small discharge current, the Cyrix will not disengage shortly after the charger has been switched off and/or disconnected, because battery voltage will remain higher than 13,5V.

Note 2: If, after the Cyrix has disengaged, the output of the battery charger immediately increases to 13,7V or more, the Cyrix will re-engage, with 3 seconds delay.


Cyrix-Li-ct- The functionality of the Cyrix-Li-ct is analogous to the Cyrix-ct. The Cyrix-Li-ct will parallel connect a lead acid starter battery and a LiFePO4 battery:

-if the Charge Disconnect output of the VE.Bus BMS is high, and

-if it senses 13,4V (resp. 26,8V) or more on one of its power terminals.

The Cyrix will disengage immediately:

-when its control output becomes free floating, signalling cell over voltage or cell over temperature, and/or

-when battery voltage drops below 13,2V.

Start assist function: a short positive pulse will close the relay during 30 seconds. A built-in transient voltage suppressor will limit the voltage spike that may occur when the Cyrix suddenly

Additional information

Cyrix Battery Combiner

Cyrix-Li-ct 12/24-120

12V system

24V system

Continuous current and breaking capacity at 12V or 24V


Breaking capacity at 48V

n. a.

Control input

The Cyrix engages when the control input is high (appr. Battery voltage)

The Cyrix disengages when the control input is left free floating or pulled low

Connect voltage

13,4V < V < 13,7V: 120 s

13,7V < V < 13,9V: 30 s

V > 13,9V: 4 s

26,8V < V < 27,4V: 120 s

27,4V < V < 27,8V: 30 s

V > 27,8V: 4 s

Disconnect voltage

13,3V < V < 13,2V: 10 s

V < 13,2V: immediate

26,6V < V < 26,4V: 10 s

V < 26,4V: immediate

Current consumption when open

<4 mA

Protection category


Weight kg (lbs)

0,11 (0.24)

Dimensions HxWxD in mm (HxWxD in inches)

46 x 46 x 80

(1.8 x 1.8 x 3.2)


Datasheet-Cyrix-Li-ion-120-A-ENVictron Cyrix Li-ct combiner 12/24V-120A spec sheet-