Victron Cyrix-ct 12/24V 120A battery coupler isolating relay battery protection

Cyrix battery coupler 120A

The cyrix battery coupler is a high-performance microprocessor-controlled relay that automatically connects batteries in parallel when one of them reaches a predetermined voltage level (indicating that the battery is charging) and separates the batteries again when the voltage drops below the float voltage level (indicating that one or both batteries are discharging).
cyrix battery couplers are ideally suited to replacing isolating diodes. Their main feature is that there is virtually no voltage loss, so there's no need to increase the output voltage of the alternators or battery chargers.

Product features

• maximum continuous current: 120 A
• permissible starting current (5s): 180 A
• suitable for 12 V or 24 V systems (automatic detection)
• virtually no voltage loss
• No D+ signal required: The Cyrix battery coupler switches depending on the battery voltage
• Battery temperature protection: In case of high overload, the battery is automatically disconnected

Intelligent battery monitoring to prevent unwanted switching

Some battery couplers (also called voltage-controlled relays or split-charge relays) disconnect a battery when a short but high-amperage load is applied. Sometimes a battery coupler won't connect a large but discharged battery bank because the DC voltage immediately drops below the disconnection threshold after the batteries are connected. The Cyrix-ct 12/24 software performs more functions than simply connecting and disconnecting based on battery voltage and a set time delay.
The Cyrix-ct 12/24 monitors the overall trend (voltage increasing or decreasing) and only reverses a previous action if a trend has reversed during a specific period. The time delay depends on the extent to which the voltage deviates from the trend.

No voltage loss

Cyrix battery couplers are ideal for replacing isolating diodes. Their key feature is that they cause virtually no voltage loss, eliminating the need to increase the output voltage of alternators or battery chargers.

Voltage detection in both directions and power supply from both batteries

The Cyrix measures the voltage of the two connected batteries. Therefore, it also turns on when, for example, the additional battery is being charged by a battery charger. The Cyrix-ct 12/24 has a dual power supply.
It also closes when the voltage on one of the batteries is too low to operate the Cyrix.
To avoid unintentional operation during installation or if one of the batteries has been disconnected, the Cyrix-ct 12/24 will not close if the voltage at either battery terminal is below 2 V (12 V battery) or 4 V (24 V battery).

Protection against overheating (e.g. due to prolonged overload)

The Cyrix disconnects when the contact temperature is too high and reconnects after the temperature has dropped.

The Cyrix can also be turned on using a push button (Cyrix remains on for 30 seconds) or a switch to manually connect the batteries in parallel. This is particularly useful in an emergency if the starter battery is discharged or damaged.

Technical information