Victron Cyrix-ct 12V / 24V VSR Electrical Relay (120A)

Victron Cyrix-ct is an intelligent battery combiner relay (also known as a voltage controlled relay, split charge relay or voltage sensitive relay (VSR)), which automatically detects the voltage of the system. The software inside the Cyrix-ct does more than just connect / disconnect based on battery voltage and a fixed time delay. It looks at a general voltage trend and reverses a previous action only if the trend has reversed during a certain period of time. This time delay depends on the voltage deviation from the trend. This compares to other relays that will disconnect the battery any time there is a short and high amperage load.

In the case of more than one battery in the system, the accessory battery (and others if applicable) would be connected to the starter battery with Cyrix-ct battery combiners. In a typical setup with the alternator connected to the starter battery, the relay will only engage and start parallel charging other batteries when the starter has reached the correct level. It also provides a start assist, where the other batteries can be used to make a parallel connection with the starter if it is discharged or damaged.

The Cyrix-ct battery combiner results in virtually no voltage loss so the output voltage of alternators or battery chargers do not need to be increased. It will also disengage if temperatures get too high (such as a long lasting overload) to prevent damage, and will reengage once it has cooled down.