Orion DC-DC activates due to maintenance charger when on shore power

Q&A and troubleshooting
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Dear Victron Community,

I am experiencing the following issue in my camper installation and would appreciate some guidance.

System setup:

  • Cerbo GX with GX Touch

  • MultiPlus-II

  • Orion Smart DC-DC charger (charging the house battery from the starter battery while driving)

  • Separate maintenance charger connected to the starter battery (active when on shore power)

Problem: When connected to shore power, the MultiPlus operates normally and charges the house battery. At the same time, the maintenance charger raises the voltage of the starter battery.

Because of this increased voltage, the Orion DC-DC detects a high input voltage and assumes the engine is running. As a result, the DC-DC charger activates even though the engine is off.

This causes unnecessary charging interaction between systems.

Goal: I would like the DC-DC charger to automatically switch off whenever AC input (shore power) is present.

Preferably, I would like to achieve this using the Cerbo GX relay to interrupt the Orion remote/enable input, without running an additional D+ wire from the front of the vehicle.

Question: Is it possible to configure a Cerbo GX relay to switch based on “AC input present”?
If not, is there a recommended Victron-native solution to prevent the DC-DC from activating due to a maintenance charger increasing the starter battery voltage?

Thank you in advance for your support.

Kind regards,
Harry Smulders

2

I know that this could be achieved through Node-RED programing. You would need to read the Cerbo manual to see if you could directly conttol the relay via ac present. You could set your DC to DC start up voltage above the maintenance charger or conversely set the maintenance charger to a lower voltage. You could swap ftom voltage based engine detection to a switched signal from the ignition.

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