Can an ORION XS 1400 allow a “backfeed” from recipient battery to donor battery?

DIY
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The installation is full Victron eco-system on a powerboat. The house bank is LFP and is charged by solar via a Victron MPPT, the auxiliary output from a MultiPlus and from the AGM starting battery via an ORION XS1400. The system was professionally installed by a colleague.

The boat was at anchor and the propulsion engine was secured. The MultiPlus was on line providing 120VAC power. The PV system was charging the LFP house bank via the Victron MPPT. Absorption voltage for the LFP bank was 14.2VDC. The starting battery was resting at a nominal 12.6VDC, normal for an AGM battery not receiving a charge. The system is managed by a CerboGX with DVCC engaged.

Periodically, the MuliPlus started throwing a High Voltage alarm.

My theory is that the voltage differential between the LFP recipient and the AGM donor (approximately 1.6VDC was enough to “back feed” (please forgive me for using such a misused phrase!) in a reverse direction through the ORION to provide a voltage (no current) at the donor terminals that was viewed as abnormal by the system and which responded with a High Voltage alarm.

What does the Hive think?

2

Full victron eco system also means that the batteries are victron, so you are using a VE.Bus BMS? Or some different battery manufacturer?

Of course a device can fail, so a reverse current is possible. But it definitely would not be my first guess here. Voltage spike would necessarely also mean a current spike in this case, since the starter battery is still connected and acts as a load.

The MP is solely connected to the house battery, so it only reacts to that. Whatever the starter battery is doing doesnt concern the MP.

Does that mean that the battery actually reached those 14.2V? Or is this solely mentioning the MPPT setting? Is the MP set correctly to both LiFePo, VE.bus BMS and the necessary voltage settings?

If the battery in non-victron, for example with an integrated BMS, its very well possible that the BMS disconnected the battery to prevent overcharging, so the MPPT was left connected to the MP only. This scenario could easily cause a voltage spike, for the MP to react to.