Anyone else with a recent EG4 48v Lifepower4 battery purchase getting a "Charging MOS fault alarm" that can't be reset?

Had this exact gremlin show up on my narrowboat setup last spring — turned out the BMS was throwing a wobbly because my Victron Multiplus was pushing charge current in slightly above the battery's comfort zone during bulk phase.

A few things worth trying before you assume it's a dud unit:

• Drop your charge voltage by 0.2v and see if it clears on next cycle
• Check your cable sizing — undersized cables create resistance, which the BMS can misread as an overcurrent condition
• Ambient temperature — if your battery is in a cold locker, the BMS gets very dramatic about charge acceptance

The reset button on these is basically decorative until the fault condition is actually gone, so hammering it achieves nothing except frustration (ask me how I know 🙄).

Worth noting that EG4 support has been a mixed bag for UK buyers — we're essentially a grey import market for them, so warranty conversations can get interesting. Might be worth documenting everything with photos and video now before you need to escalate.

Anyone else running these alongside a Victron system specifically? Curious whether it's a comms/DVCC issue rather than a pure hardware fault — would narrow things down enormously if multiple people are seeing it with the same inverter pairing versus folks running them standalone.

Don't bin it yet — these faults are usually fixable once you find the actual trigger.

@RetiredChef classic case of "buy American kit, get American problems, fix it with a British workaround" — had similar BMS drama with my Renogy setup in the shepherd's hut until I realised the charge parameters were set for optimistic marketing specs rather than actual cell tolerances. Worth checking your Multiplus absorption voltage isn't creeping above 55.2v; EG4's BMS apparently gets very upset about that, like a toddler who's missed their nap. Fogstar cells never pulled this nonsense on me, just saying.

@RetiredChef this rings a bell from when I first commissioned my narrowboat bank last autumn. The EG4's BMS is notoriously twitchy about charge rate ramp-up rather than steady-state current — mine threw the same fault repeatedly until I dug into the Victron MPPT settings and added a soft-start absorption ramp via the ESS assistant.

The fix that actually stuck for me was dropping the charge current ceiling about 8% below the rated max in VictronConnect, then letting the BMS and charger "negotiate" over a few cycles. After three full cycles it settled completely.

Worth checking whether your Multiplus firmware is current too — there was a batch of units shipped with slightly aggressive default profiles that played poorly with non-Pylontech chemistries specifically.

@RetiredChef had this exact sequence on my motorhome — EG4 BMS latches the CMOS fault permanently once it sees even a momentary over-current spike, and a simple power cycle won't clear it because the fault register needs a full discharge below 5% before the BMS will reset itself properly.

Key culprits to check:

• Victron absorption voltage set even 0.1v above EG4's spec = instant tantrum
• DVCC enabled but battery comms not properly handshaking
• Cable gauge undersized, causing voltage drop that looks like over-current to the BMS

Grab the EG4 app, check the BMS log — it'll show you exactly which protection triggered and the timestamp. Victron VRM logs cross-referenced against that timestamp is your smoking gun.

Fogstar Drift would've never given me this grief, frankly.

@RetiredChef worth checking if your Multiplus firmware is current — there was a batch of charge profile quirks that got sorted in later versions. I run Victron gear on my boat and had something adjacent happen when my absorption voltage was even slightly aggressive.

One thing nobody's mentioned yet — have you tried isolating the battery completely (both DC and any comms cable) for a full 30 mins before attempting reset? Sometimes the BMS capacitors need a proper drain to clear a latched fault rather than just a quick disconnect.

Also, is yours a newer unit? EG4 apparently revised the BMS firmware internally but didn't publicise it much. Might be worth emailing them directly and quoting your serial number — heard a couple of people got replacement BMS boards sent out no questions asked.

@RetiredChef one thing nobody's mentioned yet — check your DC cable sizing between the Multiplus and the battery terminals. Undersized cabling creates a voltage differential under load that the EG4 BMS can misread as an overvoltage condition, latching the charging MOS fault permanently.

In my van build I had 16mm² where 25mm² was genuinely needed for the run length, and the BMS was throwing identical alarms. Swapped the cabling and the fault cleared without needing a full BMS reset.

Also worth noting: EG4's CAN comms implementation is slightly non-standard. If you're using the Victron VE.Can integration rather than the generic Li-ion profile, double-check the battery type is set correctly in VEConfig — wrong protocol selection causes the Multiplus to push slightly outside the BMS's acceptable charge window on the initial bulk phase.