Victron Multiplus keeps throwing a low battery alarm but cells are fine — anyone seen this?

Had exactly this on my narrowboat setup last winter — turned out my battery voltage sensing was lying through its teeth because of a dodgy connection on the sense wires, not the cells themselves.

Few things worth checking:

• Remote sense wires — if your Multiplus is using them, a high-resistance joint will report a lower voltage than reality, especially under load
• VE.Bus Smart Dongle or Cerbo — worth checking if the alarm correlates with any decent load spike, which would suggest the DC ripple threshold is being tripped rather than actual low voltage
• DVCC settings in VeConfigure — if you've got a BMS talking to the Multiplus and the BMS is reporting a slightly pessimistic SoC, it can trigger the alarm even when individual cells look perfectly healthy on a separate monitor

Also worth pulling up the VictronConnect history and checking whether the logged low voltage events match what your cells were actually doing at that timestamp — nine times out of ten there's a 0.2–0.3V discrepancy that tells the whole story.

What BMS are you running and is this a Fogstar/EVE cell build or something else? Makes a difference to how the Multiplus is interpreting the data it's getting.

Fairly confident this is a comms or sensing gremlin rather than your cells throwing a wobble — the Multiplus is dramatic like that. 🔌

Anyone else had the false alarm saga? Would be good to get a few more data points in this thread for future searchers.

@CornishNomad had something similar-ish — mine was throwing false alarms because the DVE (DC voltage sense) cables were routed too close to the inverter's AC output wiring. Induced noise on the sense lines was giving the Multiplus completely duff readings.

Worth checking a few things:

• Are your sense wires twisted pair or just loose runs?
• What's the routing like relative to AC cables?
• Have you checked the VE.Bus comms connection if you're running a BMS alongside it?

Also — if you've got a Fogstar or similar lithium setup with its own BMS, make sure the BMS low voltage threshold isn't set lower than what Victron expects to see. Sometimes the Multiplus trips on its own internal settings before the BMS even blinks.

Victron's ESS assistant settings can also be the culprit if you've got that configured.

Really interesting thread this — similar situation on my tiny house setup last year but with a twist!

Has anyone checked their battery shunt wiring as a possible culprit? My Victron BMV-712 was sending duff state-of-charge data upstream to the Multiplus because one of the shunt signal cables had worked loose at the terminal. The Multiplus was reacting to reported voltage rather than actual cell voltage.

Worth asking — are you running VE.Bus Smart Dongle or going through VE.Configure? Sometimes the low voltage alarm thresholds get set surprisingly high from factory defaults, especially if the unit was previously paired with a lithium profile that someone tinkered with.

What battery bank are you actually running? Fogstar cells or a pre-built unit? Makes a difference for where I'd start digging! 🔧

Jumping in here because this is basically my life right now on the motorhome 🙃

Has anyone looked at whether the MultiPlus firmware is the culprit? I updated mine a few months back and suddenly it started having an existential crisis about voltages that were perfectly acceptable before. Turned out the low battery voltage threshold in VEConfigure

Great thread this, lots of good stuff already covered. One thing I'd add that nobody's mentioned yet — have you checked your VE.Bus system monitor settings in VEConfig? Specifically the DC input low voltage restart and shutdown thresholds. I've seen these get set too aggressively, particularly if someone's imported a config profile from a different battery chemistry setup. Your Multi might genuinely be reading accurate voltage but tripping on thresholds meant for lead-acid rather than lithium.

@CornishNomad your sense wire diagnosis is spot on for a lot of cases though — worth everyone ruling that out first as it's the easiest fix.

@MarineFrank if you're on a motorhome, also worth checking whether engine alternator charging is causing any voltage spikes that might be confusing the Multi's readings. Temperature compensation settings can play up with that too.