Multiplus 24/800 meldet regelmäßig Low battery: Warning

Seeing this thread pop up and it's hitting close to home — I've been wrestling with something very similar in my shepherd's hut setup for the past few weeks.

Running a Victron Multiplus 24/800 with a Cerbo GX, SmartShunt, and MPPT 100/20, paired with a Fogstar 24V 100Ah LiFePO4 (the one with integrated BMS, no external CAN management). Intermittent low battery warnings keep appearing in VRM despite the state of charge reading as perfectly healthy at the time.

A few things I've narrowed it down to:

• BMS communication gap — without proper battery management protocol (no DVCC handshake), the Multiplus is relying purely on voltage thresholds. A momentary sag under load can trip the warning even if capacity is fine
• DC cable sizing — I initially underestimated voltage drop on my 24V bus. Worth measuring actual terminal voltage under load rather than trusting the shunt reading alone
• Low battery restart/shutdown thresholds in VEConfigure** — these are often set conservatively from factory and worth reviewing against your actual battery spec

What I haven't fully resolved is whether the integrated BMS on these batteries is occasionally causing a brief current interruption that the Multiplus interprets as low voltage. Has anyone else seen this with similar setups?

Would be curious whether those of you running Renogy or other batteries with standalone BMS boards have had cleaner results. Also whether tweaking the ESS assistant settings made any difference for anyone running grid-tied configurations.

@HighlandExplorer have you actually logged the battery voltage at the point those warnings trigger? I had something similar on my boat and the alarm was firing at a higher voltage than expected — turned out my low battery warning threshold in VE.Config was set way too conservatively from a previous profile I'd copied over.

Worth connecting via VE.Bus Smart Dongle and checking the actual warning/alarm voltages under the "Inverter" tab. What are your current threshold settings?

Also — what batteries are you running? If they're LiFePO4 with a BMS, the BMS might be causing brief voltage sags under load that look like low battery events but aren't really a capacity issue at all.

@SmartSolar_Queen makes a fair point about logging, but I'd add — check your battery cable length and cross-section before assuming the cells themselves are the culprit.

I had the exact same phantom low-battery warnings on my Multiplus 24/3000 in the tiny house. Turned out my voltage sense wires weren't connected, so the unit was measuring voltage at the inverter terminals rather than at the battery — and with even modest cable resistance, that's a meaningful difference under load.

In VictronConnect, make sure "Use BMS" or remote voltage sense is properly configured. If you're running a Fogstar Drift or similar with a proper BMS that talks to the Multiplus via VE.Bus, the sense data should come directly from the pack.

Also worth checking: what's your low battery warning threshold set to in ESS/VE Configure? Default 24V can be surprisingly aggressive on a 24V LiFePO₄ system.

@Titch and @SmartSolar_Queen have both nailed the obvious culprits. One thing worth adding — check your low battery warning threshold in the Multiplus settings via VictronConnect. Out of the box it's sometimes set a bit high, especially on 24V systems, and can trigger warnings even when your batteries are genuinely fine.

On my narrowboat I had exactly this — tweaked the Low battery voltage setting down slightly and the false warnings stopped. Didn't mask any real problem, just aligned it properly with my Fogstar cells' actual chemistry.

Worth double-checking your BMS cutoff voltage too and making sure the Multiplus threshold sits comfortably above it — you want the warning to mean something useful, not just cry wolf.

@HighlandExplorer had the exact same drama in my shepherds hut — turned out my Victron BMV-712 was configured with the wrong battery capacity, so the Multiplus was essentially panicking based on a completely fictional state of charge rather than actual voltage. Double-check your BMV settings: Battery Capacity (Ah), Charged Voltage, and Peukert Exponent all need to match your actual bank — Fogstar Drift cells especially behave differently from lead-acid defaults that Victron ships with. Also worth checking in VictronConnect whether your Low battery shut-down and Low battery restart voltages under the inverter's settings are appropriate for 24V lithium vs AGM, because the factory defaults are suspiciously conservative and will cry wolf on a perfectly healthy LiFePO4 bank. 🐑⚡

@HighlandExplorer one angle nobody's mentioned yet — what's your battery temperature? The Multiplus applies a low-temperature charge disconnect by default, and if your shepherd's hut is unheated overnight, the BMS (assuming you're on lithium) may be cutting off under load and triggering that warning even with a reasonable state of charge.

Worth checking in VictronConnect whether the low battery warning threshold itself has been left at the default 24V setting — that's often too aggressive for a 24V system under any meaningful load, as voltage sag will dip below it momentarily.

Also, are you monitoring this through VRM portal? The historical data will show you exactly when the warnings fire relative to your loads — makes it much easier to isolate whether it's a genuine capacity issue or just a threshold/configuration problem.