Victron MultiPlus keeps switching to float too early — anyone else had this?

Had this exact faff with mine last winter in the van — turns out my Fogstar lithium cells had a slightly higher resting voltage than the MultiPlus expected, so it was seeing ~27.2V, thinking "job's a good'un," and gleefully skipping off to float before the batteries were anywhere near full.

Sorted it by tweaking the absorption voltage and absorption time settings in VictronConnect — bumped the absorption time from the default to a fixed 2 hours rather than letting it do the adaptive thing, which frankly has the decision-making skills of a confused golden retriever.

Few things worth checking:

• Battery voltage sense — are you using the built-in sense or have you wired dedicated sense cables? Voltage drop across your cables can absolutely fool it
• Temperature compensation — if your battery is cold, resting voltage climbs and the MultiPlus gets overconfident
• BMS communication — if you're running a smart BMS via VE.Bus or DVCC, it might actually be telling the MultiPlus to back off early for a reason

Also worth grabbing a proper data log from VictronConnect and watching what the current's doing when it transitions — if it's dropping to near zero amps before the switch, the battery's likely genuinely full and your capacity estimates are just off.

Mine's been rock solid since the tweaks, though I did nearly brick the settings file once trying to be clever about it, so maybe back up your config before poking around.

Anyone running DVCC with a third-party BMS hit this same thing? Curious whether it's more common than we think.

@Lefty72 classic Victron moment — the charger's so keen to call it "done" it'd probably declare victory halfway through a cup of tea ☕

Worth checking your absorption voltage setpoint in VictronConnect. If your Fogstar cells want 28.8V (most 24V LiFePO4 do) and you've

@Lefty72 this is worth double-checking in VictronConnect — specifically the absorption voltage and absorption time settings. If your absorption voltage is set too close to the resting voltage of your Fogstar cells, the MultiPlus hits target and bails out early before the cells have actually had chance to balance properly.

A few questions that might help diagnose it:

• Are you using a BMV-712 or SmartShunt for SOC monitoring, or relying purely on voltage?
• Have you enabled adaptive absorption or set a fixed duration?
• What's your bulk-to-absorption transition current looking like?

With my static caravan setup I found locking in a fixed 2-hour absorption period rather than letting it adapt made a noticeable difference. The adaptive algorithm can get confused if charge current fluctuates — which on solar especially it often does.

@BlownFuse good shout on VictronConnect — is there a particular absorption time minimum you'd recommend for a 200Ah lithium bank? Mine's a mixed setup, Fogstar cells in the motorhome and a separate Renogy bank in the static, and I'm never quite sure whether to trust the "adaptive" absorption setting or just fix it manually. Does the MultiPlus actually learn over time or is that just marketing fluff?

@GrumpyDrifter on my narrowboat setup (200Ah Fogstar Drift) I run absorption time at 2 hours minimum — some folks go shorter but I found anything under 90 mins was letting the MultiPlus bail out before cells had properly balanced.

Worth noting though: absorption voltage matters just as much as time. I've got mine set to 28.4V for a 24V bank — any lower and it was calling float way too early, exactly as @Lefty72 described.

If you've got a BMV-712 or SmartShunt in the mix, enabling DVCC and letting the BMS talk directly to the MultiPlus is the proper fix long-term. Takes the guesswork out of it entirely.

@OffGridJack 2 hours is conservative but not wrong. The thing people miss is that absorption time is basically irrelevant if you've got your tail current set properly. On my MultiPlus I use end-amps to terminate absorption — mine's set to around 2% of capacity. So for a 200Ah bank that's 4A. Once current drops that low, the battery's genuinely full, not just "full enough."

Victron's default settings assume lead-acid behaviour. Lithiums hit absorption voltage and the current drops fast — which is exactly why it's bailing out early.

Check your DVCC settings too if you're running a Cerbo or any BMS comms. If the BMS is reporting SOC to the Cerbo, that whole chain needs to agree or the MultiPlus gets confused signals.