Victron Multiplus keeps dropping to float too early — anyone else had this?

Mine did exactly this for months until I realised my Victron BMV-712 battery monitor wasn't properly configured as the BMS source — the Multiplus was just guessing at SOC like a sat-nav without signal and declaring "you've arrived" at 80%.

Few things worth checking:

• Tail current settings — if it's set too high, the charger thinks absorption is done before it actually is
• Battery capacity entered correctly in VictronConnect (I'd put in 200Ah when I'd actually got 400Ah of Fogstar Drift cells, whoops)
• Temperature compensation — a cold battery in a British winter will behave very differently to your summer baseline, and the Multiplus doesn't always handle that gracefully without a temp sensor fitted

The real fix for me was enabling DVCC properly through VenusOS on my Cerbo GX and letting the BMS take charge control away from the Multiplus entirely — essentially telling the inverter to stop being clever and just do what it's told.

Also worth checking firmware — there were a couple of releases last year that had quirky absorption behaviour, and updating via VRM sorted a few people out on here if I recall correctly.

What battery chemistry are you running? LiFePO4 and lead acid have wildly different absorption profiles and if someone's loaded a generic profile it'll be all over the place — the Multiplus isn't psychic, unfortunately, much as Victron would like to charge you as if it were.

Anyone else gone down the DVCC rabbit hole and found it fixed similar issues?

@DailyAdventure ooh that's a really useful find — had you changed any of the absorption time settings as well, or was it purely the BMV-712 config that sorted it?

I ask because I had something vaguely similar on my shepherd's hut setup last summer. Mine turned out to be a combination of things — the tail current threshold was set way too high, so the Multiplus was seeing the batteries as "full" ages before they actually were. Worth checking that figure in VEConfigure if you haven't already.

What battery chemistry are you running? I'm on Fogstar Drift LiFePO4 cells and getting the charge profile dialled in took me a good few weeks of fiddling. The Victron ecosystem is brilliant once it's all talking properly but there's definitely a learning curve to getting everything configured correctly together.

@DailyAdventure this is almost certainly your Tail Current threshold being set too aggressively. If the Multiplus sees current drop below that figure before absorption time completes, it'll punt straight to float regardless of actual SOC. Worth checking in VEConfigure — default is often 4% of C20 capacity but on LiFePO4 especially, I've had to drop mine to around 1-2% before it stopped cutting absorption short prematurely.

Also check your Absorption Time isn't on Adaptive if you're relying on the BMV-712 for SOC — the two can conflict badly. On my static caravan setup with Fogstar Drift cells I run fixed absorption time now, let the BMV handle SOC cutoff via DVCC, and the early float issue completely disappeared.

Run a VictronConnect diagnostic log during a full charge cycle — the data usually shows exactly which condition triggered the transition.

@DailyAdventure @Cerbo_Geek both on the right track here. Worth also checking your Adaptive Absorption setting in VEConfigure — if it's enabled, the Multiplus calculates absorption time based on the previous bulk duration. After a shallow discharge, it'll shorten absorption dramatically, which looks identical to premature float.

My setup (400Ah Fogstar Drift LiFePO4, Multiplus-II 3000) had this exact behaviour until I switched to Fixed Absorption with a manual time appropriate for my battery bank. Adaptive works brilliantly for lead-acid but can confuse things badly with lithium.

Also double-check Repeated Absorption Interval — mine had defaulted to 7 days, meaning once it "completed" absorption it wouldn't repeat proper absorption for a week regardless of discharge depth. Complete nightmare to diagnose.

@DailyAdventure @Cerbo_Geek @ExFirefighter42 — good points all round. One thing nobody's mentioned yet: double-check your battery voltage sense wiring. If the Multiplus is measuring voltage at its own terminals rather than directly at the battery, voltage drop across your cables can fool it into thinking the battery is fuller than it actually is. Even a decent run of 70mm² cable will have enough resistance to cause this. The remote voltage sense leads (the thin ones, often left disconnected) are there specifically for this reason — connecting them directly at the battery terminals gives the charger accurate readings. Combined with proper BMV integration as @DailyAdventure found, it made a noticeable difference on my setup. Worth ten minutes to check before diving deeper into the absorption settings.