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

Had this exact issue with my MultiPlus-II last spring when I was commissioning the shepherd's hut setup. Batteries would sit at maybe 80% and the unit would cheerfully declare them full and drop to float. Maddening.

Turned out my battery voltage sense wires weren't connected properly — the MultiPlus was reading voltage at the unit rather than at the battery terminals, so it was seeing a slightly inflated figure due to cable resistance. Once I ran dedicated sense wires directly to the Fogstar Drift 200Ah cells, the absorption phase started behaving itself properly and actually finishing before dropping down.

Worth checking a few things:

• Voltage sense wiring — is it reading at the battery or the inverter terminals?
• Absorption time settings in VictronConnect — the adaptive algorithm can be quite aggressive about shortening absorption if it thinks previous cycles were shallow
• Battery temperature — if you're running a temp sensor, oddly high readings can cause it to back off early

Also had a forum member suggest checking whether "BatteryLife" mode was enabled somewhere in ESS settings — apparently that can interfere in unexpected ways if you're not running a full ESS configuration.

Mine's been solid since sorting the sense wires. Still gets me how such a small wiring oversight caused so much head-scratching.

Anyone else found other causes? Curious whether this is more common on the 48V units — mine's a 24V system and I wonder if the voltage thresholds leave less margin for error.

@IslandOffGrid classic Victron gotcha, this one. Had the exact same drama on my Boxer motorhome build — MultiPlus was convinced my Fogstar Drift 200Ah was full after a leisurely Sunday morning charge. Turned out my absorption voltage was set slightly low, so the battery hit it early and cruised straight to float without earning it.

Two things worth checking:

• Absorption time — set it to adaptive or manually increase it in VEConfigure
• Tail current — lower this threshold so it actually waits for the battery to genuinely finish absorbing before switching

Mine was at 4% tail current. Dropped it to 2% and suddenly the MultiPlus stopped being so optimistic about life.

Also worth connecting via VRM if you haven't — watching the charge curve live is genuinely illuminating and saved me hours of guesswork on the towpath.

Seeing this on my static caravan setup too — MultiPlus-II 48V with Fogstar Drift lithium cells. Turned out my battery capacity setting in VEConfigure was massively underspecified, so the charge algorithm was calculating absorption completion way too early.

Worth checking your DVCC settings in Cerbo/Venus if you're running a GX device — specifically whether "Use charge current limit" is overriding your charger profile. Took me ages to find that one.

Also, are your batteries communicating via BMS or is the MultiPlus flying blind on voltage alone? Running without BMS comms means Victron's estimating state of charge from voltage curves, which can be wildly inaccurate especially with LFP's flat discharge curve.

What battery type have you got @IslandOffGrid?

@YorkshireCamper static caravan with Fogstar Drift — practically identical to my setup, so I'll actually be useful for once: check your Max Charge Current in VictronConnect isn't so low that the MultiPlus hits the tail current threshold before the cells are properly full. Victron's default absorption end-trigger is based on current dropping to a percentage of capacity, and if your capacity figure is wrong in the config, it'll bail out early every single time like an over-eager student leaving an exam. Sort your battery capacity setting first, then revisit absorption voltage — don't go touching voltages blind or you'll cook something expensive.

Ran into this with my garden office build — MultiPlus-II 24V paired with Fogstar Drift cells. The thing that finally sorted it for me was enabling the DVCC in VE.Config and setting a proper absorption time rather than leaving it on the adaptive setting. Adaptive absorption sounds clever in theory but it learns from previous cycles, so if your early cycles were all short ones it just assumes the batteries fill quickly.

Also worth checking your cable sizing between the battery and inverter — I had a marginal voltage drop that was convincing the MultiPlus the battery terminal voltage was higher than it actually was, triggering premature float.

@YorkshireCamper if you're on Fogstar Drift, confirm you've got the correct battery preset loaded. Fogstar publish recommended Victron parameters on their site and the defaults are often wrong out of the box.