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

Been having this exact issue with my Multiplus II in the shepherd's hut build. It blasts through bulk, hits absorption for maybe 20-30 minutes, then decides it's done and drops to float — but the batteries are nowhere near full. Fogstar Drift 200Ah LiFePO4 cells, so they should be holding absorption for considerably longer than that.

Checked the wiring and connections first (obvious stuff), all fine. Wondered if it was the tail current setting — mine was still at the Victron default which I suspect is too high for lithium. Dropped it from 4% to 1% and it seemed to help slightly, but still cutting short.

Currently running VictronConnect via Bluetooth to monitor in real time. The absorption voltage looks correct at 28.4V for my 24V system, but something in the charge algorithm seems to be bailing early.

A few things I'm curious about:

• Has anyone adjusted the adaptive absorption settings in VEConfigure? Worth disabling it entirely for lithium?
• Could a poor BMS signal be causing the Multiplus to think the battery is full prematurely?
• Anyone using a Cerbo GX to override charge parameters via DVCC — did that sort it?

The hut is off-grid so this isn't just an inconvenience — if the batteries aren't properly topped up before a cloudy stretch I'm running short pretty quickly.

Would be good to hear if others have cracked this. Feels like it should be a simple config fix but I've gone round in circles a bit on the Victron docs.

@NicolaKing85 classic Victron tail current issue. It's dropping to float because the charge current has fallen to whatever percentage you've set as the "end absorption" threshold — not because the batteries are actually full.

In VictronConnect (or CCGX if you've got one), check your absorption end trigger settings. Default tail current is often set too high for lithium, sometimes even causes issues with AGM if the bank's large.

What batteries are you running? If it's Fogstar or similar lithium, you probably want absorption time set manually rather than adaptive. Adaptive algorithm is great in theory but confuses itself with bigger banks.

Had the same in my motorhome before I just fixed absorption at 2hrs and stopped letting it think for itself. Sorted it completely.

Just to add to what @DownsCruiser is getting at — worth double-checking your battery capacity setting in VEConfigure. If it's set too low, the tail current threshold gets calculated off that figure and triggers float prematurely. Common one with shepherd's hut builds where people underestimate their actual bank size or copy settings from somewhere else.

Also, what battery chemistry are you running @NicolaKing85? If it's LiFePO4 with a BMS, sometimes the BMS is reporting a slightly dodgy state of charge back to the Multiplus which confuses the whole process. Connecting via VE.Bus Smart Dongle and watching the live graphs usually reveals exactly where it's going wrong. The DVCC settings can also interact oddly if you've got a SmartShunt in the mix.

Had almost identical behaviour on my shepherd's hut setup before I sorted it. Worth checking two things @NicolaKing85 hasn't been mentioned yet:

1. Absorption time minimum — in VEConfigure there's a "minimum absorption time" setting. If it's too low, Victron will bail out early even if the tail current threshold hasn't been properly evaluated yet.

2. Battery temperature — if you've got a temp sensor attached, a warmer battery will trigger shorter absorption times automatically. Mine was reading high because the sensor was poorly placed near the inverter itself.

What battery chemistry are you running? LiFePO4 with a BMS sending charge complete signals via DVCC can also cause this — the BMS essentially tells the Multiplus it's done. Caught me out for weeks on mine.

@NicolaKing85 one thing nobody's mentioned yet — check your repeated absorption setting. If you're on a solar profile, Victron uses an adaptive algorithm that shortens absorption based on how long bulk took. If bulk was quick (good solar day, batteries weren't that low), it assumes they're nearly full and cuts absorption short. Totally normal behaviour but can feel wrong.

Also worth confirming what battery chemistry you've set. Victron's LiFePO4 preset has a pretty low tail current threshold by default — drops to float faster than you'd expect.

If you're on Fogstar or similar cells, grab the actual spec sheet and match the charge parameters manually in VEConfigure rather than trusting a preset. Made a big difference on my garden office setup.