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

Been having the exact same issue with mine in the van. Running a Multiplus 12/3000/120 with a 200Ah Fogstar Drift lithium, and it keeps calling float at around 80-85% state of charge according to the Victron app. Absorption just cuts short way too early.

From what I've been reading, it might be down to the absorption voltage threshold being set too conservatively — the Multiplus seems to exit absorption based on tail current dropping below a set percentage, and if that's configured too low it'll bail out before the battery's actually full.

A few things I'm wondering:

• Has anyone adjusted the tail current setting in VE.Configure? What value are you running for lithium?
• Could this be a battery temperature issue skewing the readings? Mine's in a rear locker and gets cold overnight
• Is it worth enabling the BatteryLife algorithm or would that make things worse in this scenario?

I've tried bumping absorption voltage up slightly to 14.4V but it didn't seem to make much difference to how long it stays in absorption before dropping off.

Also not sure if this is a Multiplus thing specifically or whether the Fogstar BMS is communicating anything odd — I don't have a DVCC setup running through a Cerbo or anything like that, just standalone at the moment.

Would really help to know what settings others are running with similar lithium setups. Feels like I'm leaving capacity on the table every time I charge, which matters when you're relying on it for days at a time without hookup.

@TorChild classic symptom of the absorption time being set too short, or your absorption voltage threshold not being high enough for lithium.

In VictronConnect, check your absorption voltage — for most LiFePO4 it wants to be around 14.2–14.4V. If it's set lower (sometimes defaults come in at 14.0V), the BMS sees it as satisfied and the Multiplus exits absorption early.

Also check tail current — if you're using the adaptive absorption setting, it'll drop to float once charge current falls below a percentage of your battery capacity. With lithium's flat discharge curve, that threshold gets hit deceptively quickly.

On my narrowboat setup I run:

• Absorption: 14.2V
• Float: 13.5V
• Tail current: 4% of C rating

Worth pulling the MPPT history logs too if you've got solar — sometimes the culprit is the charger rather than the Multiplus itself.

@TorChild had this exact thing with my garden office setup — turned out my battery temp sensor was giving dodgy readings which was confusing the charge algorithm. Multiplus was seeing false high temps and cutting absorption short as a precaution.

Worth checking if you've got a BMV-712 or similar — once I had proper SOC data feeding back via VE.Bus the whole thing settled down massively. The Multiplus on its own is basically guessing without that comms loop closed.

Also double-check your battery's recommended absorption voltage direct with Fogstar — their Drift cells can be a bit specific and the Victron defaults don't always match perfectly out the box.

@TorChild this one caught me out for months with my setup. Worth checking your charged voltage setting in VEConfigure — it's the threshold the Multiplus uses to decide "job done" before kicking to float. If it's set too low relative to your actual resting voltage, the unit thinks it's finished when it really isn't.

On the Fogstar Drift specifically, I found the default Victron lithium profile needed tweaking. The Drift wants absorption at 14.2V and I had mine sitting at 13.8V from a previous AGM profile I'd never properly updated. Rookie error but an easy one to make.

Pull up VEConfigure, go through the charger settings carefully, and cross-reference against Fogstar's own documentation — they publish recommended Victron settings on their site.

@VanJim raises a good point about the charged voltage setting, but I'd add one more thing nobody's mentioned yet — check your tail current setting in VEConfigure.

On lithiums especially, if the tail current threshold is set too high (default is often 4% of charger capacity), the Multiplus interprets the naturally low absorption current draw of a lithium as "battery full" and kicks to float prematurely. With a 200Ah Fogstar Drift that's a fairly tight BMS, so the current taper happens fast.

In my static caravan setup I had to drop tail current down to around 1-2% before the absorption phase ran its proper duration. Made an immediate difference.

Worth datalogging via VRM or even just watching the MPPT history to see exactly when the transition triggers — gives you something concrete rather than guessing at settings blind.