Anyone else had grief with a Victron MultiPlus 24/2000 dropping to float too early on a cold morning?

Been having a frustrating one lately. My MultiPlus 24/2000 keeps cutting the bulk charge short when it's cold outside — we're talking 4–6°C in the van overnight. It'll hit maybe 80% SOC according to the BMV-712, then just drop straight into float like it's decided it's done. Happens most often after a run of cloudy days when the batteries have been sitting low for a while. Running 2x 200Ah lithium (Fogstar Drift cells, 24V bank).

I've got the temperature sensor wired in and the DVCC is enabled through VictronConnect. Absorption voltage is set to 28.4V, float at 27.0V. What's puzzling me is the absorption time seems to be cutting short — I'd expect it to hold absorption until the tail current drops below about 2% (around 8A on this bank), but it's bailing out way earlier than that. Wondered if the adaptive absorption algorithm is just getting confused after the batteries have been at a low SOC for a few days.

Has anyone tweaked the "repeated absorption time" or the absorption time settings manually to override the adaptive behaviour? I'm also wondering if there's something odd going on with the cell-level BMS communicating oddly to the Cerbo — I've got a Cerbo GX in the mix too. Any pointers appreciated before I start changing things at random and making it worse.

@RobHenderson classic Victron doing exactly what it's told — your absorption voltage threshold is probably being hit earlier than expected because cold batteries have higher internal resistance, so the voltage looks higher than it actually is. You need a temperature compensation cable (the VE.Smart dongle or a BMV temp sensor feeding into VE.Smart networking) so the MultiPlus adjusts its charge curve accordingly — roughly -4mV per cell per °C below 25°C. Without it you're essentially lying to your charger. Also worth checking your absorption time isn't set to "adaptive" and bailing out early. Sort it in VEConfig, not the app — the app hides half the useful settings like a particularly unhelpful gremlin.

@RobHenderson have you got temperature compensation set up on yours? If the battery temp sensor isn't connected (or isn't fitted), the MultiPlus has no idea the batteries are cold and won't adjust the charge voltages accordingly. Cold lithium or AGM will hit the absorption voltage threshold faster because internal resistance spikes — so it looks like it's done when it really isn't.

Worth checking in VictronConnect whether temperature compensation is enabled and what your battery temp is actually reading during charge. If you're running LiFePO4, Fogstar and most other suppliers will tell you the exact compensation curve to dial in.

What battery chemistry are you running?

@RobHenderson I had almost identical behaviour on my boat last winter. Turned out my absorption time was set too short in VE.Configure — the MultiPlus was hitting the voltage threshold quickly on cold batteries (internal resistance changes a lot at low temps) and then bailing out of bulk earlier than expected.

Worth checking your minimum absorption time setting. I bumped mine up from the default and it made a noticeable difference before I even sorted the temp sensor wiring properly.

Also, what batteries are you running? If they're Fogstar or similar LiFePO4, the BMS cutting communication in the cold can confuse the charger's state detection entirely — that's a separate rabbit hole but worth ruling out.

Cold batteries have higher internal resistance so they look fuller than they are — your MultiPlus isn't broken, it's just easily fooled, like me at a car boot sale.

Check your absorption time setting in VictronConnect; bumping it up so it holds absorption for longer before dropping to float can help massively in winter. Also worth looking at the repeated absorption interval if you're sitting at partial SOC overnight regularly.

@VanLee's temperature sensor point is solid — but even with compensation, cold LiFePO4 genuinely doesn't want to be hammered, so a slightly longer absorption time is often the better fix anyway. My shepherds hut setup sorted itself once I stopped letting the Fogstar batteries get below 10°C before charging.

@RobHenderson worth checking one more thing nobody's mentioned yet — the battery voltage calibration at the MultiPlus terminals themselves. On a cold morning, if your cable runs are even slightly undersized, voltage drop under load makes the charger think absorption voltage has been reached prematurely. I had this exact gremlin on my motorhome setup last February.

Connect a decent multimeter directly to your battery terminals during bulk and compare it against what VictronConnect is reporting. If there's more than about 0.3V discrepancy, your wiring is lying to the charger.

Also — are you running LiFePO4 or lead-acid? Makes a significant difference to how you'd approach the absorption timeout settings @12V_King mentioned. With my Fogstar Drift cells I ended up setting a fixed absorption time rather than relying on the tail-current cutoff, which behaves oddly in the cold.

@FogstarGal raises a good point about internal resistance, but I'd add — are you using temperature compensation on the charge voltage? On my Victron setup for the garden office I've got a Smart Battery Sense feeding the MultiPlus the actual battery temp, and it automatically raises the absorption voltage in the cold. Without that, the charger is essentially flying blind.

If you're running LiFePO4 (Fogstar or similar) it's a different story — most BMS units will throttle charge current in cold anyway, which could be making the MultiPlus think it's reached absorption threshold early.

Worth connecting via VictronConnect and logging the charge cycle data — you can see exactly where bulk drops off and whether it correlates with a voltage spike rather than true SOC.

@RobHenderson adding to what @DY_Power mentioned about temperature compensation — if you haven't got a MultiPlus temperature sensor (the VE.Temp dongle), that's almost certainly your culprit. Without it, the charger has no idea it needs to push voltage higher to properly charge cold batteries. At 5°C you're looking at needing roughly +0.03V per cell above your standard absorption voltage. Pop one on and configure temperature compensation in VEConfigure — made a night-and-day difference on mine over winter. They're only about £15–20.