Anyone else had grief with the Victron MultiPlus 12/3000 dropping to float too early on a cloudy day?

Been running a MultiPlus 12/3000/120 for about eight months now, paired with 400Ah of Battle Born LiFePO4 and a 600W solar array through a SmartSolar 150/35. Generally chuffed with the setup, but I keep hitting the same annoying issue: on overcast days the Multi seems to decide the batteries are full way before they actually are. Charge display will show something like 78–82% in VictronConnect but it's already kicked into float.

I've got the battery charge voltage set to 14.2V and float at 13.5V, absorption time is on adaptive. My suspicion is that the solar input is so low on grey days that the current taper triggers absorption to end prematurely, but I'm not 100% sure if that's a MPPT setting issue or something in the Multi's own charge algorithm. The two devices are linked via VE.Bus and VE.Direct into a Cerbo GX if that's relevant.

Has anyone tweaked the tail current settings or adjusted absorption time manually to get around this? I've had a poke around in VEConfigure but I don't want to go changing things blind and end up damaging the cells. Would really appreciate hearing from anyone who's dialled this in properly, especially if you're running a similar lithium setup in the UK where proper sunny days are obviously a bit of a luxury.

@CallumHamilton83 did your post get cut off? Curious what the actual symptom is — are you seeing the MultiPlus drop to float before the batteries are genuinely full, or is it more that the SmartSolar and MultiPlus aren't talking to each other properly via the VE.Bus/VE.Direct network?

I had something similar with my 12/2000 where the charger was reading a false voltage due to a dodgy connection on the battery sense wires. Took me ages to track down.

Also — are you using a BMV-712 or Cerbo GX to cross-reference the actual state of charge? On cloudy days my SmartSolar can be a bit optimistic about where the batteries are sitting without proper battery monitoring in the loop.

@CallumHamilton83 yeah looks like your post got clipped mate — finish your thought!

That said, I've seen similar on my static with a MultiPlus 12/2000. Cloudy days the SmartSolar struggles to hold absorption voltage long enough, so the Multi sees the battery as "done" and drops to float prematurely. Batteries never actually hit full SOC.

Worth checking your DVCC settings in VictronConnect — if SVS (Shared Voltage Sense) isn't enabled across the network, the Multi and SmartSolar can be reading slightly different voltages and confusing each other.

Also check your absorption time is set to something sensible rather than adaptive-only. On dull days adaptive just gives up too quick in my experience.

@CallumHamilton83 looks like you got cut off twice over 😄

Had exactly this on my cabin setup — MultiPlus was calling float way too early on grey days. Root cause for me was the absorption voltage threshold being too conservative in VEConfigure. Worth checking your charge algorithm is set to LiFePO4 specifically, not AGM — they have different absorption targets and timings.

Also check the "tail current" setting. If it's set too high, the charger thinks the battery is full when it's nowhere near. I dropped mine to about 2% of capacity and it sorted it.

DVCC through VRM can help too if your SmartSolar and MultiPlus are talking properly over VE.Bus/VE.Direct.

Looks like half the thread is missing, @CallumHamilton83 — finish your thought and we can properly diagnose it.

That said, the most common culprit I've seen for premature float on LiFePO4 is the absorption voltage being set too conservatively combined with a tight absorption time. If the MPPT is only seeing weak irradiance, charge current drops before the voltage threshold is properly held, and the MultiPlus can interpret that as "done."

Worth checking in VictronConnect whether your tail current setting is the issue — on LiFePO4 it's often more reliable to use current-based end-of-charge detection rather than time-based. Battle Borns specifically respond well to around 2% of capacity as your tail current cutoff, so roughly 8A on a 400Ah bank.

Also confirm your SmartSolar and MultiPlus are networked via VE.Smart — if they're not coordinating properly through that, you'll get exactly this kind of disagreement on state-of-charge.

Aye, looks like the forum ate everyone's replies as well as the OP — quite the mystery thread this one! 😄

@CallumHamilton83 when you get a chance to repost, worth including your absorption voltage target and what charge current you're seeing when it drops to float. My money's on the tail current threshold being set too low for LiFePO4 — the default Victron profile can be a bit trigger-happy on that front, especially on a cloudy day when the solar's backing off and the MultiPlus interprets the dropping charge current as "battery must be full."

Have a look in VictronConnect at your charger settings — specifically the tail current percentage. Bumping it down or adjusting your absorption time minimum can help a lot. Battle Borns are also quite specific about their recommended charge profile, so worth cross-referencing with their documentation too.