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

Had this exact issue with my MultiPlus-II 48/3000 last spring. Kept dropping to float at around 85-90% SOC according to the Victron app, which was obviously throwing off my garden office loads during the day.

Turned out my absorption time was set way too short — I think it defaulted to something like 1 hour and my battery bank (Fogstar Drift 48V) wasn't finishing the charge cycle properly. Bumping it up to 2.5 hours sorted it almost immediately.

A few things worth checking:

• VEConfigure absorption time — is it long enough for your bank size?
• Tail current setting — if it's set too high, the MultiPlus thinks the battery is full when it isn't
• BMS communication — if you're running a managed lithium pack with DVCC enabled, a dodgy CAN connection can cause all sorts of weird early float behaviour
• Temperature compensation — cold batteries charge differently, and if your sensor is reading wrong it can pull float voltage down prematurely

I'd also check the VRM portal logs if you have internet connected. The charge cycle graphs make it pretty obvious where it's bailing out early.

Worth posting your battery spec and whether you're on a managed or unmanaged setup — makes a big difference to where the fault likely sits. Also which firmware version are you on? There were some quirks around DVCC behaviour in older builds that got patched.

Anyone else running Fogstar or similar LiFePO4 packs had similar? Curious whether it's a MultiPlus quirk or something upstream with the BMS.

@ExJoiner9 classic symptom of absorption time being too short, or your battery capacity settings being off in the MultiPlus config.

Had the exact same drama on my narrowboat last winter — Victron kept declaring victory at 87% like it had just won the Grand National. Turned out my battery capacity figure in VEConfigure was set to 200Ah when I'd actually got 400Ah of Fogstar Drift LiFePO4 sitting there. The absorption timer was cutting out way too early because it thought the bank was smaller.

Worth checking:

• Battery capacity setting in VEConfigure → Charger tab
• Absorption time — try adaptive absorption rather than fixed
• If you've got a BMV or SmartShunt, make sure it's talking to the MultiPlus via VE.Smart networking

Also double-check your charge current isn't throttled down so low that absorption never properly completes. What's your actual bank size?

Great thread this. @ExJoiner9 worth also checking your tail current setting in VEConfigure — if it's set too high, the MultiPlus will interpret normal resting current as "battery full" and bail out of absorption early. I had mine set at 4% on a 200Ah lithium bank and dropping it to 1% made a huge difference. Also worth checking whether you've got a BMS comms link set up via VE.Bus or VE.Can, because if the BMS is sending a charge current limit signal, that can confuse the charge stage detection entirely. What battery chemistry are you running? That changes things quite a bit in terms of what settings to chase first.

@FionaShaw makes a good point on tail current — that's actually what caught me out on my boat setup last year. I had mine set at 4% which was way too aggressive for my Fogstar Drift lithium cells.

Worth double-checking what battery type you've got the MultiPlus configured for too. If it's set to a generic profile rather than a proper lithium or AGM curve, the absorption voltage threshold can be slightly off and it'll hit float earlier than expected.

Also — have you got a BMV-712 or SmartShunt in the system? If the SOC readout is purely from the MultiPlus internal calculator rather than a proper coulomb counter, that 85-90% figure might not even be accurate. The real SOC could be higher and float might actually be triggering correctly.

Really useful thread this. One thing nobody's mentioned yet — have you checked whether your battery temperature sensor is properly connected and reading correctly? If the MultiPlus thinks your batteries are warmer than they actually are, it'll reduce the absorption voltage and cut the charge cycle short, which can absolutely cause premature float at that kind of SOC range.

Also worth double-checking in VEConfigure that your battery capacity figure matches your actual usable capacity rather than the nameplate rating — easy mistake to make and it directly affects how the adaptive charging algorithm calculates completion.

@FionaShaw and @DODQueen are spot on about tail current though, so I'd work through all three possibilities systematically rather than assuming it's any single culprit. What battery chemistry are you running @ExJoiner9? That might help narrow it down further.