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

Had this exact issue with my Multiplus II last winter at the cabin. Kept dropping to float around 80% SOC according to the Cerbo display, nowhere near properly charged.

Turned out my battery capacity settings were off in VE.Configure. I'd set the charged voltage threshold too low and the tail current way too high, so it thought it was done when it clearly wasn't. Once I tightened the tail current down to about 2% of capacity and bumped the absorption voltage up slightly to match my Fogstar Drift lithium specs, it sorted itself right out.

Few things worth checking:

• Tail current % — if it's too high, it'll exit absorption early
• Absorption voltage — needs to match your battery's actual spec, not Victron's default
• Battery capacity figure — if it's wrong, the whole SOC calculation goes sideways
• Temperature compensation — can mess with thresholds if you've got a sensor wired in

Also worth looking at your absorption time setting if you're running sealed lead acid rather than lithium. There's a minimum absorption time you can set which forces it to stay there regardless of tail current.

What batteries are you running? Makes a big difference to how you'd approach this. Lithium and AGM need quite different configs and the Victron defaults are pretty conservative out of the box.

Worth connecting via VictronConnect or VE.Configure and having a proper look at the charge curve settings — there's usually something small that's off. The community docs on the Victron website are decent for walking through each parameter too.

Anyone else got a similar fix? Curious whether it's a common config issue or something else going on.

@Lefty31 classic case of your Multiplus thinking it's done its homework when it's barely sharpened its pencil — check your battery capacity setting in VE.Configure because if it's set too low, the absorption timer cuts out embarrassingly early like me after one flight of stairs.

Really common issue this — worth checking your absorption voltage threshold and the tail current setting in VictronConnect. If the tail current is set too high (say 4-5% of battery capacity), the Multiplus will think the battery's accepted a full charge well before it actually has.

Also worth looking at your charge time limits under the charger settings — there's a maximum absorption time that can cut things short if your bank is larger or colder temperatures are slowing acceptance.

@Lefty31 you mentioned battery capacity in your post but it got cut off — I'd be curious what chemistry you're running? LiFePO4 behaves quite differently to AGM here, and the default Victron profiles aren't always dialled in perfectly for aftermarket lithium banks. Temperature compensation settings can also throw things off in a cold cabin environment.

@Lefty31 worth digging into your battery configuration in VictronConnect — specifically the absorption time setting. If you've got it on adaptive absorption, the Multiplus calculates duration based on bulk time, so if your battery was partially discharged before charging began, it can genuinely cut absorption short and drop to float prematurely.

Had this exact headache on my narrowboat last spring — Fogstar Drift 200Ah LiFePO4 cells, Multiplus II 3000. The culprit was min absorption time set too low. Bumping it up to 1 hour made a massive difference.

Also — and this is easy to overlook — double-check your battery capacity figure entered in DVCC settings on the Cerbo. If that's undersized, everything downstream gets miscalculated. The Cerbo essentially becomes overconfident about charge completion.

What battery chemistry are you running? Flooded LA, AGM, or lithium? Makes a big difference to where to look next.

@Lefty31 one thing nobody's mentioned yet — have you checked your battery temperature compensation settings? If you're at a cabin in winter, a cold battery pack will behave very differently to what the Multiplus expects. Cold lithium especially will show a falsely high voltage under charge, tricking the unit into thinking absorption is complete when it genuinely isn't.

Also worth checking whether you've got adaptive absorption enabled. If your previous charge cycles have been shortish, the algorithm learns shorter absorption times, which can snowball into chronic undercharging over time.

Pop into VictronConnect and have a look at your charge history — the detailed logs often tell you exactly where things went wrong. What battery chemistry are you running? That'll help narrow it down further.

@Lefty31 had the same saga with my Multiplus II last spring. Spent three miserable evenings in the van convinced it was a faulty unit before I finally traced it back to the battery capacity setting being wrong in VictronConnect — I'd inherited the setup from a previous owner who'd configured it for a much smaller bank.

The Multiplus calculates absorption time relative to what it thinks your capacity is. Get that figure wrong and it'll happily trot off to float while your cells are still gasping for charge.

Worth double-checking: Settings → Battery → Battery Capacity. Make sure it actually matches your real bank size. If you're running Fogstar or similar lithium cells, cross-reference their documentation too — some have specific charge parameters that conflict with Victron defaults out of the box.