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

Had this exact issue with my Multiplus-II 3kVA last summer. Turned out the tail current threshold was set way too high in VEConfigure — it was interpreting the battery as "full" when it still had a fair bit of capacity left to absorb.

Worth checking a few things:

• Tail current setting — default is often 4% of bank capacity, which can be too aggressive depending on your battery chemistry. I dropped mine to 2% on my Fogstar 200Ah lithium cells and it sorted it immediately
• Absorption time — are you using adaptive or fixed? Adaptive can sometimes cut absorption short if the voltage rises quickly (common with lithium)
• Battery temperature — if you've got a temp sensor fitted, a warm battery will tell the Multiplus it's charged sooner than it actually is

Also worth checking whether your shore power or solar input is fluctuating — I had a dodgy Anderson connector on my motorhome that was causing micro-interruptions, which reset the charge cycle and made it look like it was bouncing to float prematurely.

What battery chemistry are you running? Lead acid and lithium behave very differently here, and the Multiplus default profile really isn't optimised for lithium out of the box. If you're on lithium without a proper BMS-to-Victron comms link (DVCC via VE.Can or VE.Direct), the Multiplus is essentially flying blind on state of charge.

Has anyone else found the Cerbo GX making this worse or better? Curious whether DVCC enabled through the GX changes the tail current behaviour significantly.

@Smudge yeah classic misconfiguration. What battery chemistry? Because if you're running lithium the tail current threshold wants to be around 1-2% of capacity, most people leave it at the Victron default which is tuned for lead acid and it's completely wrong.

Also check your absorption time minimum — if it's too short it'll bail out early regardless of tail current.

Done this myself twice on my cabin setup before I stopped being lazy and actually read the VEConfigure docs properly. Fogstar Drift cells are particularly fussy about this.

@Smudge had exactly this on my shepherd's hut build — dropped tail current to 4% of battery capacity in VEConfigure and it sorted it overnight, literally.

Worth also checking your absorption time isn't set too short; Victron defaults can be stingy if you've got a chunky bank. If you're on lithium (Fogstar Drift cells are my poison), make sure you've also ticked the BMS assistant box or the Multiplus basically ignores what your BMS is screaming at it.

Quick checklist:

• Tail current: 2–4% of C rating
• Absorption voltage: match your BMS spec exactly
• Enable the Li-ion preset as a starting point, then tweak

VRM portal is your best mate for spotting the charge curve and seeing where it bails out early — graph doesn't lie.

@BoatPaddy tried fiddling with VEConfigure on mine and somehow also managed to accidentally reprogramme the microwave, set my Fogstar batteries to "confused," and book a holiday to Minsk — tail current's sorted though 🎉

@Smudge this is really useful, cheers — I've been scratching my head over something similar with my static caravan setup. Running a Fogstar Drift 200Ah LiFePO4 and my Multiplus-II keeps ending absorption early.

Quick question though — does the tail current threshold need adjusting differently depending on battery capacity? Like, is it strictly percentage-based or is there an absolute amperage floor you shouldn't go below?

Also, @BoatPaddy — when you dropped to 4%, did you notice it affecting battery longevity at all? Wondering if pushing it lower causes the cells to get stressed during absorption.

@MrBodge73 somehow that doesn't surprise me 😂

Haven't touched VEConfigure in a while if I'm honest — slightly terrified of breaking something. Is there a straightforward guide specific to lithium somewhere on the Victron community site?