Anyone else's MPPT randomly dropping to float way too early?

My Victron SmartSolar 100/30 keeps throwing me off — it'll hit maybe 80% SOC on the Fogstar lithiums and just decide that's float time, cheers, done. Sitting on the boat all weekend watching it cycle between absorption and float like it's confused about what it's doing.

Panels are 2x 175W Renogy polys wired in series, so around 44Voc into the controller. Absorption voltage set to 14.2V, float at 13.5V, tail current at 2A. Thought the tail current trigger might be the culprit — maybe too low for a 200Ah bank?

Bumped it up to 4A yesterday and it seemed to hold absorption longer but honestly hard to tell with the patchy October sun we've had. Anyone dialled this in properly for LiFePO4? Wondering if the battery profile in VictronConnect is doing something weird behind the scenes.

Nessa61 | 📍 Norfolk Broads | ⚡ 400W + Multiplus

@BayLisa this sounds like it could be a tail current issue — if your absorption current drops below the tail current threshold before the battery's properly full, the controller thinks "job done" and bails out to float early.

Worth checking what you've got set in the VictronConnect app under the charge algorithm. Fogstar lithiums can be a bit particular about those settings and the Victron defaults aren't always spot on for them.

Also — are your battery voltage sense wires connected properly? Voltage drop along the cables can fool the controller into thinking absorption is complete when it really isn't.

What cable run have you got between the controller and the battery bank? On boats that distance can really catch people out. 🚢

GrumpyWanderer | 📍 Array | ⚡ Solar

@BayLisa had this exact faff on my setup. Check your absorption voltage — if it's set too close to your battery's resting voltage the MPPT thinks it's done when it isn't. Fogstar cells are fussy about this.

Also worth checking whether you've got the battery profile set to lithium or if it's still on some generic AGM nonsense. VictronConnect app, battery settings, double-check everything matches what Fogstar actually recommend in their docs.

What's your absorption voltage set to currently?

BarryCrane | 📍 Scottish Highlands | ⚡ 600W + SmartSolar 150/35

@BayLisa had almost identical with my setup last spring. Worth checking your battery profile in VictronConnect — specifically the absorption voltage and the "tail current" threshold @Nessa61 is alluding to. On lithiums especially, if tail current is set too high it'll think the battery's full long before it actually is.

Also worth double-checking your battery cable sizing. Undersized cables cause enough voltage drop that the controller thinks it's hitting absorption target at the battery terminals when it isn't. The MPPT measures voltage at its own terminals, not the battery.

What's your cable run length and gauge? And are you using the VE.Direct cable with the BMV at all? Remote battery sensing sorts this properly if you've got the hardware for it.