ESS JK-BMS Mode Float continuous discharging for no reason

Been having a bit of a head-scratcher with my JK-BMS setup lately and wondering if anyone else has hit this wall.

Running a DIY pack (EVE 280Ah cells) with a JK-BMS talking to a Cerbo GX, and I keep seeing the system drop into what looks like float but then just... keeps discharging. Slowly, but it's definitely pulling from the battery rather than sitting stable. Solar input is fine, cells are balanced nicely, nothing obvious screaming at me in the VRM portal.

My suspicion is it's something to do with how the JK-BMS is reporting SOC or voltage back to the Victron ESS — like the Multiplus is seeing a slightly different picture than what's actually happening at cell level. The float voltage target and the BMS reported voltage seem to be having a quiet argument with each other.

A few things I've already checked:

• DVCC is enabled with BMS control
• CVL and CCL look sensible coming through
• Battery monitor set to the Lynx Shunt, not the Multiplus

Has anyone managed to get a really solid, stable float with a JK-BMS in ESS mode? I'm curious whether this is a firmware thing — my JK is on an older version and I've been putting off updating it.

Also worth asking: is anyone using the Fogstar cells with a similar setup? Wondering if cell chemistry is playing into this at all.

Would love to hear how others have dialled theirs in. There must be a few of you running JK + Victron combos on here.

@DODQueen — oh mate, I've been down this exact rabbit hole with my boat build.

The culprit that got me was the DVCC charge current limit fighting with the JK's own logic. When the BMS signals "hey I'm full" via the Cerbo, the ESS algorithm sometimes gets confused and treats it as a float state but keeps pulling small loads through the inverter rather than grid/alternator.

Check your minimum SOC setting in the ESS assistant — if it's set weirdly (even 0%) it can cause this phantom discharge behaviour.

Also worth looking at whether your JK firmware is current. Mine was on an older version that had a known quirk where cell balancing activity was being misread by the Cerbo as a genuine discharge event.

What firmware are you running on the JK, and have you got the BMS wired via CAN or the RS485 dongle?

Check your cell voltage offsets in the JK app — mine were lying to the Cerbo like a dodgy used car salesman, showing the pack as fuller than it was and triggering phantom discharge cycles all night whilst I slept blissfully unaware in my static.

@DODQueen mine did exactly this until I realised the JK's SOC reset wasn't triggering properly because it never hit a full 100% charge cycle — Cerbo thought it was floating but the BMS was essentially lost in the woods with no map, so it kept tickling the inverter for power like a teenager raiding the fridge at midnight. Force a manual full charge to top-balance, let it sit at absorption until current drops to near zero, and watch the SOC snap back to sanity. Victron's DVCC then has something honest to work with. Also double-check your charge voltage setpoint matches between the JK app and the Cerbo — two sources of truth means neither is actually telling the truth.