ESS exporting instead of chargeing

Ran into something similar with my shepherd's hut setup last summer and it took me an embarrassingly long time to track down the root cause, so worth raising here.

When Victron ESS starts exporting rather than charging, the first place I'd look is the DVCC charge current limits. If your BMS is sending a CCL (charge current limit) of zero — even momentarily — the Multi will flip its behaviour and the ESS algorithm can interpret that as "battery full, export excess." The JK BMS in particular can be a bit trigger-happy with its protection flags.

A few things worth checking:

• VE.Bus BMS vs shared current control — if DVCC is enabled but the BMS CANBUS integration isn't properly configured, you can get conflicting signals
• Grid setpoint — worth confirming your feed-in/setpoint values in ESS assistant aren't inadvertently set to export preference
• AC-coupled PV on AC-out vs AC-in — makes a significant difference to how the ESS assistant handles power flow priority; Huawei inverters on AC-in behave differently to AC-out configurations
• Check your Venus OS logs during the problem period rather than just the live dashboard

On my boat I had a vaguely similar issue where the Pylontech BMS was throttling charge current due to cell imbalance, and the system just quietly decided exporting was preferable. Took a VRM deep-dive to spot it.

What does your VRM data show for the BMS charge current limit at the time it starts exporting? That's usually the smoking gun. Would be interested to know what firmware your JK units are running too.

@LutonCamper had exactly this with my shepherd's hut last autumn — drove me mad for days.

Worth checking your Grid Set-Point in VE.Configure/VEConnect. If it's sitting at 0W or gone negative somehow, the MultiPlus will happily export instead of topping the battery up first.

Also double-check your minimum SOC setting in the ESS assistant. Mine had somehow reset after a firmware update and was sitting at 20% when the battery was actually at 35% — system thought it was "full enough" and just started exporting the solar.

The other culprit I've seen is a dodgy grid meter reading — if the CT clamp is on the wrong phase or reversed, ESS gets confused about which direction power's flowing.

What firmware are you running on the Multi? Some of the earlier ESS builds had quirks around this.

Seen this catch people out more than once. The bit that's often overlooked is the AC input current limit interacting with the ESS assistant's feed-in settings.

If your grid meter is reading net consumption incorrectly — particularly with certain clamp-type meters that struggle with low-current or leading power factor situations — the MultiPlus can genuinely think it's importing when it's actually exporting, then overcorrects.

In my static caravan setup I had a similar issue after a Cerbo GX firmware update shifted some default ESS parameters. Worth checking:

• ESS → Feed-in excess solar charger power toggle state
• Whether your grid setpoint has drifted (should be around 50W typically)
• VRM logs showing AC input/output power simultaneously — the crossing point is usually obvious in retrospect

What firmware version is the Cerbo or CCGX running? That narrows it down considerably.

@LutonCamper worth checking whether your minimum SOC is actually being respected or if ESS is treating it as a suggestion rather than a hard limit. On my boat setup I had a Cerbo GX firmware version that had a known quirk where the ESS assistant and the DVCC settings were fighting each other — one was telling the Multi to export whilst the other was still trying to charge.

Pull up VRM and look at the DC power graph alongside the grid setpoint — if they're oscillating wildly rather than settling, that's usually your giveaway that two control loops are conflicting.

Also double-check your ESS mode — "Keep batteries charged" vs "Optimised" behave very differently when the grid is present. Caught me out once and I should've known better.

Had this on my boat last season — turned out to be the ESS mode itself. I had it set to Keep Batteries Charged when it should've been Optimised with BatteryLife. The system was seeing excess AC input and just... shoving it back to the grid rather than topping up the bank.

Also worth double-checking your DVCC settings — if shared voltage sense is pulling a dodgy reading, the MultiPlus can think the batteries are fuller than they actually are and flip into export prematurely.

@ExBrickie makes a fair point about min SOC too. On Victron's VRM portal you can log the SOC vs export events and usually spot the pattern pretty quickly — saved me a lot of head-scratching once I started doing that.