Coupure charges non essentielles en OFF GRID

Anyone else running a load-shedding relay off their Cerbo when the SOC dips below a certain threshold, or are we all just hoping the fridge isn't the thing that kills the bank overnight?

On my boat I've got a Victron Multi hooked up to about 6kWh of Fogstar Drift LiFePO4, and I've rigged up a couple of non-essential AC circuits through a contactor triggered by the Cerbo GX — electric kettle, battery charger for the power tools, that sort of nonsense. Works a treat via the relay outputs and a bit of Node-RED faffing.

The logic is dead simple:

• SOC drops below 30% → contactor opens, luxuries go offline
• SOC climbs back above 60% → everything clicks back on
• Inverter alarm → belt and braces, everything dies

Curious whether anyone's done this more elegantly with the ESS assistant or just physical relays off the BMS low-voltage cutoff instead — the BMS route feels a bit "sledgehammer to crack a walnut" since it'll just hard-kill everything rather than gracefully shed loads in sequence.

Also wondering if anyone's stacked this with a generator autostart trigger — I've got a Whisperpower tucked in the engine room but the integration feels like it needs a bit more thought before I trust it on a cold January night at anchor.

What's your priority load hierarchy looking like? Heating, lighting, comms — what makes the cut when the clouds don't show up for a week?

@Cerbo_Master yeah running exactly this on the shepherd's hut. Got a Cerbo GX with a Venus relay triggering at 20% SOC — cuts the non-essentials (kettle socket, a couple of LED strips, the little oil radiator I sometimes leave on).

Set it up through the relay assistant in VictronConnect, dead simple once you wrap your head around the logic inversion.

The fridge is hardwired past the relay obviously — learned that the hard way 😅

Only thing I'd say is set a decent hysteresis on the reconnect threshold, otherwise it's cycling the relay on and off all night which isn't great for anything. I have mine reconnect at 50%.

Works a treat, Fogstar 280Ah LiFePO4 has been much happier since I stopped letting random loads bleed it down overnight.

@Cerbo_Master doing something similar in the van but I've gone a step further — running two relay outputs from the Cerbo. First one at 25% SOC cuts the inverter loads (kettle, laptop charger, that sort of thing), second at 18% kills everything except the fridge and the 12v lighting circuit.

Took a bit of faffing in VRM to get the conditions right, but once it's dialled in it's rock solid. The EV charging side is handled separately — I've got a basic ESS assistant that throttles the EVSE well before the relays even think about triggering.

Worth noting the Venus relay is only rated to something like 6A, so make sure you're switching a proper contactor rather than running loads directly through it. Learnt that one the slightly embarrassing way.

Great thread! @Cerbo_Master I've been doing this on my narrowboat for about two years now and it's been rock solid. One thing worth mentioning that I don't see discussed enough — make sure you're using hysteresis on your relay thresholds, not just a single trigger point. So for instance, shed loads at 20% SOC but don't reconnect them until you're back up to 50% or so. Without that you get the relay chattering on and off which is miserable and potentially damaging.

Also consider using the state condition (discharging) alongside SOC — prevents unnecessary shedding on a sunny morning when the SOC just happens to be low but you're actively charging. Venus OS makes this fairly straightforward in the relay settings. Works a treat once dialled in properly.

Running this exact setup on both my garden office and boat — the Cerbo's Venus OS relay logic is solid but I'd add one thing nobody's mentioned: hysteresis.

If you trigger the non-essential shed at 20% SOC, don't set the re-enable at 21% — you'll get relay chatter killing your contactor fast. I run mine at 20% off / 30% back on minimum, sometimes 35% depending on season.

Also worth looking at Node-RED on Venus OS Large if you want more nuanced rules — time-of-day weighting, charge current thresholds etc. Way more flexible than the basic relay assistant.

@RussGreen two outputs is smart — I do tiered shedding too. "Luxury" loads go first at 25%, then the real non-essentials at 20%.

Fronius/Victron MPPT data feeding into those decisions makes the whole thing a lot smarter over winter.