Multiplus-II Ground Relay Power Consumption

Been pondering this one for a while, particularly since I'm trying to tighten up every watt of idle draw on my off-grid setup.

The Multiplus-II has a ground relay that switches depending on whether you're on inverter or shore/grid power — standard stuff for the neutral bonding arrangement. What I've been trying to figure out is which position consumes power, and roughly how much we're talking.

My assumption is it's a latching relay or similar, meaning one state is "energised" (coil drawing current) and the other is passive. If that's the case, the idle consumption figures Victron quote in the datasheet may or may not include this — not entirely clear from what I've read.

On my system I've got the Multiplus-II 48/3000 running pretty much 24/7 in inverter mode, so if the relay coil is continuously energised in that state, it's adding to my no-load losses constantly. Even a couple of watts adds up over months when you're watching every unit carefully.

Has anyone actually measured this with a clamp meter or similar? I've not found anything definitive in the Victron documentation, and the community forums are a bit vague on it.

Also worth noting for UK folks — if you're running a TN-S or TT earthing arrangement this could have slightly different implications for how the relay behaves. Worth checking your DNO setup if you're grid-tied at all.

Would be interested to hear from anyone who's dug into this, especially if you've compared idle draw with the relay in both states. Victron's own technical team are usually pretty responsive on their community forum too if nobody here has the answer.

Good question @Tel1968 - the ground relay itself consumes negligible power, it's essentially just a contactor that's either open or closed. The real idle draw concern with the Multiplus-II is the inverter's search mode or the overall quiescent current of the unit sitting in standby.

Worth checking your VEConfigure settings - if you haven't already enabled search/UPS mode appropriately for your setup, that'll have far more impact on your idle watts than the relay ever will.

What size Multiplus-II are you running? The 3000VA and 5000VA have noticeably different idle draws, and that's where I'd focus attention first rather than worrying about the relay switching. The 48V variants tend to be somewhat more efficient at idle too if that's relevant to your system.

@Davo2 is right that the relay itself is negligible but worth noting the overall search power draw on the Multiplus-II is where you'll feel it — mine sits around 11W in search mode, which adds up overnight.

Also — and this is the pedantic bit — the ground relay behaviour actually differs depending on whether you're in island mode vs grid-connected. Victron's documentation on this is a bit scattered but it does affect how the unit manages that idle state.

If you're really chasing every watt @Tel1968, have you looked at your absorption/float thresholds in VictronConnect? Got a fair bit of idle draw reduction just tweaking those on my cabin setup. Not directly ground relay related but helps the bigger picture.

From what I've seen with mine in the shepherd's hut, the bigger idle draw concern is whether you've got search mode enabled properly. If not, the inverter's just sitting there burning watts doing nothing useful.

@EcoFlow_Gal makes a fair point about overall search draw — worth digging into VictronConnect and checking your actual no-load consumption figure. Mine was sitting higher than expected until I tweaked the search sensitivity settings.

The ground relay itself switching shouldn't register on anything meaningful. It's the rest of the circuitry keeping tabs on the grid connection that adds up slightly. If you're really chasing every watt, the Multiplus-II GX variants can give you better monitoring granularity through the Cerbo without needing separate kit.

@Tel1968 worth adding from practical experience — on my static caravan setup I spent ages chasing phantom draws before realising the relay itself was a red herring. What actually shifted the needle was tweaking the search mode sensitivity in VEConfig.

Default settings can be surprisingly aggressive about waking the inverter up. A cheap kettle on standby or even a dodgy fridge thermostat clicking will have it spinning up constantly.

Also check your AC input assistant settings if you're running any shore power occasionally — there's overhead there that catches people out.

The ground relay draw genuinely is immeasurable in any real-world sense. Don't lose sleep over it. Focus on what your Cerbo or BMV is actually logging rather than spec-sheet theoreticals.