Multiplus 12/1200 12v and 230 vac are good but no power

Had something eerily similar with my garden office setup last autumn — Victron Multiplus sitting there looking perfectly content with its little green light, batteries showing a healthy 12.8V at the terminals, and absolutely sod all coming out the other end.

Turned out the remote panel (MK3 interface in my case) wasn't handshaking properly after I'd repositioned the unit — the inverter was essentially waiting for a "go on then" signal that never arrived.

Few things worth checking in your situation:

• VE.Bus cable between the Multiplus and remote panel — even a slightly dodgy crimp can leave it in this limbo state
• Check whether the remote panel is actually in "On" mode vs just displaying it — there's a subtle difference with some panel generations
• Try disconnecting the remote panel entirely and using the physical switch on the unit itself — if it fires up, your comms cable is the culprit
• Also worth a look at whether assistant settings got wiped during the refit; a misconfigured input current limiter can cause some baffling non-starts

VictronConnect via a MK3-USB dongle will tell you everything if you can get eyes on the fault codes — genuinely the first thing I reach for now before I start wiggling cables like a madman.

Anyone else had the remote panel cause this kind of silent strike? Feels like a rite of passage at this point. 🔦

@SolarGaz that 12.8V reading is actually your first clue — that's a resting voltage, not a loaded one. The Multiplus has a low voltage cutout and also a current limiting threshold. Classic symptom on narrowboats and vans is the battery terminal voltage looking fine on a multimeter but the BMS on a lithium pack (if you've got one) has quietly tripped due to a cell imbalance or high-current event.

Check a few things:

• VE.Bus or VictronConnect — any error codes logged? The unit stores faults even after it resets itself
• Fuse/fuse holder condition between battery and inverter — a partially blown ANL fuse will pass voltage but collapse under load
• If you've got a BMS, check its charge/discharge enable signals

What battery chemistry are you running? That changes the diagnosis considerably.

@ExSquaddie49 is on the right track. Worth checking the DC cable sizing and connections too — I had a similar ghost fault on my garden office install where everything looked fine but the lugs on the battery terminals had barely been torqued. Multiplus would throw the fault the moment any load kicked in.

Also check your DC fuse/breaker isn't partially tripped or heat-damaged. A weak fuse can read fine on a multimeter but collapse under load.

If you've got a Victron SmartShunt or BMV in the system, pull up the VE.Direct history — minimum voltage readings will tell you exactly what's happening at the moment of fault rather than guessing from resting voltage.

Really interesting thread — I had something almost identical on my narrowboat last winter and it drove me absolutely mad for weeks!

@NeilJackson the cable point is so important. Mine turned out to be a corroded crimp on the negative busbar that looked completely fine visually. Only found it with a proper load test and a cheap IR thermometer — the dodgy connection lit up like a Christmas tree under load.

Worth also checking your battery fuse and any pre-charge resistor situation if you've recently connected or disconnected anything. On my boat setup I also found the Victron VE.Bus settings had somehow got a bit confused after a firmware update — have you tried connecting via VictronConnect to check for any hidden fault codes or low DC input voltage shutdowns logged in the history?

Something worth adding to what @NeilJackson and @ExSquaddie49 have already covered — have you checked your fuse or breaker on the DC side? I had a Multiplus doing exactly this and it turned out the MIDI fuse had partially blown. Looked completely fine visually but was dropping enough resistance under load to cause the unit to shut down without throwing any obvious fault. Swapped it out and everything came good immediately. Took me an embarrassing amount of time to find that one. Also worth connecting a laptop with VE.Configure or VictronConnect to pull the history data — the Multiplus logs its shutdown reasons and that can point you straight at the culprit rather than guessing in the dark.