Victron Multiplus tripping out when the washing machine hits its spin cycle

Had almost the exact same grief last winter on the narrowboat. The spin cycle on our little Bosch draws a massive surge the moment it kicks in — the Multiplus II 3kVA was seeing it as an overload and shutting down before it could even react properly.

Few things that sorted it for me:

• Check your PowerAssist settings — if shore power or a generator is in the mix, make sure it's configured to pull from both sources during peaks rather than relying solely on the inverter
• ESS assistant vs standalone — I had the wrong assistant loaded which was making the overload threshold behave oddly
• AC output cable sizing — undersized cable creates voltage drop which the Multiplus reads as a heavier load than it actually is

The fix that actually cracked it was bumping the overload trip delay slightly in VE.Configure. By default it's quite aggressive, and a washing machine's spin surge is brief enough that a tiny bit of tolerance makes all the difference without compromising protection.

Worth also checking whether your battery can actually deliver the surge. I'm running Fogstar Drift 200Ah LiFePO4 and even that had some BMS hiccups early on when the surge hit — the BMS was cutting out a split second before the Multiplus could compensate.

What battery setup are you running? And is this a 2kVA or 3kVA unit? Makes a difference to what headroom you've actually got.

Others on here will have thoughts — @anyone running larger Multiplus setups, curious whether the 5kVA handles spin cycles without any tweaking or whether it's still a faff.

@Deano this is almost certainly the motor startup surge rather than the running load. The Bosch compacts are notorious for it — that initial inrush can be 3–4× the rated draw for a fraction of a second.

Worth checking two things:

1. Dynamic current limiter setting in VE.Configure — if it's too aggressive it'll trip before the surge clears
2. Your DC side: weak cells or undersized cable runs will cause a voltage sag under surge, which the Multiplus interprets as overload

On my van build I had identical symptoms until I reran the battery cable in 70mm² and the problem vanished entirely — the Multiplus never saw the sag anymore.

Also check which PowerAssist settings you're running. Sometimes bumping the AC input current limit up slightly stops it leaning on the inverter during those spike moments.

Had this exact scenario on my static caravan setup. Worth checking your transfer switch settings in VE.Configure — specifically the AC input current limit. If it's set too conservatively, the Multiplus can interpret the inrush as an overload and shut down before it even decides to pass through from grid/generator.

Also, check the PowerAssist settings. Enabling that properly lets the inverter boost from battery during the surge peak rather than tripping. Made a significant difference on mine.

One other thing @Deano — if your battery cables are undersized or have a poor connection, voltage sag during that surge will be worse than it should be. The Multiplus sees that sag and panics. Worth checking terminal torque on the battery end first, it's a quick win.

@Deano same issue on my narrowboat last year — what sorted it for me was bumping up the overload trip delay in VE.Configure. By default it's quite aggressive, but giving it even a couple of extra seconds means the Multiplus rides through the surge rather than tripping.

Also worth checking what your PowerControl input limit is set to if you're on shore power at a marina — if it's set too low, the inverter is already working hard before the spin cycle hits.

What size battery bank are you running? I found my setup was also marginal on the DC side during that surge, which wasn't helping matters. Fogstar Drift cells now sorted that for me, but it's worth ruling out.

@FinnTaylor78 already nailed the trip delay tweak, but if that still doesn't crack it — check your AC input current limit isn't accidentally throttling the inverter's headroom during surge; had exactly this on my motorhome Multiplus where the shore power limit was fighting the washing machine like two blokes arguing over the last Greggs sausage roll.

Also worth running VE.Bus System Configurator to confirm your PowerAssist is actually enabled — it should theoretically bridge the surge gap by supplementing from the battery pack rather than just throwing its hands up.

Fogstar Drift cells with decent C-rate will handle the momentary draw too; if you're on tired AGMs they'll sag under surge and the Multiplus interprets voltage collapse as an overload condition — classic red herring that had me chasing ghosts for a fortnight.

@Deano the bit nobody's mentioned yet — power assist settings. If you're on shore power or a generator at the time, the Multiplus can be told to boost from the battery to cover surge peaks rather than just tripping. It's called PowerControl/PowerAssist in VE.Configure and it completely transformed how our boat's Multiplus II handles the spin cycle.

Before I found that setting I was convinced the inverter was faulty. Spent a weekend rewiring things for absolutely no reason whatsoever. Classic.

Worth also double-checking your battery cable sizing — undersized cables cause a voltage sag right at that surge moment and the unit panics. Fogstar cells are brilliant but they can't help if the cabling's strangling them.