Victron Multiplus keeps tripping at night - think it's the fridge kicking in?

Had almost exactly this on my narrowboat last winter. Woke up at 2am to that horrible silence when you realise the inverter's gone down.

Turned out it wasn't actually the fridge compressor startup — it was the combination of the fridge kicking in while the battery voltage had sagged overnight. The Multiplus was seeing a low voltage condition right at the worst moment, then the compressor spike tipped it over.

A few things worth checking:

• What's your low voltage cutoff set to? Mine was factory default and far too conservative for a lithium bank
• Is your battery BMS talking to the Multiplus via VE.Bus or are they not integrated? If the BMS trips first it can look like an inverter fault
• Check your VictronConnect history — there's usually a clear fault log showing whether it's overcurrent, low voltage, or temperature related

What batteries are you running? If it's AGM, voltage sag at night is brutal and the Multiplus will absolutely throw a wobble when the compressor draws that startup current.

I ended up adjusting the dynamic cutoff curves in VEConfigure, which made a massive difference. Also worth checking whether your fridge has a soft start — some older compressor fridges don't, and that inrush can be savage.

What size Multiplus is it, and how big's the bank? That'll help narrow it down considerably. Others on here will have seen this too — it's a surprisingly common one on liveaboard setups.

@DorsetCamper interesting that it wasn't the compressor itself — worth the OP checking the transfer switch relay inside the Multiplus. Mine was tripping overnight on my tiny house setup and I eventually traced it to the relay contacts arcing under repeated compressor cycling, causing cumulative thermal stress that only manifested after hours of operation.

Key things to check:

• Battery voltage sag during compressor startup — log it with a BMV-712 if you have one
• PowerAssist settings in VEConfigure — sometimes the assist threshold is misconfigured
• Ambient temperature drop overnight affecting battery internal resistance (lithium especially)

My Fogstar Drift cells showed dramatically higher internal resistance below 8°C, meaning voltage sag under the same load was considerably worse at 2am than at midday. That alone can push the Multiplus into low-voltage shutdown without the relay ever being the culprit.

@DorsetCamper @DontPanic — this rings familiar from when I was commissioning my shepherd's hut setup last autumn.

What caught me out wasn't the fridge or the relay — it was the DC ripple from an ageing battery bank causing the Multiplus to read false overload conditions. Night temps dropped, internal resistance crept up, and the inverter got confused under any transient load.

Worth checking your VictronConnect history logs — the Multiplus stores fault data and you can often pinpoint whether it's tripping on overload, over-temperature, or low DC voltage. That timestamp data is genuinely useful rather than just guessing.

If you're on flooded lead-acid, cold nights are brutal for this. My move to Fogstar lithium essentially eliminated the phantom trips entirely — internal resistance stays consistent regardless of temperature.

@DorsetCamper @QuietMaker worth also checking your low battery cutoff settings in VE.Configure — the Multiplus defaults are often too conservative and a fridge compressor cycling at 2am (when solar's been down for hours and temps drop, meaning the battery's internal resistance rises) can cause a momentary voltage sag that triggers the low voltage disconnect even if your SOC looks fine.

Had almost the same scenario with my garden office setup. Bumped the low battery cutoff from 11.5V to 11.0V and set the restart voltage properly, and the phantom trips stopped overnight.

Also — what battery chemistry are you running? If it's LiFePO4 with a BMS, the BMS itself can disconnect under load spike, which looks identical to an inverter fault but the Multiplus is actually blameless.

@AlexPalmer60 makes a fair point on the low voltage cutoff but nobody's asked the obvious yet — what's your battery bank? Because if you're running lithium and the Multiplus is still configured for AGM defaults, you're tripping on protection settings that don't even apply to your chemistry.

Also worth checking: is this actually a consistent time each night? On my narrowboat the pattern was the clue — same time every night pointed squarely at battery state after X hours of overnight draw, not a startup spike at all.

What does VRM or the Cerbo show in the logs if you've got one? Gut-feeling diagnosis on inverter trips is a waste of time when Victron logs tell you exactly what threw it.

@BurnWalker raises exactly what I was going to ask — battery bank details are crucial here, but I'd add: what cable gauge are you running between your batteries and the Multiplus?

I had a similar ghost-tripping issue on my setup and spent ages fiddling with settings before realising my cable run was slightly undersized. Under normal load it was fine, but the compressor startup drew enough current to cause a meaningful voltage drop right at the inverter terminals — enough to trigger the low voltage protection even though the batteries themselves were absolutely fine.

Worth grabbing a multimeter and checking voltage directly at the Multiplus DC terminals the moment it trips, not just at the battery. If there's more than about 0.5V difference between the two, your cabling or connections are likely the culprit.