Victron Multiplus tripping on startup with my old chest freezer — normal?

Been following this thread with interest because I had almost identical issues when I first tried running a chest freezer off my Multiplus II 3000.

The compressor startup surge was absolutely hammering the inverter — tripping the overload protection within seconds every time. Turned out the freezer's motor was drawing something like 4-5x its running current on startup, which is apparently completely normal for older compressors but brutal on inverters.

Few things that actually helped in my situation:

• Enabling the PowerAssist feature — made a noticeable difference
• Adjusting the transfer switch settings in VictronConnect (the AC input current limit was set too conservatively)
• Checking whether ESS assistant was affecting how the unit handled surge loads

Worth asking — how old is the freezer exactly? Older compressor motors tend to have much higher locked-rotor currents than modern inverter-driven compressors. If it's pre-2010, you might be fighting a losing battle depending on your battery bank's internal resistance too. A weak battery can't deliver the surge current fast enough, which makes the Multiplus work even harder.

Also, what's your DC cable sizing like? Undersized cables introduce enough resistance to cause voltage sag during that startup spike, which can trigger the low voltage protection rather than the overload protection — easy to confuse the two.

Has anyone here actually measured the startup surge current on older chest freezers? Curious what figures people are seeing. Would a soft-starter like the Micro-Air EasyStart even be compatible with a compressor-type freezer, or is that purely an air conditioning thing?

CraftyRanger | 847 posts | ⚡ Solar Enthusiast

@NeilEdwards Curious to hear how yours resolved — did you end up adjusting the PowerAssist settings or was it more about the battery side of things?

One thing worth mentioning that often gets overlooked: the age and condition of the freezer's capacitor makes a massive difference to that startup spike. Older compressors can draw 4-5x running current for that first half second. I fitted a soft starter (the Micro-Air EasyStart equivalent) to mine and it was night and day — the Multiplus barely flinched afterwards.

Also worth checking your DC cable sizing and connections. A marginal voltage drop under surge load can push the inverter into protection mode even when everything else looks fine on paper. Tightening my battery terminals actually sorted a similar gremlin for me last winter.

SimonKelly | 1,203 posts | 🔋 Off-Grid Veteran

@NeilEdwards The startup surge is the classic culprit here — older compressors can pull 6–8× running current for those first few milliseconds. What's your battery bank? If you're running flooded lead-acid or even AGM, the internal resistance under that spike can cause the Multiplus to see a voltage sag and trip on low-voltage protection before the compressor even gets going.

On my motorhome setup I solved a near-identical situation by tweaking the Low DC shut-down and Low DC restart thresholds in VictronConnect — giving it a touch more headroom stopped the nuisance trips entirely.

Also worth checking: is your DC cabling adequately sized? Undersized cable adds resistance that amplifies the sag massively. I'd want 70mm² minimum on a 3000VA unit.

What firmware version is the Multiplus running?

PanelSteve | 2,341 posts | 🌞 Narrowboat Hermit

@NeilEdwards Mate, I swear old chest freezers have the same startup philosophy as my narrowboat — "I'll get going when I'm good and ready, and I'll need a ridiculous amount of persuasion

CrispyMender | 412 posts | 🔧 Cabin Tinkerer

One thing worth checking that nobody's mentioned yet — the PowerAssist settings in VEConfigure. My Multiplus II 3000 was similarly thrashing itself on compressor startup until I realised the AC input current limit was set conservatively low, meaning the inverter was shouldering the entire surge alone rather than drawing any supplementary current from shore/generator.

Also worth considering a soft-starter module wired directly to the compressor. I fitted a Turntide-compatible unit on my cabin freezer (ancient Liebherr, probably older than me) and the inrush current dropped dramatically — measured before and after with a clamp meter and the difference was genuinely startling.

The Multiplus can handle the surge, but why punish it repeatedly if you don't have to? Compressor longevity improves too.