Narrowboat inverter keeps tripping on the washing machine – 2kW enough?

Been through something similar with a static caravan setup rather than a narrowboat, but the principles are the same.

The short answer is: 2kW is almost certainly not enough for a washing machine, even if the running wattage looks fine on paper. The killer is the inrush current when the motor kicks in — can easily spike to 3–4x the rated draw for a fraction of a second. Most inverters, including decent Victron units, will trip on that even if they're technically rated above the running load.

A few things worth checking:

• What's the inverter's surge rating? Some budget units are rated at 2kW continuous but only 3kW surge, which might not be enough. Victron and Victron-adjacent kit tends to handle surges better than cheaper alternatives.
• What washing machine are you using? Smaller "compact" or newer inverter-motor machines (like certain Bosch or Zanussi models) have far lower inrush than older drum motors.
• Battery voltage under load — if your bank is even slightly undercharged, the inverter can dip below its low-voltage threshold mid-cycle and cut out.

On a narrowboat I'd genuinely consider going to a 3kW inverter minimum if you want reliable washing machine use. Alternately, run the machine only when the engine is running and the alternator is keeping voltage stable.

Has anyone on here run a compact machine like the Zanussi ZWC1301 off a narrowboat system successfully? Curious what inverter capacity people are actually using in practice.

@JubileeClipHero95 nailed it, but the sneaky villain here is surge/inrush current — my washing machine on the narrowboat pulled nearly 3x its rated draw at startup, which is basically the inverter's worst nightmare and yours.

Went through two cheapo units before my Victron Multiplus 3kVA finally stopped throwing a strop — never looked back.

Key things to check:

• Rated watts ≠ startup watts (manufacturers bury this)
• Some machines are kinder on inverters than others — front-loaders generally behave better
• A soft-start device can genuinely save you money if a bigger inverter isn't in budget

Basically, your 2kW inverter is doing its job correctly — it's just correctly saying "absolutely not."

Has anyone actually measured the inrush on their specific machine with a clamp meter? I'm dealing with a similar situation on my boat and I'm wondering whether the inverter rating or the battery's ability to handle momentary surge is the real bottleneck here.

My Victron MultiPlus is rated beyond 2kW but it still occasionally grumbles at spin cycle startup — makes me think the C-rating of my cells matters as much as the inverter spec. Running Fogstar Drift cells at the moment.

What capacity bank are you working with @JubileeClipHero95? And are you running LiFePO4 or AGM? I'd imagine AGM internal resistance would cause voltage sag under surge that trips the inverter before it even reaches its rated limit.

@GrumpyWarden yes, do this. Got a Uni-T clamp meter, measured my own machine in the motorhome and the spike was absolutely mental compared to the rated draw — we're talking 3-4x the continuous wattage for a second or two on motor start.

Point is, your inverter spec sheet matters here. Look at the peak/surge rating not just the continuous. My Victron Multiplus handles surge way better than the cheap unit I had before it. Same continuous rating on paper, completely different in practice.

Also — front loaders vs top loaders behave differently. And older machines with brushed motors are worse offenders than newer inverter-motor types.

What machine model is it? Some are genuinely inverter-friendly, some are a nightmare regardless of what you throw at them.

@GrumpyWarden that's actually the right question to ask. What machine is it specifically?

I went through this with my static caravan — ended up with a Victron Multiplus 3kVA partly because of exactly this problem. Even then my older Hotpoint was borderline.

Few things worth checking:

• Eco modes sometimes reduce motor load significantly — worth trying if you haven't
• Some machines are worse than others at startup; front-loaders tend to be more aggressive than top-loaders
• What's your battery bank? Even if the inverter can handle the surge briefly, a weak battery will sag the voltage and trip things anyway

Has anyone tried the Bosch Series 2 compact machines on a boat setup? I've seen them mentioned as relatively inverter-friendly but never confirmed it properly. Wondering if that's actually true or just forum mythology.