Anyone else had grief with inverter chargers on a narrowboat shore line?

Running a Victron MultiPlus 12/3000 on my boat and the shore line situation has been... educational. The main issue I kept hitting was the input current limiter not playing nicely with older marina pedestals that have genuinely soft supplies — voltage sagging to 210V under load, which then triggers the unit to start supplementing from the batteries rather than charging them. Took me an embarrassingly long time to figure out why my Fogstar lithium bank kept sitting at 70% despite being plugged in overnight.

A few things that helped:

• Dropping the input current limit to 10A rather than leaving it at 16A — counterintuitive but it stabilised everything
• Enabling the weak AC input setting in VictronConnect, which is genuinely designed for exactly this scenario
• Checking the shore power cable — a corroded 16A blue connector was adding measurable resistance and making the sag worse

The other thing worth flagging is earth leakage. Older marina installations can have questionable earthing, and if you've got a galvanic isolator fitted (you should have one), it's worth testing it periodically. Mine had failed silently.

Anyone else finding particular marina brands worse than others? I've noticed a couple of the older Canal & River Trust facilities near us are noticeably worse than the privately run ones.

Also curious whether anyone's running a Quattro instead — the dual AC input looks appealing if you want to combine shore power with a generator without manual switching.

@MeadowDweller the input current limit thing is a real headache. I'm not on a boat but I've dealt with similar on my shepherd's hut setup where the supply is... questionable at best.

Worth checking your PowerControl settings in VEConfigure — a lot of people leave the input current limit higher than the actual shore pedestal breaker rating, then wonder why it keeps tripping. Also make sure AC input sensitivity is set correctly, older marina supplies can be quite noisy and the MultiPlus can get fussy about that.

One thing that helped me was enabling the weak AC input setting — it makes the unit less aggressive about rejecting dodgy incoming power. Buried in the settings but genuinely useful when your supply isn't textbook clean.

What firmware version are you running? Some older builds had known issues with input current behaviour.

Has anyone looked into what happens when the shore power cuts mid-charge cycle? On my boat I've had the MultiPlus drop to inverter mode fine, but then when shore comes back it seems reluctant to re-accept the input — almost like it needs a manual nudge. Is that a VE.Bus setting somewhere or am I missing something obvious in the config? Also curious whether anyone's using the shore power with a longer cable run from the pontoon — wondering if voltage drop at the input is making the unit fussier about accepting it in the first place.

@MuddyTinker mid-cycle shore drop on my narrowboat just means the Victron shrugs, switches to inverter mode, and carries on like nothing happened — genuinely the least dramatic thing that's occurred aboard this week.

@MuddyTinker @VoltageViking worth adding that the quality of that transfer matters enormously for sensitive equipment. The MultiPlus 12/3000 has a transfer time of around 20ms, which most modern electronics tolerate fine, but older marina pedestals can introduce enough noise on the shore line that the unit is constantly deciding whether the input is actually stable enough to accept.

I solved this on my emergency backup setup by tightening the AC input sensitivity in VEConfig — there's a shore current limit threshold and also the input voltage range you can narrow or widen. Narrowboats especially suffer because pedestal wiring can be ancient and voltage drop over long pontoon runs is real.

Check your actual shore voltage at the boat with a decent meter, not just at the pedestal. I was seeing 217V at the pedestal and 209V aboard. That delta caused endless nuisance tripping.

Not done a narrowboat myself but had similar grief with dodgy shore hookups on the motorhome — older campsite pedestals throwing all sorts at the MultiPlus input.

One thing worth flagging: the shore current limit in VictronConnect is often set too high out of the box. Dial it right down to match whatever the marina pedestal can actually deliver, otherwise you're fighting the breaker constantly.

Also had good results enabling PowerControl properly — obvious in hindsight but easy to miss if you've just done a quick install. Keeps the total draw sensible when you've got other loads running alongside charging.

@CrafterDream transfer quality point is spot on — anything with a decent PSU handles it fine, but older kit can be funny about it.