Ford F150 PowerBoost 7.2 and ground fault error when charging through Multiplus II

Has anyone else run into a ground fault error when trying to charge from a Ford F150 PowerBoost's 7.2kW export? I know the F150 isn't exactly common over here in the UK, but a mate of mine imported one and we've been trying to get it working with my Victron Multiplus II as a backup charging source for the static caravan setup.

Every time we plug in and attempt to draw power, the Multiplus throws a ground fault error and shuts down. The F150's onboard generator is floating neutral, which I think is the root of the issue — but I'm not 100% sure.

A few questions for the more experienced folks here:

• Has anyone successfully fed a floating neutral generator source into a Multiplus II without issues?
• Is there a setting in VictronConnect that handles this — something in the advanced or grid settings perhaps?
• Would a neutral-to-earth bonding relay or similar fix be the cleaner solution rather than fiddling with software?

I've read vague references on some US forums about toggling something in the Victron app that apparently resolves it almost instantly, but the posts are frustratingly light on specifics. Wondering if the UK/European firmware versions handle this differently anyway given our different grid standards.

The caravan also feeds a Fogstar battery bank, so I'm keen to get this working as a supplementary input rather than relying solely on solar during the winter months.

Anyone been down this road before? Would be brilliant to get a definitive answer rather than piecing together fragments from American threads where the grid setup is completely different to ours.

SomersetCamper | Posts: 847

@IvyWalker interesting one this! The PowerBoost's onboard generator uses a floating neutral rather than a bonded neutral, which is almost certainly what's upsetting your Multiplus II. Victron's ground fault detection expects a proper neutral-earth bond at the source.

Worth trying a neutral-earth bonding plug on the F150's output before it reaches the Multiplus — basically a standard plug with neutral and earth bridged. Some folks use a small isolation transformer instead which gives you a clean bonded output and solves the problem properly.

Also check your Multiplus II settings in VEConfig — there's a ground relay option that might need adjusting depending on your setup. What's the rest of your system look like? Battery bank, any existing earthing arrangements? That'll help narrow it down.

BirchLover | Posts: 1,203

@IvyWalker yeah the floating neutral is the key issue here. The Multiplus II expects a solid neutral-earth bond on the input side, and the PowerBoost doesn't provide one natively.

Quick fix — fit a neutral-earth relay (or a simple manual switch) that bonds N-E when the PowerBoost is your active source. Some folks wire this into the Multiplus's AUX output so it switches automatically.

In VE.Configure you'll also want to check the ground relay settings — there's an option for the Multiplus to create its own N-E bond internally, which might sort it depending on your exact setup.

Done something similar when testing a generator with a floating output on my static van. Sorted it with an internal bond via VE.Configure first, took about 10 mins. Worth trying that before adding external hardware.

ExFirefighter11 | Posts: 2,341

Had almost this exact scenario when I was wiring up shore power for the boat — the Multiplus II is very particular about its neutral reference. What sorted it for us was adding a neutral-forming relay controlled by the Multiplus's aux output, so when it detects a floating source it switches in a neutral-to-earth bond before accepting the input.

@BirchLover and @SomersetCamper have the diagnosis right, so I won't retread that ground.

Worth checking your GX device settings too — under ESS → AC Input there's a ground relay configuration that sometimes needs manually enabling depending on firmware version. Caught me out for an afternoon on the shepherds hut build before I spotted it.

Victron's VRM portal will log the exact fault code which narrows it down quickly if you're unsure whether it's a configuration issue or something weirder going on with the F150's output under load.

IslandOffGrid | Posts: 412

Worth adding that the Multiplus II's ground relay behaviour is configurable in VictronConnect — there's a setting that controls whether it actively connects neutral to earth on the output side.

If your mate's running ESS or a similar assistant, that changes things further. I went down a rabbit hole with this exact topology when setting up emergency backup for my place; took a fair bit of reading through Victron's own community forums before I understood why the errors were appearing rather than just masking them.

The danger with chasing workarounds before understanding the root cause is that you can end up with genuinely unsafe floating neutral situations downstream.

Is he running any other equipment between the F150's Pro Power Onboard socket and the Multiplus II input? A proper transfer switch with neutral switching could be part of the picture here.

BorderCamper | Posts: 287

Really interesting thread this — I've been wondering about using vehicle-to-load exports for my van build so following closely.

Quick question for @BirchLover and @ExFirefighter11 — once you've sorted the floating neutral issue, does the Multiplus II behave reliably with a variable/unclean AC source like a vehicle generator? I'd imagine the PowerBoost output isn't as stable as proper shore power?

Also wondering whether the AC input current limit in VictronConnect needs dropping right down initially to avoid tripping anything whilst you're diagnosing — has anyone tested what the F150's export actually looks like on an oscilloscope? Curious whether it's clean enough sine wave output or whether there's harmonic nastiness that might be confusing the Multiplus further.

Not directly experienced with this specific setup but had similar ground relay headaches connecting to a small Honda genny on the boat.