Daniel Swaab avatar image
Daniel Swaab asked

Multiplus putts voltage on vehicle body and seems to have a short

Seems related to Why do we have shorts and stray voltage while on shore power? but didn't find the answer there.

## intro

For a year I've completed a system in my van. It seemed to work without any problems (I have not used it heavily). At some point, I was working below the body and felt electricity flowing through me when I touched a metal bar of the van and the ground. I assumed a loose wire, but after some checks, it seems (to me) that it can only be a malfunction in the multiplus. I've noticed 2 things that seem weird to me:

1. When shore power is plugged in, my multimeter shows ~50v when I connect the van body to the pavement. This goes to ~0.9 when turned off (I'll assume this is negligible). The multiplus is turned off, the battery is disconnected, and the solar panels are disconnected. Multiplus is grounded to the body.

2. The hot and neutral of the ac-out seems to be connected/(shorting?) when they are connected to the multiplus. (multimeter makes a sound when I'm pushing against the wires, multiplus is turned off). Still, I have used AC out for charging my phone or running a coffee machine.

### Question

Is there something wrong with my installation/configuration, or is there something broken in the multiplus?

### To note:

- I haven't checked the body of the van after installation. The first time was after I felt the current, so it might have been wrong from the start.

#### Relevant connections (also see schematics below):

  • shore power input -> breaker A -> multiplus (ac in)
  • multiplus -> vehicle body (ground)
  • multiplus -> (fuse) -> 12v to battery
  • multiplus (ac out) -> breaker B -> outlets

## What I did

It only seemed to happen when the shore power was plugged in, so I've started checking the connections from the entry point of the 230 into my van. (Some connections are behind walls and I can't check directly)

  1. No shore power plugged in -> no voltage
  2. Shore power + breaker of -> no voltage
  3. Shore power + breaker on, disconnected ac out, battery, solar, multiplus off -> voltage

Then checked for shorts with multimeter and the only (weird) bleeps I found:

  • ac input plug -> and van body: only the ground beeps (is it normal that the ground is always open?)
  • Breaker A Live-> Breaker A neutral ----- rarely; very shortly, crackly soft sound between neutral and live
  • Breaker B Live-> Breaker B neutral ---- sometimes; very shortly, crackly soft sound between neutral and live

## system overview

Some component details:

  • Victron Smart Litium battery 330 Ah
  • Victron SmartShunt
  • Victron Multiplus 800/12/35
  • Victron VE.bus bms
  • Victron Gerbo GX
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1 Answer
kevgermany avatar image
kevgermany answered ·

Guessing that somewhere you have live and neutral switched, or a high resistance bridge from live to neutral. Could also be that they're swapped on your shore power.

You can get AC testers that plug into sockets and use LEDs to show missing earth, live and neutral swapped etc.

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Daniel Swaab avatar image Daniel Swaab commented ·

Thx for your quick reply! I've just double-checked the connections between [shore power input -> breaker A -> multiplus ac in; multiplus ac out -> breaker B] with a multimeter and they seem fine (all devices turned off):

  • check floating voltage on the body, was not there
  • took out the ac in/out plug of the multiplus
  • checked the wires, correct N/L/PE in AC in/out plugs of multiplus
  • Followed the connections to the breakers, no shorts
  • plugged the ac-in/out back in, then found a 'short' (multimeter beeped) in AC out when connecting N and L
  • plugged in shore power (multipluss still turned off) -> floating voltage on the body of the van.

I could get a AC tester but don't have one on hand, not sure if that would give me more info for the current problem and how I would use it?

Are there any other things I could test/try?

What should I imagine for a high resistance bridge from live to neutral? Where in my system could this happen?

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