Ground to house panel? Victron Multiplus

[SolarFamily]

Setting up a basic powerwall for home to cover short term power outages. Plan to add solar panels once I get the inverter+battery working grid-tied.

Entire setup is basic at this point:

1. Multiplus 24/3000/70. Firmware updated. Mounted to basement wall. *Not grounded yet.*
2. bigbatterycom 24V A123 2.45kWh battery (one now, but will expand)
3. Heavy gauge plug from AC-IN on Multiplus to simple 20amp wall outlet next to home electrical panel (13A limit set on multiplus). Then, heavy gauge extension cord on AC-OUT to power fridge and misc. essentials during power outage.

Idea is to charge off grid power (in the immediate) and use only for essentials during outage.

Problem: If battery is plugged in, home circuit breaker trips within seconds. *Multiplus is currently not grounded, so I understand this may be a key factor.

Question 1: Is the tripping likely due to case not being grounded? Or, is it surging too many amps on initial charge (note I have it set to 13A IN limit, but still trips) and I simply need a bigger breaker?

Question 2: Where should I safely ground it? Wouldn't it be natural to simply pop the home electrical panel and run grounding wire to main panel ground bar?

Thank you for your input; this is an awesome community!

 

[snoobler]

1: possibly, but if the OUT is just an extension cord, I doubt it. There is both an AC-in limit and a charger limit. I would confirm that they're set to be compatible. I would try cutting the power way down to 5A and see if the behavior changes. If that's not a dedicated breaker, you could be tripping it because of other loads on that circuit.

Also try power-on via pre-charging the caps and connecting battery BEFORE the breaker is ON.

Also try in "charger only" mode if it doesn't work in "ON"

2: Yes. bare metal portions of the case are grounded by default. I'd do it the way you propose.

 

[SolarFamily]

Thanks for the input. I tried lowering max draw setting to 7.7 (lowest it will go) and pre-plugging in battery/turning battery on prior to turning on the Multiplus. Same problem - trips breaker almost immediately. I'll grab some grounding wire and patch into main house panel and report back.

 

[snoobler]

There's no way that AC out is on the same circuit as AC-in, right?

 

[SolarFamily]

There's no way that AC out is on the same circuit as AC-in, right?

To clarify, there's no load plugged into the AC-out, just the extension cord waiting for a load. I had tested that earlier: with the battery disconnected, the Victron passed power from house circuit > into AC-in > Victron passes directly through to AC-out and powered a test device fine. In that sense, I guess the AC out is on [fed by] the same circuit as AC-in.

 

[snoobler]

That's what I thought, I just wanted to make sure.