Home backup power from van power system?

DIY
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1

I have a MultiPlus-II 2x120 V Inverter/Charger connected to a 12volt 1120 amp hours camper van power system that I built. The input on the inverter is connected to a SmartPlug RV 50 Amp connector, which is what I use to charge the battery when it’s sitting in the garage next to the 50 amp outlet.

My question is if there would be any issues with using a 3 way switch to connect to the SmartPlug RV connector to allow switching from:

Currently unused AC Out 2 on the Multiplus

and

AC IN on the Multiplus

Would this allow me to use the AC Out 2 on the Multiplus with my same SmartPlug RV connector/charging cable to feed a sub panel in my garage that would supply critical power outlets for my home in case of a power outage. That should give around 50 amps for the sub panel, right?

When not needing backup power,I would just set the switch so that the Smartplug is connected to the AC IN by default.

2

This would be incredibly dangerous, as well as extremely illegal. Backfeeding your subpanel also backfeeds the grid, which could kill a lineman working upstream trying to restore your grid, and/or potentially start fires and the list goes on.

Absolutely 100% DO NOT do this.

Just grab some good extension cords and plug your critical consumers into your van power system, though that may require re-evaluating what would be considered “critical”.

3

Sorry for the lack of clarification. This would be in a generator subpanel that would have an interlock preventing back feeding the grid. I assumed that was a given, but you’re absolutely right that this needs to be clearly spelled out. That is a very dangerous situation!!!