Idling & Running Voltage Question

I though about your unusual symptoms I wonder if the inverter sensing wire is not connected to the 12 volt battery.

The 12 volt battery has 2 wires plugged into its fuse assy. One is the thicker lead that’s the main power cable from the 12 volt battery to the front jump point bolt. It’s bolted down to the jump bolt and feeds all the fuses in the front fuse box under the hood.

The other lead connected to the 12 volt wire is a thinner black wire that goes to the inverter and allows direct monitoring of the voltage of the remote mounted 12 volt battery. This is the sensing wire used by the inverter to calculate 12 volt battery level.

Both of these leads are on white plugs that plug into the 12 volt fuse assy on top of the battery. They are removable and easily removed by compressing there white plug lock lever. Wonder if its not plugged in and also this fuse assy has 100 amp fuse and A 5 amp fuse. Wonder if that 5 amp fuse is blown. But pretty sure it woukd throw the red triangle of death.

Or whoever is testing the car does not know how to make it READY.

Also for lurkers removing both these leads from the battery is the best and safest way to change out the 12. No sparks no drama. They exist to service the 12 volt battery. Remove the 2 wires swap in new battery plug the wires back in no sparks.