Newell Gurus

Does anyone know what this device is and its purpose? It is located on the backside of the rear panel. I am referring to the finned rectangle in the upper portion of the photo. The wire feeding it comes from the large (150 & 75 amp) 12V breakers on the rear panel.

Possibly and old battery isolator to isolate house and chassis batteries?

It appears to be a shunt used to drive a meter or monitoring by a charger/inverter.

Thanks guys. With your input and some more wire tracing I believe it to be a battery isolator.