Just got back from testing mine. It did not work until it was hooked to the vehicle. For me there was no need to look at the inverter panel. I think at least for mine it is designed to only work when it is plugged in to not drain battery power by leaving it on. I also have it plugged into my house so it would be good to know if it does stay on but I don'/t think so. LOVE the camera...so helpful.