I mounted it on the rooftop of my El Camino and it is working fine. But the infernal, er, internal combustion engine auto isn't. The inverter automatically shuts off when battery charge level is too low. That is a lot of stored energy. You may have noticed that almost all household circuit breakers will trip to off if amperage exceeds 15 Amps.
Amperage is the speed at which current is traveling.
Voltage is a measure of the volume of electricity present, available upon demand by closing a circuit. Watts is the amount of electricty produced or used. Voltage is like pressure, or, how much water pressure do you have coming through the garden hose. You may have noticed that in the middle of the night, the grid is actually selectively transformed to deliver less than 120 volts of AC power, which saves energy and you money. Not that much pressure is needed or demanded.