My vehicle has a factory 150 watt inverter installed into the dash. These inverters can run laptops, gadgets, lower wattage 120v lights etc but certainly not enough to power much else.

I also have a store purchased, 300 watt inverter which can be powered either by a 12 volt accessory plug or directly to the battery with the supplied cables and clamps.

Any inverter bigger then this such as my 700 watt inverter should only be run directly from the battery otherwise you will start cooking fuses at higher wattage's.