Q: I'm incredibly frustrated with the power outlet in my 2016 F-150. It can only operate tiny things such as a phone or a laptop charger, but it blinks and fails to operate my cordless multitool battery charger or a small air compressor. Can it be upgraded or replaced with something more capable?
A: Power inverters are cool gadgets, and it is great to have one along in a vehicle to make available small to moderate quantities of 120 volt household power. The problem is that to make much more than the 400 watts, your built-in inverter requires a well-ventilated cigar box size or larger device -- which is difficult to fit within the instrument panel -- as well as very thick power cables. And you have to take care to only operate it when the engine is running, to maintain battery charge.
Many years back, I installed a 1200 watt power inverter under the back seat of our Silverado to recharge a computer, run a crock pot and operate a small chest freezer in order to bring frozen fish home from Alaska. This required running very thick cables (pinkie diameter) directly from the battery under the truck and up through the rear cab floor. A very large (200 amp) fuse was employed to protect the circuit, and great care was used to route and protect the cables from chaffing on anything metal. The system works great, although one must absolutely remember to turn off the inverter each time the truck is parked, to avoid battery run-down.
The thing about power inverters is that in order to change 12 volts DC into 120 volts AC, there will be 10 or more times the current in the 12 volt side of the system (cabling to inverter) than what the 120 volt side can provide at the outlet (volts times amps equal watts). This is why the cables need to be huge/short, and the engine needs to be running (the car/truck battery would run down very quickly without continual charging).
Please don't consider mounting the inverter under-hood and bringing the 120 volts into the cab. The 12 volt cabling could be a bit shorter/easier to route, but the under hood temperature is too high for the unit, and it's too dangerous to run the 120 volt cord past so many metal obstacles.