I have a device that plugs into the aux power port in the car. (formerly known as a cigarette lighter)
It outputs 110vac 100watts that powers the laptop computer.
19v at 4.7 amps is just about 100 watts. You might want go a couple of watts higher to be safe. If you go a lot higher though, the current drain on the 12v input may be more than the lighter socket can handle. They used be good for 10 amps but that was back when people used cigar lighters for cigars and/or cigarettes.
Buy it. It's not worth destroying a $800 laptop. See iGo Universal Chargers & Power Adapters There stuff is really good. You by "tips" to match your device.
The power supply's primary is rated 110-240 Volts at 1.5A, shouldn't I make the calculations based on these numbers? that would make up 165 Watts (max) at 110V.