19volt laptop

First, let me apologize for what might seem like a stupid question. I am getting ready to install a HP laptop into my truck as a car computer. The ac/dc converter that comes with it outputs at 19v 4amps. My question is that I am wondering if I could wire the laptop directly to the car's 12volt system since essentially, the laptop is being powered by the internal battery, and the power supply is providing DC to charge the battery? I figured that the laptop would be perfect because it would not suffer from loss of power during car starting, etc, etc since it would be running off the internal and charging off the dc feed. The laptop also will not be using the keyboard or video, my daughter stepped on the laptop cracking the LCD which still works, but I plan on adding a 10.4" Touch screen VGA and completely giving up on in-car multimedia, the pioneer I just bought stinks, it seems like the way to go is with a car PC and USB TV/fm tuner, USB XM Radio, USB gps, USB DVD/CD, and anything else you want USB. You get full screen DIVX, DVD, SVCD,VCD, you get it all. I'm rambling now, but anyways, I could always use a inverter, but since the laptop natives off of DC power, I was wondering, someone please help and toss a answer my way, I don't know much about power systems.

BTW, my truck has (2) Optima D31 "huge" batteries, and a Ohio 200amp gen. (If that matters)

Thanks

It's not a good idea to hook up your laptop directly to your car's power.  Car power is unstable and it's also the wrong voltage and amps to charge your laptop battery.  Depending on the type of laptop battery you have, you could blow it up or cause it to swell and leak or just not charge it.  You'll need a voltage regulator and chargeing circuit for your laptop.  That's what the AC to DC converter is doing, it's not just converting AC to DC, it's also regulating a constant voltage and current charge the laptop.  Hope that helps.

Oh, by the way, an option you have is to get one of those DC to AC adapters for the car and hooking up your AC to DC converter to it.  Just make sure the DC to AC adapter can put out enough amps for your laptop.  Or you can look into other car multimedia systems (Kenwood makes a really good system and so does Eclipse and Alpine isn't bad either).  Good luck.