How can I safely power a laptop from my car battery without burning it out?

[Miller44]

Hello,

I am installing a small laptop computer in the dash of my car. My question is:

If the power supply from the battery of the laptop (which I do not have) is 12.65 volts at 2200 mA and I want to power it from the car battery (12.65 volts). Will the laptop only draw 2200 mA or will it burn out? And how would i lower the amperage if I need too? I have built minor circuits and have some knowledge on circuitry but I am just a little confused by this. Any advice would be appreciated!

 

[DaveC426913]

Hello,

I am installing a small laptop computer in the dash of my car. My question is:

This is a driving hazard.

 

[schip666!]

Ignoring the hazards I plunge ahead...

Your device will only draw the amount of current it "needs" at it's specified supply voltage. However automobile electrical systems can go up to around 14 volts when being charged, so your computer might feel like drawing more current than it should. It's probable that the guts of the computer are well enough designed that this won't be an issue, but they might be close enough to their design limits that an extra volt or two could push them over to the dark side. Pretty much the only way to know is to try it and see if anything heats up too much.

 

[Miller44]

Awesome, that was my initial thought but I had to check. I bought a lot of 5 so if one goes ill be fine. And for saftey measures ill wire it to the parking break ;]. Thanks again!

 

[MATLABdude]

I'd recommend going with something like this, instead:
http://www.targus.com/us/product_details.aspx?sku=APD80US
http://www.targus.com/us/product_details.aspx?sku=APM69US
http://us.kensington.com/html/17588.html

As schip666! says, car electricity isn't always very clean. These are designed to just plug into the cigarette lighter, buffer out any spikes or garbage, and step up/down the voltage to whatever the laptop needs (I think the second Targus and the Kensington also allow you to plug them into the wall as well, if you happen to want that functionality).

I used one a previous model of the first Targus, which worked quite well--just plug in the model of your laptop on their page and it'll tell you which tip is required (and whether it's supplied with the unit, or whether you need to get them to send you a free one). I think both these companies (and others, including RAM mounts) supply in-car laptop mounting solutions as well, assuming you don't want to build your own, or just leave it on the dash.