Has anyone ever... ?

[Korbel]

I'm about to start a new project and I was wondering if anyone else has done anything similar.

I'm going to build a power supply to work on a car electrical system...

My first thought was to simply use a ac adapter for cigarette lighters. but it seems like ALOT of power loss converting the cars DC electrics to AC then back to DC in the PSU. so my goal will be to go straight from my car's fusebox to my custom PSU to a computer housed in the trunk of my Eclipse.

as a monitor I'll be using a dash mounted LCD display used for DVD applications

I'm not sure if I should use an IR keyboard but this is a definate trackball application...

If anyone has any suggestions they are welcome...

[Captain Slug]

I've seen it done and the appearant limitations keep you from supplying anything above 70Watts. So a Via C3 application would be best for what you're trying to accomplish.

Search around, there are quite a few how-to pages concerning DIY DC-DC power supplies in cars.

[TheKid5739er]

u figure that would take a hit on the alternator, drain ur battery real fast, but then again, i know s*** about cars:p

[twump]

alot of places online sell dc-dc power supplies. they are pricey though

[CrackedSKull]

if you're going to go directly to car's electrical system, you got to have some way to regulate(level out) the voltage. The voltage in a car is quite unstable, especially when you start the vehicle.
Maybe you could use one of those big capacitors people use for their amps.

So how do plan to get to 5v, and 3.3v, even 12v(the alternator puts out about 13.5v while running). Just a bunch of resistors?

[trend]

good idea, i have never thought of doing it without a converter, goodluck

[Erland]

U can do it my room mate is .......he just took a ac/dc converter and clipped the ends off and hooked it right to his backup battery...

He has his main battery up front and the pos. from it goes to the pos of the backup and then to the ground.......hook up the converter to the battery via a capasitor and there u go it SHOULD work....voiding all warentees.....but it will work....

[Korbel]

So is what you're talking about a DC to AC converter or is he just throwing things together.... if it's a DC/AC converter that you plug wall outlet plugs into then it is not what I am looking for...

I'm trying to prevent the battery-life losses and I(squared)R losses {which means electrically generated heat} inherrant in converting DC to AC then back to DC. I've been cruising my Digi-Key catalog and a few websites with no such luck on anything under $300 so I think I am going to design the entire circuit...

I did find an entire AT/ATX power supply that runs from DC but I could not find a price anywhere @ Citadel Technology (http://citadeltechnology.com/)

Well I'll be going to the drawing doard this weekend...

[Penguin4x4]

Try an amp isolator. It isolates a certain number of amps from the car's alternator to a second battery. So, a 275A alternator with 12V=3,300W total system power, with a 100W amp isolator, that would be only 8.3333A. A stock alternator runs@70A, so you can easily isolate 100A with a 275A alternator,(1,200W).