Thread: How do you guys manage to power your carputers?

there gonna tell u to

i think u should juice an inverter... w/a shutdown controller

Originally Posted by eldorado99

I was trying to contemplate building my own carputer using an old Dell I have sitting around which is a P4 1.3 with a 250W ATX power supply. Is it possible to power that using a modified sine wave inverter? Could I wire up a ups to my car battery? Do I have to buy a DC to DC power supply? I am really in the dark here so if you guys could enlighten me I would appreciate it. Wouldnt a 250W power supply on a 300-400W inverter load my alternator almost constantly and burn it out in a fairly short period of time? How do you handle the power spikes from starting the car and turning on the headlights? I'm sorry, I have a lot of questions Is it even feasable to use my old Dell desktop? I have been reading quite a few posts but I am getting a little confused of the various methods you guys are using for power. Also my car is a bit of a clunker but it is in fairly good working order, how good does it have to be? The car works normally and everything and doesnt stall out, its just an old, tired car (1984 Ford LTD).

Damn right we're going to tell you to search!!!!
You've got a few options.
1) Inverters. Some people love 'em. They're less efficient, since the inverter converts the car's DC power to AC, then the computers PSU converts AC back to DC.
2) DC-DC power supplies. They come in various flavors by various manufacturers with various features. I'm sure you could find one that meets your needs.
3) Since the UPS operates on 110v (or 220v if you're in Europe)AC, how are you going to get that UPS wired to the battery, which is 12vDC? Think about it.

The biggest power fluctuation in a car that needs to be dealt with (if it's important to you) is cranking, i.e. when you turn the key to start the motor. Most of the power goes to the starter to turn the engine over to get it started. I believe the voltage jumps significantly (or does it drop significatly?), and that spike can fry PSUs, motherboards, drives, inverters, etc, if they can't handle it or the power isn't regulated.

Again, search around here and you'll get the answers.

Yup, also do a search or browsing around the power supply and show off your project forums for idea and stuff.
But also remember DELL is suck because the PSU in their PCs are not standard PSU. Maybe the wires are all reverse, I don't know. But I know for sure is you can not buy any PC PSU off the shell and put in a DELL PC and expect it to work. You have to buy the PSU from DELL.
Now with the above note, DC-DC PSU is out of the picture for you. Well not exactly cuz you can re-order the wires on the ATX connector. There are only 3 or 4 that I think usefull: Opus, Mastero/Sproggy, Keypower and the new M1-ATX.

Your best bet now is Inverter, if you do it right (wire and stuff), it will be okay. It may not survive the cranking, because of old car that take longer time to start. Get a better, more capable battery will help the inverter continue pushing out power while the car the crank (survive cranking). Try to buy an inverter with the lowest working voltage also help. Do you know the car voltage while the engine is cranking? If the car drop to 10V for example, you buy an inverter with the working voltage of 10V or less (I don't think there is any but you never know.)

As for load on the charging system. There will be but not much. The power the PC/Inverter used is not much more than a 2 100W foglight. Usually truck can handle that load.
Good luck

I don't think ALL Dell computers use the Dell proprietary (looks like an ATX but isn't) power supplies. Your best option is to manually compare what you have against the ATX spec with a voltmeter. If you have the Dell specific crap, then search Google for an adapter. Otherwise you can try something beefy like the Opus 150W to power it. Don't know if it will do it or not. You could take a few current readings to be sure.

Otherwise, an inverter based solution may be the best.

If I just didn't turn the computer on before or during the startup of my car it would avoid all of these jumping voltage problems, no?

Originally Posted by eldorado99

If I just didn't turn the computer on before or during the startup of my car it would avoid all of these jumping voltage problems, no?

No, just the biggest voltage fluctuation.
Car's power isn't a constant voltage. The computer needs a constant voltage to operate.

looks like u didn't even read a thread

If you don't turn on your comp (for example put it in standby) when starting then you should be okay.
BTW, I used to power my lappy through the inverter and it sucked *** because the inverter had a "feature" that made it shut down whenever the voltage dropped, so it would shut down for a second or two every time I opened a window or used my windshield wipers. When the inverter shut down, so would the computer so I had to restart. That sucked big time so I ditched the inverter and connected the laptop directly to the battery. For you that's not an option though, but just telling you about the kinds of problems you might run into.