Car Wattage Problem

Jaz · 04-30-2005, 11:22 AM

Hi all

finally got my car pc working properly with the powersource out of the car,
ive now moved it into the car.

the power source in the back, and the car pc in the front.

Now what is happening is the pc is acting like its not getting enough wattage. hard drive wont spin proplery and motherboard doesnt power up until the 2nd request. but then still wont get into xp because of the hard drive.

however this was working fine on the same power source, out of the car.

Now will this be the problem? i am running only the positive wire up the whole legth of the car... The ground for the power source is grounded in the boot, and the ground on the computers psu is grounded at the front of the car.
Will this effect the amount of wattage it can pull? if not im stuck.

jcdillin · 04-30-2005, 11:44 AM

Need more info,

what power supply, what motherboard, what size wire did you run

evandude · 04-30-2005, 11:45 AM

First off, WHAT is your power supply?

in my experience, the hard drive won't spin up properly when the input voltage is too low. Sounds like you are dropping a lot of voltage between your "power source" and your computer, over the long wire... why don't you put the power supply up back?

Bugbyte · 04-30-2005, 11:46 AM

If it's an ITPS, it won't work properly when the car is off. Even if it's not, try starting the car, then starting the PC.

Jaz · 04-30-2005, 12:51 PM

other details are irrentlivent. i just wanted to know if having different grounds points would effect wattage.

wasnt the problem, something else had changed... i was using the cigerette lighter on the jump station instead of the clamps. seems the ampage on the cigerette lighter is regulated where as on the clamps its not...

basically i have got a 2nd battery (a jump station), running a 200watt PW-200 whatever power supply.

In my house, hooked up to the battery it works fine and did for over an hour with no problems on multiple occassions.
Now i have got it in the car, same setup as in the house, and it doesnt work fine.
it worked for about 7minutes then stopped working correctly.

back to the drawing board i guess...

ATXaccord05 · 04-30-2005, 01:00 PM

what guage wire are you running as your power?
are you sure you have a good ground point?

test at where the 12v in/out is with a multimeter and check what your voltage is.

Jaz · 04-30-2005, 01:08 PM

voltage was right. 12.64volts or something similar.

grounding points, one is using same as head unit, other is using a main car grounding point, which brake lights etc use.

Power cables are rated up to 17amps.
i was under the impression though that cables rated lower will still supply the current, but will be unsafe and may melt etc.
i have a feeling a 13amp cable may be used at one point.

but 13.5amps is the peak for the car psu anyway.

might just try and run a ground direct from battery to pc and try that

Auri · 04-30-2005, 01:24 PM

Running from the battery is so much more convenient than using an inverter. If you have an ITPS you can just set your computer to hibernate when you kill the ignition and then it will come right back to where it left off. Of course, that all assumes you have reliable power going to your machine... look into a direct battery connection - you'll never go back

BTW, I discuss all that in my book Geek My Ride, available from Amazon now. I've set up a web site if you have any questions (www.geekmyride.net).

Good luck!

-Auri

Mcnovy · 04-30-2005, 01:26 PM

use as short ground cables as possible.!
use youre chassis etc.!
test the voltage on the computer, and not on youre psu.!
you wire have som voltage drops, så the most accurate wuold be to test the voltage on the yellow cable on the harddrive.!
use minimum as thick ground cable, as youre "hot" cable.!

Jaz · 04-30-2005, 01:32 PM

im not using a invertor, im using technically a battery (which is also a jump station)

I am using the chassis as a ground, and i have short cables at the moment.

Arathranar · 04-30-2005, 01:33 PM

17A wire doesn't mean it's thick enough to avoid a large voltage drop over a long piece of wire. What gauge wire is it? What is the voltage at the computer?

ATXaccord05 · 04-30-2005, 01:57 PM

what is your alternator rated at?

Jaz · 04-30-2005, 02:44 PM

hasnt got a voltage drop out. 12.64volts are being delivered to the front of the car.

not sure about alternator, thats not an issue at the moment.

Arathranar · 04-30-2005, 02:51 PM

Quote: Originally Posted by Jaz

hasnt got a voltage drop out. 12.64volts are being delivered to the front of the car.

So that 12.64 V is under load? I.e. with the computer connected and drawing it's 13 A?

Jaz · 04-30-2005, 04:28 PM

well the computer doesnt seem to be working properly unfrotunatly. lol

but yes the time it did successfully boot it had that voltage.

13amps is the peak power tho, it shouldnt be pulling that all the time... hardly at all i expect. maybe at spin up, but cant see it getting to 13amps.

i dont think my setup can be any more than 150watts under load

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