Car Wattage Problem

**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

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

**Mcnovy** · 04-30-2005, 04:37 PM

what is the voltage when you turn on the CarPc..?
if the voltage drops, maybe you should try putting a Cap close to the Pc..!
the best way to messaure the voltage would be with a osciloscop, og a analog multimeter..!

**KyleYankan** · 04-30-2005, 05:06 PM

Jaz - try connecting to the known voltage again - the one where it did work. See if the PSU fried or something

**George00** · 04-30-2005, 11:05 PM

OK, grab a multimeter and stick it into the yellow / black wires on a HDD molex connector. If it's analog, the polarity matters, if it's digital it won't.

See what the voltage is THERE. My guess is 9 or 10 volts, Ideally it should be around 11.8 to 12.3.

Now measure the INPUT to the PSU of the PC at the computer. If it's low, get a thicker + wire.

I'm guessing you used too high gauge wire and there's a lot of voltage drop on it.

**Jaz** · 05-01-2005, 12:41 PM

done a few measurements now.

At the car psu when its off, there is 12.2volts
when its on its at about 11.6 (i guess this is the problem)

when i go to back of car and measure the battery, it also is 11.6 when computers on.

And when computers off its 12.2 volts.

i guess the battery isnt up to the job.

cant work out why it worked well for so long in the house tho.