Will a power cap help me?

**smiler** · 12-08-2007, 07:46 PM

hi, this is my first post........
i have had a car pc for a few months now, and have wired it a bit strange to most i think, its a dell optiplex sx270, it runs off of 12v so i just wired it straight into the 12v ignition, now it has worked fine all summer but when the nights started gettiing darker and i had to turn the lights on on my way home from work the pc tends to die at junctions, i imagine this is because of a power shortage due to headlights on, revs dropping and brake lights coming on etc etc........ what i want to know is if i was to wire a power cap into it to stable the power would this sort my problem? and if so how many farad to go for?

sorry for being a complete n00b!

Heres My car BTW

Also when i install the power cap i will be moving the PC to the boot of the car and doing a few other little things like on/off timers etc

**DarquePervert** · 12-08-2007, 09:37 PM

That's not a car. It's a mini van.

And a cap is just a bandaid for your situation. It may help, but it's not going to fix anything.
Search for "BIG THREE" on these forums.
You're going to want to look at a new battery and possibly a beefier alternator.

**JimmyFitz** · 12-08-2007, 10:24 PM

Originally Posted by smiler

hi, this is my first post........
i have had a car pc for a few months now, and have wired it a bit strange to most i think, its a dell optiplex sx270, it runs off of 12v so i just wired it straight into the 12v ignition, now it has worked fine all summer but when the nights started gettiing darker and i had to turn the lights on on my way home from work the pc tends to die ...

Do you have an automotive (regulated) supply?

http://www.mp3car.com/vbulletin/advf...iew&advfaqid=2

**pokki** · 12-09-2007, 12:22 AM

Don;t waste you money on a Capaciator, put you money towards a 12 volt regulator and sufficient wiring.

**smiler** · 12-09-2007, 07:14 AM

Thanks for your replys, no i dont have any kind of regulator at all, and i know my wiring is rubbish, that was why i was going to re-wire everything when i got the power cap.

Not meaning to get at any of your replys (this is literally because i dont know!)
would a capacitor not regulate the voltage anyway then?

next ill get on to researching bigger alternator etc i think

thanks
smiler

**john1701** · 12-09-2007, 07:57 AM

do the big 3, don't buy a capacitor.

**lbridges** · 12-09-2007, 08:32 AM

Originally Posted by smiler

...
would a capacitor not regulate the voltage anyway then?

next ill get on to researching bigger alternator etc i think
...

A bigger alternator might only work for when you're at speed as some (most?) bigger alternators don't produce their enhanced output unless the engine is at speed. Not your problem, at least as described.

A capacitor doesn't "regulate" voltage, it is a short term electrical storage device.

I would expect a capacitor to solve the problem for a few seconds (at best) and that's it, so no, I would not recommend it.

The long term solution would be a regulated power supply.

A little more detail on other fixes described....

It could be your battery is on it's last legs and has built up excessive internal resistance.

A potentially simple fix is to remove the battery cables, clean them and reinstall. Voltage drops in a normally functioning system are due to resistance - and dirty cables are a cause.

The "Big 3" mentioned is a way of addressing resistance of the battery cables and might work if your electrical cables are in bad shape. The "3" are: new heavier gauge wire from alternator to battery, heavier gauge wire from battery to ground, and heavier gauge wire from battery to engine ground. The heavier gauge wiring has less resistance. One thing many people overlook when doing the big 3 (if you go that route) is forgetting to fuse the wire from the alternator to the battery...it needs to be there to prevent possible electrical wiring fires.

**DarquePervert** · 12-09-2007, 08:54 AM

A regulated power supply is going to protect the computer.
Don't get me wrong. That's a GOOD thing, but it's not going to alleviate any of the OP's electrical issues.

**smiler** · 12-09-2007, 09:15 AM

on the model before this one i had a dell sx260 running through a M2-ATX which was fine but when i upgraded to the sx270 the M2-ATX wouldnt run it, and it was in those few seconds of frustration i thought well the pc runs from 12volts what if i just run it from the car live! but it worked! and that was how it stayed so my issue with getting a regulated power supply is that it has to be powerfull enough and also i am on quite a tight budget for the time being because we had a baby 2 weeks ago today and he is in special care and its costing us a fortune in fuel to get there and back every evening.
so what type of psu shall i go for now? or maybe shall i go down the lines of an inverter and the original AC adaptor? it just seems pointless going from 12 to 240 back to 12

picture of the back of an sx270 with the power in port circled.
what i have at the moment is the plug going into there cut off before the ac bit.

Thanks for all your suggestions and help it is appreciated!!

smiler

**RedGTiVR6** · 12-09-2007, 11:16 AM

I would recomend doing some searching on here as others have used the same PC for their CarPC systems.

There are more powerful PSUs out there besides the M1 or M2 ATX.

Sorry to hear about the little one. Hopefully everything goes well and congrats on the new addition to the family.