Electrical newb in need of help

**SM60** · 10-27-2008, 08:11 PM

I'm planning a car pc build (early stages). Before I really start to put money into it I want to make sure I know all the major factors.

As far as the computer and software is concerned I'm good, but when it comes to hooking it up to my car's power system I'm lost.

From what I've read and researched I'm going to use a DC/DC regulator. The problem is I cannot find a simple how to on how to connect it to the car battery and then to the monitor and pc.

I'm probably going to use a Carnetix CNX-P1900. I've searched the forums several times but can't find a FAQ or how to for connecting DC/DC regs to batteries.

Any info or links is appreciated.

**funkyphil** · 10-28-2008, 12:16 AM

http://store.mp3car.com/ProductDetai...Show=TechSpecs

this is the one I have and it works awesome. Real simple hook up too, all you have to do is this. there are three wires to get power going. a red, black, and white. the red gets power from the postive of the batter, the black gets grounded, and the white is your ignition wire or acc wire. this wire will give the powersupply it's on/off power.

I have my monitor hooked up to the same power as my ignition and grounded to the frame, but I have added a secondary push button switch so that i can shut it off at will.

this works for me and i been using it for about a year now and have not had any problems with it.

Good luck and have fun

Phil

**DarquePervert** · 10-28-2008, 08:03 AM

Originally Posted by SM60

I'm planning a car pc build (early stages). Before I really start to put money into it I want to make sure I know all the major factors.

Good thinking.

As far as the computer and software is concerned I'm good, but when it comes to hooking it up to my car's power system I'm lost.

From what I've read and researched I'm going to use a DC/DC regulator. The problem is I cannot find a simple how to on how to connect it to the car battery and then to the monitor and pc.

Connecting the PSU to the car battery is simple. You run a wire of sufficient gage (I recommend 10awg) to the battery and connect it to the (+) terminal. There should be a fuse on this line within a foot of the battery to protect the wire in case of a short.
THe ground wire can either go back to the battery's (-) terminal or to a ground point on the chassis. The ground point should be bare metal.
If your PSU has an startup/shutdown controller, the ACC or IGN line should go to a 12v source that is switched on/off with the car's ignition. Likely sources are the radio harness, cigarette lighters and other equipment that only functions when the car is running.

I'm probably going to use a Carnetix CNX-P1900. I've searched the forums several times but can't find a FAQ or how to for connecting DC/DC regs to batteries.

Since you're so srearly on.. I'm going to ask you why you intend to use a Carnetix P1900. What sort of system are you looking at, and are you certain that the Carnetix will be suitable for that application?
Since you're in the planning stages, let's make certain you're looking at the proper PSU fo your system.

**SM60** · 10-28-2008, 01:47 PM

I picked the CNX-1900 mainly because of the dual output, so I only have to run one wire to the regualtor from the battery and then I'd have 2 outputs, 1 for the cpu and one for the monitor.

I plan to use a low power solution (VIA or ATOM processor) so the power would definitly be sufficient and stable. There would also be extra power in case I add anything in the future or upgrade

Thanks for the replies, the wiring sounds simple enough, glad to have that cleared up.

**DarquePervert** · 10-28-2008, 05:22 PM

See, the Carnetix units outpus a single voltage and are designed for laptops or miniPCs such as the AOpen Pandora or a MacMini.
If you're going to use a system based on an ATX-compliant motherboard, the Carnetix would not be the best choice to power your system.
There are ATX-compliant power supplies available such as the units from Opus and Mini-Box that are far more suitable for an ATX-compliant setup.

Monitor power can be taken from a HDD power connector, as well, so you're covered in that regard.

**SM60** · 10-28-2008, 06:00 PM

Ok good to know, in that case I'll probably choose something more like what funkyphil pointed out.

Everything sounds simple enough now. Hopefully you'll see my project up in the forums soon. Thanks guys.

**Bugbyte** · 10-28-2008, 11:43 PM

You are looking for a TERMINAL RING. You'll buy one of those in the electrical section at the hardware store and match it to the wire gauge you are installing.

This is a 10 AWG (gauge) terminal ring:

You can crimp the ring to the wire. I also soldered mine to ensure the connection, but you'll need to use a torch if the wire gauge is heavy. Maybe one of the gun-type irons with the pull trigger might work, but you need a lot of heat for it.

You can see how it is done in the video that is linked in my signature. Get a grommet when you get the terminal ring so when you pass the wire through the firewall it doesn't chafe.