Noob looking to run 12V DC line in 04 Accord

**jimforcy** · 10-22-2007, 01:35 PM

Hey everyone.

This is my first post here although I've been researching my project for a few weeks on the boards. I am still in the research phase but am trying to figure out exactly what steps I need to go through. The computer itself is coming together nicely and is pretty easy for me because I am a computer repair technician. My problems arise from the fact that I have very little experience with car customization short of the fact that I put new speakers and a new head unit in my '92 Mazda Protege.

For this project I want to purchase a DC-DC power supply for a desktop PC mounted in the trunk. I need to know how I might go about laying the wiring from the battery to the trunk.

My questions are these:
1. What safety considerations do I need to take when connecting the wiring to the battery?
2. What kind of wiring do I need? (Gauge I believe is the term)
3. What kind of connectors do I need to connect the wiring to the battery?
4. What kind of connectors do I need to connect the wiring to the power supply?

I know these are probably things that can be found here on the forums but I have been unable to get ahold of them with search. I also understand these are pretty basic. Once I get things figured out on this front and on fabrication I will be ready to roll. Thanks in advance for your help!

- jim

**2k1Toaster** · 10-22-2007, 01:45 PM

1.) Try to prevent sparks. Dont let the terminals touch obviously. I like to remove the battery run the wire, hook it up to the components, and then put the battery in and hook the wires to the battery. It is a pain but it makes me feel safer.

I had an uncle who is an engineer so he has his iron ring and when jumpstarting a car, that ring made a good contact point and electrocuted him. Fused the iron to him!

2.) Look at the table in the link. You want maximum power transmission for the guage. And it never hurts to go bigger. It doesnt cost too much more: http://www.powerstream.com/Wire_Size.htm

3.) You could solder it if you want, but that would be stupid. As long as it is metal to metal, you are ok. I like using ring terminals. You feed the wire in one end and it comes out in a flat loop that easily connects to the battery. usually there is a screw in those battery terminals so you thread the screw threw the loops, and screw it back on. That is how I did it at least.

4.) For this you can use your imagination. You want something you can disconnect usually, and most power supplies like the M1/M2/Opus have quick connect already. So to make the connection from battery wire to power supply wire I do suggest soldering. Solder it well, and cover with heatshrink. Tape is fine short term but has a tendancy to come unsticky and then you have bare wires with lots o' amperage flailing about.

**jimforcy** · 10-22-2007, 05:23 PM

Great reply. A few more questions:

5. I plan on using a 7'' Lilliput screen for this setup. I hear the side input causes problems and sometimes needs to be desoldered. Are there any guides to show this process??

6. In terms of placing my computer in the trunk, will I have to take my seats out to run wire? Its ok if I do but I was wondering if there are any VGA cables that have end connectors that pop off so that I can thread the vga cable though some tight spaces in the car? I searched and was not able to find anything.

- Jim

**Pint** · 10-23-2007, 09:44 PM

Regarding running a line - I would suggest using an suitable inline fuse close to the battery.

Also it's might be worth thinking about connecting a distribution block/fuse box incase you want to supply power to other components in the future. Therefore it pays to use a thicker gauge wire from the battery.

When you disconnect the battery, disconnect the earth first.

Older type batteries (unsealed) vent hydrogen which will ignite from sparks. Hence another reason sparks near a battery are not a good thing. I had a battery (that I had just charged up = lots of hydrogen) half explode on me once . The acid from the battery burnt holes in my clothes......