Laptop Power On - No Ignition Power

musters · 10-16-2007, 04:38 PM

Initial Problem:
My car's fuse box is completely full with other peripherals. I took my car to two different mechanics who said the same thing, they can't run another power line that runs off the ignition. The second guy I went to said he could wire up the circuit if I really wanted, but that the Toyota wires would probably melt because they weren't meant to take that much load.

Current Setup:
So after much disgust I went ahead and just wired directly to my battery and put in an in-line fuse with a switch. I have a main power button in my dash that gives power to my laptop, and also triggers the power on of the laptop.

Aftermath:
A year later, I'm getting tired of remembering to turn off my computer when I turn off my car. A few times I have forgot and subsequently my car battery was drained.

Would anyone be able to provide any useful suggestions that I might be able to implement into my current setup that would allow me power-on with the ignition? I have search the forums on relays and possible solutions there, but they either require some piece of hardware which I can't guarantee will work, or some type of schematic that is way above my soldering skill level.

I need a simple switch that does the following:
- If I have power (from a in-dash light or something), then open the switch, if I don't have power, close the switch.

Thanks in Advance.

DodgeCummins · 10-16-2007, 10:46 PM

It depends on how much power you are talking about.

One possibility would be to get an automotive relay, connect it to you ignition switch to control the power from the battery to your laptop.

http://www.the12volt.com/relays/relays.asp

So #85 to ignition switch power, #86 to ground (metal chassis ground)
#30 to your battery power, and #87 to the laptop power supply.

You can get relays mail order etc...but I was able to get one...with a nice wiring harness from my local car audio/ alarm dealer/installer.

sliturnek · 10-17-2007, 09:18 PM

i ran a relay for mine but how do i set it to auto start when there is a active power connected?

DodgeCummins · 10-18-2007, 10:15 PM

Perhaps in BIOS?

auspiv · 10-18-2007, 11:06 PM

set the power settings in windows to turn off after running on battery for a time. i have my computer set to hibernate (no power draw) after 3 minutes of running on battery. to get there: control panel-display-screen saver tab-power settings.