Wednesday, December 5, 2007

Legal to Drive, Part 2, and 12V hack

As you may recall, I registered the car so it is street-legal. The State of Colorado followed up with a new title issue, which arrived today - note the FUEL option. Hopefully this will be all I need to claim the Colorado alternative energy vehicle tax credit. I've scribbled VOID over this to make it harder to use this image for nefarious purposes:

I also engaged in a little 12V hackery this week. Like TimK, I was bothered by the voltage drop caused by 20+ feet of wire between the aux battery and any devices. So, I hacked mine. I took a different approach than Tim. Figuring that the two wires were connected in the engine compartment, I just cut them at the front firewall:

And then I put ring terminals on the end of all four wires and put a 1/4-inch bolt through them. This shows two of them bolted together:

This also provides the power takeoff point for my heater. I want to be able to run it without the key inserted (on those cold winter days), so I need unswitched power. I wrapped this securely with electrical tape once I had all the wires installed on the bolt.

This helps because instead of the 20-or-so feet of wire between the aux battery and any devices (because the wire runs to the engine compartment and back before plugging into the 12V system), the "short" introduced by the ring terminals and bolt provide a much shorter current path which results in a much lower voltage drop. Previously, the 12V system was dropping to 10.3-ish volts with the lights, brake lights, and a turn signal on. Now, it stays at 11.5 or better.

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