Monday, April 20, 2009

Homebuilt Diesel DC Generator

Awhile back, I wrote a piece on Possum Living about a cheap generator I built using an automotive alternator. You can read that article here. As I covered in the article, automotive alternators have poor efficiency, which severely limits their usefulness. However, they are still better than nothing at all, and a lot of people are interested in them, so I continue to test and write about them.

One of the things I mentioned in the article was the fact that I have an air-cooled diesel engine that I planned to break in by using it with an automotive alternator for awhile, before using it as the power plant on a diesel motorcycle. I also touched on the possibility of bypassing the internal voltage regulator of the alternator, to assert manual control of the charging amperage, as well as possible use as a welder.

That is what I have been working on today. I dragged out the 10 hp air-cooled diesel engine a couple of days ago, and mounted and belted to it the same Delco alternator I had used in the project I wrote about in the original article. Then I discovered that it wasn't putting out any amperage. I'm not sure exactly what the problem was, but it was something in the regulator. As soon as I troubleshot it to that point, I decided that was the perfect opportunity to bypass the regulator and manually control the output, since it was something I wanted to do anyway. So I opened the case, cut the connections from the regulator to the brushes, and soldered a couple of wires to the brushes, bringing the wires out of the case. One of the wires I connected to ground, and to the other I soldered a couple of power resistors, one 10 ohm and the other 2 ohm. These resistors limit current to the field coils, and hence, output current. By connecting a jumper wire from a battery (either the starting battery or the battery under charge) to either of the two resistors, or bypassing the resistors, I have three output levels, which turned out to be approximately 10 amps and 35 amps, and full power in the bypass position.

I shot some video footage while testing, but since I recently switched completely to Linux (from Windows XP) and do not have a compatible movie editing package yet, I will have to wait to upload it to Youtube.

BTW, as you will see when I do post the video, I was wearing a Ruger old model Single Six on my belt. I debated removing it, but since I am a go-for-it kinda guy and don't care much what the lefties think of me anyway, I elected to leave it on.
I made a video of cold-starting the diesel manually (although it does have electric start as well); it was having problems that I was initially attributing to possible water in the fuel, since we had a storm here last night and the genny was barely covered with a dogfood bag, but it turned out to be nearly out of fuel. Then I made another video showing the genny outputting power. Later, I plan to make videos showing the power being put to use, and perhaps a video of me welding with it.

So that's what I have been doing. How about you?

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