BikeGen, Stage 1: Increasing Output

Well, my idea that decreasing resistance on the alternator output line from the 3Ω would increase output seems to be valid, though I still don't understand why.  I went back to RadioShack and picked up four more 10Ω 10w resistors. I put them in parallel on the output line and started pedaling, as soon as the alternator's field cut in, 1.75A flowed out and I was still pedaling easily.  With my ultimate target of about 100w captured, this level of output was about 21% of the way there.  To get this I put six 10Ω 10w resistors and one 8Ω 20w resistor all in parallel for a total of ~1.38Ω of resistance and up to 90w of power dissipation.  So far, no one has been able to explain to me why this reduces the load on the alternator and I haven't found anything that helps me make sense of it.

Turns out that the rheostat that I burned up was only half burned up.  I was able to wire up the other pole on it and get dialable resistance the other way.  This way actually makes more sense anyway, clockwise decreases resistance (Ω) and increases how hard it is to pedal.  With the rheostat in place, I was just about to commence testing when one of the connections shorted out.  This caused the wires to go red hot almost instantly, burning all the coverings off in the process.  Oops.

Luckily, I didn't fry the alternator, or myself.  This did serve as a good reminder that I'm dealing with a very powerful source of electricity, and that it really was time to clean up my wiring and reduce the number of exposed terminals I had.  Also, I really should get around to putting some more fuses inline...

Here we are, post-cleanup:

With this arrangement and my trusty wife assisting by turning the rheostat, I was able to dial the power output from 1.75A, all the way up to 9A.  This was major, major progress.  However, the high output quickly fell off down closer to 5A.  My theory on that is that I'm still overheating the rheostat, causing the resistance to increase.  I was able to dial in the resistance to a level I could sustain for a good workout this morning though.   So my final numbers at this point are sustained output of 2.35A or 28w, enough to power a big CFL light bulb and 28% of my hopeful goal.  The total theoretical resistance on the line now is about ¼ Ω, but I think that's increasing with heat so I don't have a great way of measuring that yet.  I'm feeling good about the resistor situation, once I get the resistance dialed in, or adjustable to reliable levels, I'll rewire everything up into a control box I can mount on the handlebars.  I also see the need to minimize the mechanical loss coming on down the line, so I've got some thinking to do there too.