Help me reduce my carbon footprint and big fat gut!

So I'm trying to arrange a set up where every morning I pedal my bike, in a training stand, attached to a car alternator, attached to a deep cycle battery which will ultimately be feeding all those computer peripherals that I have scattered across my desk. No exercise, no DSL, etc. (And no, I don't do subsistence farming in my back yard (yet) so I know I'm not really doing much environmentally besides reminding myself how much energy all those littler peripherals suck.) Anyhow, I've seen numerous articles where people are easily getting 12-14 volts out of their alternator. At a level of effort that feels like 20 mph on level ground I'm getting maybe 3v. Any idea what I'm doing wrong?

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Austringer (author) 9 years ago
In case anyone comes along looking for this sort of thing I've worked out my issue. An alternator needs a reference voltage and I didn't have mine set up right. The cool part of this is that you can control the resistance of the system by varying the reference voltage rather than using some kind of mechanical resistance.
LinuxH4x0r9 years ago
You probably have a bad gear ratio set up.
Austringer (author)  LinuxH4x0r9 years ago
Well, it's a 27 inch wheel turning a 2 inch cylinder which is connected to the old friction wheel (essentially a 6 inch flat pulley) on which I've set a v-belt which drives the alternator (maybe a 2.5 inch pulley). So from wheel to alternator that's about a 32 fold increase. A 27 inch wheel turns about 750 times in a mile, so at 10 MPH you're doing 7500 RPH or about 125 RPM. So the alternator is going about 4000 PRM (just guesstimating on the speed here - my bike comp is on the stationary front wheel). I'm not sure how big the damper pulley is on a Corvette (what my alternator is officially for - believe it or not, it was the cheapest) but I'm gonna guess between 5 and 7.5 inches, so I should be producing the same amount of juice as a Corvette doing 1300-2000 RPM. A review of the '05 Vette says, "at 85 mph in sixth gear, the engine's only turning at 2,400 rpm" so I have to assume I should be in the working range.
Kiteman9 years ago
You could try this idea.
trebuchet039 years ago
Is there a load on the alternator (such as a battery in need of charging - or a big fat resistor)?