I have thinking about this idea for at least a year, and I was wondering what you guys had to say.
The idea would be to build a verticle axis windmill using my 33rpm/v treadmill motor, which is good for 16 amps continuous, maybe higher. The diameter would be about 3-4 feet. The idea would be to use 10 1.2v 10Ah Nimh cells in parallel, to make a 1.2v, 100Ah pack. Then I would make a second battery holder so I could transfer the cells to make a 12v 10Ah pack. This way, the windmill would only take 40-45 rpm to hit cut in speed and there would have to be no gearing. Plus, on ebay you can buy these cells for $3.58 a piece shipped, so it would only cost $36 for the pack. I was thinking you could buy a Pb battery, which is about 10Wh/$ compared to the 3.4Wh/$ for the nimh, but you couldn't discharge the Pb as far, and it would be very heavy + possible spills.
If I charged the nimh cells in parallel, they would be balanced, and I doubt I could over charge the cells with my treadmill windmill @ 100Ah. Plus, the idea is scalable in sizes of 10 cells. A 10 cell pack would give me 120Wh, which I could then charge my laptop from.
I haven't designed the windmill yet, but I calculated a tsr of 1 and 8mph windspeed + 3ft diameter ~70-80 rpm, which would be awesome. I just wonder if the motor would burn out at 200-300 rpm because I currently have no data for this.
Always getting into a mess
Taylor