With nothing to do for a couple of hours, I decided to build a gravity powered generator to experiment with. As can be seen in the photo below I basicly threw it together with tie straps, some boards, and old parts lying around the shop.
I took an old electric scooter that the grandkids had discarded and removed the rear frame with the motor, sprockets, and sprag unit intact. I removed and discarded the old electric 24 volt motor and replaced it with a 90 volt motor which is now being used as the generator. The gear ratio of the sprockets is about 6:1. I removed the tire from the wheel which now makes it a homemade pulley (with the sprag unit included) that has a cord and weight connected to it from the ceiling through a small pulley and down to the floor. The sprag unit allows me to easily wind up the cord on the pulley without going through the gearing mechanism. When I let the 8 ounce weight fall (10 feet), the generator turns and powers 10 leds for about 19 seconds. The other gear setup shown on the orange table (see the photo above) is a 70:1 configuration in which I will connect to the generator using the same method at a later time. I estimate that it should run the same load for about three and a half to four minutes. The generator load is adjusted by adding or removing weight until a smooth slow fall is achieved to deliver maximum power to the leds. A video of this experiment can be seen
here.
Conclusion
Wider gears ratios could be used, but I don't have a clue as to how wide you could get. Using this reverse method a tremendous load will occur on the small output gears whenever you run through a wide gear ratio pattern. Theoretically speaking, if one could use something like a 1000:1 planetary gear head (they are available and can be purchased), the weight fall time of 10 or 12 feet could last a good hour or more. If you were to raise the ceiling pulley to a mere 40-60 feet, now you are looking at a astounding 8 hours or so. Being that we could turn the generator 1000 times verses 1 turn using nothing but weight, this question begs to be asked: Would it be possible to collect enough joules from the generator, which could then be used to power a small motor that would turn the sprag pulley unit and lift the weight back up to the ceiling pulley?
Gravity Power Experiment Photo
