Instructables

BIKE GENERATOR?!

hey, I'm much more of a mechanical guy than an electrical one, and yeah, I'm trying to be won over, but I think this project might help me bridge the gap if I can get it rolling. what do you guys think about buying maybe six or so friction light generators and disconnecting the lights, putting two on the front wheel, four on the rear, (they rub on the side of the tire) and wiring them all together to produce a power source? like I said, I'm horrible with electrical stuff- maybe you could even build a larger generator like I saw in another instructable, but do you think it'd be possible to either create a car-adaptor-style outlet, or even a functioning regular power outlet with that idea? what about an electric bike that charges itself while pedal in that sense? talk to me people!

askvictor6 years ago
I think hub generators tend to be more efficient (no hysteresis from the rubber of the tyre) and you can get 3W out of one at cruising speed; probably up to 6W at high speed (6V is most common but you can get 12V). Also, that many dynamos rubbing the side wall will deteriorate the tyre kind quickly... What i'd really like (and one day may build it when I have time) is a dynamo and a small-ish gel cell, with a regulator in between; when you're stopped/going slow, the device runs off the gel cell, when you're going at speed it runs of the dynamo, when you're going real fast (or the device is switched off) the dynamo charges the gel cell. That would be cool.
NachoMahma6 years ago
. It would be much easier, electrically and mechanically, to use one larger generator. . Make sure the generator will put out the voltage and current you need at the RPMs that you will be using. Get one that will output the volts required at the lowest speed you will use, then use a voltage regulator to control the voltage at higher speeds.
Nkevin90 (author)  NachoMahma6 years ago
sounds good; all I need now is the schematic for such a dynamo. I was thinking about that too; what speed would I need to be going at to satisfy the required amount of voltage, and I figured I would set it at the lowest speed, pursay, rather, hook up a speedometer to the front wheel and maybe make power available at a steady eight miles per hour or so. and a voltage regulator would be a must, though I didn't even know what something what would control the voltage would be called originally- ha haa. I've heard lots of stories of people going too fast with similar setups containing no regulator, only to have them supply too much power and burn out bulbs of lights.
. For a few LEDs, something in the 78xx series will probably work. You can use the bike frame for a heat sink. If you want 12V, just Google 7812 (5V = 7805, &c)
. For charging batteries, &c, you will probably need a different regulator, but I'm not sure which one(s).