I’ve always wanted to make something from a bicycle and alternator that would power a tv or small appliance or whatever. Anybody know of a website or page where someone has done something like this (successfully)? It would be kind of nice to know how much wattage/power can be generated. I suppose a battery storage/inversion process would add stability to the whole system, too.
Thanks.
Most automobile alternators are rated at 60 or 80 amps, though some are only 40 and some are 100 (possibly higher nowadays, but I’m not aware of any). I would figure approximately 1/10 of that amperage at 120 V AC.
Higher ampacity alternators are typically found on emergency vehicles. The Leece-Neville website shows ampacitites up to 325 for 12 volt systems.
It’s pointless to use an alternator rated for much over 40 amps anyway, since a typical person can’t generate much over 400 watts for more than a few seconds anyway–maybe a minute or so, if you’re a world-class athelete. At 12 V, that works out to about 33 1/3 amps. For longer, more useful periods of time, you’lll need to drop the output considerably to around 100-200 watts, and even in that range you’ll only hold out for maybe 15-20 minutes, or less, depending on your level of fitness. You might be able to power a TV (~50-70 W) long enough to watch a full-length feature film, if you’re in pretty good shape.
Most of the cars I teach on have either a 160A or 180A alternators. When testing of output, the 180s will put out almost 200A!
[QED** the exercise bikes that I ride at various hotels usually tell me I am putting out 100-150 watts or so. compare this to Lance Armstrong who IIRC can put out 600 watts!
Out of curiosity, how long can you maintain that output? And do the bikes tell you your peak output as well as the average?
Ok, ok, I get that I won’t be able to generate much in the way of power, so I guess I need to charge a battery and run something 12 VDC. Still, all in all, any webpages showing successful applications? I mean, how many r.p.m. does an alternator need to produce what amount of power? I suppose I could fudge it on the fly, but I’d sure like the gearing, etc., done up front for me (more importantly, a good idea on how to connect the alternator to the wheel).
Thanks.
Here is a decent one.
Thanks. Just what I wanted. I didn’t realize there were so many problems to overcome. Straight Dope and it’s readers/posters rock!!!
You might want to check out this book, and if you decide that’s too complex for you, you could always make your own solar cell.