Originally Posted by george_n_texas
I heard wheelchair or other mobility chairs have really deep charges to them...I am also interested in this to power my laptop in the woods. the Laptop uses very little juice and I already have an inverter I used truckin. I am sure the solar thingy would let me use it at leaste an hour or so a day.
As a side note I met a dude that had the idea of using a car alternator with plastic blades from a cheap electric fan as a windmill generator...just add voltage regulator, battery and walah. He was a roughneck from the oilfield...those guys fabricate almost half the stuff they do. He said he got the idea when his fan belt broke and he spun the alternator by hand to charge the batteries enough to get to the gas station.
You really need a permanent magnet alternator to get the most efficiency. You have to have 12v connected to a unmodified alternator to excite the field of the electromagnet. Being a DC system you also have to have your batteries relatively close to the gen. or you'll lose a lot of voltage unless you use heavy (expensive) welding cables. Also I don't think the blade from a box fan is going to be big enough to do much. Most of the alternator wind generators I've seen have a large (4'+) prop and a gear up pulley system.