This recipe yielded a generator that puts out about 8A @ 12VDC while pedaling at what many would consider an uncomfortable pace. That's a good amount of power (the same as what many gas generators put out), but it could be tweaked to make things easier.
For practical purposes, this setup can charge 12V batteries and keep things like phones going pretty well. Running larger things like laptops or appliances would be another story.But hey, when it's dark in the winter and your solar panels aren't charging and the trails are buried in snow, how else will you keep in cycling shape?
Charging a battery directly from this rig is probably not a good idea. The voltage spikes pretty high (30-40?), and I run it through a charge controller that can smooth that out to something the batteries will appreciate more.
*This is an introductory post. The plan is to assemble more details and numbers, but who am I to stop you from reverse-engineering it from photos while I'm up to other stuff?
- Spare wheel (donated, salvaged, free)
- Treadmill motor (used, salvaged, eBay, $40?)
- Bike Trainer/Stand (used, Craigslist, $30?)
- Automotive Belt (new, < $20)
- Angle Iron with pre-drilled holes (hardware store, < $20)
- Misc. nuts, bolts, washers (hardware store, < $20)
17.8 V from spinning wheel by hand