ebike motor > to > wind turbine conversion?

[monster]

hi

back in science class at school i remember that a motor run backwards was just like a generator.

is it possible to strap fan blades to an ebike wheel and have it generate current from the wind?

if so this could be a tremendous source of cheap renewable energy for everyone.

 

[dirty_d]

yea you could but i wouldnt just use the wheel you should make it all from scratch. you would need pretty big blades too.

 

[v_tach]

if so this could be a tremendous source of cheap renewable energy for everyone.

Wind turbines are nothing new. They work great as long as you have the area to mount them... and of course sufficient wind.

 

[monster]

i relise wind turbines are nothing new but e-bike motors are, and could be a nice cheap wind turbine precursor.

i'm lazy and dont want to have to take motors apart or mess around with coils and magnets.

has anyone looked into this before?

 

[TylerDurden]

has anyone looked into this before?

There's some crossover between the circles of interest. Both camps are swinging the same cat: one from the head, one from the tail...

Efficiency is the name of the game (or the cat).

In the case of wind turbines, high-eff bike motors could be used for geared systems. Direct-drive turbines need beefier bearings than most bike motors have, to handle the loads of large blades and strong gusts.

FWIW, the current hot DIY turbine generator is the brushless DC (BLDC) motor from a Fisher & Paykel washing machine. (I think it could make a very interesting bike motor.)

http://www.watchtv.net/~rburmeister/smart.html

 

[Geebee]

One of the unite geared motors would make a wonderful generator, just use the fitted sprocket to adjust for your wind speed requirement.
Oatleys's did have some info on their site about it previosly.
Mind you you can buy a complete wind generator for $400 au.

 

[BiGH]

exactly - unless you had the bits laying around - its much easier to buy a predesigned kit. Plus they look lovely.

all white and modern, like a ipod for the wind

i wouldn't mind some of those "twizler" (yes i have been shopping at the american supermarket) style ones that mount vertically and can have some very beautiful designs, but the cost is high and efficiency is poor.

 

[monster]

hi

i just did a test today to see if it was possible to use a bike motor as generator. it was easy to get volts. but when i hooked up a battery to try to charge it, it just span the wheel.

the amps seem to be more interested in coming out of the battery than going back in. what would i need to do to prevent this? in low winds your battery would discharge through spinning the turbine as a motor!

 

[fechter]

The solution to that is to install a diode between the generator and batteries. This prevents the current from flowing back into the generator.

From your test, you can see how fast the motor needs to spin to match the battery voltage. It will need to spin slightly faster to actually charge the batteries.

Another generator option might be a surplus dc treadmill motor. These are cheap on eBay. Since most of them are 90v, they don't need to turn as fast to generate into the batteries. Avoid gears if possible.

 

[monster]

hi



i did a few more tests and found that i could hand crank at about 15volts and 2amp ! with a 12v lead acid battery for charging. the bike speddometer said 25k/h = 350rpm



what kind of diode? rating required must be pretty high?
so higher voltage motors require less speed?


i think that if i could stick decent blades to it and get it high enough then i could make a half decent wind generator out of this bike and i didn't even have to dismantle an electric motor!

this is a really good way of recycling your old (slow) electric bike motors, pitty i just sold mine.



Regards, Matthew

 

[fechter]

Yes, the higher the motor voltage or number of turns, the slower it needs to turn to get charging voltage.

The diode would need to take the maximum charging current and be rated for the battery voltage. Schottkey diodes have a lower forward voltage drop, so I'd recommend those, but any big diode should work.

 

[zogworth]

warning, mega old thread revival.


Just posting for completion for other future searchers.

schottky diode's are what you're looking for. Very high rated and low voltage drop.

Tread mill motors are okay but vary wildly.

The best way to tell is to divide the max RPM by the number of volts, as per the rating plate.

Then multiply that by 15.

That gives you the amount of RPM you will need to generate the 15v you need to charge your 12v battery (including some inevitable losses)

If the figure is less than say 200RPM you're onto a winner, and a nice set of blades will see you producing power, anything more than that and you'll have to start thinking about gearing up.

 

[Samd]

You'll get a better watt per dollar output using standard NEMA 17 bipolar steppers than for a bike motor. Same goes for a wrecked LG or Fisher and Paykel drive unit reconfigured for an alternator.

Don't waste a bike motor - put it on a bike!

 

[zogworth]

industrial A.C. servo motors are popular now too, and they're 3 phase for more control.