Hub Motor as a Generator

[Bikerz]

Morning all

I would like to use a hub motor as a generator to charge a 12V battery (or even a 48V bank). Im happy to create a bridge rectifier and use a charge controller, however the hub motor is a bit of a struggle as I dont understand if I need one that doesnt free wheel or cant be a front wheel one etc.... Can you advise?
I will put on back of an old push bike with a stand and cycle, so really just want the cheapest hub motor I can get away with.
Any advice from you guys would be great tho.

Thanks

Sheldon

 

[haulincolin]

Cheapest hub motor is probably a low-wattage geared front motor. Geared motors usually have a one-way bearing in them so they can roll forward without having to turn the planetary gear system. If you find one that's made to take a disc brake, you can just flip it over, bolt a cog to the disc rotor mounting points, and run it backwards. That way you will spin the planetary system and the motor (which is what you need in order to run a generator) rather than just the one-way bearing.

 

[Bikerz]

Thanks

http://www.ebay.co.uk/itm/322120448135?_trksid=p2060353.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT

Thats no good then?

 

[Bikerz]

Cheers. I was searching generator and generate with no luck

 

[wesnewell]

Thanks

http://www.ebay.co.uk/itm/322120448135?_trksid=p2060353.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT

Thats no good then?

It's a direct drive hub motor. All DD hub motors can be used as a generator as long as you can find a way to turn the motor and use a proper controller for the voltage you want. The problem is it's a front hub. There's usually no way to turn it like there is with a rear hub that takes a freewheel.

 

[friendly1uk]

DD RWD with a wind generator sourced charge controller.

 

[teklektik]

Rock the Bike!

 

[Bikerz]

Rock the bike so expensive!

http://www.ebay.co.uk/itm/36V-250W-26-Rear-Wheel-Electric-Bicycle-Light-Motor-Cycling-Hub-Conversion-Kit-/222128264545?hash=item33b7e05561:g:0xMAAOSwMN9XRFU~

I could get this and use just the hub motor?

Then in future I should even use rest to make a e-bike!

 

[LewTwo]

Thanks

http://www.ebay.co.uk/itm/322120448135?_trksid=p2060353.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT

Thats no good then?

It's a direct drive hub motor. All DD hub motors can be used as a generator as long as you can find a way to turn the motor and use a proper controller for the voltage you want. The problem is it's a front hub. There's usually no way to turn it like there is with a rear hub that takes a freewheel.

wide flat belt on the od of the hub ???
off course that means tossing the spokes and the rim.

 

[teklektik]

The problem is it's a front hub. There's usually no way to turn it like there is with a rear hub that takes a freewheel.

Not really.
As mentioned above - use a 6-bolt brake mount sprocket (widely available for gas motor bike conversions). Since the drag of the generator is going to prevent much free-spinning anyway, you shouldn't miss the freewheel - this is going to be like pedaling uphill all the time, so 'no coasting' should be the case.

A DD will regen either way so you can flip the motor over if need be to get the sprocket on the drive side. Big difference is that front/rear motors mount in dropouts of 100mm/135mm respectively so get whatever matches your bike-frame-generator thingie. (Convert a used exercise bike?)


Also - Not sure how ad hoc your charger plans are, but - if you are going to rectify and add a charge controller yourself, you may be able to get away with a stock alternator diode trio as an off-the-shelf part...

 

[WoodlandHills]

What is the cut in speed for power generation and how much torque does it take to keep spinning? Is it possible to use the creek out back as a power source? It may not make much, but it will spin 24/7/365....

 

[mauimart]

Here is a system I put together. It consists of a cheap rear hub motor connected to a 3-phase rectifier which in turn feeds a DC/DC converter. It will do 300W if the rider is up to it.

https://endless-sphere.com/forums/viewtopic.php?f=3&t=56895

 

[Bikerz]

The problem is it's a front hub. There's usually no way to turn it like there is with a rear hub that takes a freewheel.

Not really.
As mentioned above - use a 6-bolt brake mount sprocket (widely available for gas motor bike conversions). Since the drag of the generator is going to prevent much free-spinning anyway, you shouldn't miss the freewheel - this is going to be like pedaling uphill all the time, so 'no coasting' should be the case.

A DD will regen either way so you can flip the motor over if need be to get the sprocket on the drive side. Big difference is that front/rear motors mount in dropouts of 100mm/135mm respectively so get whatever matches your bike-frame-generator thingie. (Convert a used exercise bike?)

View attachment 1
Also - Not sure how ad hoc your charger plans are, but - if you are going to rectify and add a charge controller yourself, you may be able to get away with a stock alternator diode trio as an off-the-shelf part...

Thanks. Fronts seem cheaper and easier to come by but I cant see how I can mount that sprocket, please note I cant weld or have a welder so hoping for a bolt solution.

 

[Gregory]

It bolts on to the 6 disc brake holes.

 

[Bikerz]

It bolts on to the 6 disc brake holes.

On a front Hub it has brake disk mounting holes on all of them?

 

[Gregory]

No, not on all of them.
But on the one you linked on eBay it does.