# Hub motor Generator



## Ziggythewiz (May 16, 2010)

What was the cause of the lack of success? Low voltage, too much voltage, low amps? 

I've made one with an old computer motor, that was too easy to turn > too high voltage, but with two of those together I could run a small TV. I was going to switch to an alternator, as that's supposed to have the best voltage regulation capabilities to maximize your current output.


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## major (Apr 4, 2008)

Inframan said:


> but I have tried buidling a stationary bike generator to charge a set of ups batteries using several different motors, 2 treadmill motors, a scooter motor, and an alternator without much success


Hi Infra,

Read this thread: http://www.diyelectriccar.com/forums/showthread.php/need-help-setting-up-charging-system-49583.html Charging batteries with human powered generators is a lost cause. Like I told bigwilly, if he is willing to work for one cent per hour, my house needs painted  

Regards,

major


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## Anaerin (Feb 4, 2009)

Bang Goes The Theory tried this. They had 120 professional cyclists on 80 bikes pedaling to try and keep a family home powered for a single day.



Spoiler



They failed



The full special is online somewhere, but a clip of the setup (and one of the high-power sections) is here:


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## Ziggythewiz (May 16, 2010)

That's retarded. They could barely keep up with the shower, needing 100 watts/person. A pro should be able to maintain 300 watts for quite a while. Their system didn't appear to use batteries either, spoiler alert - if you design an 'experiment' to fail, it will.

My house uses 30 kWh/day. 15 pros could keep it powered, including battery losses. If 80 couldn't handle it, what kind of house were they powering? That place must burn as much as Al Gore's 'green' mansion.


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## Inframan (Jan 30, 2011)

Many people pay gyms 300 sometimes 500 dollars a year to work out and I am not looking to power an 8.5 kw shower more like a 330 watt laptop and various lighting in my apartment.Those people do not look like pro cyclists, some of them look quite pudgy to me. The treadmill motors were a lot weaker than a lot of people said they were. They were rated at 110 and 130 volts, the scooter was even weaker. I think the 130 volt treadmill motor put out 1 amp when charging a 12 volt battery
Try as I might I just couldn't adapt the alternators shaft to bikes flywheel there were a lot of problems with the friction drive and it was a lot of work at that point and when someone told me about the hub motor idea it just seemed to make the most sense.


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## Ziggythewiz (May 16, 2010)

Inframan said:


> Many people pay gyms 300 sometimes 500 dollars a year to work out


That's right. It's not about saving $$$ by generating electricity. It's about doing something cool and useful instead of something dull and monotonous. My motivation was to cut back on tv watching while getting some exercise using a bike powered tv.



Inframan said:


> The treadmill motors were a lot weaker than a lot of people said they were. They were rated at 110 and 130 volts, the scooter was even weaker. I think the 130 volt treadmill motor put out 1 amp when charging a 12 volt battery
> Try as I might I just couldn't adapt the alternators shaft to bikes flywheel there were a lot of problems with the friction drive


I did mine with a lawnmower belt around a bare bike wheel connected to a pulley on my motor shaft and that worked great. I used a 12v high RPM computer motor, so volts were easy but amps were not.

Ideally you should use a 24V DC motor so you can get the ~12v you need for your inverter by spinning at half the nominal RPM of the motor. An alternator should also work well, but I didn't have mine working before I got started on the EV. I should be able to get that done later this year, after my EV enhancements and upgrades are 'complete'.


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## Inframan (Jan 30, 2011)

So does anyone know where I could get a hub motor for cheap?


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## Lectric (Oct 7, 2010)

I recently made a bicycle generator with a bicycle hub motor. I can produce an average of 100 watts of power an hour at a time (or 100 Wh of energy), as measured with a "watt's up" DC power meter. I considered the treadmill motor idea, but I didn't care for the prospect of adding additional gearing or belts to connect the external generator to the bicycle.

I used a 9 continents brushless hub motor ($215 USD, pn M2807RD26 from http://ebike.ca/store/store_motors.php - not cheap, but a respected shop), a 3 phase rectifier bridge, and a UPS (inverter and battery system) to power the television, laptop, lightbulb or other small load. My television draws 85 watts.

The motor makes 1 volt for every 8.9 RPM. I calculated I would need a 4.0 gear ratio to generate decent power to charge my battery at a normal pedal cadence (60 to 72 rpm). So I purchased a more expensive freewheel with an 11 tooth small gear. It turns out that with a gear ratio of 2.44, I can generate 100 watts for an hour with a 60 rpm cadence. My wife produces 50 watts for half an hour with a 2.05 gear ratio. It appears I overestimated the internal impeadence of the battery under charge. So I could have saved some money with a more standard freewheel assembly.

I had to make some parts to mount the bicycle to the trainer stand. Most trainer stands I encountered attach by clamping on to the axle of the rear wheel. The hub motor has a bigger than standard axle (length and diameter) and the wires exit at the end of the hollow axle.

The purpose here was not to make cheap electricity, but to get some exercise after the kids are in bed. Producing electricity is a side benefit and really illustrates how "cheap" the power from the utility is compared to human power. 

There are some hub motors on ebay (~$100 USD), but finding a cheaper hub motor source would be nice.


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