Exercise bicycle generator

[Jay64]

Looking to do an exercise bicycle generator similar to what Forrest did in:
http://endless-sphere.com/forums/viewtopic.php?f=41&t=30175

We got an old exercise bike that you can use both the pedals and the arm things.


I have some smaller motors in a box that I got from someone long ago. Looks like the MY1016-H will be the perfect motor for this project, this is pictured in the above pic.

The bike has a 2 stage reduction 45/14 and 45/18. (The two larger sprockets were pretty much totally covered, so it was hard to get an exact count, I might be off by 1 tooth.) and an early mod made a third reduction, but we are going to have to redo that, so I don't have numbers for that reduction yet. Actually, if someone can give a good number for that 3rd reduction, that would be cool. We are looking to do a 12v charge out of this setup. Spinning the motor with an electric drill set on 2 will full throttle gave about 8 volts coming out of it.
Our goal is to be able to jump on this and add extra electricity for days when the solar panels or windmill didn't get enough power through the day, or if there are some extra power needs. We want to have this set up for a big party in March where DJ Chill Will is going to be spinning using Off The Grid made power. We think it would be cool to have everyone at the party take turns and jump on the bike generator for a few to help keep the music going. With 50+ people there, this shouldn't be a problem at all. We do plan to have the power from the bike go into a battery bank.
Any thoughts, opinions, advise, etc. is greatly appreciated and encouraged.

 

[Jay64]

I how would I be able to use a hub motor as a generator?

 

[bigmoose]

Just an aside, the Lifecycle brand exercise bikes use a small 12 volt alternator as the load into a resistor bank. The program your "load" by modulating the field current.

 

[John in CR]

I how would I be able to use a hub motor as a generator?

Just switch regen on and crank the motor.

 

[Farfle]

3 phase bridge rectfier will, do what you want

 

[Samd]

32mm low Kv outrunner motor dropped onto a 26" bike wheel with friction would make a great 3 phase alternator for 50 to 100 watts....

It would be just like running Kepler's ebike drive in reverse as a rectified alternator (if you add some diodes of course):
http://www.endless-sphere.com/forums/viewtopic.php?f=6&t=34165

On a 26 inch wheel, a 32mm low kv outrunner should give about 6 volts and 10 to 25 amps output at 14- 25kph equivalent road pedaling...
Worth a shot..

 

[mauimart]

I took an old decommissioned mountain bike and coupled it to an auto alternator. It's a simple belt drive direct from the bike rim to the alternator pulley. The only major cost was the bike trainer ($90). The rest of the parts were scrounged. The display/control panel is a case of an old "digital" brand computer. The radiator fan blows cool air up to keep the rider comfortable. I also tied in a cheapo 400W inverter so I can plug in AC accessories if needed. There is a 12 volt battery that is constantly being trickle charged. You would be surprised how much of a load the alternator puts on the bike when powering the fan and a 60W bulb. Granted it's not the most efficient system.

 

[Samd]

Love the Mach5 power sticker!

I guess the good thing about charging batteries versus the resistive loads above is that batteries usually don;t have as high internal resistance, so there's less resistance on the pedals at the time of charging. But you lose some efficiency.

Love the belt drive idea...

 

[Chalo]

The generator bike I made uses a 12V battery to set the system voltage and to mediate between generator and load. It features a Unite MY1016 scooter motor as the generator, with 52/16 and 90/11 two stage step-up gearing. I used a two-sided track hub on the stationary bike's wheel to serve as the jackshaft. I built it up with a heavy tire, thick tube, and heavy steel rim to provide inertia-- except for that, it didn't need a wheel at all, just a hub.

When you start pedaling, voltage is applied to a 40A automotive relay. When its threshold voltage is reached, the main circuit closes. There is a big Schottky diode in the circuit to keep the battery from driving the motor; the relay is there to give an automatic hard disconnect and totally prevent any reverse current leakage when idle.

As pedal speed increases and voltage rises to higher than the battery's voltage, current flows into the battery from the generator. I mounted an antique airplane ammeter to read net current flow in or out of the battery. There is an automotive digital voltmeter to monitor instantaneous system voltage.

I can make 400W relatively easily with this rig, though that gets tiresome very quickly and probably lays a beating on the generator's brushes. With all-chain drive and only 500mV of drop across the power diode, it's about as efficient as it could possibly be with such a simple and cheap motor/generator at its heart.

Chalo