I either had all of the parts or was able to scrounge them for free, so the whole project cost me nothing. It requires basic soldering and welding skills, but no fancy circuitry knowledge is needed.
- old washing machine motor
- old bicycle
- bridge rectifier
- old UPS and battery
- 20ga wire
- angle iron
- cheap multimeter
- soldering setup
- welding setup
- angle grinder with cutoff wheels
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Step 1: Sourcing Parts
The washer I already had, but can be easily found for cheap or free if they're broken. The motors are quite robust, so it is usually another part of the machine that breaks first. The brands that may have the right kind of SmartDrive motors in them are: Fisher & Paykel, LG, and Whirlpool. The most common (in NZ) are the F & P and they say "SmartDrive" right on the button panel.
a helpful resource for identifying types of washers
how to tell what kind of motor you have
how to get the motor out of the washing machine. Note: I didn't remove the shaft or seals/bearings from the drum, I just cut out the section of the drum that housed the shaft assembly. See 1st photo.
The bike frame I picked up for free at the Green Bike Trust.
The UPS and batteries I got for free from my local computer repair shop. It is often cheaper for companies to buy a whole new UPS rather than replace dead batteries, so old ones can usually be found in abundance. This is how to rejuvenate old UPS batteries.
The bridge rectifier I pulled out of an old car alternator I had lying around.
Step 2: Rewiring
In order to get the optimal voltage output from the generator, you need to re-wire the windings of the stator. I used the instructions from this website:
They are using the motor for a wind generator, but the idea for the bike is the same. I had a 42 pole stator and rewired it in 3 phases of 7 groups of 2 poles for a 24v configuration. I know that sounds kind of confusing, but read the website carefully, it's very informative and isn't too hard to follow once you get the basic concepts down.
Before reattaching the stator to the shaft housing, I cut the shaft off 2 1/4" from the housing, or about 10 1/2" overall. Next I fitted the chainring cassette over the cut end of the shaft. The ID of the cassette was slightly smaller than the OD of my motor shaft, so I had to machine it down a little bit. If you know anybody with a metal lathe, take it to them, but the method I used also works in a pinch. I clamped the shaft housing in my bench vise and put my electric drill on the threaded end. While the shaft was spinning I was able to evenly grind down the diameter of the cut end of the shaft with an angle grinder. Sorry I didn't get a photo of this.
Step 3: Welding
The first thing I did to the frame was replace the wheels of the bike with upright sections of 3/4" angle iron. Keep the chainring cassette off of the rear wheel though, you'll need that later.
By doing this you can make the height of the bike anything you want, just make sure the pedals still clear the ground.
Then weld something to the bottom of the uprights to give the bike some lateral stability. My feet are 15" wide.
I also welded a short section of angle between the fork and the frame, to keep it from turning.
The first photo is a closeup of the rear detail. The right side of the rear fork is left intact for mounting the derailleur, and the left half is cut to accept the housing of the motor shaft. I used a chunk of 3"x3" square steel tubing to house the whole shaft assembly, and welded it directly to the bike frame. You could also fabricate a bracket out of angle iron if you don't have any square tubing.
The motor shaft has to sit on the same axis as the rear axle of the bike used to be on. As you can see in the second photo, the motor shaft doesn't extend beyond the cassette into the right half of the fork. So you need to make sure that whatever method you use for securing the shaft bearing assembly, it is very solid. I put a couple supports in between the two halves of the rear fork, and ran a wee bit of angle from one of them to the square tubing to solid things up a little bit.
Once everything is test fit and spinning like it should, take it all apart again and paint up the frame. Note: try not to spin the generator too much while it is engaged without a load attached. Apparently it can build up quite a charge, and you wouldn't want to get zapped.
Step 4: Finishing Touches
Now that the stator is configured for lower RPMs and the mechanics are spinning soundly, all that's left is to hook the power into the UPS and you'll be off the grid! The first step is to rectify the AC to DC, and you do that using a bridge rectifier.
If you can find a 3 phase rectifier, go with that, but you can also use 3 single phase rectifiers with their DC outputs hooked together in parallel. Mine was out of the dead alternator from my Austin Mini.
I grounded the negative wire from the rectifier to the bike frame and ran the positive wire from the rear of the bike to the UPS at the front of the bike through the handy eyes where the brake line used to run.
Next I ran the ground wire back off of the front of the bike frame and used a couple bisexual 1/4" spade clip splitters to connect both wires into the UPS batteries while still keeping them connected to the UPS. I had to put a couple holes in the UPS case to run the wires through as well.
I added a multimeter in as an afterthought, you could install a proper voltmeter gauge, but these cheap meters only cost half as much.
And you're done! Now just connect whatever appliance you want to your UPS as per normal, and keep the batteries topped up by pedaling!
P.S.- if you're going to be using it in your living room, be sure to put a drop cloth down. (see last photo)