Car parts turned traitor, again.

Today I tested the Toyota Tercel engine fan motor I'd gotten from a friend's scrapped car. I did not expect it to be very powerful, but turns out that it has actually got some decent power to it, even at only 12v--it draws about 4amps at 12v with just the plastic fan as a load, and only about 400ma with no load on shaft at all. Of course, it's designed to run really fast, rather than give a lot of torque, but gear reduction will fix that. The fan motor is a nearly-sealed motor, with just a drainage tube at the bottom allowing inside access, so it's essentially weatherproof--ideal for the bike project.

I did the testing on the same bike I tested the scooter motor on, my spare "experimental" bike, the Kensington that doesn't have a fluorescent paint job. No pics yet, as I am still recharging the camera's battery (I forgot to do so after the last bunch of pics and video, and it had been sitting for a while before that, too). That's the bike that has the large scooter's sprocket bolted and JBWelded to it's rear wheel, on the left side (because I can't remove the freewheel for it from the scooter's wheel).

Coincidentally, the flatted shaft the fan motor has almost perfectly fits the scooter motor's small sprocket (a little loose, but not enough to worry me for testing purposes), so I tested it with a hacked-together mount in place of the dying scooter motor, and it will spin the bike tire (with bike upside down) at a fantastic speed, enough to shake the entire bike badly from the tire's circumferential imbalances (it has Slime in the tube, and the tire itself isn't perfectly round). Once I load it down by actually riding the bike, it doesn't give enough power to start moving the bike by itself, but it does add some speed to it if I first get up to speed by pedalling. I need to test using the bike computer/PDA to see what the difference in acceleration and speed are with and without the motor, though, as well as the actual speeds I'm going (guessing about 15mph).

Under load, at 24v, using my repaired scooter speed controller (which requires 14v minimum to even start), it draws about 10 amps max at ramp-up to speed, and about 4 amps steady at 1/2 speed. I can't run it at full speed, because that would spin the motor shaft so fast it will cause the chain to jump off of it's sprocket (it does get a lot of torque at it's top speed). The gear reduction is being done by a very large sprocket at the wheel end:

and a very small sprocket at the motor end:

It's not enough, for this motor. I need a second reduction step, probably for any car fan motor I use. The only way I can do this at this moment is to take the small sprocket and put it on an idler shaft along with another large sprocket, and then another small sprocket on the motor shaft. Chain runs from motor to large sprocket on idler, and a separate chain from small sprocket on idler to large sprocket on bike wheel. That would be enough reduction to give me torque at a low enough speed to be useful on the road, without the chains jumping ship every time I throttle up. :)

Oh, and the magnet-in-glove trick to control a hall sensor on the handlebar for a throttle works great. :) I just mime the motion of turning a throttle like on a motorcycle, and the motor revs right up. Only problem is that I need a biasing magnet to keep the Hall sensor outputting 0V when no glove magnet is near it, because otherwise it outputs 1/2 of it's nominal throttle control voltage, making the system start at 1/2 speed with no rider on it. :-(

I used the entire controller system, including headlight, battery meter, and keyed "ignition" switch from the scooter for this test, just zip-tied to the bike in appropriate places for now, since it'll be coming on and off the bike a lot for modifications as I continue all this testing.