90V Brushed Motor

[Harold in CR]

I have a 90V DC Brushed 2.25HP treadmill motor. I'm wanting to put it on my build bike. If it is run at a lower voltage, say 72 volts, would that heat up the motor, while trying to run up these steep hills I have to go up ??

I'm thinking about buying a 100V controller, but, haven't tried to calculate the max amperage I would need, yet.

Is this motor decent to use, at a lower voltage, or, do I need to up the batteries to 150V or so ???

 

[amberwolf]

Depends on how you gear it and what power you expect from it.

I was using one in my first motor tests on CrazyBike2, at 24V and 36V, and had planned to use it that way on the bike, just geared to give me the desired speeds at less than half of it's specified RPM and power output.

Because its mostly flat around here, I didn't anticipate any problems despite no current limiting in the controller I was using (actually I didn't even know about that sort of thing yet), so it's power level for sustained use would be pretty low--it would still be sucking some amps on startups, but would have time to cool with the alternator fan I'd installed over the drive end to suck air thru it, between stop/starts.


I expect it'll work ok as long as your controller has current limiting, so that you can determine the most power you can safely put thru it on those hills.

Remember that brushed motors already get hotter than brushless, and the commutator's enemy is high currents (especially at higher than normal voltages). Since you'll be running it at a lower voltage than normal, perhaps retarding it's timing might help, but I don't know if it even can be done with your motor--it couldn't with the one I used (although I think it can with another one I got much later but haven't taken out of the treadmill yet).

Another thing to remember is some treadmill motors are rated for treadmill duty, which is not 100% duty cycle at 100% power, but some others *are* rated for continuous duty.

 

[Harold in CR]

This motor had a fan, of sorts, inside the heavy flywheel. I could mount another fan on the shaft. It has ventilation holes on both ends of the motor, so, another fan is a piece of cake.

If I put this motor on the 2 speed tranny, it should make a decent hill climber, especially if I get a run at the hills, in high gear, first, then do the speed shift as soon as the motor starts to lug. Keep the RPM's high as possible.

I was just hoping to get double use out of 36V multiple packs.

Thanks, AW. 8)

 

[amberwolf]

Some pics, and then test vids at the end:
http://electricle.blogspot.com/2009/01/motor-tests-mounted-on-crazybike-v20.html

http://electricle.blogspot.com/2009/01/motor-pulley-to-freewheel-and-sprockets.html

http://electricle.blogspot.com/2009/01/motor-demo-video-shaft-failure.html

Just the vid at the end of this post:
http://electricle.blogspot.com/2009/02/first-ride-success-learned-from.html

 

[Harold in CR]

All good info, AW. Thank you.

It's not that I don't understand gearing and such, it's just that I never messed with electric drive systems.

I once built a 2 wheel scooter using bicycle headpost and steering, welded to an angle iron (Bed frame stuff). My Dad welded the sprocket to the wheel barrow rear wheel. I had 1 of the same wheels in the front, also. I put a 4 HP Cushman engine on it, off a salt spreader. You had to pull the start handle UP, instead of mashing it down, like on Cushman scooters.

Once It got running, I had a lever to mash with 1 foot and that tightened the belt. It went so fast, I got both eyes full of tears and nearly ran off the blacktop road. NOT much traffic back in those days. I was 12 or 13 at the time.

If the engine gets overpowered, it pulls down real bad or dies. If electric gets overpowered something usually burns up, and, I'm like you, I can't afford to burn stuff up, if it's possible to avoid.

On the sawmill we built, I used 13" trailer wheels and tires. Figured out the gearing at speed so the blade ran correctly. That too was gasoline engine. I have to look up the calculators and get the gearing near as possible.

You are the only one I know of that has played with the treadmill and wheelchair motors, so, I ask you mainly what to expect, so I can relate to that when I get close to powering up anything.

Really appreciate your posting of links and such. Thank you, Harold in CR.

 

[amberwolf]

REdiculous also used a treadmill motor for his pusher trailer, but it's running off an AC inverter, powered by SLA batteries, IIRC.

Packratworkshop.com has a fair bit of info on using powerchari motors to run his homemade trikes, although I think he's given up on them and gone ICE, IIRC.