Dumpster find: how can I test/operate the motor?

I'd really like to make this bike operational again. It's in pretty rough shape though. The speed controller and battery are missing, and the wire that goes into the rear hub motor was cut. There's no markings on the bike indicating brand or model number.

I was hoping to test the motor to see if it even works. But even assuming it does work, I have no idea how I would find compatible parts and wire the motor up.

Pictures attached. The pic with the closeup of the wires is what leads into the motor.

The wires:

• 3 thicker wires (power wires?): Brown, Green, Blue
  5 thin wires (presumably for the hall sensors?): black, red, green, blue, yellow

Part #'s I found on some of the components:

• On the motor hub, it says 500w-12054045
  On the rim of the wheels it says CST e-bike pro 3811 16x3.0 36F c-1488-72
  On the brake hub, there’s some rusted over letters and numbers, but they are hard to make out. But it looks like TIAN YU 100 BRAKE
  On the back of the brake handle says “Wuxing” 65P-D0

Thanks very much for any advice!

Pictures (I had trouble attaching them directly, so uploaded to imgur.com instead):
https://imgur.com/a/ezQ07Tr

Aw man, it had almost found its way home.

I love salvaging things, but only if they're worth something to me when fixed up. That bike would not pass.

The green, blue, yellow(ish) thicker wires are motor phases. Thin green, blue, yellow wires are Hall sensors. Red is +5VDC, black is GND. Just about any cheap BLDC controller will do. Use 36V 20A if you want to abide by the 500W rating. If you get a 36-48V controller, then you can choose to turn up the speed with a 48V or 52V battery later.

You'll have to figure out the phase and Hall wire assignments by process of elimination; the color codes rarely match when the parts weren't made to work together.

If it's a geared hub, first thing I'd advise it bolting the motor in a truing stand or a fork, and spin the rim in both direction by hand. This gives you a first glance of the hub's internals: gears and clutch. One direction should offer little resistance and maybe trigger a rapid clicking sound: that's the freewheel in the clutch. The other direction should offer much more resistance but still be easy to turn: that's the lock in the clutch, which engages the gears. Too much resistance could be a sign of poor lubrication or broken gears.

Second step would be checking if halls work properly and phases are not shorted; see guides on this page: https://ebikes.ca/learn/troubleshooting.html

If everything is in order, you need a controller (don't see one listed in your description), a throttle and a power source to spin the motor up.

Even before testing halls, I would do a simple test to make sure there's no short in the phase wires, which would be a repair only for the truly dedicated who place a low value on their time or just like spending it that way. To test for a phase short, clamp the axle in a vise and turn the wheel. Then short the 3 combinations of phase wires together. Each should make the wheel harder to turn. Then short all 3 together and it should get harder still.

If it's a geared hubbie, small diameter and turns freely in one direction and can hear/feel the internal gears turn, I wouldn't even bother with it at all since the wire harness is cut. They are more complex, so more prone to failure and you could get through the harness repair only to find out the clutch is blown.

John in CR said:

Even before testing halls, I would do a simple test to make sure there's no short in the phase wires, which would be a repair only for the truly dedicated who place a low value on their time or just like spending it that way. To test for a phase short, clamp the axle in a vise and turn the wheel. Then short the 3 combinations of phase wires together. Each should make the wheel harder to turn. Then short all 3 together and it should get harder still.

If it's a geared hubbie, small diameter and turns freely in one direction and can hear/feel the internal gears turn, I wouldn't even bother with it at all since the wire harness is cut. They are more complex, so more prone to failure and you could get through the harness repair only to find out the clutch is blown.

Click to expand...

(the hub is silent for all the following tests):

• All three phase wires together, the wheel will barely turn (there's lots of magnetic resistance).
• When (any) 2 wires together, I can turn the wheel, but it seems to move with brief magnetic pulses resisting movement.
• When no wires are touching, the wheel moves freely in both directions.

I don't know if there's gears in the hub.

I bought an $11 BLDC motor controller from an overseas retailer. Looking forward to powering up the motor. I'm hoping I don't even need to use the Halls...if I understand the BLDC motor controller correctly, it doesn't necessarily need to use the Halls.

qwerkus said:

If it's a geared hub, first thing I'd advise it bolting the motor in a truing stand or a fork, and spin the rim in both direction by hand. This gives you a first glance of the hub's internals: gears and clutch. One direction should offer little resistance and maybe trigger a rapid clicking sound: that's the freewheel in the clutch. The other direction should offer much more resistance but still be easy to turn: that's the lock in the clutch, which engages the gears. Too much resistance could be a sign of poor lubrication or broken gears.

Second step would be checking if halls work properly and phases are not shorted; see guides on this page: https://ebikes.ca/learn/troubleshooting.html

If everything is in order, you need a controller (don't see one listed in your description), a throttle and a power source to spin the motor up.

Click to expand...

The wheel turns freely in both directions - no clicking or resistance (as long as I don't short the phase wires together).
Do you think I can avoid messing with the Halls if I use a BLDC universal controller? A youtube video I watched implied I could get away without using the Halls if I used a controller that can handle it.

Balmorhea said:

Aw man, it had almost found its way home.

I love salvaging things, but only if they're worth something to me when fixed up. That bike would not pass.

The green, blue, yellow(ish) thicker wires are motor phases. Thin green, blue, yellow wires are Hall sensors. Red is +5VDC, black is GND. Just about any cheap BLDC controller will do. Use 36V 20A if you want to abide by the 500W rating. If you get a 36-48V controller, then you can choose to turn up the speed with a 48V or 52V battery later.

You'll have to figure out the phase and Hall wire assignments by process of elimination; the color codes rarely match when the parts weren't made to work together.

Click to expand...

This made me smile. I hear you: the ebike isn't worth anything. But I enjoy playing around with tech and learning. This offers lots of opportunity for next to free. This ebike may never be usable again - but I'm having fun with it.

I've got a cheapy controller ordered and looking forward to playing around with it.

Thanks for all the advice, everyone! Very helpful!!

bitbrain said:

The wheel turns freely in both directions - no clicking or resistance (as long as I don't short the phase wires together).
Do you think I can avoid messing with the Halls if I use a BLDC universal controller? A youtube video I watched implied I could get away without using the Halls if I used a controller that can handle it.

Click to expand...

Sounds like a DD hub and not a geared one. Do you have a picture ?
Yes, sensorless (without hall) is possible, but will require a more expensive controller, like the Grin phaserunner ($300). Since its a dumpster find, I'd stick with cheap stuff, and get a chinese KT sine wave controller ($40).

There are cheaper sensor less controllers out there. But might be harder to find.

If you have the tester, test the halls. not real hard. Just match colors on the thin wires to the tester and see if its ok.

If it is,, buy a dirt cheap sensored controller, but find one with self learning, or self study, they call it various things. Then it will run any motor easy, once the controller does its self learning thing.

qwerkus said:

Sounds like a DD hub and not a geared one. Do you have a picture ?

Click to expand...

See second image on this link:
https://imgur.com/a/ezQ07Tr

bitbrain said:

qwerkus said:

Sounds like a DD hub and not a geared one. Do you have a picture ?

Click to expand...

See second image on this link:
https://imgur.com/a/ezQ07Tr

Click to expand...

Probably DD. I had a similar one here for repairs; it was totally rusted inside. Might be a good idea to check yours. Go and test phase + halls using the tutorials linked previously. If you can t manage a simple operation like this, I m not sure the whole refitting operation is a good idea. Than get a controller and let the fun begin

Great, no shorts in the phase wires.

Doing the halls is simple, not something to try to avoid. Sensorless control only works reasonably well if you get the bike going with the pedals first.

Just connect the hall wires too, taking care that the negative (black on every controller I've seen) and +5V (red on every controller I've seen) are connected properly. Connect the others color on color, and make temporary connections with the phases color on color to start. Use just short small throttle pulses to test, since unfortunately there is no common standard for wiring among motor and controller manufacturers. Of the 6 possible combinations of phase wires one will be valid with a nice smooth start and little sound. If that valid combination spins in reverse, simply swap 2 of the hall wires (not neg or +5V obviously) and find the new valid phase combo for forward of the remaining 5 possible. Just relax and be systematic when doing the combos swapping only 2 wires for each try. Alligator jumpers simplify the process just be sure to avoid shorts. Many motors have what I call "false positive" wiring combos that will spin the wheel, but have a rough start and draw lots of unnecessary current, so be alert for false positive results. Before declaring that wiring is conquered, it's good practice to connect an ammeter between the battery and controller to measure the no-load current. That's wheel in the air spinning at WOT (Wide Open Throttle). Quite low no-load current means you got it right.

Thanks all for the great advice. I'll look into the Halls!

Some information I put together on testing... have a look. May help with testing halls with out a controller.





Regards,
T.C.