Need help with 72 volt controller that is frying my motors

[Ch00paKabrA]

Hi, I have 2 motors at the moment and now both of them are not working. the 2 motors are a MW Motors 36v 250w motor (made by bafang and just rebranded) and a MAC 6T. I got the MAC 6T in trade from someone here on the forum so I don't know its history. However, both motors ran great on a 36 volt 250w controller that I had them hooked up to. the MW Motors motor has about 4000 miles on it with this controller and the controller was just used to test the mac 6t. I also have a 72v 500w controller that both motors ran fine on but the little one kept getting hot and it fried for some reason. it was cheap so I just threw it away and ran the 36v controller again for a while.

I just received a new 72 volt 350w controller for the small motor (which is a torque wind so it only goes 15mph on 36v in a 24 inch wheel). I hooked it all up and it had a self learning wire that you plug in and it is supposed to sort itself out. I did not realize that this self learning function bypasses the throttle so when I connected the wires the bike flew across the basement and the rear wheel bounced a few times when it hit the far wall and then even though the motor was spinning like a madman, the wheel was not turning. I believe I fried the clutch.

This morning, I decided to hook up the mac to what it would do on 72v 350w and I made sure that the rear wheel was off the ground this time. I hooked everything up and plugged in the self learning wire and the internal of the motor spin but the wheel never turned. Not even one revolution.

Obviously that controller is going in the trash bin.

Did I really just fry 2 clutches?

I hooked up the old 36v 250w controller and the internals of moth motors spin but not the wheel.

I am at my wits end here. How can a MAC clutch go like that (if it is the clutch) on only 350 watts unloaded.

If it will help I can take photos of the MW Motors motor but I haven't taken the MAC apart yet.

Any input would be much appreciated since now I am human power only.

 

[Gregory]

Sounds like you have the MAC spinning in reverse.

 

[r3volved]

Short the learning wires again (wheel off the ground)
As mentioned, it probably learned reverse

 

[DAND214]

The self learn works just fine if yo, plug it in then didconnect it when it's running correctly.
so what I did when i had them, turn the bike upside down so the wheel can spin freely. Connect the wires togeather, if it spins forward disconnect them. turn the throttle and see if it works properly, if not connect them again till it sets itself and disconnect again.

The controller shouldn't hurt the mac when you are only using 36v, sould be the same for the MW or Bafang.

Strange thing is. How can the controller work on 36v if it's a 72v controller. LVC should be way above the 42v peak of the 36?

Dan

 

[Ch00paKabrA]

The 72v controller was running on 2 36v batteries in series.

I will hooking everything up again. to see if it the self learn works.

Thank you all for your comments.

 

[r3volved]

Good luck! Hopefully it's the easy fix

 

[DAND214]

The 72v controller was running on 2 36v batteries in series.

I will hooking everything up again. to see if it the self learn works.

Thank you all for your comments.

72v is too much for both of the motors.

Dan

 

[spinningmagnets]

There's a chance it might be eddy current heat from higher RPMs than the motors were designed for.

As an example, the MAC was designed to run at 36V and 48V, but when builders began running it at 60V and 72V, it would spin faster and it would get very hot if it was run at the higher RPMs for any length of time. Paul at em3ev.com came out with a MAC that had thinner laminations, so it could run at 60V and 72V without excessive eddy current heat, and the upgraded MAC also had a factory-installed temperature sensor.

I don't know what the problem is for sure, but that's one possibility.

 

[Ch00paKabrA]

There's a chance it might be eddy current heat from higher RPMs than the motors were designed for.

As an example, the MAC was designed to run at 36V and 48V, but when builders began running it at 60V and 72V, it would spin faster and it would get very hot if it was run at the higher RPMs for any length of time. Paul at em3ev.com came out with a MAC that had thinner laminations, so it could run at 60V and 72V without excessive eddy current heat, and the upgraded MAC also had a factory-installed temperature sensor.

I don't know what the problem is for sure, but that's one possibility.

I am no expert by any means but I just can't think that it was heat for the Mac. It literally did what it did immediately and there was no heat evident in either the controller or motor since both were cool to the touch.

Today I will try everything again, As far as 72 being too much, it probably is. I just happen to have 36v batteries and it was easier to just run them in series than to break them apart and re-weld them. I have not really finalized what the voltages I will use will be. These are cheap Chinese controllers that I will experiment with before buying a high quality one for good. Since I have no experience with different voltages, I wanted to try them myself and spending $100 on a controller that may or may not work for me seemed like a poor choice at the time.

Thank you all for the input. I cannot emphasize how helpful you all are.

 

[spinningmagnets]

Good call, if the failure was immediate, it could not be heat from eddy currents. Sorry to hear about the toruble, best of luck...

 

[wesnewell]

Volts don't kill motors, watts do.48V at 10 amps is 480W. 100V at 10 amps is 1000W. Either will burn up a 250W motor under the wrong conditions.

 

[dogman dan]

I'm just wondering where you found a 72v 350w controller. 72v 3500w, that's plausible.

Have fun actually frying those motors when you get er running.

 

[Ch00paKabrA]

I'm just wondering where you found a 72v 350w controller. 72v 3500w, that's plausible.

Have fun actually frying those motors when you get er running.

like I indicated in an earlier post, it is a cheap controller that I am just trying out to see how it does. I will be very cautious while testing it.

Here is where I got it: http://www.aliexpress.com/item/72V-...evel-Brake-or-Low-Level-Brake/1788643237.html

By the way, Thanks for the advice. I reconnected everything and did the self learning connection twice and it is working. I took it on test run with the MW Motors 250 watt motor and it has increased top speed from 16 mph (torque wind on a 24" wheel) to 26mph (this was against the wind though).

After I had the issues, I figured I would take advantage of the inability to ride and disassemble the whole bike and strip and re-paint the frame. I took another frame that I had laying around and slapped it together quickly. No shifter for the deraileur just high gear. I bolted the controller to the rear disc brake bracket and gorilla taped all the wires in a bundle. Its not how I like to ride but it worked.

Thanks again for fixing my ignorance.