Suddenly Going in Reverse

[ToughRowToHoe]

Hi have a 36V bike build (thanks to this board for the early pack build) that has been running for quite a while (since 2009). Started off with a 500w Golden Motor kit with what they called at the time their Magic Pie controller. Looking at their site, the model is at least similar in appearance to the BAC-281P. Eventually switched wheel out for a 500w Cute 325rpm geared motor which was much lighter and allowed me to pedal. Been running that motor with this controller since 2018. A few weeks ago, I pressed the throttle and just heard the motor spinning. Assumed the nylon gears in the Cute motor had worn out. However, if I put the wheel in the air, it slowly spins backwards despite the freewheel in the motor. It does the same thing plugged into another Cute motor. I've tried to research the issue and see posts related to new installs with two hall sensor wires needing to be changed or learning controllers that need to relearn. I don't think this controller has a learning function though it is supposed to work without hall sensors. Any ideas what is going on and what to do to fix it?

 

[AGS]

There have been a number of posts about this issue with dual mode controllers.

This problem occurs either when either a hall sensor goes bad or the controller gets confused and switches from sensored mode to uncensored mode by itself.

I wouldn’t fit a dual mode controller on a sensored motor. It is very dangerous if the controller decides to switch itself from sensored mode to uncensored mode by itself.

 

[Chalo]

Have you tried unplugging the Hall wires and seeing if the problem goes away, or changes substantially?

Also, does the unwanted movement stop when you unplug the throttle?

 

[ToughRowToHoe]

There have been a number of posts about this issue with dual mode controllers.

This problem occurs either when either a hall sensor goes bad or the controller gets confused and switches from sensored mode to uncensored mode by itself.

I wouldn’t fit a dual mode controller on a sensored motor. It is very dangerous if the controller decides to switch itself from sensored mode to uncensored mode by itself.

If that is the issue am glad to have the freewheel.

 

[ToughRowToHoe]

Have you tried unplugging the Hall wires and seeing if the problem goes away, or changes substantially?

Also, does the unwanted movement stop when you unplug the throttle?

Thanks. Will try unplugging the Hall wires. The motor is only running with throttle input.

 

[Chalo]

The motor is only running with throttle input.

So, the unwanted backwards operation only happens when the throttle is plugged in? If true, maybe try another throttle and see if the weirdness persists.

 

[ToughRowToHoe]

Finally got a chance to really look through the wiring. The motor wires were melted. It does move forward with the halls unplugged but the motor makes a grinding sound and the motor wires get really hot. Tried another throttle and controller. Operates the same.

 

[fechter]

Sounds like something is shorted. Shorts between phase wires are hard to test for due to the low resistance of the windings.
One test is to disconnect the phase wires and try spinning the wheel backward by hand. If the phases are shorted, there will be excessive resistance to turning.

You may need to take apart the motor to inspect and possibly replace the melted phase wires.

 

[ToughRowToHoe]

Thanks much. The resistance to turning the wheel is pretty high.