Intermittent response from Throttle

[Tbnrider]

I am using a 902 250W motor with a 10A 36 Volt BACO28X Speed Controller, and Twist Grip Throttle.

For a while now, sometimes when I open the throttle from either a standing start or while riding, I get no response from the motor.  It was usually just intermittent for a few seconds, then the motor would kick in.  Lately however, I have experienced considerable delay, a minute or more, before the system starts to kick in.

I set up the bike in my shop to replicate the problem.   I checked over all the connections and the battery voltage.
I did experience the problem intermittently.  In case the problem was the throttle, I connected in another spare throttle and , for a while, everything seemed to work normally.  But eventually the same failure occurred, and seemed to be permanent.

I noticed that whenever the failure happened, the motor felt like it had locked up  The wheel spun freely forward (the 902 motor has a one-way clutch in it) but offered considerable resistance to spin backwards as if it was trying to regenerate against a short circuit.  With the throttle disconnected. it experienced the same fault.   With power shut off. the wheel turns freely backwards (thus turning the motor), but when turning power back on, the motor locks up again.

So where can the problem be?  Failure of the speed controller? What can I do to check it out further?  Do I need a new ESC?

Roy

[Bikemad]

Hi Roy,

From your description of the fault it would appear that something in the controller is causing one or more of the MOSFETs to be incorrectly energised in a closed state, which would cause the considerable resistance you have observed when the wheel is turned backwards.

If the resistance was being caused by MOSFETs that had completely failed in a closed state (which is what often happens when they do fail) then the considerable resistance would still be felt with the power turned Off.

I don't think it is a Hall Sensor problem, as an intermittent fault with a Hall Sensor inside the motor should only cause a problem while the throttle was actually being activated.

Unfortunately, I think a replacement controller will be required to cure the problem. 

Alan

[Tommycat]

Testing for Blown Mosfets with a multimeter

[Tbnrider]

Hi Alan
 
 Thank you so much . I sort of thought I might have to replace the ESC.

I have another bike with the same 902 motor on the front wheel so I will hook it up to the faulty system and, if the same problem  occurs, that should definitely narrow the problem down to the ESC.
And I will do the test for blown MOSFETS, but even if the resistance remains even with power turned off, it still sounds like a MOSFET problem, which would justify a new controller.  So I will replace the controller.

But if the system works OK with the different motor , and still exhibits the fault with the original motor, what then? 
That would seem to indicate a problem with the motor, possibly a short in the wiring?  Anyway I will cross that bridge if I come to it.

Thank you again for your expert help

Roy

[Tbnrider]

Further to my problem with intermittent throttle response with a 902 motor and 10A controller, I ordered and received a new controller (ESC), a Magic V2 Universal Controller, which came with new wiring harnesses.  The new ESC looks exactly like the old one it replaces..

When I connected it into my e-bike in place of the original controller, nothing worked.  I have 3 other bikes with the same motor and control system, and that are working well. So I started to try substituting different combinations of ESC, 902 motor wheels, and wiring harnesses.  Everything works fine with other ESC's, wiring harnesses and 902 motor wheels. All units appear to be in good working condition, EXCEPT the new controller. After trying many permutations of the main modular components of two e-bike systems., only one of the modules in every  combination failed to operate, the new ESC.

So am I missing something?  Could it be that the new ESC requires reprogramming?  is there anything else I could do to test the new ESC try before returning it for replacement to the company?

Roy