e-bike with a magic controller

[Raevin]

I am working on a e-bike with a magic controller.. the throttle checks out .8v - 3.8v. Battery voltage confirmed at controller. No motor spin or stutter with or without hall effect disconnected.
If I pull the motor connections on the controller should I see voltage on any pins?
On the removed wires can I apply battery voltage to the blue and yellow to test hub function?

[Bikemad]

Hi andto the forum.

As you haven't mentioned which motor you are using I will assume that it is most likely a minimotor.

The only voltage you should see on the controller's motor wiring with the motor disconnected is the +5V feed to the Hall Sensors which can be measured between the Red and Black wires on the Hall Sensor connector.

I wouldn't recommend applying battery voltage to the Blue and Yellow Phase wires as the current will be very high and is likely to produce a big spark and could overheat the Phase windings if left connected for too long.

It is better to measure the resistance between each pair of Phase Wires in turn (Between Yellow & Green, Green & Blue and Blue & Yellow) to confirm that all of the three readings are very similar.
Alternatively, with the motor disconnected from the controller try touching together each Phase Wire Pair in turn while turning the wheel backwards. If the Phase windings are good, the wheel should be difficult to turn backwards manually while each of the three pairs of Phase Wires are touched together.

If the Phase Windings check out OK and are all the same, it may be a Hall Sensor problem.
Unfortunately, the minimotors will not run in sensorless mode because the motor needs to be turning so that the controller can detect the movement, but the internal freewheel mechanism (unidirectional clutch) prevents this from happening.
Take a look at this post and this video for information on testing the operation of the Hall Sensors.
With a minimotor, you will have to turn the wheel backwards while testing the Hall Sensors as the unidirectional clutch prevents the wheel from turning the motor in the forward direction.

If a minimotor has been overloaded for too long it can overheat, causing the insulation on the Hall Sensor wires to become damaged due to excessive heat build up in the motor windings:



When the insulation melts, it allows the inner copper wires to short circuit.

Alan
 

[Raevin]

Thanks for the guidance . I looked up the motor and looks like a mini. The wheel will not rotate backward at all. I did find a broken wire (green) and spliced in a new piece but same condition. The user stated that the bike needed to be peddled to go which I assume may have been due to-the broken wire. I measured the resistance of the motor windings …each phase .4 ohms. I see high resistance between neg and each disconnected motor wire and a climbing high resistance from positive to each motor terminal.prob a capacitor charging.I will test the hall sensors next. Thx for the links to the hall sensor tests.

[Bargo]

As I have been digging into similar problems in the past, one recommendation would be that you start the throttle as slow as possible for testing, because otherwise logic kicks in and does not allow movement if wheel does not have any load. It could be a firmware dependent setting. if you say motor works on pedaling then PAS logic works which may mean there is a dead diode or two in the front and back faces of the controller somewhere near the throttle signal. try to replace it with another T3 diode, also you might have burned a 4.72k resistor, which first hits the throttle signal on the board

[Raevin]

Pedal assist before throttle does not work. I will measure the throttle resistance. Thanks for the info. I am trying to borrow another controller to swap in.
I measured between the black and green on the throttle and red to green at the controller connector.
Both return 32 megs with no change with lever position.
Bad throttle?

[Bikemad]

The wheel will not rotate backward at all.

If you cannot rotate the wheel backwards, it sounds like the motor may be seized. With the minimotors, the freewheel mechanism (unidirectional clutch) allows you to rotate the wheel in the forwards direction freely without turning the motor, but the wheel should turn the motor when you try to rotate it backwards.
If the motor does not turn, it may be a seized bearing or a buildup of rust between the rotor magnets and the stator assembly that is jamming it solid.

As your motor is not turning, there is not much point in trying another controller until the motor has been freed off first. 

Here is a drawing showing the location of the bearings:


Click the drawing to enlarge.

Check out this post to see what's inside a minimotor.

Alan

[Raevin]

I think your assessment is right. I will disassemble the motor. Is it worth changing out the hall effect devices while Im in there?
Thanks for the detailed illustration.

[Bargo]

if the sensors still have kohms in reading and similar values then I guess you save yourself sometime by not doing it but its always better to have new ones as they tend to easily die (but it will be mostly reading in ohms at that point.