Display speed cycling from 0 to 70kph

[gogreenpower]

Hi Guys,

I have a problem with my display, whenever I use the throttle or pedal assist the speed displayed ranges from 0 to 70km/h, it goes up and down every few seconds. It's a generic controller/display combo. I believe the speed is being sensed through the motor as there is no external magnet/speed pick up.

Other than that, the bike operates as expected.

Show I pop open the motor and have a look at the wires or is this a controller issue?

 

[amberwolf]

If it's a geared hubmotor, then it will only show speed when the motor runs if there is no separate speed sensor.

The overly high speed in these cases is then because it is using the motor hall sensor and the motor spins several to many times faster than the wheel, so the settings in the speedo display have to be changed to the right number of poles (magnets) to make the speed right.

Some geared hubmtoros have a speed sensor with a (usually white) separate wire from the hall sensors, if your ocntroller has a separate speed wire input available.

Some systems are already wired for this but teh display has a setting in a menu somewhere to change to use it this way.


Might not be why you are having htis issue, but it's not uncommon.

 

[gogreenpower]

It's a hub motor, Smartmotion is the brand. Brushless I assume.

The speed displays when pushing the bike, as well as the throttle and pedal assist.

The fault is common to all 3.

Either the white wire from the hub or something in the controller?

 

[amberwolf]

If the speed sensor is on the white wire, you can try checking for connection or wire / cable faults along that path. With non-geared motors it may use just one of the hall sensor wires (usually green / yellow / blue), and these are more prone to signal issues because they are more direclty affected by motor currents, so they usually have problems under high load and high throttle, and not always with no or low load, or no or low throttle.

If the speed sensor is a separate hall on the white wire, it could be that the magnet(s) inside the hub shell have come loose and are falsely triggering the sensor, or the sensor itself is misplaced, etc.

If the fault is common to all modes of movement, does the speed displayed between problem events ever read correctly in any mode?

Did the system ever work right, and if so, what happened between the time it worked and the time it didn't?

 

[gogreenpower]

The system was working one day and stopped the next. Just noticed the throttle doesn't work as expected. It used to push the bike to 6km/h without pedaling, now it's barely noticeable, does seem to work in combination with the pedal assist by providing a little boost.

Controller is a KT36SVP, and it's used in a hilly area so I think the controller might be cooked. I'll order a new one and see

 

[E-HP]

The system was working one day and stopped the next. Just noticed the throttle doesn't work as expected. It used to push the bike to 6km/h without pedaling, now it's barely noticeable, does seem to work in combination with the pedal assist by providing a little boost.

Controller is a KT36SVP, and it's used in a hilly area so I think the controller might be cooked. I'll order a new one and see

Are you up for opening the motor? If you cooked something, you could have cooked the hall sensors, including the one used for speed readings. They may hang on partially cooked and fail completely a while later. If the bike is partially working, that would be my guess, since controller failures usually just take the bike out.

 

[gogreenpower]

I can open the motor but I'll try the controller first, it's not my bike. It has a new type of Julet connector that I'm struggling to find, ever seen these?