Random error 30 + faulty speed reading + motor won't start

[issor]

I've recycled a folding bike 500W hub motor, adapting it to my bicycle, that involved stripping apart all the cables and modify the axle to fit the new bike (135mm spacing).

Before lacing it to the 26inch rim I tested the motor on the bench and it seems to be working without any issues, so I proceed lacing it to the new rim and putting all the components on the bike.


Now I've the following problem: when I pedal the motor starts running only for a few seconds and then it stops, if I start pedaling again the motor doesn't start, I have to turn off and on again.

Sometimes the error 30 appears on the display.

I also noticed that the speed shown on the display undergo sudden changes, like from 10 to 60kmh when I'm moving at the same speed.


Test done:

Controller settings: I'm sure all the settings are correct (speed sensor number of magnet, pedal assist sensor magnet, wheel diameter etc)

Cables damage: I've checked the cables from the motor before and after soldering with a tester, these are ok.
Also the motor connector appear to be ok.
Certainly the length of these cables have changed after the modification (maybe +5cm) I don't know if such small length difference the length could cause such problem.
I've got some doubts regarding the cable that goes from the controller to the display, but I can't check those properly because of the Juliet type connector.

General setup: for this build I used a cheap 48v 10.5Ah battery with 30A BMS. Brake sensors, lights and handlebar switches for the lights are not connected beacuse I don't need them (I also tried connecting them but that does not solve the problem). The controller that I'm using it was originally mounted on the folding bike from which I've taken the hub motor, so it's compatible.

Pedal assist sensor: in order to use the original sensor on this bike I had to do reduce the thickness of it. So I grinded some plastic from it. I don't have photos of that. A faulty sensor could cause such issue? I don't think it's damaged because during the bench test it was working normally.

Many thanks in advance and sorry for my bad English, I'm not mother tongue.

 

[E-HP]

I've recycled a folding bike 500W hub motor, adapting it to my bicycle, that involved stripping apart all the cables and modify the axle to fit the new bike (135mm spacing).
View attachment 383733
Before lacing it to the 26inch rim I tested the motor on the bench and it seems to be working without any issues, so I proceed lacing it to the new rim and putting all the components on the bike.
View attachment 383732

Now I've the following problem: when I pedal the motor starts running only for a few seconds and then it stops, if I start pedaling again the motor doesn't start, I have to turn off and on again.

Sometimes the error 30 appears on the display.
View attachment 383731
I also noticed that the speed shown on the display undergo sudden changes, like from 10 to 60kmh when I'm moving at the same speed.


Test done:

Controller settings: I'm sure all the settings are correct (speed sensor number of magnet, pedal assist sensor magnet, wheel diameter etc)

Cables damage: I've checked the cables from the motor before and after soldering with a tester, these are ok.
Also the motor connector appear to be ok.
Certainly the length of these cables have changed after the modification (maybe +5cm) I don't know if such small length difference the length could cause such problem.
I've got some doubts regarding the cable that goes from the controller to the display, but I can't check those properly because of the Juliet type connector.

General setup: for this build I used a cheap 48v 10.5Ah battery with 30A BMS. Brake sensors, lights and handlebar switches for the lights are not connected beacuse I don't need them (I also tried connecting them but that does not solve the problem). The controller that I'm using it was originally mounted on the folding bike from which I've taken the hub motor, so it's compatible.
View attachment 383734
Pedal assist sensor: in order to use the original sensor on this bike I had to do reduce the thickness of it. So I grinded some plastic from it. I don't have photos of that. A faulty sensor could cause such issue? I don't think it's damaged because during the bench test it was working normally.

Many thanks in advance and sorry for my bad English, I'm not mother tongue.

Was the display purchased with the controller as a paired set?

 

[issor]

Was the display purchased with the controller as a paired set?

Yes, it's the kd21c

 

[issor]

I tried the push-assist function and the motor worked for about one minute. After a few seconds I tried again and it didn’t work anymore.
At this point I would assume the motor is ok, I think the problem is in the speed reading: the display keeps showing crazy, random speeds, causing the motor to shut off.
Is there a way to test the controller?
Can you recommend an inexpensive controller?

 

[docw009]

Have you looked at a KD21C manual to find out what Error 30 means on that system? That is the first thing one should do. Understand the error code and find out what the controller is telling you,

I asked Google AI, and it says "On a KD21C e-bike display, Error 30 signifies abnormal communication, indicating a failure in data exchange between the display unit and the internal controller. For more details, visit sixthreezero.zendesk.com."

That means you have bad or no data communications between the controller and the display. Data received includes wheel speed, battery level from the controller. Data sent tells the controller what PAS level to use.

Possible causes are, bad controller, bad display, bad wiring, and a combination of all three.

Here is the link for a K21CD manual.

https://ride1up.com/wp-content/uploads/2021/01/KD21C-Display-Manual.pdf

Here is a image of the Julet Connector,, Here's how most displays work. VCC and GND are power (battery volatge) and ground. TX and RX are low voltage serial data leads. Lock is 0 volt when display is off, and at battery voltage (VCC) when display is on.


I believe you can bypass the disp;ay and test your cntroller. I've done thos several times on my own controller.,I suggest you ask an expert. Call up your Google AI in your native language. Ask it "How can I jumper my ebike controller connector to run without the KD21C display?" It should give you a good answer. Share it with us.

By the way, I have jumperef controllers before there was AI sneaking around, They all powered up and run w/o displays,

 

[issor]

Thank you very much, I will proceed to test the controller without display as soon as possible.

Apparently on KT controllers you need to short the red(VCC) and blue(K) cables, but I couldn't find any info about my X865-AXC002 48V 22A controller.
I will try the same way.

 

[issor]

Quick update: cable jump between red and blue pins

I did few pedal strokes to trigger the pas but nothing happened

 

[TommyCat]

Chack to see if you have 5vdc available. Goes to PAS and throttle, enables communication to work...


Regards,
T.C.

 

[issor]

I replaced the controller and the display with a 25A KT + LCD04 (22A would have been enough as well) and now it works

 

[docw009]

Thanks for the resolution,