Controller KT-36ZWS-XFC01F Problem

[ilexk]

Hello everyone!!

My folding beach bike has stopped working.

XMUS 250 20"
KT36ZWS-XFC01F controller

First, I noticed it was failing when I started from a standstill; I noticed it lacked power.
Then it worked fine, until I came to a stop again and the same effect repeated.
Pedestrian mode also didn't work.

The next day, it didn't work at all.
The display works on another kit without any problems.

Where could the error be?
The controller?
The motor?

I've tried the controller on another kit, a 250w 36v Q100, and it doesn't work.

Can anyone give me any tips?

Thank you.

Best regards.

 

[thelarkbox]

First confirm the battery is in good condition fully charged and isnt dropping volts with a nominal draw, bad cells or dodgy bms could cut off power when the controller starts up??

afaik the controller should supply the display with battery level voltage on its pin #1 or the red wire, google for julet pinouts, the following pic is for a jytcon controller connection. KT may? differ??

no battery voltage on pin#1 would clearly indicate a controller issue assuming full voltage is available from the battery?

your above swap tests and no battery voltage on display pin#1 would indicate a controller failure, you could open up and look for loose connections to the pcb or visibly blown components? depends on your level of confidence.

 

[Nealh]

Has it been ridden on the beach ?

 

[saneagle]

your above swap tests and no battery voltage on display pin#1 would indicate a controller failure, you could open up and look for loose connections to the pcb or visibly blown components? depends on your level of confidence.

Pin 1 has a direct connection to the battery positive wire going into the controller, so it can't really have missing voltage unless the cable has been chopped.

 

[saneagle]

Hello everyone!!

My folding beach bike has stopped working.

XMUS 250 20"
KT36ZWS-XFC01F controller

First, I noticed it was failing when I started from a standstill; I noticed it lacked power.
Then it worked fine, until I came to a stop again and the same effect repeated.
Pedestrian mode also didn't work.

The next day, it didn't work at all.
The display works on another kit without any problems.

Where could the error be?
The controller?
The motor?

I've tried the controller on another kit, a 250w 36v Q100, and it doesn't work.

Can anyone give me any tips?

Thank you.

Best regards.

I'd start by doing the MOSFET test:

Disconnect the motor cable and battery from the controller. Measure the resistance (200k scale) between the red battery connection and each of the three phase wire connections, then repeat with the black battery wire. Each set of 3 readings should be the same as each other and in the range 7K -24K. Though can be higher as long as they're all the same. Due to the capacitor across the battery wire, you can get a constantantly changing measurement while it charges. In that case, try swapping your probes round. Even though can be a moving result, the only important thing is that all three move in a similar way.

 

[ilexk]

Thanks for your contribution, I fixed it by replacing the controller.

Regards

 

[saneagle]

Thanks for your contribution, I fixed it by replacing the controller.

Regards

There's nothing in the controller that can make it go intermittent. It would always either work or not work, and if it stopped working for some reason, it can't fix any problem that would cause that and then start working again. In other words, anything that's intermittent has a cause outside of the controller. One significant potential cause is the main motor connector not in far enough, and when it breaks contact, it can cause the MOSFETs in the controller to blow.

In the entire 14 years dealing with ebikes, I've only ever seen four problems in controllers:
1. Blown MOSFETs, which happens when a connection breaks down, the motor runs too slow up a hill, or someone tries to stop it with a brake when something else is making it go.
2. Blown power track on the pcb. The causes are the same as 1. It's just a case of which blows first.
3. Blown 5v regulator. Caused by a short anywhere that carries 5v, like throttle, PAS, hall sensors or speed sensor.
4. Software destroyed. Happens when someone wrongly connects battery voltage to one of the data wires.

I'd say 90% of non-functioning controllers have blown MOSFETs and 10% have blown 5v regulators. The other two are very rare.

Both 1 and 3 are easy to check and have causes outside the controller. I'm, telling you this because if you don't find and eliminate the cause, you'll be looking for another controller soon. Hopefully, it was the motor connector not in far enough, but if it's the 5v regulator that blew, the cause is still there - like water in the throttle or any other connector, water in the motor or frayed/damaged wire somewhere.