Kunteng KT-14A controller doesnt work

[ubik76]

Hello everyone,

what could be the cause of this new Kunteng KT-14A controller not communicating with my motor?



I tried all sort of things, like changing the motor phase wiring with the scheme below (courtesy of Tommycat)


All I wanted was to replace the original controller (see below) with a programmable one just to increase the speed a bit.



The kunteng display turns on but it shows 0 battery charge (although fully charged), motor doesnt spin with PAS and throttle either.
I am running out of options..

Please let me know.
Thanks.
V.

 

[Comrade]

but it shows 0 battery charge (although fully charged)

If it thinks your battery is flat, why would it go?

It says "low voltage protection" on the front.

 

[ubik76]

Great Comrade,

any suggestions to fix the problem?

 

[AHicks]

I would start by checking each wire coming from the controller, to make sure each is going to where it's supposed to go.

You don't mention which display you are using, so I will advise that if it's not a Kunteng/KT display, that controller is never going to work....

 

[Comrade]

any suggestions to fix the problem?

Step #1 is find the problem.

From what I understand, a KT display gets full voltage from the battery (who knows why) instead of getting that info from the controller. So it probably measures it too.

How many volts do you have on the red and black wires going to the display?

 

[E-HP]

a KT display gets full voltage from the battery (who knows why) instead of getting that info from the controller.

Do you know an example of a display that shows battery level or battery voltage, that doesn't get full voltage from the battery?

 

[Comrade]

a KT display gets full voltage from the battery (who knows why) instead of getting that info from the controller.

Do you know an example of a display that shows battery level or battery voltage, that doesn't get full voltage from the battery?

The only display and controller I ever owned (singular) are Kunteng. But I don't see a logical reason why the display should be doing the measurements in the display. There is a microprocessor in the controller. There is a digital communication channel between the controller and the display.

No need to step down 54V twice. In the controller, and in the display. It's inefficient if anything. I would imagine the OP's KT controller is just as horribly designed as mine, using an LM317T that is driven extremely hard and very likely to fail prematurely without a heatsink modification.

Let me show you this.

 

[E-HP]

a KT display gets full voltage from the battery (who knows why) instead of getting that info from the controller.

Do you know an example of a display that shows battery level or battery voltage, that doesn't get full voltage from the battery?

The only display and controller I ever owned (singular) are Kunteng. But I don't see a logical reason why the display should be doing the measurements in the display.

OK, I guess the display makers are just defying your logic. Usually everything comes down to what's cheaper anyway.

 

[Comrade]

OK, I guess the display makers are just defying your logic. Usually everything comes down to what's cheaper anyway.

Or more likely reason behind seemingly stupid design decisions is that the Kunteng ecosystem evolved over time. Any complex system (or not that complex) but with many moving parts, went through design iterations with the constraint of keeping some sort of continuity and backward compatibility.

Maybe KT used to be like Cycle Analyst, keeping all the logic in the display. But then KT added a microcontroller chip to the motor controller and moved some logic there.

 

[E-HP]

OK, I guess the display makers are just defying your logic. Usually everything comes down to what's cheaper anyway.

Or more likely reason behind seemingly stupid design decisions is that the Kunteng ecosystem evolved over time. Any complex system (or not that complex) but with many moving parts, went through design iterations with the constraint of keeping some sort of continuity and backward compatibility.

Maybe KT used to be like Cycle Analyst, keeping all the logic in the display. But then KT added a microcontroller chip to the motor controller and moved some logic there.

I don't know of any displays that don't get battery level voltage. You can search around and see the pinouts. All of the common manufacturers do. Besides for the voltage readout, it may also have to do with how controllers are turned on and off.
I only asked because at first it sounded like you knew of some.

 

[Comrade]

I don't know of any displays that don't get battery level voltage. You can search around and see the pinouts. All of the common manufacturers do. Besides for the voltage readout, it may also have to do with how controllers are turned on and off.

The on/off feature might be the reason. I'd imagine most controller designs available now are old designs. They are not using any components released in the last 5 years. There has been a lot of development in high efficiency DC-DC step down chips. That's what the controller would need. A very low current standby circuit running on 50V+ that would listen to the display.

What powers KT controllers now is an almost 50 year old LM317.

 

[ubik76]

Comrade,
I like your thinking,
do you have any idea where I could find the wiring diagram of this damn controller?
I tried googling for hours using "Kunteng kt 36/48 VPR-CYD1F" which is what it says on the sticker above but couldnt find much...

btw I am using the KT-LCD5 below, which I bought together with the controller.

 

[Comrade]

do you have any idea where I could find the wiring diagram of this damn controller?

It should be the same for all KT controllers.

5 wires. Black. Red. Yellow. Green. Blue.

You are interested in voltage on black and red.

 

[docw009]

You can take the display out of the equation. Most KT controllers can run w/o them. Start by jumping the red wire to the blue one on the 5 pin JST connector to the display, Jumper the yellow wire to the black. You're sending the start signal, which is battery voltage, to the KT DC-DC converters, which powers it up. The yellow-black jumper is not always necessary, but prevents transient data from getting in. The controller will have a default PAS and throttle is enabled, They may have even included a jumper with the display. I got them with my last orders.



Make sure you've got the throttle wired right. Motor should run. If not, check your brake connections. Better yet, unplug them. If it still don't run, maybe the phase/halls are wrong, but KT doesn't vary here. They always put the colors right on phase and Halls to match the Bafang motors. You have a meter and can verify 4.3V on red to black?



One thing about KT displays. When first connected, the battery icon may be blank. It takes the motor to run for a few seconds before the icon is correct.

 

[hemo]

If you aren't getting motor drive via PAS, one may have the C1 value set incorrectly. It depends on the sensor type use.

 

[ubik76]

Nothing works...
I tried all sort of things, like swapping the hall sensor cables to see if there was some mismatch but still nothing. Clearly there is current from the controller cause I measured 3.68V at the Throttle cable when the controller was plugged to the motor and battery.
I also tried "jumping" the display, still nothing.

Battery is 48V 15AH I dont think is the problem, the display turns on, it just doesnt comunicate with the motor (250W)

Somehow the shitty original controller works, but the KT doesnt.
I suspect it might be something “simple”, related only to the power circuit, perhaps once I get proper reading of the battery charge everything will work…. hopefully.
any idea how to copy "what works in the original controller" and modify the KT?

 

[TommyCat]

Nothing works...

I suspect it might be something “simple”, related only to the power circuit, perhaps once I get proper reading of the battery charge everything will work…. hopefully.

I've read where the battery charge display does not correctly populate till after the motor runs for a bit... Lol, it's right above...

Would you mind posting your display parameter settings on your KT LCD5?

Still no indicators showing up? (Throttle, PAS, and Brake...)



Regards,
T.C.