KT motor controllers -- Flexible OpenSource firmware for BMSBattery S/Kunteng KT motor controllers (0.25kW up to 5kW)

[Anonymous95]

Good evening everyone,
I have a fat bike with 1000w motor, 48v 20ah battery, the controller is a dual mode KT bluetooh. Having problems like that the bike jerks in a few moments, I started investigating. I discovered the cause by doing various tests with my bike and that of a friend of mine with 1500w motor and KT bluetooth control unit. We realized that the problem occurs only if we use the bike without the app (KT smartbicycle). So if we use the app the bike works well, but if we use the display without the app the bike gives problems and jerks. We have a lcd5 and a lcd8h. The parameters are the same both on the app and on the display. I tried to unplug the dongle from the controller but nothing changes. Do you have solutions? We don't want to keep the app running all the time.

I tend to point out that, both my friend and I have this problem so I'm thinking kt bluetooh controllers suffer from this problem.

Thanks to everyone who will answer and sorry for my bad English.

[Anonymous95]

Help me

[sylvain_wm]

Hi everyone,
I bought a KT72V and a 72V battery, my motor is a 48V.
Can I use the 48V motor with this voltage?
In my opinion, there is no problem but I'd like to be sure...

have good day.

[mehmetoz1980]

Maybe,if reducing the current it not be a problem.so the strength does not increase too much

I have 48v motor too (golden motor magic pie 5)

I've read many high voltage mods to my motor.
this is a dd motor.

I think,more suitable in this regard.

In this case it is wise to use a temperature sensor.

[sylvain_wm]

Thank you for your reply.

[sylvain_wm]

Hi,
I bought a KT72VSVP. I tried to program it and it doesn't work.
I have already programmed a KT48VSVP, and had no problems.
I dont know what to do.
Does somebody have an idea?

Have a good day.

[atkforever]

Hello Sylvain,

Can you give more details about what isn't working? Can you flash it properly?

Maybe your undervoltage limit is too low or If you use no display there are 2 wires on the display socket to short : red and blue.

[sylvain_wm]

Hi,

I can flash it.
The LCD display works but :
- the speed remains at zero while I pedal.
- the battery indicator remains empty while the voltage display by the LCD is 81V.
I checked the speed signal, the torque and PAS signal...
The hall sensors work well...
Here is the screenshot of my OSEC configurator.

config.png (68.26 KiB) Viewed 227 times

[sdobbie]

Does anyone have a schematic for the KT controllers? I was especially interested in a diagram of the 12 fet one. I was also considering removing the dissipation resistor and replacing that with lm2596hv step down module to reduce power consumption.

[sylvain_wm]

Hi sdobbie,

Does anyone have a schematic for the KT controllers?

page 2 of this post. But it's not recent and it's for a 6 mosfet.

[atkforever]

Hi,

I can flash it.
The LCD display works but :
- the speed remains at zero while I pedal.
- the battery indicator remains empty while the voltage display by the LCD is 81V.
I checked the speed signal, the torque and PAS signal...
The hall sensors work well...
Here is the screenshot of my OSEC configurator.
config.png

And motor doesn't spin ? try to untick External Speed sensor

[sylvain_wm]

And motor doesn't spin ? try to untick External Speed sensor

No, the motor doesn't spin, and no noise... nothing happens...
Here are 2 pictures of my controller.

20210217_130544.jpg (1.68 MiB) Viewed 212 times

resistors.jpg (210.91 KiB) Viewed 209 times

On the second photo, the two resistors heat up a lot !!! I measure 22V at their terminals ... that's huge!!!

[atkforever]

Did you try to adjust the "Motor spec angle" parameter? start from 0 and increase by 5.

An other thing, you say battery your battery is at 81V, 235 as overvoltage value seems a bit low to me, try 240 for instance.

[sylvain_wm]

Did you try to adjust the "Motor spec angle" parameter? start from 0 and increase by 5.

An other thing, you say battery your battery is at 81V, 235 as overvoltage value seems a bit low to me, try 240 for instance.

I tried 241 for overvoltage value.
I unticked External Speed sensor...
I tried different angles...
Nothing.

I wonder why my LCD display doesn't display the battery capacity and the speed...?

[stancecoke]

Nothing.

Make sure, that the brake is not active, otherwise the controller sticks in startup:
https://github.com/stancecoke/BMSBatter ... ain.c#L100

Flash in Diagnostics mode and log the sent data with an USB-UART-Converter or a HC-05 bluetooth module.
Show us the log.

https://github.com/stancecoke/BMSBatter ... stics-Mode

regards
stancecoke

[sylvain_wm]

Make sure, that the brake is not active, otherwise the controller sticks in startup:

How can I know if the brake is not active?

Flash in Diagnostics mode and log the sent data with an USB-UART-Converter or a HC-05 bluetooth module.
Show us the log.

What data do you want me to send?

In Diagnotics mode I notice the ui8_BatteryVoltage = 156 while I measure 80,5V... I expected more than 235...

[stancecoke]

How can I know if the brake is not active?

If the controller is sending data in diagnostics mode, everything is OK with the brake.

What data do you want me to send?

by default this parameters are sent:
https://github.com/stancecoke/BMSBatter ... ain.c#L193

Code: Select all

printf("%u,%u, %u, %u, %u, %u\r\n", ui16_control_state, ui16_setpoint, ui16_motor_speed_erps, ui16_BatteryCurrent, ui16_sum_torque, ui16_momentary_throttle);

The ui16_control_state gives the first indication, of what is happening.
You can check the meaning of the control state with the little tool, or "by hand"
https://github.com/stancecoke/BMSBatter ... leshooting

The probably critical bits for over- and undervoltage are not implemented in the tool. So you have to analyze them by hand
2048 undervoltage
4096 overvoltage

In Diagnotics mode I notice the ui8_BatteryVoltage = 156 while I measure 80,5V... I expected more than 235...

obviously the calibration factor for the voltage is different for your high voltage controller.

regards
stancecoke

[sylvain_wm]

I used the default parameters and received this :

Screenshot_BlueTerm.jpg (110.58 KiB) Viewed 171 times

Weird, the transmission is bad? I didn't have this problem with my other KT 48.

ui16_control_state = 28
ui16_setpoint = 0 and sometimes 5
ui16_motor_speed_erps = 0
ui16_BatteryCurrent = 313 ?????
ui16_sum_torque = 0
ui16_momentary_throttle = 73 ?????

I don't really understand these values.

[stancecoke]

There's very much noise on the UART line obviously.

The values are OK so far.
What kind of torque sensor are you using? You have to apply torque and turn the pedal at the same time to make the motor start.
Does the last value increase, if you apply torque on the crank?
You should print out the value of ui16_time_ticks_between_pas_interrupt_smoothed for checking the PAS interrupt. The value has to decrease, the faster you are turning the pedals.
The PAS interrupt seems to be the problem...

For debugging, it would be easier to test with a thumb throttle and not in torquesensor mode.
The values for throttle min and throttle max are not correct, obviously.

Concerning the not working display: have you checked the last XOR of the checksum? See the FAQs in the wiki how to check.

regards
stancecoke

[sylvain_wm]

Thanks for your help.

What kind of torque sensor are you using?

I use a torque sensor from aliexpress : https://fr.aliexpress.com/item/33027685 ... 6c37IkGFF5

For debugging, it would be easier to test with a thumb throttle and not in torquesensor mode.

I'll do this first thing tomorrow morning.
It's getting late here in France.

[sdobbie]

I tried changing ui16_current_cal_b -= 1; using values between -10 and 10. Negative values made the wheel rotate itself and positive values did nothing to remove the resistance. I did accidentally change ui16_current_cal_b >>= 4; to >>=8 and as soon as the controller was switched on, the wheel spun up to ridiculously high speed, even faster than my old controller, without any throttle input which brings me on to the issues I have been having with the speed limits. It doesn't seem to matter what I set them to, some lower values give me slightly higher speed and setting them all to maximum makes the motor even slower. Gear ratio is totally random, As I increase it from 1 in steps of 5, some values give me higher speeds and others lower. For example, gear ratio 88 runs quite fast and on 89 it's much slower. It still doesn't spin as fast as the old squarewave controller I had no matter what settings I use for wheel circumference, gear ratio, etc. These are my current settings. I don't have any torque sensor or pedal assist connected to the bike. The hub motor is geared and is on a 20 inch wheel. Is there a way to just bypass or remove all the speed limit code as it seems to have some sort of bug in it?

Untitled.png (127.1 KiB) Viewed 141 times

[stancecoke]

Negative values made the wheel rotate itself and positive values did nothing to remove the resistance.

This is exactly the expected behaviour. Set the offset to a value that lets the wheel rotate slightly when the wheel is in the air and the throttle is closed. Then there can't be a resistance any more, as the motor will always produce a little positive torque.

The hub motor is geared and is on a 20 inch wheel

?! a geared motor with regen?! There are only very few motors with this strange setup.
I recomment to read the wiki carefully, everything is explained there.

regards
stancecoke

[sdobbie]

Yes, the clutch in the motor has been welded.

No, everything isn't explained in the wiki. You mention schematics, where can I find them? Temperature sensors are mentioned. Where do I connect the sensor? x4 throttle doesn't even have a setting for it's upper and lower limit like the normal throttle does. Your suggestion to set all the speed limits to 100 does not work and you have done nothing to explain the strange behavior of the gear ratio setting. I don't want the wheel to rotate slightly by itself as that is wasting power. If I pedal faster with no throttle or regen input, the controller consumes more power. It is far worse efficiency wise than my old controller.

[stancecoke]

No, everything isn't explained in the wiki. You mention schematics, where can I find them? Temperature sensors are mentioned.

To be honest, you're getting on my nerves ...
Please use the search function, try to understand what's happening in the code.
For the use of the BluOSEC app, ask @Xnyle, he has developed it, I'm not using it.
Nobody asked you to use our open source firmware.

regards
stancecoke

Edit:

I don't want the wheel to rotate slightly by itself as that is wasting power. If I pedal faster with no throttle or regen input, the controller consumes more power. It is far worse efficiency wise than my old controller.

Please show us logs of the power consumption of both controllers in various ride situations. The slightly spinning wheel will only draw very few current, maybe 400 mA. To have a measurable impact on the system efficiency, you would have to ride without electric assistance most of the time.

[sylvain_wm]

Hi,

You should print out the value of ui16_time_ticks_between_pas_interrupt_smoothed for checking the PAS interrupt. The value has to decrease, the faster you are turning the pedals.
The PAS interrupt seems to be the problem...

It's OK, the value decreases while I pedal faster.

For debugging, it would be easier to test with a thumb throttle and not in torquesensor mode.
The values for throttle min and throttle max are not correct, obviously.

There is a problem : I connected a thumb Throttle as you suggested. I checked the signal on the 18 pin of the processeur, everything is OK : 0.8V min and 2.9V max for the THROTTLE signal. The problem is that I don't see any change with the BlueTerm app: i16_momentary_throttle remains zero.