KT controller puzzle

jfk

100 µW
Joined
May 22, 2022
Messages
7
I am redoing my bike with a new hub motor and controller (35A), KTLCD8H...

Went through and tried to match all the settings in the controller to a RAD which is the closest. But then tried everything I could find in the documentation that might turn the throttle on or off.

After quite a bit of fiddling walk mode works perfectly in the right direction, nice and smooth, reports 24 watts. Brake interrupts seem to be working.

But I have no throttle, not sure if PAS Is working. If I set it to 5 I can get the throttle icon to appear on the screen intermittently but it doesn't appear to be feeding in power as I pedal with the tire off the ground.

I have tried with only throttle connected. Went through all the hall and phase combos, etc... Still no throttle and no PAS.

Is it possible to have an incompatible throttle or PAS sensor? This bike was working until the tiny controller it came with quit. So thought a good time to upgrade.
 
jfk said:
I am redoing my bike with a new hub motor and controller (35A), KTLCD8H...

Went through and tried to match all the settings in the controller to a RAD which is the closest. But then tried everything I could find in the documentation that might turn the throttle on or off.

After quite a bit of fiddling walk mode works perfectly in the right direction, nice and smooth, reports 24 watts. Brake interrupts seem to be working.

But I have no throttle, not sure if PAS Is working. If I set it to 5 I can get the throttle icon to appear on the screen intermittently but it doesn't appear to be feeding in power as I pedal with the tire off the ground.

I have tried with only throttle connected. Went through all the hall and phase combos, etc... Still no throttle and no PAS.

Is it possible to have an incompatible throttle or PAS sensor? This bike was working until the tiny controller it came with quit. So thought a good time to upgrade.

If the motor worked smoothly in walk mode, put the phase and hall wires back to that configuration before diagnosing the throttle and PAS.
Can you provide a pic of the throttle connectors, both on the controller and throttle side. Being able to see the wiring colors would also be helpful for the pic.
 
Pics of PAS, Throttle, motor, controller. One thing I didn't mention. I don't think I am reporting speed while pedalling (on the stand)
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PAS on KT controllers is brown-black-yellow and is a male plug.
Throttle is red-black-blue, and is a female connector.
The speed sensor input is red-white-black, and is a female connector, usually a white one.

From your pictures, I think you have your PAS sensor plugged into the throttle input, and the TH (throttle) plugged into the PAS input. Sure, the genders match, but they're wrong.


page1.jpg
 
Interesting. The masking tape is on the bike side of the pictures. Those were fished and identified cause I didn't trust the mfr.

So you are saying that the old controller and the new controller had the connector gender swapped?

Should I pull all the pins and swap the connectors to correct and then put all the wires right?

That would certainly explain it all cause the throttle signal icon was coming up when I pedaled so some weird throttle input from the PAS maybe.

Be nice if there was a real standard and documentation for all these.
 
I went thorough a similar deal with my controller replacement. I had to flip the white and black, from the controller. You can pull the pins out, gently. Also, I had to change my P4 to 0 and my C4 to 3, to get my throttle to work.
 
That did it. Cut the connectors off the old controller that is dead and inserted them carefully and twisted wires and all works.

Now the issue is going to be tuning and I don't think I am registering speed yet. But both throttle and PAS woke right up. So the bike will work now. Feels pretty strong jumping from 22A to 35A. The guy shipped me the wrong controller and the other one is on the way but it's gonna be a bit so this gets me back moving again. I want this all standardized so I ain't guessing in the future.

Six wires to solder and shrink wrap tomorrow.

Where does the speed input come from? From the hub motor? Hall sensors?

Thanks so much!
 
Oh, awesome! I had issue with the speed being displayed properly too. The P1 setting needed some adjustment. This is your gear ratio multiplied by the amount of magnets in the motor. I wasn't sure how many magnets my motor has, so I had to count how many times my wheel "cogged" while manually. After some guessing and some math, I ultimately went with 80. I double checked the speed accuracy with a speedometer app on my phone.
 
If you have the more advanced KT displays, like LCD3, LCD8, and a few others, you can lower the power by up to 50% changing the C5 setup parameter.

If you don't have a KT display and using the jumper plug they ship on the 5 pin flat connector, also shown in the guide, then it defaults to a single PAS and active throttle, and no tuning. If you plugged in a foreign display, the display and controller speak different electronic dialects and cannot communicate, but you will still get a default PAS and a throttle. No speedometer, and changing PAS is not detected by the controller.

Finally, if you have a KT display with your KT controller, the speedometer input is often built into the motor cable on many motors, and woukd be picked up by the white wire in the 2x3 white connector. If you don't see anything on the motor side of the cable, then you have to install an external speed sensor, which uses the above white plug. You also have to set the P2 parameter.
 
The white wire in the hall sensor plug is the speed wire. How it works is going to depend on what generation motor you have. If it's an older motor, the speed may work only under power, then quit when gliding. Later motors have the speed sensor relocated internally, and they work full time just fine.
 
When a display doesn't show speed when coasting, I believe that means two things. First the display is calculating the speed using the Hall sensors, and secondly it's a gear motor, which doesn't spin the Hall's when coasting. Motors that have speed sensors locate the magnet in the hub so the sensor always gets triggered.

On a KT display, you set P2 to a nonzero value to indicate there is a speed sensor. The value is the number of times the sensor flashes per revolution. This is usually once, but some bafangs use six.

On a couple of my KT displays, the lcd tracks speed when the motor spins, but when coasting, it goes nuts for a bit until it finally settles down. One display used to work ok with an internal sensor, but it died, so I had to install an external one. The other one never had an internal sensor and always needed an external one. Probably a noisy signal.
 
How does one install speed sensor and then wire it into a KT controller.

My motor, I think has a white wire in the cable but the controller side has none.

Is it as simple as crimping a pin an then routing the wire to... somewhere on the board?
 
jfk said:
How does one install speed sensor and then wire it into a KT controller.

My motor, I think has a white wire in the cable but the controller side has none.

Is it as simple as crimping a pin an then routing the wire to... somewhere on the board?

Not sure if you are asking one question or two.
The KT controller normally gets a speed signal via one of the hall sensor signals. There is an option that supports an external sensor (spoke magnet, frame mounted sensor); and still a third option for the models that support it, to accept a speed sensor signal from the motor:
To install an external speed sensor, it's just like you would do on a bicycle, with a wheel magnet attached to a spoke, and the sensor mounted on the chainstay, seatstay, fork. The KT controllers that support external sensors, have a three pin plug, usually red, white, and black, that connects to the sensor plug. You have to make adjustments in the setup accordingly.

Normally, the hall sensor signal used for speed is from the hall sensor plug going to the motor. In most cases, that harness only has 5 wires, with the sixth slot unpopulated. Same on the controller side. For units that support a sensor from the motor, and where the motor has a built in sensor, that slot is populated on both sides. You should check the connector on your controller to see if it has the 6th wire (white). If so, then you're set.

If not, check to see if it has the three pin external speed sensor connector. If it does, you may be able to feed the white wire from the motor, to the signal pin of that connector (like it's using an external sensor), since the 5V and gnd are common on both the motor and controller end.
 
E-HP said:
jfk said:
How does one install speed sensor and then wire it into a KT controller.

My motor, I think has a white wire in the cable but the controller side has none.

Is it as simple as crimping a pin an then routing the wire to... somewhere on the board?

Not sure if you are asking one question or two.
The KT controller normally gets a speed signal via one of the hall sensor signals. There is an option that supports an external sensor (spoke magnet, frame mounted sensor); and still a third option for the models that support it, to accept a speed sensor signal from the motor:
To install an external speed sensor, it's just like you would do on a bicycle, with a wheel magnet attached to a spoke, and the sensor mounted on the chainstay, seatstay, fork. The KT controllers that support external sensors, have a three pin plug, usually red, white, and black, that connects to the sensor plug. You have to make adjustments in the setup accordingly.

Normally, the hall sensor signal used for speed is from the hall sensor plug going to the motor. In most cases, that harness only has 5 wires, with the sixth slot unpopulated. Same on the controller side. For units that support a sensor from the motor, and where the motor has a built in sensor, that slot is populated on both sides. You should check the connector on your controller to see if it has the 6th wire (white). If so, then you're set.

If not, check to see if it has the three pin external speed sensor connector. If it does, you may be able to feed the white wire from the motor, to the signal pin of that connector (like it's using an external sensor), since the 5V and gnd are common on both the motor and controller end.
I think I am asking 1 question. Sorry for the late reply.

The hub motor I have has 6 wires at the hall sensor red/black - power...

yellow/blue/green for the hall sensor taps...

White for a speed sensor...

On the controller same connector there is no white wire at the mating connector. If I wired that pin back to the controller is there a place on the circuit board to connect it so I could get speed sense to get all the way back to the circuit board. As in what label on the board...?

I believe my hub motor has 6 magnets for speed sense on the rotor cover so that it can clock speed when coasting.

I can crimp a pin and solder the other end if that will work. Just don't know where.
 
jfk said:
E-HP said:
jfk said:
How does one install speed sensor and then wire it into a KT controller.

My motor, I think has a white wire in the cable but the controller side has none.

Is it as simple as crimping a pin an then routing the wire to... somewhere on the board?

Not sure if you are asking one question or two.
The KT controller normally gets a speed signal via one of the hall sensor signals. There is an option that supports an external sensor (spoke magnet, frame mounted sensor); and still a third option for the models that support it, to accept a speed sensor signal from the motor:
To install an external speed sensor, it's just like you would do on a bicycle, with a wheel magnet attached to a spoke, and the sensor mounted on the chainstay, seatstay, fork. The KT controllers that support external sensors, have a three pin plug, usually red, white, and black, that connects to the sensor plug. You have to make adjustments in the setup accordingly.

Normally, the hall sensor signal used for speed is from the hall sensor plug going to the motor. In most cases, that harness only has 5 wires, with the sixth slot unpopulated. Same on the controller side. For units that support a sensor from the motor, and where the motor has a built in sensor, that slot is populated on both sides. You should check the connector on your controller to see if it has the 6th wire (white). If so, then you're set.

If not, check to see if it has the three pin external speed sensor connector. If it does, you may be able to feed the white wire from the motor, to the signal pin of that connector (like it's using an external sensor), since the 5V and gnd are common on both the motor and controller end.
I think I am asking 1 question. Sorry for the late reply.

The hub motor I have has 6 wires at the hall sensor red/black - power...

yellow/blue/green for the hall sensor taps...

White for a speed sensor...

On the controller same connector there is no white wire at the mating connector. If I wired that pin back to the controller is there a place on the circuit board to connect it so I could get speed sense to get all the way back to the circuit board. As in what label on the board...?

I believe my hub motor has 6 magnets for speed sense on the rotor cover so that it can clock speed when coasting.

I can crimp a pin and solder the other end if that will work. Just don't know where.

I haven't seen a KT controller that didn't have a white wire available at the motor connector.

There SHOULD be 3 phase wires, and 3 hall sensor wires, both sets being green yellow blue, for a total of 6 wires. Additionally, you should have a white (speed sensor) plus power and ground. That's 9 wires total, and they should be on both sides.

Am I to understand your motor or controller are different?
 
jfk said:
I think I am asking 1 question. Sorry for the late reply.

The hub motor I have has 6 wires at the hall sensor red/black - power...

yellow/blue/green for the hall sensor taps...

White for a speed sensor...

On the controller same connector there is no white wire at the mating connector. If I wired that pin back to the controller is there a place on the circuit board to connect it so I could get speed sense to get all the way back to the circuit board. As in what label on the board...?

You may need someone willing to open up their controller and check where the white wire goes on a controller that has one. Mine has the separate speed sensor connector like in the diagram below, but doesn't have the extra/sixth white wire on the hall plug (the diagram below has both and both are white). I went out to my garage but mine is buried in a box with ebike stuff, but too much a pain to get to right now. :(

HTB1DZK3NXXXXXbxXVXXq6xXFXXXM.jpg
 
AHicks said:
jfk said:
E-HP said:
jfk said:
How does one install speed sensor and then wire it into a KT controller.

My motor, I think has a white wire in the cable but the controller side has none.

Is it as simple as crimping a pin an then routing the wire to... somewhere on the board?

Not sure if you are asking one question or two.
The KT controller normally gets a speed signal via one of the hall sensor signals. There is an option that supports an external sensor (spoke magnet, frame mounted sensor); and still a third option for the models that support it, to accept a speed sensor signal from the motor:
To install an external speed sensor, it's just like you would do on a bicycle, with a wheel magnet attached to a spoke, and the sensor mounted on the chainstay, seatstay, fork. The KT controllers that support external sensors, have a three pin plug, usually red, white, and black, that connects to the sensor plug. You have to make adjustments in the setup accordingly.

Normally, the hall sensor signal used for speed is from the hall sensor plug going to the motor. In most cases, that harness only has 5 wires, with the sixth slot unpopulated. Same on the controller side. For units that support a sensor from the motor, and where the motor has a built in sensor, that slot is populated on both sides. You should check the connector on your controller to see if it has the 6th wire (white). If so, then you're set.

If not, check to see if it has the three pin external speed sensor connector. If it does, you may be able to feed the white wire from the motor, to the signal pin of that connector (like it's using an external sensor), since the 5V and gnd are common on both the motor and controller end.
I think I am asking 1 question. Sorry for the late reply.

The hub motor I have has 6 wires at the hall sensor red/black - power...

yellow/blue/green for the hall sensor taps...

White for a speed sensor...

On the controller same connector there is no white wire at the mating connector. If I wired that pin back to the controller is there a place on the circuit board to connect it so I could get speed sense to get all the way back to the circuit board. As in what label on the board...?

I believe my hub motor has 6 magnets for speed sense on the rotor cover so that it can clock speed when coasting.

I can crimp a pin and solder the other end if that will work. Just don't know where.

I haven't seen a KT controller that didn't have a white wire available at the motor connector.

There SHOULD be 3 phase wires, and 3 hall sensor wires, both sets being green yellow blue, for a total of 6 wires. Additionally, you should have a white (speed sensor) plus power and ground. That's 9 wires total, and they should be on both sides.

Am I to understand your motor or controller are different?

That is exactly what I am saying. No white wire on the controller side KT48V. White wire on the motor side Bafang 750w 48v hub motor. So where is the white wire supposed to connect to the board? I can solder and I have the connector pins and crimpers.

Not only that I have three of these 35A controllers and none of them have the white wire... Weird.
 
jfk said:
That is exactly what I am saying. No white wire on the controller side KT48V. White wire on the motor side Bafang 750w 48v hub motor. So where is the white wire supposed to connect to the board? I can solder and I have the connector pins and crimpers.

Not only that I have three of these 35A controllers and none of them have the white wire... Weird.

Until someone can verify where the wire goes on their controller, you may be able to search on KT controller circuit boards and look a the images for the white wires, but there's a few, so you have to be careful. There's several pics of KT boards on the KT open source firmware thread as well https://endless-sphere.com/forums/viewtopic.php?f=30&t=87870&start=3125

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