Can a KT controller be killed this easily?

[Tezzy]

Hi everyone,

I didn't like the controller on my new e-bike as it had a really long 'slow start' throttle curve. I changed it for this one because it has the correct 9 pin motor cable. At first it went well, I wired in the motor, battery, throttle and display (I used the 810 display that came with the bike). I took it for a 2 minute spin and it was perfect. I then decided to wire in the brake cut-offs, which had two wires from each brake and finally I wired in the 3-wire PAS. The PAS wire colours did not match and no wiring diagram was supplied (ie. it didn't say which PAS wire was what) , but both had a black, so I connected black to black and decided to trial and error the other two. The first combo didn't work. So I swapped the two wires and this time PAS appeared to work. I took it for a spin and started peddling. It gave me two short surges of power assist and then went dead. Now the motor produces no power at all, even with throttle and even after I disconnected the PAS wires. The battery powers on, the display lights up as usual, but no power to the motor. Is it possible to kill a new controller just by getting the PAS wires the wrong way around?

 

[E-HP]

1. First try disconnecting the brake cutoff switches and see if it runs.
2. Yes, you can fry the controller, or specifically the 5v supply circuit, by an improper connection. Use you multimeter to check the voltage on the PAS wires on the controller side PAS connector or throttle connector. If you fried the 5v, then PAS, throttle, and the motor hall sensors will not work.
3. The 810 display is not compatible with the KT controller. You can get it to power up, but pressing the other buttons may cause issues since the signals won’t be understood by the controller.

 

[docw009]

There is a digital 810, five wire version, that will connect to a KT, but since they have different protocols, the KT is ignoring it, and running with throttle and a default single level PAS.

There is also an analog 810, 4 wire version, that you have to be lucky to wire to a KT to get it to power up w/o blowing it up.

Did the KT come with a jumper on the display connector? Jumper allows it to run w/o display. Pull off the 810. Plug in the jumper. See if KT's throttle works again,

Here's the jumper. Cross red/blue, yellow/black. Latter isn't really needed, in my experience,.

 

[fill]

I can confirm shorting red/blue controller/display contacts will 'turn on' the controller headless and accept throttle input/control 'out of the box' - to enable pas generally the pas sensor etc needs selecting/enabling via the config procedure..

to test the pas sensor wiring, when connected to 5v and gnd correctly the signal pin should fluctuate between 0-4.5v when the magnet disk rotates within range of the sensor.

 

[Tezzy]

1. First try disconnecting the brake cutoff switches and see if it runs.
2. Yes, you can fry the controller, or specifically the 5v supply circuit, by an improper connection. Use you multimeter to check the voltage on the PAS wires on the controller side PAS connector or throttle connector. If you fried the 5v, then PAS, throttle, and the motor hall sensors will not work.
3. The 810 display is not compatible with the KT controller. You can get it to power up, but pressing the other buttons may cause issues since the signals won’t be understood by the controller.

Thank you for taking the time to reply. Your post has helped me. After the first KT controller died I bought another of the same and this time installed it without connecting PAS. The 810 display worked in the sense that it let me turn on and off the controller. I rode the bike and it worked as hoped...until I went down a hill and exceeded 32kph at which point the motor shut off, which is not unusual because the bike's top speed is only 32kph and even on the stock controller the motor would shut off once I exceeded this. But when I slowed down and the motor spooled back up, it could only power me up to 14kph for a minute or so, gradually getting slower over the next few minutes until it was completely lifeless and the controller was dead. I could not get it to work again. I do not understand what is killing these controllers, but when you mentioned that the 810 display is not compatible I now wonder if having that wired up is destroying the controllers. The 810 display I have is the 5 pin one and the wire colours exactly matched the display wires of the KT controller.

I removed the second dead controller and re-installed the stock controller and the bike functions as it did when new. However, the stock controller is not nice to ride with because of its super long soft start of over 10 seconds. When I let off on an incline I must wait for it to spool up before it helps me up the hill again. The KT controller, while it worked, functioned normally, with no long delay in spooling up after applying power.

 

[Tezzy]

There is a digital 810, five wire version, that will connect to a KT, but since they have different protocols, the KT is ignoring it, and running with throttle and a default single level PAS.

There is also an analog 810, 4 wire version, that you have to be lucky to wire to a KT to get it to power up w/o blowing it up.

Did the KT come with a jumper on the display connector? Jumper allows it to run w/o display. Pull off the 810. Plug in the jumper. See if KT's throttle works again,

Here's the jumper. Cross red/blue, yellow/black. Latter isn't really needed, in my experience,.

View attachment 361019

Mine is the 5 pin 810. The KT controller I bought did not have a jumper. I do wish I could just run without a display. I have a DC voltage meter that can show me battery levels and I can wire in an on/off switch. I just want a controller that's always on when connected to the battery. But I really want to stick with controllers that have the 9 pin waterproof motor connector, so that I don't have to deal with trying to match up all the hall and phase wires. That's why I chose the controller that I did. There is also limited space in the frame where the controller is located, so controllers with a massive collection of cables coming out of them are a no go.

 

[Tezzy]

I can confirm shorting red/blue controller/display contacts will 'turn on' the controller headless and accept throttle input/control 'out of the box'

Thanks. Is this true for the controller that I have? I just need to solder the red and blue wires together and the controller will be on all the time whenever it's connected to the battery?

 

[docw009]

To be sure, we're talking about this 810LED? I've owned several bikes with the 4 wire version which is analog. I also have a five wire digital version that came with an ebikeling controller I never used.

They have the same pinout, so the digital 810LED can start the KT controller. I think that as far as the Kt is concerned, the 810LED is sending it garbage data. The 810 has the same problem. It may turn out that after a set period of time, the 810LED gives up and shuts off the controller,

I suggest making a jumper plug, Your connector should match the colors in the middle picture. Blue and red together starts the controller.

 

[E-HP]

Thank you for taking the time to reply. Your post has helped me. After the first KT controller died I bought another of the same and this time installed it without connecting PAS. The 810 display worked in the sense that it let me turn on and off the controller. I rode the bike and it worked as hoped...until I went down a hill and exceeded 32kph at which point the motor shut off, which is not unusual because the bike's top speed is only 32kph and even on the stock controller the motor would shut off once I exceeded this. But when I slowed down and the motor spooled back up, it could only power me up to 14kph for a minute or so, gradually getting slower over the next few minutes until it was completely lifeless and the controller was dead. I could not get it to work again. I do not understand what is killing these controllers, but when you mentioned that the 810 display is not compatible I now wonder if having that wired up is destroying the controllers. The 810 display I have is the 5 pin one and the wire colours exactly matched the display wires of the KT controller.

I removed the second dead controller and re-installed the stock controller and the bike functions as it did when new. However, the stock controller is not nice to ride with because of its super long soft start of over 10 seconds. When I let off on an incline I must wait for it to spool up before it helps me up the hill again. The KT controller, while it worked, functioned normally, with no long delay in spooling up after applying power.

Can you describe your battery or provide a pic of the label? My guess is your battery can only/barely keep up with the current draw of your stock controller. The slow ramp may be set in order to reduce current draw under acceleration. With the new controller and no restrictions, the current draw is causing the voltage of the battery to sag until one or more cells hits the low voltage cutoff of the battery BMS or of the controller.

 

[fill]

Thanks. Is this true for the controller that I have? I just need to solder the red and blue wires together and the controller will be on all the time whenever it's connected to the battery?

Yes, tho solder is overkill imho, a bent clip in the plug end would be my solution,
@E-HP above makes a valid point, check your battery/bms for its Maximum Drain value (in Amps Not AmpHours) and ensure thats above the max amp rating of your controller. And if not you will need a compatible LCD display in order to configure the controller to limit the amp output to BELOW your batteries capacity to supply.

 

[Tezzy]

Can you describe your battery or provide a pic of the label? My guess is your battery can only/barely keep up with the current draw of your stock controller. The slow ramp may be set in order to reduce current draw under acceleration. With the new controller and no restrictions, the current draw is causing the voltage of the battery to sag until one or more cells hits the low voltage cutoff of the battery BMS or of the controller.

Thanks. The battery is 36V 10.4AH. There is no mention of how many amps it can provide. It's an interesting idea you have, but I have doubts, because I have another cheap e-bike with a small motor and only a 6AH 36v battery which has no such low throttle curve and it provides immediate power when given throttle. I can't imagine a new 10.4AH ebike battery being unable to provide a few hundred watts without needing to be ramped up over 10 seconds. Also, if that were the case, then it would not make sense to me that the controllers are being killed, yet the battery worked perfectly with the second new controller until that got killed. And then the battery worked perfectly again with the original controller when I went back to that. If the battery bms was just shutting down due to not being able to meet the current needs of the controller, the controllers would not be permanently failing each time.

I was thinking the slow ramp up was there because this bike was sold as pedal assist only and the slow power curve was to make pedalling feel like a smoother, less jerky experience. The controller has a plug for throttle, the bike just didn't come with an actual throttle. When I tried the KT controllers they worked perfectly until I went over 32kph and then failed. I am wondering if the 810LED display has that speed limit programmed in to meet my country's regulations and when I go over it, it sends garbage data to the controller (because it's not compatible), killing the controller. I've ruled out pedal assist being the culprit of the failures, so now I think it's the display killing them. Is that possible?

 

[Tezzy]

To be sure, we're talking about this 810LED? I've owned several bikes with the 4 wire version which is analog. I also have a five wire digital version that came with an ebikeling controller I never used.
View attachment 361033
They have the same pinout, so the digital 810LED can start the KT controller. I think that as far as the Kt is concerned, the 810LED is sending it garbage data. The 810 has the same problem. It may turn out that after a set period of time, the 810LED gives up and shuts off the controller,

I suggest making a jumper plug, Your connector should match the colors in the middle picture. Blue and red together starts the controller.
View attachment 361032

Yes that's the display, the 5 wire one with the 6km button.

 

[Tezzy]

To be sure, we're talking about this 810LED? I've owned several bikes with the 4 wire version which is analog. I also have a five wire digital version that came with an ebikeling controller I never used.
View attachment 361033
They have the same pinout, so the digital 810LED can start the KT controller. I think that as far as the Kt is concerned, the 810LED is sending it garbage data. The 810 has the same problem. It may turn out that after a set period of time, the 810LED gives up and shuts off the controller,

I suggest making a jumper plug, Your connector should match the colors in the middle picture. Blue and red together starts the controller.
View attachment 361032

If I buy this controller (again) and connect the blue and red display wires will it power up and function without a display?

 

[docw009]

Buy a KT controller from PSWpower and they include the shorting plug, if you buy the model with flat connectors.