KT36 controller cutting out on redone 350W ebike

[tkessler3]

I recently redid a low end 350W ebike that had failed, maybe still in ways I don't fully understand. It died, the battery inflated, and then the local dealer closed. It sat in storage for a long time. I recently redid the 36V battery with a new Daly BMS, and replaced the old controller with a KT36 500W sinewave and LCD8H display. Everything powers up fine and the display/controller parameters seem to configure properly.

If I start the bike under load, the bike accelerates for about 3-4 seconds then the controller kicks out. If I recycle the throttle, it does the same. If I put the bike on a stand, I can start the motor and it will keep running up to about 6 km/hr. But when I ramp to a higher speed, the hub motor starts making a racket and the controller ceases motor drive.

Here is a video ( in Spanish). https://photos.app.goo.gl/DKutCHFtuWjdTFXD7

The motor seems to be a low end 350W geared hub. I don't know how many magnets yet, I can do the cog test if necessary, does anyone know looking at the motor? Maybe geared 4 or 5 to one? How critical is the P1 setting? I also read sine wave controllers need to be paired to the motor, but I can't find a procedure and parameter to adjust. Is it the C2 phase setting? Or maybe my motor is no good at higher speeds? Any suggestions on the other settings?

 

[amberwolf]

If "controller kicks out" means that it ceases powering the motor (but does not turn off the display) then it means the controller is detecting a problem and shutting down. That can be from voltage on the battery dropping too low under load, and the controller LVC kicking in, or a wrong phase/hall combination, or some other issue or setting.

If the Daly BMS has Bluetooth, you could try connecting to it with your phone via their app, and see what it tells you at the moment the "controller kicks out". Specifically, if any cell drops lower than others, and what the total voltage is at the moment.

If your controller has a self-learn or "autotune" function, you can use that to setup the phase/hall wire combination correctly. If it does not, you'd need to manually find which of the 36 possible phase/hall combinations correctly drives the motor forward with the lowest no-load current and no unusual operation or sounds even at full throttle off-ground.

Gearing of many geared hubmotors is 4:1 or 5:1, but some are different. Number of poles on them varies too, so unless you can find specific data on that exact motor, you'll probably need to do the "cog test" of manually turning the wheel backwards *very slowly* and counting the cogging you feel, *or* measuring the number of pulses per wheel rotation on any of the three green/yellow/blue hall sensor wires (with it hooked to the controller and controller powered on, to provide power and pullup voltage to the halls).


When you say you redid the battery with a new BMS, do you also mean you replaced all of the cells, too? If not, then if the battery had swollen up (failed cells) you'd need to replace them (all of them, preferably) with new cells capable of outputting at least the current required by the new controller (whatever it's as-marked current limit is, preferably double that or more for best operation / least voltage sag under load).

I recently redid a low end 350W ebike that had failed, maybe still in ways I don't fully understand. It died, the battery inflated, and then the local dealer closed. It sat in storage for a long time. I recently redid the 36V battery with a new Daly BMS, and replaced the old controller with a KT36 500W sinewave and LCD8H display. Everything powers up fine and the display/controller parameters seem to configure properly.

If I start the bike under load, the bike accelerates for about 3-4 seconds then the controller kicks out. If I recycle the throttle, it does the same. If I put the bike on a stand, I can start the motor and it will keep running up to about 6 km/hr. But when I ramp to a higher speed, the hub motor starts making a racket and the controller ceases motor drive.

Here is a video ( in Spanish). https://photos.app.goo.gl/DKutCHFtuWjdTFXD7

The motor seems to be a low end 350W geared hub. I don't know how many magnets yet, I can do the cog test if necessary, does anyone know looking at the motor? Maybe geared 4 or 5 to one? How critical is the P1 setting? I also read sine wave controllers need to be paired to the motor, but I can't find a procedure and parameter to adjust. Is it the C2 phase setting? Or maybe my motor is no good at higher speeds? Any suggestions on the other settings?

 

[E-HP]

If I start the bike under load, the bike accelerates for about 3-4 seconds then the controller kicks out. If I recycle the throttle, it does the same. If I put the bike on a stand, I can start the motor and it will keep running up to about 6 km/hr. But when I ramp to a higher speed, the hub motor starts making a racket and the controller ceases motor drive.

What speed is showing in the display when the motor cuts out?

 

[tkessler3]

Gents, thanks. The battery are all new cells and it appear to be holding up fine, i.e. the display is not turning off nor is the display showing a dip in the voltage reading. I can put an analog meter on it to be sure. Now I wish I had bought a BT BMS!

I don't see an autolearn mode anywhere, nor for C2; I will cycle through them and advise if I can find one where the problem ameliorates.

The controller kicks out about 7-8 km/hr which is when the motor racket increases greatly.

I wish I could deeper technical info on the KT controllers. I found the LCD8H manual, which is pretty good, but lacks info on say, the significance of the P1 setting, or what the C2 setting is really doing. If the controller is cutting out without losing power, shouldn't it display an error code?

 

[docw009]

This is a sinewave controller, so it's not a square wave sensorless model, right?

Your P1 value is 2x too high for a normal 5:1 geared motor with 16 magnets.Typically ships with a default value of 87, which is like 16 magnets and 5.1:1 gearing, It could be controller is losing sync at high RPM .