Speed reading erratic on KT-LCD8HU with Bafang G063

[jfortier]

I recently put a Bafang G063 on my ebike that has a KT Controller and LCD8HU display. The speed reading was solid with the original TruckRun motor that came with the bike. I noticed the problem yesterday. I did get info that the motor has 16 magnets, not 20 so I changed P1 to 80 from 100. P2 stayed at 6 as the motor has 6 magnets. Today I changed P2 to 0, rebooted and changed it back to 6, and rebooted with no change. Still erratic showing speeds in the 40's, then down to 2, up to 18, rapidly changing, and sometimes just reads 0. The controller is about a month old.

I am also using C2=1 with this motor, but not the last. The motor would not run for more than a few seconds before neing shut off and would groad. Tech support had me change that.

Any thoughts?

Here are all my settings;

Lim = 30
Dim = 29
Unt = 3
P1 =80
P2 = 6
P3 = 1
P4 = 0
P5 = 15
C1 = 7
C2 = 1
C3 = 1
C4 = 0
C5 = 10
C6 = 5
C7 = 1
C8 = 0
C9 = 0
C10 = N
C11 = 0
C12 = 5
C13 = 0
C14 = 2
C15 = 6
L1 = 0
L2 = 0
L3 = 1
L4 = 5

 

[jfortier]

I did a factory reset and set the lim to 20kph (all other settings the same as above), and the bike holds steady right about 12mph, setting P1 to 100, it holds at 15mph. So just the display of the speed is affected. Note, the speeds mentioned are from my Cycle Analyst, and the KT was reading 0.0mph.

 

[koner]

this might point you right way

 

[jfortier]

this might point you right way

Thanks. I think both of their issues were related to external speed sensor. I'm using the internal one, which it is all plug and play.

 

[koner]

Thanks. I think both of their issues were related to external speed sensor. I'm using the internal one, which it is all plug and play.

both work the same using hall sensor and magnets. maybe check if the hall sensor is secured inside motor?

 

[docw009]

I think it's been established thru the years that P1 is used by the KT controller to compute speed when driving the motor, but probably has minimal effect on actual performance. Going from 80 to 100 is 25% more indicated speed,That matches with your reported 12 and 15 mph,

On the other hand, the KT controller needs the wheel sensor to compute speed when coasting, I also think it also this number that is used in the odometer, A few years ago, I was frustrated that two bikes I owned with the same motor/rim were giving different odometer miles after a ride, because they had different size tires,, I had the bright idea of adjusting P1 til both bikes showed the same speed, riding side by side, The odometer difference stayed,

So what is the problem now? Is the LCD8H working right and showing the speed now, or is it zero? Don't need a speed sensor to show speed when motor is running,

 

[jfortier]

I think it's been established thru the years that P1 is used by the KT controller to compute speed when driving the motor, but probably has minimal effect on actual performance. Going from 80 to 100 is 25% more indicated speed,That matches with your reported 12 and 15 mph,

On the other hand, the KT controller needs the wheel sensor to compute speed when coasting, I also think it also this number that is used in the odometer, A few years ago, I was frustrated that two bikes I owned with the same motor/rim were giving different odometer miles after a ride, because they had different size tires,, I had the bright idea of adjusting P1 til both bikes showed the same speed, riding side by side, The odometer difference stayed,

So what is the problem now? Is the LCD8H working right and showing the speed now, or is it zero? Don't need a speed sensor to show speed when motor is running

I was not aware that the limit as set by limit used the P1 calculation. I assumed it used the speed from the speed sensor and the P2 magnet number.

I ended up setting P2=0 to get the speedometer from P1 as the speed sensor was erratic and sometimes read 0. Now I get a steady speed, but not when coasting. And I do have the cycle analyst speedometer from the magnet and sensor on the front wheel, but it's much harder for me to see.

 

[docw009]

Ok. Noisy speed sensor from the motor. Not much you can do easily.

 

[jfortier]

Ok. Noisy speed sensor from the motor. Not much you can do easily.

It was also suggested that Bafang has a temp sensor that uses the same wire as speed. "Amplitude of the pulse is the temp reading, and duration of the pulse is the speed reading" and the KT controllers are not good at separating the two signals.

Either way, as you say, Not much I can do.