KT 45A controller and LCD8H display on Bafang G062, speedometer issue when coasting

[amradio]

I have a KT 45A controller (sine wave) and LCD8H display. When I pedal or use the throttle, the speedometer works properly and shows the correct speed. As soon as I stop pedaling or using the the throttle, the speedometer drops to about 4 to 6 km/hr. (it doesn't matter what my actual speed it, the speedometer shows a low value). If I pedal while slowly applying the brakes, the speedometer also drops to 4 to 6 km/hr. I have a Bafang G062 hub motor. While pedaling or using throttle from a couple km/hr to 45 km/hr, the speedometer works as it should and matches the GPS on my phone.
Any suggestions to make the speedometer work while coasting?

Here are the settings I have:
Bafang G062
6 pole magnets
Reduction ratio of 1:5
Magnet poles 20

Max speed – 72km/hr
Wheel Diameter – 23 (I have a 20" x 4" fat tire, and actual diameter is about 23")
Metric – 0
P1 - 100
P2 - 6
P3 - 1
P4 - 0
P5 - 0 for instantaneous voltage, or about 22 for smart voltage (I have two 52 volt batteries, 15 ah each)
C1 - 2
C2 - 0 for sine wave controller (Is this correct?)
C3 - 0
C4 - 0
C5 – 10 for maximum current
C6 – 1 to 5 brightness
C7 – 0 (1 if you want cruise control to work)
C8 – 0
C9 – 0 (password off)
C10 – n (restore settings)
C11 – 0
C12 – 7 (Voltage for battery cutoff)
C13 – 0
C14 – 2 or 3 (power assist tuning for PAS, 1 for lowest assist, 2 for general assist, 3 for stronger assist)
C15 – walk assist, 4 for 4km/hr, 5 for 5km/hr and 6 for 6km/hr
L1 – 0
L2 – 0
L3 – 1
L4 – 5 (screen time out, enter number above 5 for screen time out minutes)

 

[harryS]

Fpr Bafang motos, P2 is generally six. That is the number of pulses from the internal motor speed sensor for one revolution of the wheel.

Maybe Bafang made a mistake, or the fancy red motor connector isn't working. If there was no speed signal, I think the speed would be zero, not a low number. Try P2 = 1.

If it still doesn't work, you can get an external speed sensor and patch it into the controller.

 

[amradio]

Fpr Bafang motos, P2 is generally six. That is the number of pulses from the internal motor speed sensor for one revolution of the wheel.

Maybe Bafang made a mistake, or the fancy red motor connector isn't working. If there was no speed signal, I think the speed would be zero, not a low number. Try P2 = 1.

If it still doesn't work, you can get an external speed sensor and patch it into the controller.

Changing P2 to 1 causes the speedometer to be very slow to respond and the speed still drops off when coasting.
Can you explain how the external speed sensor works? Will settings need to be changed in the display? How would the external sensor take control or precedence over the original magnets? This external sensor would "take over" for the speedometer and the trip meter?

 

[Slaphappygamer]

P1 is 50
Magnet poles are 20. Magnet (/2) pairs are 10. Gear ratio is 5:1 (5x1). 5x10=50.

Try changing C1 to 3. If that still doesn't help, try 0, 1, 4, 5, 6, and 7 as well.
Other settings seem fine.

I’ve had this very problem. I know it can be fixed. I changed many parameters (LCD8H and 25A KT controller) and I got it working. Though I’m not sure which parameter fixed it. Patience will get you there.

 

[amradio]

P1 is 50
Magnet poles are 20. Magnet (/2) pairs are 10. Gear ratio is 5:1 (5x1). 5x10=50.

Try changing P3 to 3. If that still doesn't help, try 0, 1, 4, 5, 6, and 7 as well.
Other settings seem fine.

I’ve had this very problem. I know it can be fixed. I changed many parameters (LCD8H and 25A KT controller) and I got it working. Though I’m not sure which parameter fixed it. Patience will get you there.

From the manual "P1 = motor gear reduction ratio× number of motor magnet pieces". It says magnet pieces, not pairs. I can try 50, but I tried 87 and that made the speedometer very messed up. At 100, the speedometer is accurate while pedaling or using throttle.
Also, P3 is either 1 or 0. Those are the only options.

 

[AguassissiM]

It has been a while since I played with my settings and these are what works for me, you're more than welcome to try them out and see if it helps....

 

[harryS]

KT controllers use the white wire in the 9 pin motor connector for the internal motor sensor in the motor.

If you're good at things electrical, you can tap the white wire coming out of the red motor connector to see if the signal flips when the motor is spun. If it does work, maybe it's worth pursuing a warranty claim on the 45A.

If the motor doesn't have a speed sensor, or if it blows up (this has happened to my Bafang motor after salt water got inside), then you can buy an external speed sensor. It's a device with power (5V), ground,and signal.

It will be a pain in the neck if your 45A KT controller doesn't have an external speed sensor connector. You'll have to add a connector that matches the speed sensor and run its wires into the 45A box, tapping into the signal white wire and grabbing 5V power from it or the PAS connector.

I've done this a couple of times. All in a days work for DIY ebiker.

.

 

[PCeBiker]

KT controllers use the white wire in the 9 pin motor connector for the internal motor sensor in the motor.

The weird thing is that the speedometer works fine unless the OP stops pedaling and lets go of the throttle.

So how does the controller/display know the proper speed when you're pedaling or throttling?

I’ve had this very problem. I know it can be fixed. I changed many parameters (LCD8H and 25A KT controller) and I got it working. Though I’m not sure which parameter fixed it. Patience will get you there.

Can you post a picture of your settings? It sounds like your settings might get his speedo working?


These are my current settings on my 26" fat bike with a Das-Kit motor,..

Interestingly, my P1 setting is always yellow.

All the other settings are white until I adjust one or more,..

Then when I save the settings and restart the display, all the settings are white except P1.

I don't know what's going on, but I've never hooked up my PAS sensor, and that might have something to do with it?

P1=87 was what got my speedometer dialed in perfectly and I've never had my speedometer reading anything erroneous.
As far as the controller thinks, I never pedal (which is 98% true. )


@amradio maybe try adjusting your PAS sensor parameter, or disconnect it and see what happens?

Maybe the forward, reverse or magnet count on your PAS sensor is wrong and it's confusing your controller?
Your problem seems to be tied to your PAS sensor?

Try ghost pedaling really slow and see if your speedometer keeps working?

 

[Slaphappygamer]

From the manual "P1 = motor gear reduction ratio× number of motor magnet pieces". It says magnet pieces, not pairs. I can try 50, but I tried 87 and that made the speedometer very messed up. At 100, the speedometer is accurate while pedaling or using throttle.
Also, P3 is either 1 or 0. Those are the only options.

You’re right. Pieces, not pairs. I was remembering a different controller. Also, I was talking about C1, but typed P3. I corrected my post. Sorry about the error.

Here were my settings, but this was for a Shengyi DWG22.

Also, the “Bolton upgrade kit” is just a KT controller with the same display. Have you tried the settings they recommend?

 

[PCeBiker]

C15 – walk assist, 4 for 4km/hr, 5 for 5km/hr and 6 for 6km/hr

I just noticed that you have a C15 setting that my display doesn't have.

That must mean that you have a different firmware version.
Maybe it's got a glitch?

It's almost as if the controller is going into walk mode speed when you stop pedaling or hit the brake?

 

[PCeBiker]

Also, the “Bolton upgrade kit” is just a KT controller with the same display. Have you tried the settings they recommend?

That looks promising.

Here's a quote,..

My Das-Kit motor is apparently a rebranded MXUS 750 Watt motor, so me chosing P2=6 was probably the right choice for me?

I can't find any information on my motor. It's all proprietary.

 

[amradio]

Thanks everyone. I will try these suggestions today and post back later with my findings.

 

[amradio]

Here are my current settings. You can see from the Bafang spec sheet, P1 should be 100 and P2 should be 6.
I tried changing P3. On setting 1 or 0, same speedometer results
Changed C2 to 1. Nothing works. No power at all to motor. Changed back to 0.
C1 - settings 1 and 2 work the best for pedal assist to work. 3 and 4 will work, but only kick in after you manage to get up to about 10km/hr. Settings 5, 6 and 7 do nothing
I unplugged the PAS sensor. The speedometer works on throttle, but drops again to 4 to 6 km/hr while coasting. If I only pedaled the speedometer read about 2km/hr. I could only pedal so fast and speed didn't show the correct speed.
I'm stumped. Am I missing something or would the controller or display be faulty?

 

[amradio]

The weird thing is that the speedometer works fine unless the OP stops pedaling and lets go of the throttle.

So how does the controller/display know the proper speed when you're pedaling or throttling?

This is exactly what is so confusing. Why does the speedometer work correctly when using throttle or pedaling, but when coasting it drops off to 4 to 6 km/hr. Makes no sense.

 

[Slaphappygamer]

….

 

[amradio]

I reset the display. C10. Selected Y and shut it off. Turned the display on and put in my settings I had, and I had the same issue. Pulled out my log book of each entry change I've done already and I started over.
Left P1 at 100. Started P2 with 6, then 5 and walked my way down to 1. Now with 1 in the setting for P2, it is allowing the speedometer to work all the time. The speedometer is a bit slower to react when taking off, but it works when coasting. Why it worked this time is beyond me. It didn't work before. All I did was reset the display and started trying all the settings again. I'm glad its working. My neighbors must have thought I was nuts going up and down the street stopping and going for hours. Thanks for all your help. Here are my current settings for the Bafang G062 with KT 45A controller. I will still need to do some research on P5 and C12 for voltages with 52V batteries. The only manual I can find lists 48V as the highest voltage. The display does say up to 60v on the back of the unit.

 

[Slaphappygamer]

Glad to hear it! I knew you’d get it to work.

 

[PCeBiker]

,.. Started P2 with 6, then 5 and walked my way down to 1. Now with 1 in the setting for P2, it is allowing the speedometer to work all the time.

Well, that's strange.
Maybe Bafang messed up like @harryS mentioned, and you've only got 1 speed sensor magnet in your motor?

When I first installed my KT controller, I thought that the number of magnets was the number of magnets on the motor itself. I didn't know that there were separate speed sensor magnets in the motor with a hall sensor monitoring it.

The speedometer is a bit slower to react when taking off, but it works when coasting.

That makes sense.
If there is only a single speed sensor magnet, the computer has to do a lot of guessing about the rate of acceleration.
If there are 5 or 6 magnetic pulses for each rotation of the wheel, the computer can see the acceleration better and give you a more accurate speed reading.

 

[amradio]

Well, this controller with the Bafang G062 is amazing. It climbs hills with ease. I have only gotten about 10km on the bike as I was away for some time. I took the bike out yesterday and was riding on some hills. Then I was riding on a paved road and all of the sudden I lost all power and my display. I can't turn on the display or do anything. The batteries are very closed to charged and show about 55 volts output. I measured them individually and common on the output of the battery blender (dateX2). Any suggestions?

 

[amradio]

It ended up being the LCD8H display. For some reason it just died. The retailer I bought it from sent out a replacement and I'm up and running again. The old display was an LCD8H and the new one is an LCD8HU. It has a USB port on the back.