Help! Replaced a Bafang 250W motor with a BFSWX02 36V 350W Bafang Rear Hub Motor

[Wimi]

Hi All
My Bafang 250W Rear Hub motor died and I Replaced it with a BFSWX02 36V 350W Bafang Rear Hub Motor, Now when I ride the bike the speed on the LCD is totally irrational, I might be doing 4 km/h and the spedo say 45 km/h. I thought that this was because the original controller was for a 250W motor, so I have replaced the Controller with a " KT Controller 36V 350W Controller Electric Bike Controller with display" , however the incorrect speed issue still occurs.
Does anyone know how/where the speed information is generated from, and what might be causing the issue, as the PAS does not engage due to the speed registered being higher than the maximum settings for the PAS.
Thanks in advance for any advice

 

[Nealh]

One has to enter the settings in the display and see what the P2 value is.

Turn the display on depress the +/- buttons simultaneously for about 5 - 10 secs, the basic settings will display, quickly press the on/off button going thru the first sequence of basic flashing settings. When the last one stops flashing press the two buttons again for up to 10 secs to enter the P settings, press on/off button again to get to P2.

 

[vfr400]

The original motor had 1 magnet in the hub for the speed sensor and the SWX02 has 6, so it reads six times the speed. If you can't find a setting in the LCD, you can open the motor and prise five magnets off the plate. They'll probably fall off in time anyway.

 

[Wimi]

One has to enter the settings in the display and see what the P2 value is.

Turn the display on depress the +/- buttons simultaneously for about 5 - 10 secs, the basic settings will display, quickly press the on/off button going thru the first sequence of basic flashing settings. When the last one stops flashing press the two buttons again for up to 10 secs to enter the P settings, press on/off button again to get to P2.

Hi Nealh
Thank you for this, do you have any more info on what these P settings are for? as P1 goes from 0 to 999, P2 I am assuming is for the number of magnets in the Pickup as it goes from 1 to 6, P3 and P4 look like they are a simple on /off switch, and P5 is like P1.
Thanks again for pointing me in the right direction

 

[vfr400]

leave P1 for now
p2=1
p3=1
P4=0

 

[Nealh]

P1. Is setting based on the internal gear ratio x motor winding magnets used, with a correct figure and P2 set correctly it gives a ear enough odo reading.
P2. Is wheel speed pulse or magnets sensed per revolution.
P3. Speed control or current control for PAS use.
P4. How the throttle works. Always active or Pedal first.
P5. Voltage mode. 36v /5 -15, the figure used shows how the battery fuel is used and set abut right will show real time battery usage inc voltage sag and voltage rebound.

 

[Wimi]

P1. Is setting based on the internal gear ratio x motor winding magnets used, with a correct figure and P2 set correctly it gives a ear enough odo reading.
P2. Is wheel speed pulse or magnets sensed per revolution.
P3. Speed control or current control for PAS use.
P4. How the throttle works. Always active or Pedal first.
P5. Voltage mode. 36v /5 -15, the figure used shows how the battery fuel is used and set abut right will show real time battery usage inc voltage sag and voltage rebound.

Thank you

 

[Nealh]

One can adjust P1 once P2 is working correctly.
P1 adjusts the odo reading to within about 0.1 - 0.3km/h or so. Set the display max speed to 25km/h, then use a GPS to see if the display odo reading is close. If display reading is quite close but under reads increase the P1 value by 1 each time then test/ repeat. If display over reads reduce by 1 and test /repeat.
Once set one then knows the cut off for legality is near as a damn correct, then if you wish you can set the cut off to what ever you like knowing that the indicated odo reading is near true.

Let us know if the P2 setting worked correctly or not.

 

[Wimi]

One can adjust P1 once P2 is working correctly.
P1 adjusts the odo reading to within about 0.1 - 0.3km/h or so. Set the display max speed to 25km/h, then use a GPS to see if the display odo reading is close. If display reading is quite close but under reads increase the P1 value by 1 each time then test/ repeat. If display over reads reduce by 1 and test /repeat.
Once set one then knows the cut off for legality is near as a damn correct, then if you wish you can set the cut off to what ever you like knowing that the indicated odo reading is near true.

Let us know if the P2 setting worked correctly or not.

Hi Nealh
Thanks I managed to get the P2 setting to work and reflect a more realistic speed, I also believe that my PAS should be working, as the little red led is now active, as I don't have a throttle, I have I have left my P4 at 0. However I cant seem to get the Motor to engage while peddling (the bike is on a bike stand) . Im not sure if this is related to the way the 3Phase motor cables are connected to each other, and if I can swap them around, If I plug in the old 250W controller the motor engages. Im not sure where to look from here, so if you have any advise I would be greatfull.
Have a great day

 

[vfr400]

If you have a throttle connector and no throttle, you can use a paper clip to short the red wire to the signal wire (not black) to test the motor. You have to switch on before you make the bridge and remember that the motor will go immediately to full speed as soon as you make the bridge.

 

[Nealh]

Which PAS sensor/ disc are you using and is C1 set correctly ?
C1 settings can be found after the P settings have finished, one holds the same two buttons again.

 

[Wimi]

If you have a throttle connector and no throttle, you can use a paper clip to short the red wire to the signal wire (not black) to test the motor. You have to switch on before you make the bridge and remember that the motor will go immediately to full speed as soon as you make the bridge.

Hi Vfr40
Thanks for that but if my P4 =0 and short out the throttle, then my wheel does a slight ± 1/10 turn and then stops. No further rotations. If I set P4 = 1 nothing happens at all. I have tried with my P3 setting 0 and 1 and the same result occurs.

 

[Wimi]

Which PAS sensor/ disc are you using and is C1 set correctly ?
C1 settings can be found after the P settings have finished, one holds the same two buttons again.

Hi Nealth
Unfortunately my KT-LCD1 display does not have the Option of C parameter settings, unless I am having a " Mans " look. I have attached Photos of the PAS, LCD, Controller, motor and Manual if that helps

 

[Nealh]

Correct yes, LCD1 has no C parameter option. If the new controller had an incorrect setting one won't know without an LCD that can access the C parameters.

With my LCD1 or 2, I simply plug in my LCD3 to make any changes.

 

[vfr400]

I can't figure out what's going on. You started by saying that the motor was working, but the speed displayed was wrong. Now you're saying that the PAS doesn't work and you have no throttle. How was it working before then?

 

[Nealh]

I dont't or can't understand why people start having issues esp with KT controllers, they are so easy not to get wrong. People seem to change/swap out items often for no good reason and spend money to try and overcome issues, then when the issue is still present decide to buy or change another part without rhyme or reason.

I think the issue is back in #1 and is a parameter/settings issue. Wimi replaced the hub motor then replaced the working controller (15a ?) with another (17 or 20a) because of the motor magnet count/speed readout, thinking the controller was faulty when it wasn't. Problem being possibly that the new controller has some parameters maybe set wrongly, having only an LCD1 any C parameters/settings can't be looked at to see them.
The basic displays LCD1 or 2 are ok and work ok but are no good if you need to change any C parameter/settings, with an oem bike or an all in supplied kit the user parameters (which can't be accessed) will be pre set if supplied with LCD1 or 2.
Once users start buying different controllers or PAS for instance then it is possible they aren't set up correctly.
Probably best option is to refit the old controller and simply adjust the P parameters to match the current settings, the PAS and old controller will still be matched.

 

[Wimi]

I dont't or can't understand why people start having issues esp with KT controllers, they are so easy not to get wrong. People seem to change/swap out items often for no good reason and spend money to try and overcome issues, then when the issue is still present decide to buy or change another part without rhyme or reason.

I think the issue is back in #1 and is a parameter/settings issue. Wimi replaced the hub motor then replaced the working controller (15a ?) with another (17 or 20a) because of the motor magnet count/speed readout, thinking the controller was faulty when it wasn't. Problem being possibly that the new controller has some parameters maybe set wrongly, having only an LCD1 any C parameters/settings can't be looked at to see them.
The basic displays LCD1 or 2 are ok and work ok but are no good if you need to change any C parameter/settings, with an oem bike or an all in supplied kit the user parameters (which can't be accessed) will be pre set if supplied with LCD1 or 2.
Once users start buying different controllers or PAS for instance then it is possible they aren't set up correctly.
Probably best option is to refit the old controller and simply adjust the P parameters to match the current settings, the PAS and old controller will still be matched.

Hi Guys
Apologies if I have confused the issue I hope this clears it up. The Bike was purchased in 2013 and all the wiring is inside of the frame (oldcontroller.jpg) and the controller (B3.jpg) is inside the base of the Bottle Battery Holder. As the original Battery is dying and I was unable to get an exact replacement, I decided to add a new battery on a rear Bike rack hence the wiring "B" . As I did not want to cut any wires before I was sure that the new controller would work I have spliced 3 cables into the PAS wires so that I could connect it to the new controller hence "A". The original LCD (B4.jpg) only allows me to set the wheel size and km/mph and no other Parameters. So if I plug the new motor to the existing wiring and peddle the motor engages and runs as expected, except for the fact that my speed on the LCD goes higher that the Maximum setting and so it then disconnects before it is of actual use while cycling.
So I went to a bike shop and they advised to get a new controller, which I did (NewController.jpg), This I have wired up as follows, I matched the pins on "D" to the same pins on the existing female plug, and it looked like the Motor Hall wires were the same pins and wires as the original wiring. So to test the new controller I plug the motor into "D" , the LCD goes into "F", the PAS wires go into "G", and I leave the Throttle "E" and Brakes "H" unconnected. Then I turn the Crank after playing with the P settings and see if the motor will engage. At the moment my P settings are as follows P1=0 as I dont know what my gear reduction ratio is, P2=6 this seems to have resolved my erratic and incorrect speed on the LCD, P3 I have tried 0 and 1, and in both instances the motor does not engage, P4 if I set it to 0 and bridge the connector, the wheel jumps, but does not rotate, and P5 is at 15.
It looks like from reading your post that it might be beneficial to get a LCD that allows me to manipulate the C settings and hopefully resolve my issue.
Thanks again for all your advice and help so far

 

[Nealh]

The original controller (bottle battery) was a Lishui model, the new one a KT and you did correctly buy a KT lcd. What is unknown are the KT C parameter/settings so it might be likely that one may be a miss.
Most Bafang's use a 5:1 gearing ratio x 16 or 18 winding magnets so P1 setting is about 80 - 84, use a gps to verify the speed and if the display reads different one can adjust it. But first one needs the PAS to work.

Connections D Hall wires. Don't even turn the bike on but sounds like you have. If any of those wires touch then you will fry the hall sensor's. One should have received a White connector block with the hub motor to mate with the controller one. The correct Hall connector has the designation DJ7061-2.8-21.

The output wire colours for the PAS/ throttle aren't the normal KT colours, are you 100% sure the PAS is connected to the correct connector ?
A link to the controller seller you bought from might help.