P settings info reqd

stevenatleven

Pedelecer
Apr 18, 2011
212
140
Fife
My latest build is a Bafang BPM 48v 500w front hub motor. Its working fine and i really like it.
The specs for the motor say Magnet Poles 16, so times 5 I set P1 to 80, the speed detection signal says 6 so I set P2 to that. However it doesn't show any speed at that setting, it shows the true speed at settings 1 and 5, it shows wrong speeds on all the others .
So my question is since its working fine on 1 or 5 can i just leave it there or is there something else I need to do and can I damage the motor running it on a wrong P setting.
I'm running the motor with a KT 10A rated 20A max controller and a LCD 3
 

vfr400

Esteemed Pedelecer
Jun 12, 2011
9,822
3,986
Basildon
P2 is the number of pulses per revolution of the wheel from the speed sensor. You can't have 1 and 5 give the same result.
If you have a wheel magnet sensor, P2=1
If you have no speed sensor, P2=0 and it will use the motor pulses to calculate the speed, but that will be zero when free-wheeling.
I've never seen a motor with an internal speed sensor that wasn't 1 or 6 magnets, though the magnets do come unstuck.

If it works correctly with P2=1, then you would see the speed displayed at 1/5 of its value if you set P2=5.

It worries me a bit that you say it shows the same speed with P2=1 and P2=5; however, if it's correct with P2=1, then leave it like that.
 

stevenatleven

Pedelecer
Apr 18, 2011
212
140
Fife
Thanks for the reply vfr400, like you say all of the Bafang motors i have had and read about are 1 & 6.
When I cycle next to my wife to confirm the speed 1 & 5 setting show i dentical speeds. pedaling or freewheeling. I will leave it on 1 anyway. Here are the motor specs if it helps.

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