KT controller limited in speed..

[PeterpDahl]

Hardware:

KT 15A controller w/o hallsensors
LCD: LCD9 with throttle
Motor: Generic 250w 36V hub motor

I'm slowly putting together a custom build made from parts I had laying around, that means a KT 15A controller without Hallsensors and a spare 250w 36V hub motor in a 26" wheel.

Now I have not hooked up a speedsensor as ti is right now, I'm still testing things out. However when using the throttle I will never get it to go very fast (~20km/t ish). Speed limit is set to 72km/h on the display. Now my question, is this because I do not have a speedsensor hooked up?

When starting from a stationary I can see it delivers about 500W as expected (Battery voltage is just 35V), but it tapers of before really gaining any useable speed.

Display settings are:
lim: 72km/h
dim: 26"
unt: 0
P1: 110
P2 6
P3: 1
P4: 0
P5: 12
C1: 4
C2:0
C3: 8
C4: 0
C5: 10
C6: 6
C7: 0
C8: 0
C9: 0
C10: N
C11: 0
C12: 4
C13: 0
L1: 0
L2: 0
L3: 0
L4: 5

So will the max speed be affected by not having a speed sensor hooked up?

 

[AHicks]

Speed sensor is only about the speedometer I believe.

You might try messing with your P1 setting. I believe that setting calibrates the speedo.

 

[PeterpDahl]

Since i do not have a speed sensor speed always reads 0

 

[E-HP]

Is it faster when the battery is fully charged to 42V? If so, the controller isn't limiting the speed.

 

[HK12K]

You never detailed your battery specs so it may very well be battery sag related, at least in part. That said it will not go very fast because a 36v 15amp system does not go very fast. Especially when it's trying to overcome the forces involved with turning a wheel of that diameter.

 

[PeterpDahl]

You never detailed your battery specs so it may very well be battery sag related, at least in part. That said it will not go very fast because a 36v 15amp system does not go very fast. Especially when it's trying to overcome the forces involved with turning a wheel of that diameter.

And you hit the nail on the head. The controller is a 20A, not 15A as I wrote - however it is a _cheap_ and _old_ battery so it sags quite badly.. I did mess with the settings, and now I have speedo (when the motor is turning..) and I have more speed.
I did not disconnect the wite wire on the controller, so it was capped at -30%.

I also tried a good 48v battery made of good quality 21700 cells and with a BMW that is capable of 30A - and now it goes quite a lot better.. The display showed 800+W peak (the battery is fully charged at 54.4V) and it goes faster than what I like to try right now. (Front brake is disconnected)

I’m quite impressed by the old 36v 250W motor - pushing 800W and 54V..

So it is a power/voltage/battery issue.

My new settings are:

lim: 50km/h
dim: 26"
unt: 0
P1: 100
P2 0
P3: 1
P4: 0
P5: 00
C1: 0
C2:0
C3: 3
C4: 0
C5: 10
C6: 2
C7: 0
C8: 0
C9: 0
C10: N
C11: 0
C12: 3
C13: 0
C14: 2
L1: 0
L2: 0
L3: 1
L4: 5