Ebike slower after controller upgrade

vacious

1 mW
Joined
Apr 30, 2014
Messages
11
Hi all,
I've just replaced my FIIDO D4S controller (14a peak) to a KT controller of 20a peak, along with a KT LCD4 display.
The bikes working, and torque has increased as I'd hoped, however speed has mysteriously dropped quite a lot.
With the old controller, the wheel would spin (unloaded) at 32-36km/h depending on battery change, but with the new controller and display, this has reduced to 24-27km/h.
It doesn't appear to be a controller imposed speed limit, as I can further reduce the speed by imposing a lower limit via the controller.

It feels as if the controller is somehow delivering a lower voltage to the motor.

Any idea on what could be causing this?

Thanks!
 
Have you set up all of the P and C settings correctly?
 
Ah, I just realised, you can’t set up the advanced settings using an LCD04 display.
 
I do have access to C & P settings (just a bit fiddly with the small display) :

P1 : 104
P2 : 0
P3 : 0
P4 : 0
P5 : 15

C1 : 0
C2 : 0
C3 : 5
C4 : 0
C5 : 10
C6 : 4
C7 : 0
C8 : 0
C9 : 0
C10 : N
C11 : 1
C12 : 4
C13 : 0
C14 : 2
C15 : 6
 
I just checked the unloaded speed with a fully charged battery : 27.1 km/h with the new KT controller vs 36km/h with the previous controller.

Wondering whether it's a faulty controller, or perhaps a damaged connection could cause this?
 
I've attached a photo of the motor which has a bit of info on a sticker.

On this website, the guy explains an identical upgrade (I've basically followed what he did). He found what appears to be this motor on Alibaba, counted 20 magnets and a gear ratio of between 4.33 & 5.2 which is how he ended up with 104 for the P1 setting...no link to this motor though unfortunately.
16853826147914677745555773868771.jpg
 
I also forgot to mention that I took the bike out for a ride to check with that the speed being displayed is accurate, and it is - So the wheel is definitely rotating slower than it did with the previous controller (also sounds a lot slower).
 
Changzhou JiaBo Machinery Manufacturing Co.,Ltd is the motor manufacturer if that’s any help.
 
Does the motor have hall sensors? If it does, and you can access the motor hall ground wire and any one of the sensor wires *with the motor still plugged into the controller*, you can connect a voltmeter across those two wires, then manually turn the wheel *backwards*, starting with the valve stem in the exact "noon" position (or any other easy-to-match-perfectly spot). Count the number of times the voltage reading changes. That number, or twice that number, is the number you can put into the "pole count" setting.

You can also isntead try to "feel" the "cogging" of the motor as you turn it backwards, and count those, but it might be hard to feel those.
 
Have you connected the 3 speed switch to the ‘high’ setting? If you don’t have anything plugged in, it defaults to medium. A simple wire jumper is usually enough.
 
Thanks for the tip...this sounds hopeful! I found this diagram (below),which corresponds to my controller. it suggests disconnecting the white wire to disable the 30% speed reduction (almost exactly the amount I'm missing. However, disconnecting it hasn't made any difference.

Is this what you meant? I can't find any reference to a 3 speed switch

1685390921009.png
 
Solved it - The Display just needed a factory reset after disconnecting the speed limit wire.

Thanks very much for the pointer....would still be stuck without that!
 
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