KT Controller - Strange Behaviour

[Sparksandbangs]

I realise that there might not be an answer to this.

I have a downhill on my regular journey. The bike is geared so I can get it up to 27/28mph under my own steam, no assistance 15.5mph cut out.

When I get up the next hill and the bike drops below 15.5mph there is no assistance. Legal throttle does nothing though the spinning symbol is seen on the LCD3. Doesn't matter how low I let the speed go or even if I stop there is no assistance. About 30 to 40 seconds later it cuts back in.

I can obviously stop this behaviour by not going that fast. I will try to do some experiments over the next couple of days to see if there is a speed threshold where this occurs.

 

[saneagle]

Maybe the centrifugal force from the fast spinning is jamming your clutch. Which motor is it?

You can tell if the motor is working if you set the display to show actual power taken from the battery. If watts is zero, the controller is not sending any power. If you see around 1 amp (36w at 36v, 48w at 48v), the clutch is slipping. Any more power indicates that the motor is doing something.

 

[Sparksandbangs]

Maybe the centrifugal force from the fast spinning is jamming your clutch. Which motor is it?

You can tell if the motor is working if you set the display to show actual power taken from the battery. If watts is zero, the controller is not sending any power. If you see around 1 amp (36w at 36v, 48w at 48v), the clutch is slipping. Any more power indicates that the motor is doing something.

It's an AKM100.
I'm guessing that you are referring to watt meter on the display (middle right). Fairly sure it was at zero but will check again tomorrow.

 

[Sturmey]

I dont know if this is relevant or not but I fitted a front akm100 201rpm lately and it behaved weirdly until I changed the P1 setting which was 88 to 200.

 

[Sparksandbangs]

I dont know if this is relevant or not but I fitted a front akm100 201rpm lately and it behaved weirdly until I changed the P1 setting which was 88 to 200.

I set it up multiplying 16 by the ratio. It only needed tweaking up a bit to get the cutoff to match the displayed speed.

 

[Sparksandbangs]

Today's update. 22mph with a stinking headwind. No issues 0W showing on the display. Will try a bit harder tomorrow.

Lost the rubber foot off my stand on the journey. Very annoying but I don't think it is related to my issue. Wish I'd superglued it on.

 

[saneagle]

Today's update. 22mph with a stinking headwind. No issues 0W showing on the display. Will try a bit harder tomorrow.

Lost the rubber foot off my stand on the journey. Very annoying but I don't think it is related to my issue. Wish I'd superglued it on.

The question is how many watts show when it's doing 15 mph, 18 mph and 20 mph. If the watts go down, you're speed-limited by the motor windings. Surely you would have seen that already?

 

[Sparksandbangs]

The question is how many watts show when it's doing 15 mph, 18 mph and 20 mph. If the watts go down, you're speed-limited by the motor windings. Surely you would have seen that already?

There are no Watts showing. The power cuts out at 15.5mph. It will be tapering off up to that point.

If you mean after I slow down then I will have to wait until the behaviour happens again. Depends on traffic and my leg power. I will try to replicate the behaviour and keep updating.

 

[Sturmey]

I set it up multiplying 16 by the ratio. It only needed tweaking up a bit to get the cutoff to match the displayed speed.

I think the newer akm100sx motor has 16 magnets and a gear ratio of 12.6:1, (which gives a p1 value of slightly over 200). This means, at the motors nominal 201rpm, each pair of magnets (pole pair) is flying by the coils at about a rate of 100 X 201 = 20,100 per minute. I think they call this the erpm or commutation speed.
If your clutch was sticky, and you are clocking up 28 mph downhill, you motor would be going at nearly double that speed and perhaps the controller doesn't like this as this could be at the limit of some controllers.
Anyhow, just a thought.

PS. What voltage are you running the motor at ?

PS (again). I have corrected the above as I think you count the magnets to get the P1 setting but I think its the pole pairs that count for the erpm,

 

[Sparksandbangs]

201rpm 36V motor running at 48V so 268rpm.

I will keep testing.

 

[saneagle]

201rpm 36V motor running at 48V so 268rpm.

I will keep testing.

Why don't you pedal the bike up to the motor's maximum speed and give us the data on watts vs speed, so we can see where the ramp is and when it ends? I just can't understand what you're telling us. It's all so imprecise.

What size wheel is it in?