Help! Erratic controller behaviour - is it a programming issue?

[Slightlypedantic]

Yes, the cable is rated at 30A so perhaps I'm being "slightly pedantic"!

Looking at setting C1, which has a table that seems slightly unclear, please could you confirm my thinking is correct:

Forward 5 signal, 8 signal, 10 signal means the number of magnets that pass the sensor before power kicks in.

Reverse 6 signal, 10 signal, 12 signal are for use if the sensor is going round the other way, depending on which side the sensor is fitted.

As I intend using a left side sensor I may have to use the reverse settings.

"Sensitivity" governs how quickly the power ramps up after kicking in.

I'm not sure how the display/controller knows how many "signals" (magnets passing the sensor) I want. C1= 01 could be any of three signal/sensitivity combinations. Presumably there is a simple explanation...?

I'll probably start with C1= 01 if forward is correct or C1= 06 if reverse is correct. Otherwise it'll be a case of experimenting to find a setting that works for me.

Hopefully I've got that right and just need to experiment.

 

[saneagle]

Use whatever C1 works. Try them all until one works.

 

[Slightlypedantic]

Okey dokey. Thanks.

 

[Slightlypedantic]

I finally got back to it yesterday, after a long break. Up and running today!

Yesterday, I removed the JYT controller from the Yose battery base, removed the circuit board and compound and soldered a 12 AWG silicone lead on to the battery socket with an XT60 connector at the other end.

This morning I used the bag Yose supplied with the original kit to house the KT 36/48V 17A controller and connections. I mounted the LCD 3 and KT-V12L PAS sensor, plugged it all together and tidied up the cabling. It was good not having to lose about 3 feet of a 1T4 cable around the battery base and the KT installation looks much neater. being a black bike the cabling isn't too prominent.

I changed a few settings and went for a test ride. The Aikema 95RX motor (oem model for Yose) felt a bit harsh. C2 was set to 0 by default, so I experimented and found that C2=4 was smoother. All the other values made horrible noises.

I tried P1 = 163 (using my reduction ratio 8.15 based on counting the number of teeth on the reduction gears) and P1=88 (based on the reduction ratio 4.4 supplied by Yose). The bike seemed to go well on 163 but felt sluggish on 88. I left P1 at 100 while I went for a ride and got used to it. During the ride I adjusted the maximum speed from 60kph to 25 kph. This resulted in the assistance tailing off at about 9-10 mph, suggesting that P1 needs to be about 60% higher to avoid the controller thinking the bike is going faster than it really is. So I suspect my value of P1=163 was about right. I'll change it tonight and check by riding tomorrow, perhaps making minor further adjustments as necessary.

With the maximum speed set to a high value the bike seemed to fly along, easily holding 16-17mph into a strongish headwind in level 2, and coping with a steep hill in level 3. In level 1 it was easy to ride safely along the sea-front promenade amongst the pedestrians.

What a difference the KT controller makes compared to the JYT speed controller! I'm really pleased.

A very big thank-you to saneagle for helping me up the learning curve. Next time (Carrera mtb conversion?) I should know what I'm doing!

Pic below of the converted bike: My wife's first "proper" bike, "Black the Elder", is a Specialized Sirrus bought cheaply on EBay quite a few years ago. He's had lots of adventures, including a tour in Albania, and now has a new lease of life with lots of tlc and the electric conversion. My wife says all inanimate objects are masculine, hence BtE is a "he". Hmmm....

(Btw, "Black the Younger" was a newer Specialized Diverge (gravel bike), which also did a lot of European touring but fell from favour and went to live elsewhere after I built her a Spa Cycles "Audax" steel road bike with a "Vivaldi" wheelset from DCR Wheels at Lewes. It's the most smooth riding, comfy and generally nice to ride bike she has ever had. He's called "Mr Red". The main problem is she won't let me ride it/him.)

 

[Slightlypedantic]

Hi Saneagle (and anyone else),

This morning, with maximum speed set to 25kph and P1 set to 163 (as calculated from the gear teeth), motor assistance started tapering off at 15.5mph with watts dropping to around 10 at 16 - 16.5mph. Mostly using level 1 or 2, occasionally 3 if it's particularly steep. Ace!

Just one niggle. The motor sounds a bit harsher than it did with the original JYT sine wave speed controller, louder at higher power levels. I can feel the harshness as a buzz of vibration through the pedals and bars at level 3 and above. I can live with it but it doesn't sound like a "right" sort of noise if you know what I mean.

I checked the two workable C2 settings and finally settled on C2=0 (default) which seemed marginally smoother. The LCD3 display only offers C2= 0 to 5, whereas the LCD3 manual I found online says C2 can be 0 to 7.

The LCD3 display shows a parameter C15, defaulted to 6, for which there is no definition in the manual - could this be relevant? Don't know if it's a safe one to experiment with.

The seller describes the KT 36/48V 17A SVPRD controller as "sine wave" rather than "dual mode" so presumably L3 has no effect. I tried L3=0 but no noticeable effect.

Is there anything else I could try?

Perhaps the motor/reduction gears just need running in? Total so far only about 100 miles including JYT use.


Thanks again!

 

[saneagle]

Asuming that it's a controller for a sensored motor and you have hall sensors, there are a couple of things I can think of. The higher the current you run, the more you can feel the commutation pulses, and the slower the commutation (bike speed and reduction ratio), the more you feel it. Putting that together, if it's at low speed, don't worry about it, but if it's at high speed, we might need to investifate a bit.

 

[Slightlypedantic]

Yes, it's a sensored motor. Aikema 95RX. Reduction 8:1 on 700c. The controller KT 17A SVPRD was sold as a sine wave model for which I think Hall sensors are necessary to work properly? If however he motor is working in unsensored mode for any reason, would that mean it is using square wave instead?

At lower speeds the pulses are more noticeable but not particularly harsh. The noise/vibration becomes more noticeable as speed picks up (as well as in higher power/current levels). Harder to say about high speed due to wind noise and dodgy hearing, but certainly noticeable at medium speed, say 7-12mph.

Restricted to 25kph it pulls strongly until the controller starts tapering off at 15.5mph. Unrestricted, the motor seemed to top out at about 18-19 mph downhill (light load). It felt smoother at these higher speeds, possibly because the current starts tailing off as back emf increases.

It "feels" as though it might be using square wave drive or there is a slight timing error. Just that harsh edge instead of smooth whirring.

 

[saneagle]

Yes, it's a sensored motor. Aikema 95RX. Reduction 8:1 on 700c. The controller KT 17A SVPRD was sold as a sine wave model for which I think Hall sensors are necessary to work properly? If however he motor is working in unsensored mode for any reason, would that mean it is using square wave instead?

At lower speeds the pulses are more noticeable but not particularly harsh. The noise/vibration becomes more noticeable as speed picks up (as well as in higher power/current levels). Harder to say about high speed due to wind noise and dodgy hearing, but certainly noticeable at medium speed, say 7-12mph.

Restricted to 25kph it pulls strongly until the controller starts tapering off at 15.5mph. Unrestricted, the motor seemed to top out at about 18-19 mph downhill (light load). It felt smoother at these higher speeds, possibly because the current starts tailing off as back emf increases.

It "feels" as though it might be using square wave drive or there is a slight timing error. Just that harsh edge instead of smooth whirring.

Where did you get 8:1 from? I'm sure I've seen listings of the latest 95 and 100 versions stating around 4.5:1. Looking at the spare gears for them, the ratio looks a lot lower than the old Q100, which was 8:1.

 

[Slightlypedantic]

Interesting.

I saw a set of spare idler gears for 95RX on AliExpress yesterday and they were 18/40 teeth, same as mine are.
For an older version 95 perhaps? Mine was supplied a year ago.

Yose quoted 4.4, consistent with what you have found. I counted the gear teeth, which suggested 8.15*. That gave P1 = 88 (Yose) and 163 (teeth count). When I set P1 to 88 and max speed to 25kph, the motor cut out at about 9 mph. When I changed P1 to 163 the motor started cutting out at 15.5 mph. So I assumed the reduction ratio of 8.15 was about right. (But you know what they say about assumption...)

Yose said the motor is wound for 190 - 200 rpm wheel speed. That works out at about 25kph (200 x 2100/1000 x 60), but I know that the motor goes well over that speed when max speed is set high (60kph). It was pulling well at 17mph when I went past 3 cops pretending to pedal hard!
200 rpm @ 4.4:1 = 880 rpm motor speed.
200 rpm @ 8.15:1 = 1,630 rpm motor speed.
I have no idea whether either or both figures are plausible!

There must be a logical answer but atm it's confusing.


* Helical gears - motor 18 teeth, idler 40 teeth. Straight cut gears - casing 66 teeth, idler 18 teeth. I counted them all several times to be sure. So, 40/18 x 66/18 comes out at 8.15:1. What I wasn't sure about was the effect of the idler gear assembly rotating in the opposite direction to the idler gears, but since P1 = 163 worked well I stopped worrying about it. Perhaps idler assembly rotation makes a big difference and Yose was right with 4.4, but then what about P1 = 88 being so far adrift? I might be missing something?

 

[Slightlypedantic]

PS Any idea what the mystery setting C15 is? Thanks.

 

[saneagle]

Interesting.

I saw a set of spare idler gears for 95RX on AliExpress yesterday and they were 18/40 teeth, same as mine are.
For an older version 95 perhaps? Mine was supplied a year ago.

Yose quoted 4.4, consistent with what you have found. I counted the gear teeth, which suggested 8.15*. That gave P1 = 88 (Yose) and 163 (teeth count). When I set P1 to 88 and max speed to 25kph, the motor cut out at about 9 mph. When I changed P1 to 163 the motor started cutting out at 15.5 mph. So I assumed the reduction ratio of 8.15 was about right. (But you know what they say about assumption...)

Yose said the motor is wound for 190 - 200 rpm wheel speed. That works out at about 25kph (200 x 2100/1000 x 60), but I know that the motor goes well over that speed when max speed is set high (60kph). It was pulling well at 17mph when I went past 3 cops pretending to pedal hard!
200 rpm @ 4.4:1 = 880 rpm motor speed.
200 rpm @ 8.15:1 = 1,630 rpm motor speed.
I have no idea whether either or both figures are plausible!

There must be a logical answer but atm it's confusing.


* Helical gears - motor 18 teeth, idler 40 teeth. Straight cut gears - casing 66 teeth, idler 18 teeth. I counted them all several times to be sure. So, 40/18 x 66/18 comes out at 8.15:1. What I wasn't sure about was the effect of the idler gear assembly rotating in the opposite direction to the idler gears, but since P1 = 163 worked well I stopped worrying about it. Perhaps idler assembly rotation makes a big difference and Yose was right with 4.4, but then what about P1 = 88 being so far adrift? I might be missing something?

I think you're right. The reduction must be 8.15:1. To get the max motor RPM, lift the wheel off the ground and spin it up to maximum unrestricted, then compensate for the battery voltage by multiplying that by 36 divide by actual battery voltage. 201 rpm is 15 mph with a 26" wheel. Do the maths to convert your speed to RPM.

 

[Slightlypedantic]

Max. no-load speed, level 5 = 18.9mph = 30.4kph. ( I tried C2 = 0 and C2 = 4 with exactly the same results.)

Battery voltage 39.8V (Digital voltmeter. Assumed no significant voltage drop due to negligible current.)

Max speed normalised to 36V: 30.4 x 36/39.8 = 27.5 kph or 27,500 m/hr (=17.1mph).

Tyre circumference 2165mm or 2.165m. (Measured on garage floor, 1 revolution. +/- 5mm? Marathon Greenguard 700-32 has 3mm latex under tread, hence slightly higher value than 2152mm obtained from tables seems plausible).

Wheel rpm = 27,500 / (2.165 x 60) = 212 rpm. (Slightly higher than Yose Power figure 190 - 200 rpm.)

 

[RogerA]

C15 is the walk assist speed (6kph is the maximum legal permitted I think). I think it's a new feature in the KT software. I bought a replacement display earlier this year and it was on that, but wasnt' on the previous one.

 

[Slightlypedantic]

Thanks Roger. So that's not an issue in the context above. Good to know.

 

[saneagle]

Max. no-load speed, level 5 = 18.9mph = 30.4kph. ( I tried C2 = 0 and C2 = 4 with exactly the same results.)

Battery voltage 39.8V (Digital voltmeter. Assumed no significant voltage drop due to negligible current.)

Max speed normalised to 36V: 30.4 x 36/39.8 = 27.5 kph or 27,500 m/hr (=17.1mph).

Tyre circumference 2165mm or 2.165m. (Measured on garage floor, 1 revolution. +/- 5mm? Marathon Greenguard 700-32 has 3mm latex under tread, hence slightly higher value than 2152mm obtained from tables seems plausible).

Wheel rpm = 27,500 / (2.165 x 60) = 212 rpm. (Slightly higher than Yose Power figure 190 - 200 rpm.)

Great work. Thanks.

 

[Slightlypedantic]

PS With max speed set to 25kph (P1 =163, i.e. 8.15 x 20), the no-load speed is 15.8mph.

 

[Slightlypedantic]

Update:
I'm coming to the conclusion that either:

That's just the way it is.
The motor seems significantly stronger than it did with the JYT speed controller, which may have had a lower current limit - no way of knowing. (Label on JYT says 15A max, 8A rated, but programmed max current could be lower?) So it would be noisier/harsher due to higher torque, and may get quieter as the gears etc. bed in. I'll try altering C14 =2 (default) to C14=1 and see what happens. (C14=1/2/3 = "Weak/General/Stronger assist strength of motor". Not sure what that means... Perhaps it alters the spread of power levels so that level 1 can be more gentle or stronger ?)

Edit:
C14=1 felt immediately quieter, however the Watts in the lower power levels was reduced substantially (around 60% reduction in level 1 and 40% in level 2). In higher levels it still sounded a bit rough. At least I know now what C14 does.


I may have damaged* a Hall sensor wire?
Would that result in the controller defaulting to square wave? (L3=0) If so, presumably it would be a bit harsher/coarser sounding. If it's just running square wave I'll live with it. But how to tell?
*With my arthiticky thumbs playing up I struggled to grip the motor lead plug hard enough to push it into the socket. So frustrating. To get it right home I had to wriggle it side to side. Then I found I'd forgotten the rubber end cap and had to unplug it again which was even harder. D'oh! I don't think I would have done any damage as I wasn't holding the cable, but it's always possible.

Any other thoughts?

I've learnt some useful things from this exercise and feel a lot more confident about configuring the controller. Thanks Saneagle.

 

[saneagle]

Update:
I'm coming to the conclusion that either:

That's just the way it is.
The motor seems significantly stronger than it did with the JYT speed controller, which may have had a lower current limit - no way of knowing. (Label on JYT says 15A max, 8A rated, but programmed max current could be lower?) So it would be noisier/harsher due to higher torque, and may get quieter as the gears etc. bed in. I'll try altering C14 =2 (default) to C14=1 and see what happens. (C14=1/2/3 = "Weak/General/Stronger assist strength of motor". Not sure what that means... Perhaps it alters the spread of power levels so that level 1 can be more gentle or stronger ?)

I may have damaged* a Hall sensor wire?
Would that result in the controller defaulting to square wave? (L3=0) If so, presumably it would be a bit harsher/coarser sounding. If it's just running square wave I'll live with it. But how to tell?
*With my arthiticky thumbs playing up I struggled to grip the motor lead plug hard enough to push it into the socket. So frustrating. To get it right home I had to wriggle it side to side. Then I found I'd forgotten the rubber end cap and had to unplug it again which was even harder. D'oh! I don't think I would have done any damage as I wasn't holding the cable, but it's always possible.

Any other thoughts?

I've learnt some useful things from this exercise and feel a lot more confident about configuring the controller. Thanks Saneagle.

KT controllers are not dual mode, so they won't switch between sensored mode and sensorless like some other controllers do.

AFAIK C14 adds a ramp to the PAS startup. The different settings are the steepness of the ramp.

 

[Slightlypedantic]

I've ridden the bike a bit more and, from watching the wattage on the display, it does seem that C14 adjusts the spread, and possibly spacing, of the power levels. For example: In level 1 C14=1 gave around 25-30W and C14=2 gave around 60-80W. Likewise, level 2 gave around 90W and 130W. The readings fluctuate rapidly so it's hard to give definite figures. I haven't yet been able to assess the higher power levels since consistent hills would be needed to keep below the 25kph limit, and there's yet to be any need for levels 4 and 5 anyway.

It's possible that all levels change together such that level 5 power varies, or that the spacing of the levels changes such that level 5 always gives full power. I haven't tried C14 = 3, but expect that to be excessively lively. C14 = 1 is may be better for battery life.

I couldn't tell if C14 affected ramping as well, as I felt the different amounts of power could be masking this.

I obtained an up to date KT manual from the AliExpress supplier and noticed that three previously blank settings in manuals downloaded from the internet (C5 = 0, 1, 2) have now been populated with alternative ramping settings. This must be a recent software change and probably explains what I found with C14, whose function may have been changed at the same time.

On the motor noise, I decided to fit wider tyres so, while I had the wheel out, I swapped the motor internals with my spare motor. The noise was similar but more subdued and less objectionable. The motor performance was identical. So I'm thinking that the noise might actually be mechanical noise from the reduction gears, in which case it should reduce as they bed in.


EDIT:

C14 "Assist strength of motor"
I found a long and fairly steep hill this afternoon. With C14 = 1 ("Weak assist strength of motor"), I found that levels 1 to 4 were all lower in power than with the default (C14 = 2), with a big step up to level 5, which gave full power (bike accelerated uphill until it hit the 15.5mph limit).

With C14 =2 ("Normal assist strength of motor"), levels 1-4 are stronger and the difference between levels 4 and 5 is less marked. I haven't yet tried C14 = 3 ("Strong assist strength of motor") but it seems reasonable to suppose that levels 1 to 4 would all be stronger still, with a smaller step up to level 5.

My feeling from this ride is that KT have actually programmed 7 power levels, mapped as follows:
C14 = 1 - ("Weak assist strength of motor") - selected levels 1-4 are mapped to actual levels 1-4.
C14 = 2 - ("Normal assist strength of motor") - selected levels 1-4 are mapped to actual levels 2-5.
C14 = 3 - ("Strong assist strength of motor") - selected levels 1-4 are mapped to actual levels 3-6.

In all 3 cases selected level 5 is mapped to actual level 7 (= full power).

This would be relatively easy to implement from a programming point of view and fits the C14 parameter description well.

C5 Current limit/Soft start
C5 is currently set to 10 (default), which allows the full 17A for which the controller is rated. I'll try playing with C5 = 0,1,2 sometime to explore these (new) soft start settings. C5 = 10 seems quite satisfactory except if pulling away in a higher power setting - perhaps that's where the soft start settings come into their own.

 

[saneagle]

I've ridden the bike a bit more and, from watching the wattage on the display, it does seem that C14 adjusts the spread, and possibly spacing, of the power levels. For example: In level 1 C14=1 gave around 25-30W and C14=2 gave around 60-80W. Likewise, level 2 gave around 90W and 130W. The readings fluctuate rapidly so it's hard to give definite figures. I haven't yet been able to assess the higher power levels since consistent hills would be needed to keep below the 25kph limit, and there's yet to be any need for levels 4 and 5 anyway.

It's possible that all levels change together such that level 5 power varies, or that the spacing of the levels changes such that level 5 always gives full power. I haven't tried C14 = 3, but expect that to be excessively lively. C14 = 1 is may be better for battery life.

I couldn't tell if C14 affected ramping as well, as I felt the different amounts of power could be masking this.

I obtained an up to date KT manual from the AliExpress supplier and noticed that three previously blank settings in manuals downloaded from the internet (C5 = 0, 1, 2) have now been populated with alternative ramping settings. This must be a recent software change and probably explains what I found with C14, whose function may have been changed at the same time.

On the motor noise, I decided to fit wider tyres so, while I had the wheel out, I swapped the motor internals with my spare motor. The noise was similar but more subdued and less objectionable. The motor performance was identical. So I'm thinking that the noise might actually be mechanical noise from the reduction gears, in which case it should reduce as they bed in.

You can't test by riding the bike because the speed of the motor is changing all the time, and as the speed goes up, the current goes down. The best way to test is to lift the motor wheel off the ground, power up with the throttle and apply the brake to get the speed down to about 4mph under full power. Read the current or power from your LCD wile the wheel is slowed right down. Obviously, don't hold the wheel with the brake for too long.