KT Controller programming accuracy

[the_horak]

I'm hooking up a KT30 w/ LCD5 to my stock motor on my bike. All I know is that it's geared, 48v, rated for 750/1500 and says Matsui on it. I want to know the gear ratio and the number of magnets in the motor to program the C settings in the controller. I'm having trouble finding anything technical on the motor. I feel like it's a safe bet that the ratio is 1:5. Is there a safe bet for the number of magnets? Is there a way to know without disassembling the motor? Also, is it a big deal if I am close but not exact? What are symptoms that come from having this setup wrong?

 

[E-HP]

Wheel diameter, P1 and P2 are used to calibrate the speed on the display. They don’t affect performance. For clutched geared motor, an internal speed sensor is required, since the hall signals normally used for determining speed aren’t present when coasting (not under power). P1 is irrelevant for a clutched geared motor. P2 and wheel diameter are used, so motor magnets and gear ratios don’t matter.
If you look at the hall sensor connector from the motor (the small conductors) and see 6 wires instead of 5, the 6th white wire is the speed signal input the controller will use to determine speed. Typically the number of magnets used by a geared motor speed sensor are between 1 to 6. If you don’t see the white/speed conductor, then you may need to mount the type of sensor using a magnet on the spokes.

 

[Chalo]

When I set up a KT controller on an unknown motor, I use an optical tachometer or a BPM video on Youtube to determine the wheel RPM, then 4QD's road speed calculator to turn that number into a calculated road speed. Then I set P1 to whatever value makes the display agree with the calculated value.

If I'm using a tire or a wheel size that differs from the preset diameters enough that the display speed is significantly different than what I get on a GPS speedometer app, I'll go back to P1 to dial in the value for a more accurate reading.

 

[the_horak]

Wheel diameter, P1 and P2 are used to calibrate the speed on the display. They don’t affect performance. For clutched geared motor, an internal speed sensor is required, since the hall signals normally used for determining speed aren’t present when coasting (not under power). P1 is irrelevant for a clutched geared motor. P2 and wheel diameter are used, so motor magnets and gear ratios don’t matter.
If you look at the hall sensor connector from the motor (the small conductors) and see 6 wires instead of 5, the 6th white wire is the speed signal input the controller will use to determine speed. Typically the number of magnets used by a geared motor speed sensor are between 1 to 6. If you don’t see the white/speed conductor, then you may need to mount the type of sensor using a magnet on the spokes.

I assumed that these settings were for things more important for speed. I've got the white speed sensor in the motor and made sure I got a KT controller with the speed wire in the hall sensor wiring. So then do I not have to worry about P1 at all. That's great to know, thank you.

 

[docw009]

My wife and I have similar bikes with same motor (Q100H), same LCD3, KT controllesr, same 20" rim but different tires. Schwalbe Big Apples, 20x2.15 and 20x2.00. Her mileage was always higher, which makes no sense to me, as with the bigger tires, it should be lower.

Amyway, I ratio'ed the P1 setting down 5%, and it seemed our speeds matched when riding. Odometer didn't change, riding the same set route. The LCD3 must use speed sensor and the entered wheel diameter for mileage, and P1 for speed.

 

[the_horak]

My wife and I have similar bikes with same motor (Q100H), same LCD3, KT controllesr, same 20" rim but different tires. Schwalbe Big Apples, 20x2.15 and 20x2.00. Her mileage was always higher, which makes no sense to me, as with the bigger tires, it should be lower.

Amyway, I ratio'ed the P1 setting down 5%, and it seemed our speeds matched when riding. Odometer didn't change, riding the same set route. The LCD3 must use speed sensor and the entered wheel diameter for mileage, and P1 for speed.

Maybe. Are your motors geared or regular direct hub motors? Seems like the geared ones don't use P1 but I'll play around with it like you did. I'm just glad it's not for anything other than speed/distance.

 

[E-HP]

I assumed that these settings were for things more important for speed. I've got the white speed sensor in the motor and made sure I got a KT controller with the speed wire in the hall sensor wiring. So then do I not have to worry about P1 at all. That's great to know, thank you.

I defer to docw009 since it's been a long time since I messed with my KT controller (I used an external speed sensor).

 

[docw009]

Maybe. Are your motors geared or regular direct hub motors? Seems like the geared ones don't use P1 but I'll play around with it like you did. I'm just glad it's not for anything other than speed/distance.

They're geared and the P1 I use is 205, I've counted the number of times my Hall motor tester flashed when turning the wheel backwards, and its around that number. Easy to lose count when it 50 pulses per quarter turn. I didn't bother reconciling the difference in what I counted and 205.

Internal speed sensor.

 

[the_horak]

They're geared and the P1 I use is 205, I've counted the number of times my Hall motor tester flashed when turning the wheel backwards, and its around that number. Easy to lose count when it 50 pulses per quarter turn. I didn't bother reconciling the difference in what I counted and 205.

Internal speed sensor.

Good to know, thank you. It's a full custom controller swap so I am still figuring it out. Thankfully, the stock motor uses the standard wire colors. I don't have a tester, and I don't do this enough to warrant one. I'm thinking I'll just open the motor. I can get magnet count and gear ratio with certainty that way.

 

[E-HP]

You only need a voltmeter to test without opening the motor:

https://www.ebikes.ca/documents/HallSensorTestingFinal.pdf

You can also test without the controller connected if you have a ~5v source. See the "2) Bench testing not using a controller." section:

Testing BLDC motor's Phase Wiring - Hall Sensors and Wiring. - Electricbike.com Ebike Forum

Testing electrical components of a typical hub motor with a digital multi meter. First take a few minuets and look over the wiring going into the motor for cuts, scrapes, missing insulation and other wiring issues or poor connections that should be resolved first. Smell for...

electricbike.com

 

[docw009]

And some people will tie two phase wires together and rotate it (backwards if geared), counting the bumps as the shorted coil passes thru a magnetic field/

 

[the_horak]

Thanks all!

 

[the_horak]

So I just decided to open the motor. I know there's other ways to do it, but to be honest this seems the easiest way and it really isn't difficult. 20 magnets and the gear ratio is 5:1 on the dot

 

[slaphappygamer]

This is something I started watching out for. Sometimes “magnet pairs” are referenced and other times only “magnets”. You have 100 effective “magnets” and 50 “magnet pairs”.

 

[the_horak]

This is something I started watching out for. Sometimes “magnet pairs” are referenced and other times only “magnets”. You have 100 effective “magnets” and 50 “magnet pairs”.

I have never heard of that so thank you for bringing it up. I guess I can put in my numbers and if it's not right I can think of them as pairs.

 

[amberwolf]

The term normally seen is "poles" or "pole pairs".

Most of the UVW-ABC hall sensors in hubmotors are open-collector latching types, so when they detect say, a north pole passing, they latch on, and don't unlatch and turn off until a south pole passes by. So it takes a pair of poles to provide a signal cycle on the sensor.

Some are non-latching types, and those change whenever the field changes enough to pass the trigger point. They may be used in motors that don't have a continuous ring of magnets of opposing pairs, to be sure of telling the controller when a magnet is actually passing them, but not trigger at any other time.

 

[the_horak]

The term normally seen is "poles" or "pole pairs".

Most of the UVW-ABC hall sensors in hubmotors are open-collector latching types, so when they detect say, a north pole passing, they latch on, and don't unlatch and turn off until a south pole passes by. So it takes a pair of poles to provide a signal cycle on the sensor.

Some are non-latching types, and those change whenever the field changes enough to pass the trigger point. They may be used in motors that don't have a continuous ring of magnets of opposing pairs, to be sure of telling the controller when a magnet is actually passing them, but not trigger at any other time.

So it's an "on" magnet followed by an "off" magnet? Should that change how I calculate if I put my data into the controller's P settings?