Basic technical information

[peddlar]

I recently bought a kit to convert my old mountain bike.

It came with :-

Bafang g020 rear hub motor as a complete wheel ( no model number on the motor)
KT15A motor controller
KT LCD3 Display
and all the required cables but absolutely nothing in the way of instructions.

After purchase of some longer machine screws and a rear rack to mount a battery it all fitted together and mostly worked.

I thought it might need a bit of tuning to get things quite right and that's when I found the details required setting up the KT-LCD3 were hard to find. Lots of information on how to go thru the settup on YouTube but less on what to punch in. The Bafang website told me the gearing ratio and number of magnets to set the P1 parameter but not the wheel speed pulse rate.

It would seem to be a common conversion combination.

Trying some setup parameter combinations actually took the level of working percentage way down

Is there somewhere I haven't yet found that is good source for the info required.

Still trying to reduce the list of things I don't yet know I need to know...

 

[vfr400]

You shouldn't need to adjust anything in the settings. It'll work fine straight out of the box. The type of motor makes no difference.

There are some settings you can adjust to suit your choice.
P3=1 for PAS current control (recommended) and P3=0 for PAS speed control, where each level gives a different max speed.

The throttle can be independent (P4=0 zero start) or dependent on pedalling (P4=1 non-zero start), or it can be completely disabled. To be legal C4=1 and P4=1 gives a 6km throttle until you start pedalling, then the throttle gives max power as long as you're turning the pedals. That way, with P3=1, you get a different power with each PAS level and you can use the throttle to start up then start pedalling. Pedalling will be at whatever PAS power you set, normally a low level, then when you need a spurt of power, you can use the throttle to override the PAS. That way is the most logical and convenient and is why we recommend the KT controller above all others. I don't know of any others that can do that.

You can look at the manual here, though there can be slight differences in software and some settings, though the differences are normally pretty obvious.

https://www.bizobike.com/uploads/5/7/0/9/57094291/handleiding-bizobike-kt-lcd3.pdf

Can you tell us where you got the kit (link preferred) because it would be a good choice for other people?

 

[peddlar]

Thanks for the reply

I don't have a problem driving the KT LCD3 display as I found a good video on
www.youtube.com/watch?v=B0F6x8V0NZQ

and I had already found the manual on the link you mention

The manual says the P1 parameter

The P1 settings are a motor characteristic parameter where:
P1 = Motor Gear Reduction Value x Number of Motor Magnets

The Bafang G010 and G020 motors have different gearing ratios so would appear to need different P1 values

It's the same on P2

The P2 parameter is a setting mode for wheel speed pulse signal. If wheel generated 1 pulse signal by a revolution, the P2 value should be set to 1. If the wheel generated 6 pulse signals by a revolution, P2 should be set as 6.

I can't find any documentation what my Bafang motor generates per revolution so without getting my oscilloscope out I have to try different numbers and see what gives the best result

The kit was bought on Ebay and sort of worked out the box but not 100%
If I can get a good working set of Ps and Cs for the KT LCD3 I can pass it on for other buyers

 

[Nealh]

Set the value to 1, go for a ride and see what the speed readout says vs a gps readout if wrong it will be wildly out, also freewheel and see if it still reads.
If no joy try 6, no damage will occur by selecting the wrong value.

 

[vfr400]

I've never set P1 on any bike that I've fitted a KT controller to, and I've fitted a lot. You shouldn't need to adjust it unless you have some weird motor. It is necessary on sensorless motors.

 

[vfr400]

You have one or six magnets in your motor's speed sensor arrangement. It should be obvious which one you have from the speed readout. It will be correct, 1/6 the correct speed or 6 times the correct speed depending on whether you set 1 or 6 and whether you have one or six magnets.

If I can get a good working set of Ps and Cs for the KT LCD3 I can pass it on for other buyers

Tell them not to touch anything except P3, P4 and C4.

 

[peddlar]

Thanks for all the wise words.

I think the Bafang spec should have mentioned the speed indicator and that the kit supplier should have given a bit more on assembly / settup instructions

So apart from a minor complication in that the magnetic brake sensor moved so the brakes were apparently on and the result was no power after changing the LCD3 settings I seem to be good now

 

[peddlar]

So having done a conversion on one bike I was sure a second would be easier.
Apart from some bits needing mounting in a different place it was all much easier.

All powered on ok but it became obvious pretty quickly that the pedals need turning the wrong way to get the system to give power.

The guy on this video suggests you can change the C1 setting but unhelpfully doesn't say to what. It is current set to 3 for a 12 magnet PAS and I have tried the 4-7 settings with no luck.

Any ideas

 

[vfr400]

You've put the magnet disc on upside down. Flip it over. Not all KT controllers have the function to reverse the PAS in the software.

We're still waiting for you to tell us where you got the kit from. Ebay is big. Have you got a link to the listing?

 

[Nealh]

The PAS magnet disc is on back to front, magnets have a N or S orientation so any force is push or pull. There are three options, rotate the disc face, push each magnet out and put them back in again reversing the face (simply done by detecting if you need the push or pull side) or one can reverse the sensor by 180 degrees.

 

[peddlar]

Well it's mounted the same way as the first kit I did and that's working the right way.

It has a smooth side labelled " working side" that is the side with the pickup on both bikes and a side with a lip .

So doesn't look wrong

On this bike I couldn't mount the pas sensor on the saddle tube (too much stuff in the way ) so it is on the lower tube and not pointing exactly to the centre of te PAS disc like the first one.

Could that be the issue?

 

[peddlar]

I'll try the disk tother way if I can or try reversing magnets

thanks

 

[vfr400]

Well it's mounted the same way as the first kit I did and that's working the right way.

It has a smooth side labelled " working side" that is the side with the pickup on both bikes and a side with a lip .

So doesn't look wrong

On this bike I couldn't mount the pas sensor on the saddle tube (too much stuff in the way ) so it is on the lower tube and not pointing exactly to the centre of te PAS disc like the first one.

Could that be the issue?

None of that matters. it works when you pedal backwards, so it's the wrong way up - simples!

It's always best to test the PAS before you fit it to make sure of the orientation and direction, especially as some sensors are handed. Also, check again before reassembling the crank, which will often save a lot of time and bother. It takes 10 seconds to test, but about 10 minutes or longer if you didn't test and got it wrong.