Pedal backwards...go forwards

[Richardab]

Building my second ebike with a Q128c motor. My first Q100c when I pedal forward I go forward, pedal back does nothing, but the Q128c pedal forward goes forward AND pedal backward goes forward, is this normal for Q128 or have I done something wrong.

They both have the same Kuntung controller and the same battery. the q100 has a KT-LCD3 control and the q128 has an eggrider. Certainly no settings in teh eggrider to change this, but I don't recall anything in the LCD3 either so I don't think its the control.

The crank sensor has the arrows spinning in the right direction, although the actual sensor points the different way to my q100, but I think I tried it both ways round and it did the same.

Any thoughts out there?

 

[Nealh]

Some PAS sensors are double halled and can result in forward motion with back pedal.

 

[Woosh]

as NealH said, some controllers are programmable for SH (single Hall) only or DH (dual Hall) only. If your controller turns on the motor when you pedal either forward or backward, you need a King Meter DH sensor which won't output the wrong signal when pedaling backward.

 

[Richardab]

I am pretty sure the sensor is exactly the same as the one I have on the q100. But the magnetic disk is different model to fit round the holowtech crank. Is the magnetic disk the thing that is dual or single?

Am I doing any harm at the moment?

 

[Richardab]

Ahh just googled king meter...that is the disk I used, but I didn't use the sensor that came with it because the connectors weren't right. Can this be corrected on the Kuntung controller using the LCD3

 

[flecc]

Combine it with Retro-Direct transmission and you could have a two gear pedelec, pedal forwards for high gear and motor, or pedal backwards for low gear and motor! Or four gears with two chainrings as here:

Explanation link
.

 

[Richardab]

The mind boggles!

 

[Woosh]

I am pretty sure the sensor is exactly the same as the one I have on the q100. But the magnetic disk is different model to fit round the holowtech crank. Is the magnetic disk the thing that is dual or single?

Am I doing any harm at the moment?

it's easy to check.
Spin the cranks forward, if the motor turns on, you have installed the magnet disc the right way and your problem is the sensor.

If the motor does not start, good news, flip the disc to have the other side facing the sensor, problem sorted.

 

[vfr400]

There's a setting in the LCD that might sort it out. It determines how the controller interprets the PAS signal and its sensitivity. It's parameter C1, which has 8 values from 0 to 7. Try each of them until you get the correct operation. No harm will be done if you set it it wrong.

 

[sjpt]

Reminds me of my old DAF; forward to go forward, backward to go backward. When they got bought by Volvo they changed it to the international standard for automatic transmission: forward to go backwards and backwards to go forwards.

 

[jeff St.Clair]

Yes my converted rockhopper does that as well I tried the sensor both ways and it was the same ...I had a bit of trouble getting the PAS to work smoothly when I first did this conversion ...the magnet disc has eight magnets , changing the settings on the LCD for twelve magnets made the PAS much smoother ...I keep meaning to order a twelve magnet disc to see how that would work ....but it works fine "if it ain't broke don't fix it "....

 

[harrys]

I've been there with the backward pedals. I flipped the magnet disk around. It worked right.

 

[Richardab]

Just to follow up on this. I am having a few teething issues with the eggrider control cutting out, so i swapped the KT-LCD3 from my road ebike. Pedalling forward did nothing and pedalling backwards made it go forwards so i swapped the orientation of the sensor and its working fine on the LCD3.

Interestingly swapping back to the eggrider is also now working correctly so i don’t know what was going on. Still having issues with the eggrider in other departments so will be running both controls till its sorted.

Will post a general build thread abouth the bike later.