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Installing Pedal Assist Sensor - How far from the sensor should the magnet be?

Posted: May 04 2021 9:14am
by shoangore
I just picked up a MP5 with pedelec along with a 52v Luna battery to replace my borked Tidalforce hub on my Montague Paratrooper. Everything is working right now except for the pedal assist.
I'm wondering how far the sensor has to be from the magnets, and if the magnets have to be perfectly centered with the sensor? For some reason my sensor and the magnets do not line up perfectly - the sensor is set out a few mm further so that the magnets on the disc are a bit off center when passing:
sensmag.jpg
sensmag.jpg (10.03 KiB) Viewed 65 times
Is that the reason why it's not working? The only way I can think of resolving this is drilling the hole that the sensor is sticking through to be larger, then twist it a little so that it is in line with the magnets but wanted to see if that actually would help. The sensor is about 1.5mm away from the magnet disc. I'm pretty sure the disc is installed the right direction, and that the sensor IS working (if I hold a magnet on the disc over the sensor and swipe around in circles, it'll trick the bike into thinking I'm pedaling and the wheel starts spinning)

Re: Installing Pedal Assist Sensor - How far from the sensor should the magnet be?

Posted: May 04 2021 2:31pm
by E-HP
shoangore wrote:
May 04 2021 9:14am
I just picked up a MP5 with pedelec along with a 52v Luna battery to replace my borked Tidalforce hub on my Montague Paratrooper. Everything is working right now except for the pedal assist.
I'm wondering how far the sensor has to be from the magnets, and if the magnets have to be perfectly centered with the sensor? For some reason my sensor and the magnets do not line up perfectly - the sensor is set out a few mm further so that the magnets on the disc are a bit off center when passing:
sensmag.jpg

Is that the reason why it's not working? The only way I can think of resolving this is drilling the hole that the sensor is sticking through to be larger, then twist it a little so that it is in line with the magnets but wanted to see if that actually would help. The sensor is about 1.5mm away from the magnet disc. I'm pretty sure the disc is installed the right direction, and that the sensor IS working (if I hold a magnet on the disc over the sensor and swipe around in circles, it'll trick the bike into thinking I'm pedaling and the wheel starts spinning)
They should line up, They should be as close as possible without rubbing together. You photo is useless for diagnosing the problem, since you can't zoom in enough to see what's going on with your PAS.

Re: Installing Pedal Assist Sensor - How far from the sensor should the magnet be?

Posted: May 04 2021 3:23pm
by shoangore
E-HP wrote:
May 04 2021 2:31pm

They should line up, They should be as close as possible without rubbing together. You photo is useless for diagnosing the problem, since you can't zoom in enough to see what's going on with your PAS.

Whoops, I forgot to upload the photo. This is what it looks like - I did bend the bracket a bit so that it's very close to the magnets now (.5-1mm away at any given point) but it doesn't seem to help any. I did double check the wires and PAS on the screen

Re: Installing Pedal Assist Sensor - How far from the sensor should the magnet be?

Posted: May 04 2021 3:47pm
by E-HP
shoangore wrote:
May 04 2021 3:23pm
E-HP wrote:
May 04 2021 2:31pm

They should line up, They should be as close as possible without rubbing together. You photo is useless for diagnosing the problem, since you can't zoom in enough to see what's going on with your PAS.

Whoops, I forgot to upload the photo. This is what it looks like - I did bend the bracket a bit so that it's very close to the magnets now (.5-1mm away at any given point) but it doesn't seem to help any. I did double check the wires and PAS on the screen
I think the sensor and magnet need to line up better than that. Not sure if you can take off the sensor and carefully bend the bracket so that the sensor can move inward more or not (or take the bracket all together and use hot glue or something like that to attach the sensor so it aligns better).

Re: Installing Pedal Assist Sensor - How far from the sensor should the magnet be?

Posted: May 04 2021 5:16pm
by TommyCat
Did you try turning the crank in reverse... just to check if it works in that direction?

In case you'd like to check for the voltage pulses @ the sensors output.


Image



Regards,
T.C.

Re: Installing Pedal Assist Sensor - How far from the sensor should the magnet be?

Posted: May 04 2021 8:45pm
by shoangore
Thanks for the troubleshooting! I installed it on the gear side of the bike and got it working, problem is it gets in the way of the crank shaft reattaching, so I'll have to modify it or just go completely without.