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Pedal assist cutting out

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I just received a new KT LCD8H, and hooked it up with the new 35 amp controller I have. The pedal assist kicks on and off for no apparent reason. It will do it at any speed, so it's not a speed governor issue. The pedal assist will only work for about one second at a time and give me a burst of power and then cut off every couple of seconds. Is anybody know what could cause this, or how it could be fixed?

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I bought the LCD from eBay, and the controller from Bolton eBikes. I have narrowed down that the LCD is not the problem though. I unplugged it and put the little cap back on that came with the stock bike on the LCD outlet from the controller side. So even bypassing the LCD, the problem remains. The magnet looks to be lined up correctly, but I'm not exactly sure how I would know for sure. Comparing it to my wife's Sondors that works correctly, everything looks like it's on there properly. (Mine is the black one and hers is the white one)



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I wouldn't have imagined compatibility between the controller and screen being an issue, since The KT screen and KT controller combo is pretty common, and there are very little Sondors original factory electronics left on the bike. I've changed the motor to a 750 watt motor, changed the controller to a 35 amp, changed the battery to 52 volt, added aftermarket LCD, and I'm about to upgrade the brakes to Shimano hydraulic brakes. The bikes don't even look much like Sondors bikes anymore 

Thank you for the help though. It definitely will give me an idea of how to proceed from here to get the pedal assist working again.




Edited by Josh Davis
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Thank you for the help. I'm sorry if I left out any pertinent information. I only said what I thought was relevant, but I see what you're saying. I bought the display new from a seller who ships directly from China. That was definitely a mistake, since it did not come with the proper connections to match the controller. I had to buy an extension cable to make it work, but it was still not long enough to reach, which is why that wire is run right down the middle of the bike, which I hate. if I had to do it over again, I would have ordered the screen from the same place I bought the controller, and it would have saved me a lot of frustration. I have not noticed any damage to the wires right now though. The larger batteries and controllers wouldn't fit in the plastic boxes, which is why they were removed.

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  • 8 months later...
1 minute ago, Reddy Kilowatt said:

My 52v 17.5 & 20 Ah batteries and 35A controller fit quite nicely in the Sondors Triangle Battery box. My 52v 14.5 rectangle battery fits underneath my rear rack. The value of this forum, is mostly the vast amount of information and data it contains. The best way to use it is to explore its content. 


I originally had everything stuffed in the battery box, but it was not ideal for me for multiple reasons. Partially because I couldn't get it to stop rattling around the box when off roading. And also because my aftermarket battery had the charging port on the wrong side.

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4 minutes ago, Reddy Kilowatt said:

So in other words, you bought an incompatible battery to work effectively with your Original Sondors.  The exact point of my previous post in this thread,  on how to use this forum. 



Yeah, I guess so. Thanks by the way, for helping me with the pedal assist issue a while back. I did not realize the magnet sensor could slide around like that.

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  • 4 months later...

The PAS on my wife's Smart Step was cutting in and out.  Sondors sent a new controller and same problem existed.  I cleaned the inside of the magnetic pickup ring with WD40 and problem is gone.  Think it was way dirty as we ride  lot of back dirt roads.  Carry an old rag in your bag to clean the magnet wheel and sensor if you have a similar problem.  Michael 

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  • 2 months later...

More likely, the mag wheel was more than the thickness of two business cards from the pick up, which is recommended. Mine has to be actually touching the pick up and I use a light coat of  clear silicone on the crank axel to keep  more securely in place. The flexible tabs on the mag wheels do wear and get less stable. I’m on my 3rd PAS unit.  Although WD40 is not sold as a lubricant (Water Displacement formulation 40) it does contain petroleum distillates and can cause the disc to slide on the axel.  

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