Need LOTS OF help with an upgrade I've ben working on.

[Mcmattwich]

So I agreed to help upgrade a bike I was contracted to build a battery for. I have built my own bikes, so the required controller upgrade (was going for a higher voltage battery so was necessary) seemed straightforward enough. But it's been an array of problems since . Here are the stats as I know them:

1. Bike is sondors original fat tire, 750w motor upgrade done prior to me

2. Had kt 52v controller originally with lcd3

3. Now running 62.9v battery, with a controller by NB power on amazon, 72v 40 amp, there's no number on it, but it says DC moto by lithium power on it. Sw900 screen


Problems

1. On take off from a dead start with throttle, or high level PAS, the motor wants to make a grinding noise. I'm guessing too high of an amperage, however, setting p14 on the display is not letting me change it.

2. The speedometer is wayyyyyy off. Like it's showing 62mph at a trot.

Please help. I'm extremely handy if any physical changes need to be made to the controller, but I've had this thing for a while. He's patient, but I don't want to be that guy that failed to accomplish something I was supposed to be good at, I've never had this much trouble with any build or upgrade in my life. And it seems like simple stuff

 

[Mcmattwich]

Not at all! I'm so impressed by the responsiveness here, I have always looked at es posts that were posed to answer questions I had, I figured the ones with such outpour were outliers and there were endless amounts of unanswered desperate bastards that went unnoticed. First post though and I've gotten all the angles.

Hey speaking of which anyone know anything on the speedo? The motor has a white speed wire, however neither the controller nor the display has an input for it. Im hoping it evens out adjusting the wheel size, but with it already set at 26 I'm not too hopeful that's all the problem

 

[E-HP]

Not at all! I'm so impressed by the responsiveness here, I have always looked at es posts that were posed to answer questions I had, I figured the ones with such outpour were outliers and there were endless amounts of unanswered desperate bastards that went unnoticed. First post though and I've gotten all the angles.

Hey speaking of which anyone know anything on the speedo? The motor has a white speed wire, however neither the controller nor the display has an input for it. Im hoping it evens out adjusting the wheel size, but with it already set at 26 I'm not too hopeful that's all the problem

I believe in most cases, the controller MCU takes pulses from one of the hall sensors, and uses the wheel diameter and motor characteristics you set through the display, to compute the speed (and send the result to the display). If the controller has an option of connecting an external sensor (the type with a spoke magnet, and sensor attached to the frame), then the controller will use that (parameters also set through the display). The downside of the former, if you have a geared hub, is that it won't display speed when the motor is coasting, since there is not hall sensor pulse. It will show speed only when the motor is powered. That's why for geared hubs, an external sensor is the best option.

 

[Mcmattwich]

Yeah there's no sensor wire. But it adjusts quite a bit, by .1 of an inch at a time on the wheel. He won't care if the wheel size is set wrong if it makes the speedo right