Bike repair and improvements

So, after testing the bike for a few trial runs it stopped working. Connecting to the controller I got an error saying “Post static gate test” which usually means there’s a problem with the controller having a mosfet fused to ground or the postitive terminal.

So, a bit displeased I started taking the bike apart but before putting in an RMA I decided to test another controller I’ve got sitting around, and got the same error with that one.. so, the problem seemed to be with the motor, which was a bit wierd. Connecting my second motor to the controller confirmed that the motor was the issue since it ran without any problems.

After doing some measuring I was a bit confounded as all the resistances seemed to check out and sure enough when I connected the motor windings to the controller it all worked. However, when I connected the hall sensor array it stopped working again.. Hmm..

I just had to take the motor apart to find out what’s wrong with it, and on opening it up I found a bit of water inside that’s not supposed to be there. After drying the motor the error on the controller disappeared again and everything seems fine.. although, where the motor sits on the bike, just in front of the rear wheel, I’ll need to make sure water cannot get into the motor. Even though I’m adding all kinds of fenders the motor is going to be suscepted to moisture and water..

Taking the motor apart the seal that sits between the stator casing and the end bells on the motor crumbled to dust which is probably why the water got in there in the first place.

I decided to take the motor apart properly to check for damages and it turns out there was none. Getting the rotor out of the stator was insanely hard though as the magnets in the rotor is immensely powerful on this motor!

If you get your fingers caught between the stator casing and the end bell on the motor I guess you’d have to leave your fingertips inside the motor. I’m not looking forward to putting it back together again.. I’ll have to come up with some contraption to make it not slam back cause I reckon that’d make the motor self destruct and take half of the garage, both my hands and my left liver with it as it goes…

As I had the motor apart I thought I’d add a thermistor to be able to have the controller reduce power if the motor gets too warm. The Lightningrods motors come with a thermistor if you ask Mike to install one, which I happeded to forget..

The normal way of adding a thermistor is to make a hole in the case and route a cable from the thermistor to the controller through there but I didn’t like the idea of adding another cable to the motor. Two is enough I think. So I instead opted to replace the 5 lead cable that goes to the motor originally with a 6 lead cable instead. To be able to fit the larger cable I had to make a new grommet for the motor casing though.

Fist a bit of CAD, and then I printed it from solid TPU.
Turned out OK and pushing the cable into the grommet was SUPER hard, so it’s a tight fit.
The grommet is a great fit in the motor too so it should make a good seal. I cut the original cable and soldered and insulated the new cable to the old, matching the colors as good as I could.
I also soldered the thermistor between the negative lead and the new brown lead (colors for future reference by me) and went on with tidying everything up.
I used epoxy to secure the thermistor to the motor as close to the rotor as I could and tucked all the wires away neatly. Taking some measurements everything seems to be in working order so the last step was to add molex crimp terminals to the other side of the added cable to fit the 6 pole connector for the controller.
All done for now. Tomorrow I’ll try to get the rotor back inside the motor. I’ll add liquid seal to the end bells before putting it all together again hopefully keeping the water outside the motor for the future.

Taking the motor apart I saw that the conformal coating on the hall sensor PCB was missing in part, probably allowing the problem to occur in the first place. I used epoxy to cover the PCB to hopefully make the motor more resilient to failure in the future even though some moisture might get inside.

Well, to be continued..

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