Power Wheels Racer 2.0: Update 2

This week in the workshop we focused on the electronics for the electric kart. After spending over a week trying to diagnose and fix whatever caused our first ESC to not work we decided to purchase another unit (Link here: https://www.amazon.com/dp/B00DB0DNO6/). Once it was here I referred to the wiring diagram supplied by the seller for the hookup guide.

To save time and stop me from cutting wires unnecessarily I decided to take advantage of the standard ring terminals used on the ESC. I cut off the connectors I had already soldered on the old esc and crimped on ring terminals on the ends. It looks a tad messy, but everything is secure and protected from potential shorts. Additionally, all this wiring is temporary and once everything finds its final mounting position on the frame.

With everything wired up and plugged into our new (old) 48v battery pack I attached a spare throttle from last years build. Unfortunately, it didn’t work. I started checking voltages on the throttle and noticed it was seemingly stuck at full throttle, so I removed it and tried another spare and that worked fine. The motor spins and seems to be functioning perfectly. I’ll need to use the built-in calibration to program the ESC but that’ll wait until we select a final throttle mechanism and get the frame mocked together. I was curious about the speed of rotation, so I quickly made a 3D printable part to attach to the motor shaft.

The idea here was to film the piece rotating with my phone’s 240fps slow motion video and then go frame by frame until one rotation had passed and the calculate the RPM based on that. Once I took the video I found that even at 240fps the motor spun much too quickly for my camera to clearly discern a single rotation. Even still I estimated that the motor was spinning at about 2800 RPM which is much too high, and I don’t think it is at all accurate.

Next steps for the car will be to finish welding up the frame and mount the electronics in their final positions and get the steering built. Once that’s through and we will be discussing the body of the car which will be made of fiberglass.


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