I'd spent the week assembling bits and pieces, soldering and crimping, fixing things and getting things running. I managed, somehow, to avoid frying the DC-DC converter supplying the 12V power for the controller and contactor after connecting its 12V leads to the 130V battery. I checked everything with a multimeter. I ran through every possible combination of wires and, on the very last possible sensible combination got the motor turning over without sounding like it was trying to chew up a cheese grater. I uploaded a video at the time. It was still sounding a bit odd and the controlle was occasionally cutting out when I backed off the throttle, so I got a friend with an oscilloscope to come over and have a look at the signal. I also layed out the controller flat on the table, which meant I could get the power wires straight rather than crossing over eachother. We fired up the motor on Friday and had it running for five minutes or so. The waveform looked OK, but since neither of us really knew what a bad or good waveform looked like it was somewhat moot.
At this point we noticed the cheap plastic caps that came with the lugs that I'd bought for the power leads were melting. Then the solder in the power wires started melting (why they put solder into the wires is beyond me). I went and got my thermometer cable for the multimeter and determined that the power wires were sitting at about 70°C! And that was only running for five minutes! This raises all sorts of questions.
Anyway, I decided to get a better video than the previous one. Armed with the knowledge that my phone had a high-definition video camera, I tried taking videos with that. Kate suggested putting light on the motor so you could see it moving rather than just a dark blob. I tried my other video camera, a ContourHD unit that I bought for attaching to the front of the bike, on helmets, and so forth - but the field of view is too wide and the sound is pitiful. And in a burst of idiocy I deleted the good video and kept the eight second out-take. (As strange as it may seem, these weren't excuses to start the motor up again.)
So now that I've got the video uploading away I thought I'd write this update. I should feel happier - a major milestone has been passed, and theory has turned into practice. But the major work now is to try and get a battery frame welded up on the bike; I want to use a professional metal fabricator for that. That has to go past the engineer to get his approval. Then I have to get all the batteries, controller, contactor and other parts actually in it, and attach all the cables. Then I have to get the 12V system working. Then I might be ready to actually run it down the street.
So it still feels a long way off. And I'd like to get the bike at least running in some fashion for the first practice event of the TTXGP at Wakefield Park near Goulburn at the end of April. And there's that cable heating problem to watch, or better yet fix. And how does one register an electric motorbike anyway? It still feels like a long way to go.
Here's the 'better' video:
All posts licensed under the CC-BY-NC license. Author Paul Wayper.