It comes! And goes. And comes again!

Wednesday, August 15th, 2007 @ 0:52 | Project Build Reports, Snuffles

What an exciting day. The ginormous brushless controller arrived from Hong Kong today, and it is ginormous indeed. In fact, it’s bigger than I had planned for, warranting a slight on-the-fly redesign of some of the structure. It also turned out to be quite troublesome – in that whichever sweatshop worker in Southeastern China assembled it was sufficiently drunk at the time to reverse the power input wires.. that is, red to – and black to +. This led to quite a harrowing adventure where I just barely manage to tie down the controller’s white, poofy soul.

And also some mechanical work.

It's actually backwards from the original installation. But before that, here’s a shot of the beginnings of the instrument pod. I reused the orignal controller casing because by some strange cosmic alignment, the guts of a 80 amp relay slips perfectly into the space previously occupied by the stock motor controller. This also means I saved one more long wiring run to get to the power meter, which is now right next to it. The meter itself, with no mounting holes, will probably be tape-welded to the controller box.

And by tape-welding I mean gray 3M outdoor mounting tape. It can hold up the universe.

Ooooh, shiny. Really shiny. And here it is. The 100 amp, 12-lithium cell (44v) brushless controller, along with a handy programming card. I tried listening to BESC morse code once before and vowed never to do it again, and this programmer lets me select parameters and tune the controller as needed.

Ignore the crossed wires. Testing the rig on the table, using a small outrunner. This was AFTER almost losing the controller to reverse-polarity shorting. How did that happen?

Notice the wires between the meter and controller are crossed, and obviously wrong in color, and not matching the label. But that’s actually the correct way – before I switched them, of course. The first test of the controller, using a small lithium polymer battery (Not the giant SLA seen here) resulted in the controller dead-shorting the battery. This was strange. Next, it tried to dead-short the 12v SLA (thank goodness small test cables saved it) and a 12 volt power supply before releasing a little poof of smoke.

Uh oh. I fired off a support email to United Hobbies asking if it might be a DOA. With nameless stuff, I gave it an extra chance of that being the case. Then I looked at the bottom label a bit closer and discover something horribly wrong – the wires were switched. Now, me being used to red = positive and black = negative, ignored this once-over inspection, so it very well could have been my own fault, but it could have happened to anyone.

So I carefully reversed the wires and tried again. It would struggle a bit, beep the motor, but would heat up intensely and not start the motor. Figuring it was toast anyway, I cracked it open and noticed only one bank of transistors was cooked. The controller uses all (48) of the same transistor, so I carefully plucked the tiny, surface mount chips from the other legs and replaced the burnt ones.

And that was how Charles saved the day. Sort of. The controller works, but might as well be a 60 or 70 amp one, with a few transistors missing. But at least it’s something. That will not spare UH, however, as I still intend to prod them about this…slight mix-up.

It's not that exciting yet... After calibrating and making sure nothing else would smoke on power, I moved the test to the floor and tested all systems. The result is that all systems are functional – including the awesome controller controller! I was surprised such a contraption could fool an advanced electronic device. 12 volts wasn’t too exciting on the motor…

Now it's REALLY fun! … but the full 28 cells was. I was worried about rotor balance from the start, but the increased voltage makes it much worse. I had to hold the thing down to prevent it from vibrating across the floor.

Written off as increased appeal to the opposite gender.

I would mill a cool pattern into this, but actually having a mill would help with that. Here are some mechanical bits. This is the left side “armor plate” and mounting surface for the electronics. This was my only slab of 2.5″ wide aluminum, so I’ll need to get more before work can continue on the right side. They will be secured to the scooter frame by standoffs and bolts.

I'd tap that. Wait, I just did. The scooter does not fit in my drill press. Nor most drill presses, actually, so I did alot of the work by hand drill and careful eyeballing. It worked pretty well. The aluminum used in the frame is a soft and rather gummy one, and it threaded like absolute misery. Fortunately I don’t have to do too many holes on it. Wide shot is not for close-ups.

Let's play 'Guess the function of the black box'! I’m a terrible photographer, but this isn’t an art site. The ESC, with mounting ears, will be bolted to the frame. The CCFL power supply will most likely be tape-welded, as it is flat and light. Conveniently enough, the motor wires and controller wires are just long enough to meet and be soldered together in the middle, and be restrained to a standoff.

If only I had 2 inch hole cutters. One side plate installed. Standoffs are a bit too long for my taste, so I might get shorter ones. The other side plate will have a big circle thing cut out of it to account for the motor. They will be joined at the back by a UHMW skid plate, for slipperyness. Looks like wheelie-bar mounting isn’t too promising, so it might be left out. ESC and CCFL driver goes on the left side, controller-controller and power distribution on the right. Main switch and power meter by the handlebars, and the throttle will be designed and implemented as needed (Or I can just hold the little dial in my hand and fiddle with it while cruising…)

Home stretch! One more week! I really should be doing more productive things, but this is more fun.




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  • Operation RESTORING BROWN Episode VI: Return of the Van Lights; the Conclusion
  • Late Stage #PostmodernRobotics: Welcome to Your Waifu is Trash, the Robot Dumpster Fire

    One Response to “It comes! And goes. And comes again!”

    1. Roger Sandstrom Says:

      Hi! great project you are putting together i hope it will be running soon,
      interesting to see what kind of performance data it will produce.
      If there are any errors in the text i am sorry, but my excuse is that i am
      from SWEDEN.