Motor Controllers Autopsy And Analysis

What The Hell Has Been Going On Here?

Motor Controllers Autopsy And Analysis

I mean really, its been four months. Thats not cool. Which means now I get to try to sum up a whole lot of things in as few words as possible. This should be interesting.

ChipiKart

I did finish it.

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See? It even ended up looking somewhat presentable with the Mercedes 300SL body on it. I ended up using 120A Kelly controllers on it, as the hacked jasontrollers just werent cutting it. I regret nothing. Proper controllers are a thing of beauty.

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With it being a racing power wheel and all, I raced it. The crowds really enjoyed that something with really tiny wheels could go so fast. Unfortunately, I started hitting some serious problems.

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During qualifying at Kansas City Maker Faire, my right motor committed suicide. On hard acceleration out of the first corner, the shaft twisted so hard that it snapped itself off inside the motor. I disconnected it and raced on one-wheel drive, which was disappointing. With both motors, I had qualified third overall against some much larger and more powerful cars. Chipikart had some potential.

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Unfortunately, realizing that potential was not meant to be. During the races at Detroit Maker Faire, the body was completely destroyed and both of my sensor boards were severely damaged. No good. But I brought it out to New York and raced there anyway. And there, Chipikart met its ultimate demise when the rear and was completely run over by a larger car. Both motors were internally shorting, and the sensors were gone. Chipikart was no more.

But it was a lot of fun, and a learned a lot along the way,  so its not really a loss. I got some fantastic batteries and controllers to re-use in the future. I found out that by putting 3600W to each rear wheel, I can wear down a set of colsons to the hard plastic core in just under 25 minutes. And I think I set a couple power wheels drift records. But most of all, I built a chibikart for $435, which is almost exactly 1/3 the cost of the original. And thats pretty cool. Now that Im not racing, Im going to finally finish putting together all the drawings. Probably.

 Real Cars

I bought one.

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Its a 1987 BMW 535i, and it has quite a colorful past. Im not going to dwell on it too long, since you can read about it here. I document some of the more entertaining repairs here. You should check it out.

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Oh, and I autocross it. Because its loud, slow, entertaining, and also because body roll.

Design

Ill leave you with a taste of things to come now that I have time to write about them.

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This is a limited-slip differential, sized to fit in a power wheel. Its 3.25 in diameter, 3 wide, and weighs 2.5lb. More on this soon, because Im away from tools for the next few months and so all I have is CAD. This is going to get interesting.

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