Paul & Sabrina's cheap DIY 144v motor controller

[Christ]

+2 for a project box or something... you don't want to fry this thing up b/c someone spilled their beer.

Question about the 5-second full throttle - Is that an adjustable feature? B/c I think that as a safety feature on a bike, it's cool, but on a car, as a safety feature for anything other than the electronics, I don't see it being necessary to limit it for that long.. I can understand a pedal sequence lock out though, so you can't "start" the car w/ the pedal depressed (getting throttle signal from the pots), since that would obviously create a very dangerous situation for someone not prepared for such an event to occur.

Just my pair of Lincolns

Great work so far!

[MPaulHolmes]

Hey Christ! Ya, I just made it 5 seconds just for no reason at all. It can be anything. I think you're right. Maybe like 1 second might be plenty. That was an awesome idea about heating the screws and letting them cool inside the LEXAN (oops, was that only for plexiglass?). I'm going to follow your advice if I ever get any of that stuff! Ebay is too expensive right now. I'll look around town like you guys were suggesting.

[MPaulHolmes]

Just this second, I bought 2 new oscilloscope leads that have the 10x voltage feature...

Then I looked over at the lead that I already have, and it has the 10x option! Dang it! Crappola!!! I'm an idiot! If I had a fork right now, I'd jab myself in the eyeball with it.

[Christ]

Well, you can do it with lexan too, but IIRC, polycarbonate lets off fumes that you don't really want to be breathing... and it's very soft as far as polyplastic materials go, so it's quite easy to just use some clear oil (think: WAHL haircutter oil) and a tap, and a little patience with Lexan... Plexi will almost always crack right near the end of the project, b/c you'll slip up thinking you're in the "Home stretch" LOL.

The melting with screws thing is a way to cheap out on something if you can't get Lexan for cheap.

Inversely, if you don't worry too much about weight, you could find a house being remodeled (check craigslist or freecycle as well) for an old breaker box, which you could cover with a single sheet of polycarbonate or plexi.

A friend of mine pointed out that if you use a high-speed drill/driver, and you have a bit for regular (not self tapping) sheet metal screws (just pointed screws, like you use for aluminum down spouts), you can run the driver in reverse and give it some pressure against the plexi, and it will "burn" it's way into the plexi and set there, so that you can extract it later.

Doing this does weaken that spot in the plexi though, by "work hardening" it, which means that spot won't flex any more, and may crack over time from vibration.

On the plus side, if you're using a breaker box or something similar, you only need one sheet of plexi, which you can (very slowly) drill holes through without having to cut threads into it. Once the holes are drilled, use a countersink (again, very slowly) on both sides to lose the sharp edges, so that it's not as prone to crack, and you should be OK with it until you get some Poly... poly or acrylic sheet is definitely what you want in the end though.

Sorry for the long, if not helpful, post.

[Intrigued]

Originally Posted by MPaulHolmes

Just this second, I bought 2 new oscilloscope leads that have the 10x voltage feature...

Then I looked over at the lead that I already have, and it has the 10x option! Dang it! Crappola!!! I'm an idiot! If I had a fork right now, I'd jab myself in the eyeball with it.

LOL! Welcome to the rest of us! It's a BIG BOAT we're in.

Actually, it'll be good to have a couple of extra leads around for WHEN, not IF, you fry one of 'em...

[Christ]

I, personally, am glad that I have a few of many of my tools... considering that I just burned up a $300 MAC Multi-meter a few weeks ago.

Mislabeled wires seem to be a big reason that people get hurt when working with electricity... I took wires that were marked 60DC and tested them on the DC setting, only they were 440VAC contacts in an elevator control box (brake contactors). They were only getting 220VAC, but that still caught my M-Meter, which was expecting to see ~60VDC, on fire.

After consulting the documentation for that particular elevator control, I found out that the 60DC line is a SINGLE WIRE CONNECTION that runs WITH the 440VAC bundle... it's a computer controlled line that switches the E-brake contactor in case of a voltage fault, to stop the elevator and ring for help.

Gee. I love elevator techs. Better yet, I love knowing enough to wear protective equipment even when you're working with something that (if labeled correctly) wouldn't be able to hurt you at all. Better safe than sorry, I guess.

Damn for the $300 I lost though... someone's getting billed for that one.

[MPaulHolmes]

Man, I'm glad you weren't hurt. My multimeter is $2.99. I wish I had a $300 one!

[Christ]

Yeah, better the tool than me. I liked that tool though. *moment of silence* LOL.

[MPaulHolmes]

I finally figured out how to use the STK500 as an in system programmer (ISP). So, I can add a 6 pin plug on the outside of the controller so that the microcontroller can be reprogrammed while leaving it "in system" (hence ISP). So, you can even make it possible for other people to program their own controller with the features that they want, like ramp up time, current limit, etc... Like if you know you are going to drag race for just a little while, you could set the current limit really high, or if you want to go for long range, you could set the rampup to be long, and the current limit to be low.

[Christ]

For the rest of the world's understanding - The EV equivalent to "tune on the fly".

LOL.

Sorry, had to. :P

So does that mean you can just leave an interface hooked to it, like a laptop or a PDA on the passenger seat w/ the wire hooked to adjust it on the fly in real time? Or will you have to actually flash the controller each time you want to change a parameter?

Would be cool if you could just feed tweaks w/o flashing entirely... like a RAM memory setup, although that would be dumped on each shutdown, so it's probably not feasible.