Paul & Sabrina's cheap DIY 144v motor controller

[MPaulHolmes]

Originally Posted by Christ

By the way, the exact posting background color code is #F5F5FF, for anyone interested. I hate reading page source.

Thanks Christ! It was nice to read it how I meant to post it. Yep, it's C/C++. Some of it is sort of obscure. Especially the weird crap about making the microcontroller do stuff. That was a few weeks of anger trying to wade through that stupid 300 page ATMega8 documentation. I still want to give a peanut butter and karate-chop sandwich to whoever wrote/designed those dang micro-controllers.

[tech2]

Originally Posted by MPaulHolmes

I think that would work! Awesome idea! It would look way cooler than a tachometer too! I'm going to try that.

I have saved a lot of "techie" stuff over the years working in a related field, so if you are looking for anything related to parts to experiment with, PM me, and if I have it, or can find it, I'll try to help ya out.

[MPaulHolmes]

Thank you! I see you have 3 posts! Welcome to Ecomodder! It's really an amazing community of people with a wide range of abilities. We would have never successfully completed our electric car without the help of the people on here (drilling the dang aluminum using rubbing alcohol comes to mind!).

[tech2]

Hey paul,
I was just sitting here skimm-reading and thinking, (I haven't had enough time to read the entire post), and I saw where you referred to being parked uphill, and flooring the accelerator,...blah...blah.... CONTROLLER IS NOW ON FIRE!!
This made me wonder, why does everyone use a standard tranny?
I want to use a small vehicle like a metro, (or smaller if there is one available to me!), with an automatic tranny, and a forklift main drive motor, and I have always wanted to find a way to re-program a controller so that the massive current isn't being introduced there every time you stop at a red light, then start off again in city driving conditions. I had planned on adding a large flywheel approximately 3 inches thick, for inertia to keep the motor spinning just like an internal combustion engine would, and not use deceleration braking on the controller, just let it free-roll along at an "idle" when you slowed down, and the only time it would be completely off would be when the main contactor was released (key switched off). In other words... when you turned the key on, the motor would gradually ramp up to an "idle" state, and you would be ready to drive off just like you had an internal combustion engine. The rest of the controller would be similar to what your are doing here for control. I have kicked this idea around for years, and wonder what you and other readers may think.

// sorry if I hijacked your post, blame it on me being a "newbie" here.

Bye the way..... you are doing a heck of a job on this project!!

later

[tech2]

5 now.... and thanx!

[MPaulHolmes]

That's a very interesting idea. If I understand right, you could keep the motor spinning at it's optimal rpm, and use it to keep the flywheel spinning, and when you need acceleration, take the energy stored in the flywheel. This sounds very intriguing! I hope you try it! Make sure you document your process and results! That's very original. I like that idea.

[Intrigued]

Originally Posted by tech2

This made me wonder, why does everyone use a standard tranny?

Hey, that is a pretty neat idea: using a heavy flywheel. We'll have to see if anyone with experience can punch holes in the theory. It would be a breakthrough if it worked!

The reason so many have stayed away from automatics is that you lose up to 15% of your efficiency to the torque convertor, which just sits there and turns the energy into heat when not locked up. There is such a delicate balance between carrying enough batteries to get any range versus being able to make the car able to carry all of the weight versus getting any speed out of the thing...etc that most folks just try to find a standard tranny.

Some of the automatic guys just connect directly to their input shaft - no flywheel or torque convertor. Saves weight to help with the balance of weight/power/speed that way, too.

Many guys with rear-wheel drive rigs just adapt the motor directly to the driveshaft, and save more weight that way, but it's pretty well a given that you'll have to run the higher voltages and amperages to be able to take off.

It'll take a month of Sundays to go through them, but there are three threads here of folks who have done just what you're thinking of doing. Here is the link to the three. You'll learn a lot!

[Intrigued]

Oh, yes! Welcome, Tech2! Your screen name reminds me of the two GM scan tools I have managed to keep around the old hacienda.

Hey Paul! I just thought of a joke I heard in COBOL class (hey, I said OLD ASE tech...) that I bet you can finish...

"There are only 10 kinds of people in the world: those who understand binary notation,..."

(fill in the blanks!)

[MPaulHolmes]

AND THOSE THAT DON'T! (10 is 2) hehe.

[MazdaMatt]

Paul,

Due to the differences in processors and the availability to different users, what do you think of the concept of a "drive board" seperate from the "control board"? Ie, what if there was a board that had an input of logic-gnd, logic-5v, pwm signal, battery pack ground, battery source voltage and an output of motor terminals and 0-5V current sense and temperature sense?

This way, the controller could use any method of control on any digital platform for any skill level or accessability of designer... that is "black box" the left and right halves of your schematic so they can be built independantly.