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-   -   Ben's "Cougar" ReVolt Controller (

bennelson 02-22-2010 01:59 PM

Ben's "Cougar" ReVolt Controller
Hi everyone,

I thought I would separate out a dedicated thread from my Electro-Metro information for just my experiences with the "Cougar" - the very first ReVolt Open Source EV Controller.

This controller was the one originally constructed by MPaulHolmes.
He built it, then tested it in his EV SuperBug at 72V. That was spring of 2009. He then sent it to me to test at higher voltages, to "test until destruction", which only took me about 4 days. Once I found a design flaw, I mailed it back to Paul for design improvements and repair.

For a number of reasons, I didn't end up getting the controller back until the fall, but it did now come with a cool "Contactor Control" lead - the magic yellow wire that makes the car that much more automated by having the ReVolt run the main contactor and pre-charge for me.

The other super-cool new feature available was the RTD Explorer software, designed by Adam. With a laptop computer, I could now see and graph information directly from the controller. Amperage, pedal position, PWM, and other vital intel could be graphed and saved for later analysis.

Unfortunately, this also got me in trouble.
I managed to get a "tablet" pc, which I thought would be perfect to run as an in-car display, directly connected to the controller. Unfortunately, I didn't realize that the way the power was rigged to the tablet pc meant that the RS232 port (which carries power! I didn't know that!) pushed a little too much voltage into the logic board of the controller!

Poof! The controller stopped working. Thank goodness no magic smoke was let out! All damage was confined to the logic board. Too bad I am not so good at troubleshooting electronics! Paul tried helping me do a bit, but in the end, it just seemed easier to build a new board.

So, that brings you up to the present time - me building a new logic board for the Cougar. The really weird part is that the PDF file of how to build to controller is photographs of THIS controller! It's a very strange form of DejaVu.

Here's a little video of what I did just the other day.

MPaulHolmes 02-26-2010 12:28 PM

Go Ben Go! Now you see why I innocently suggested mailing you the bag of control board parts and bare control board. IT takes forever soldering that dang thing! hahaha

bennelson 03-07-2010 10:22 PM

Finally! I got the controller up and running again.

I am much better as an EV test pilot than an electronics assembler....

Today, I finally got the whole thing put back together, but still couldn't figure out why the error light was going crazy. I called and pestered Adam, and he helped me connect to the computer and find the error code indicating the current sensor. Turns out the current sensor blew out when the logic board went.

The bad news, it's almost a $30 part!

The good news? My buddy Chris had one right there that I stole, ahem, BORROWED.

It plugged right in, and BAM! The controller worked!

Once it was working right, I threw it on our official EV Club controller tester.
Although, with the tiny test motor, it was more of a "meow" than a Cougar roar!

I still have to get the whole thing back in the car.
Oh, and I spilled coffee on it on the way home. Is that bad?

MPaulHolmes 03-07-2010 10:27 PM

Ben, is that the LEM 500 or LEM 300? I think it might be the LEM 500. Don't drive it! It will have VERY high current. I don't know what would happen. Like 800 amps or something I think.

bennelson 03-07-2010 11:11 PM

More POWER!!! ARrr ARR ARRrrr.

I know I still would need to tweak the software no matter what anyways, so it's not like I was going to just throw it in the car and go.

Mostly, I just needed a working current sensor. I didn't realize that it was maybe a little different.

Tom had a couple of current sensors around, but none of them were big enough to fit around the bus bar!

jyanof 03-23-2010 05:49 PM


Originally Posted by MPaulHolmes (Post 164877)
Don't drive it! It will have VERY high current. I don't know what would happen.

hehe, there's only one to find out... i know i'm curious :p

But, glad to hear the controller is working again and that you're almost back on the road.

bennelson 03-23-2010 06:26 PM

I got a new "correct" current sensor from Paul, and installed it.

The controller is now mounted in the car, and working properly, although I haven't done any reprogramming of the controller yet.

I still need to tweak the controller, and program it to run the main contactor again.

MPaulHolmes 03-23-2010 06:52 PM

It's working?! What was the problem?!

bennelson 03-23-2010 07:11 PM


Originally Posted by MPaulHolmes (Post 167376)
It's working?! What was the problem?!

I don't know. I think something weird was going on with the charger or batteries.

I still have some more work I have to do on the car, tweaking it, cleaning a few things up, etc.

I would like to make a "Build Your Own Electric Car" instructional DVD, but I would like the car to look half-decent first!

bennelson 04-11-2010 09:39 PM

I played with my controller a bit today.

I am not sure why it was acting weird on me.

I now have a new Serial to USB adapter, so I could hook it up to the tablet computer again.

I re-hooked up the main contactor to run from the Cougar controller. There have been a few times when the contactor wouldn't pop down. I think it might need rebuilding, or it may be that my car battery is running a bit low, and has exactly not enough voltage every once in a while to pop the contactor down.

If I just tap it, it pops right down.

I adjuste the Ki and Kp settings on the controller and got my acceleration a little more smooth and even. I also set the amp limiting all the way up. I can spin the tires in first again!

Also, I now have just over 2000 miles since electric conversion!

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