Paul & Sabrina's cheap DIY 144v motor controller

[MPaulHolmes]

I just sent e-mails mails to those who purchased from us that they will be getting tax refunds in the mail...

-Sabrina

p.s.
If you went through the store and I missed you just let me know.

[MPaulHolmes]

http://www.youtube.com/watch?v=M1X68Zvm79o

ya. Not wood this time! hahaha

[squiggles]

Very nice, but I did not see it sign the artwork "The Cougar", how will anyone know it is the genuine article

[MPaulHolmes]

that would put me over the 500 lines of gcode limit on the free version of Mach 3!

[squiggles]

Did anyone consider diodes packaged like these
http://ixdev.ixys.com/DataSheet/L578.pdf
Could save a bit of space in the layout and a lot of soldering.

[Intrigued]

Originally Posted by MPaulHolmes

Lou,

I took the tax option off the store site. Having not done something like this before, I'm not a tax expert. I just took the advice of someone else who seemed to know tax stuff and was trying my best to be lawful.

Sorry about all the trouble. If you notice any other problems with the site please let me know.

sabrina@paulandsabrinasevstuff.com

I check that often, so I could fix things right away if you send something that way.

Thanks.

-Sabrina

Hey guys, according to a lawyer who was one of my Business instructors at the university, the online tax issue is going to be a real sticky one. The only sales tax for sure is in-state, depending upon which state you are from, but there is a lot of goings-on right now from state-to-state, and also a push nationally to just require the tax online - period. I didn't think to ask whether a business would need to charge home state or buyer state taxes...

The problem is, many states and the Fed are losing a lot of sales tax money online that would have normally gone into the coffers. A lot of money that they are thinking of finding other (tax) ways to get if they can't get the online tax money...

[jyanof]

Originally Posted by TheSGC

A feature that I would like to see on the Revolt is a current sensor on the battery side so you can limit the battery current to keep the abuse low on the floodies. Maybe it can be done in the software, but a hardware limit would be nice.

Figuring out the battery current should be pretty easy in software. Since we're measuring motor current and we know what the PWM duty cycle is, battery current will be motorcurrent*PWMduty (where PWMduty is from 0 to 1).

That won't include any accessories you have pulling amps from the battery, but anything else would likely add up to just a couple amps and will be just noise among the 100's of amps going to the controller.

It would be pretty easy to code up a software limit for battery current. I might suggest tripping an alarm or something instead of hard limiting - sometimes you need the power, ya know?

As an aside, I've noticed that it's really easy to hold the battery current constant depending how you set up the throttle response. The way mine behaves right now, I can pretty much step on the throttle halfway and the battery amps peg at about 200A and'll stay there all the way up to 45 mph without hardly changing throttle position.

[MPaulHolmes]

Hey LouMan! It does have a diagnostic output from time to time. What I mean by that is that one of the software versions does do that. The software is there for outputting data. Right now, I guess I could have it cycle through sending temperature, current, and throttle. There isn't much else to send at this point. I don't have a practice controller right now, so the software that would be sent right this second would just be a basic one that doesn't send data, since that's the code that I know works just fine. As soon as I start changing code without driving it, I can't know for sure that I messed up on some tiny thing.

So, if anyone wants the data output, they would have to wait a few weeks for the microcontroller, since I'll have a controller done by then, and I can test the software again.

By the way, Joe had his first microcontroller latchup at 16 MHz, where he had to turn the car off and then on again. It happened under particularly hard acceleration. Fortunately, we have a very good idea how to fix it. Basically, I've ordered some schottky diodes that should deal with it. They need to be added to the control board. It's not a hard thing at all, and very cheap. I think adding them to the throttle input and possibly the temperature A/D and current input should take care of it. Also, I may slow the ramp rate just a hair, since the problem is related to rate of change of current.

[drbobwoolery]

Paul, I have a B&K 1472c oscilloscope I have no current need for. If you want it, I'll ship it. I have a Fluke 97 and a dinosaur Tektronix 547 with 4 trace preamp, so this (inherited) scope is spare.
Re: liquid cooling. X-ray tubes and HV circuits are filled with transformer oil. I bought 5 gallons of Shell Diala AX (for $20),15 years ago, and use it to refill any such I open up.

There was one mention of Alumox. Please use it between the copper heat spreader and any aluminum parts. Both corrosion and heat transfer should improve.

I'll shut up now, and resume reading at post 1541. Don't try to edit this forum thread, as it is a joy to read. If a noobie cannot enjoy Moby Dick, read the Classics Illustrated comic book and go on.

bob (drbob at comcast dot net)

[MPaulHolmes]

FIRST, IF ANYONE HAS BOUGHT THE CONTROL BOARD BILL OF MATERIALS FROM THE WIKI, IT HAD A MISTAKE IN IT. R16 SHOULD BE 3K AND NOT 1K. I FIXED THE BOM TO REFLECT THIS CHANGE.

I'm going to triple check the other parts too. The circuit actually works with the rest of the stuff how it is, but I want to make sure it is all right anyway.

Hey Bob! My oscilloscope is working again. It is a little flickery sometimes, but I like the sense of danger of living on the edge!