Ben Nelson's Electro-Metro Build thread - Page 126 - Fuel Economy, Hypermiling, EcoModding News and Forum

Russ · 09-30-2009, 09:02 PM

Ok does someone have a nice primier on "battery group"?
Even just another thread?

I found a knowledge gap that I need to fill.

Thanks,
Russ

Daox · 09-30-2009, 09:07 PM

A battery group is just a standard for the physical size of a battery. A group 24 usually has a capacity of 70-85 Ah.

MPaulHolmes · 09-30-2009, 11:19 PM

Hi Ben! One thing you could change is use metal end caps with rubber grommets. I also can't remember if I used R15 = 220 and R16 = 6.8 kOhm. If that one guy is handy, you could ask him to check to see if they are what they should be. A consequence of using the older values of 330 and 3 kOhm could be radio interference. I had a talk with Fran about that about a week ago. hehe.

Also, there is a tiny code change that should happen because maybe the code was causing what I thought was latchup of the microcontroller. I think Joe already has a fix on his. It only comes up occationally under very hard acceleration.

Fran is helping out with making the code better, so I think I'll wait a little bit before shipping out a new micro, but I'll definitely send one out. Don't worry.

TheSGC · 10-09-2009, 08:38 PM

Any updates on the performance of the Open Source Controller?

MPaulHolmes · 10-09-2009, 09:16 PM

ya its working great! haha just kidding. bootloader is done and works for Adam! I'm still having trouble verifying the code once it's uploaded to the microcontroller, so it's not working for me yet, but it will be soon. Then I can mail Ben a microcontroller, as well as the rs232 thing, since like an idiot I didn't add it since I didn't think it would be needed. haha. Then Ben will be able to upload any software he wants onto the microcontroller.

bennelson · 10-09-2009, 09:18 PM

Quote:

Originally Posted by TheSGC

Any updates on the performance of the Open Source Controller?

No, not really.

I have played around a little bit, running the car at 96 volts. It seems a bit peppier, but I didn't do any long runs on 96V to see if range improved.

The main thing holding me back right now is that my charger is set to 72V. It is adjustable to up to 108V, but it requires some odd resistor that you pop in to change the voltage output.

Usually, I go straight to Tom (EV Dodge Neon dude) for all my weird electronic needs, but he is out of town right now!

Also, I am using the best 6 of the batteries that I have. If I add more batteries in series, each one is likely to be worse than the last, so I do have some issues with diminishing returns there.

In other issues, the controller does output some RF noise that I pick up in the FM band, and it came from Paul set in the "wienie-mode". So I can no longer burn rubber, like I could with the Curtis controller.

I think once Tom gets back in town, we will have to trick out the controller and charger!

PS: ER - looks like Paul was typing that last post while I typed this one! Yeah, the upgrade and the RS232 would be super-cool!
Say Hi to Sabrina! She is a super-nice lady!

MPaulHolmes · 10-09-2009, 09:24 PM

Yes, Ben. You are using code with a PI loop that was tuned for 144v. So, at 72v, you should use PI constants that are 2 times bigger than the ones Joe is using. I'll also make the ramping rate a lot higher if you want to try that. I don't think anything would blow up.

bennelson · 10-09-2009, 09:32 PM

I think I could go for a steeper throttle ramp.

I had it cranked up on the Curtis.
I just had to remember to be real light pulling away from a stop, and also, it was easy to over-accelerate in reverse, but it sure was cool squealing the tires!

PS: I also got to visit the Wienermobile today!

TheSGC · 10-09-2009, 10:13 PM

If I remember right, you have a K&W BC-20 charger?

If you do, I have the same one in my EV setup for 96 volts, using a resistor setup I made because I couldn't get my hands on the proper one.

I even have the manual for the charger, and if you want it I can set you up with a resistor setup for a 96 volt, or any other voltage. I have been thinking of making a small board with adjustable settings so I can adjust the charger on the fly, I just haven't done it yet cause I have been lazy.

bennelson · 10-09-2009, 10:43 PM

Yep, I've got the BC-20.
I have a manual for it to....um..here...somewhere.

I did try using a Potentiometer in place of the resistor to make an "adjustable" for it. But that didn't work at all!

Please forward me any info you can on making your own resistor setup for it.

For anyone without the manual, Mr Sharkey has a copy on his web page.
http://www.mrsharkey.com/SCT/bc20.pdf