The Worlds Fastest 1100 pound electric car

[Lock]

Fun to read about the BYU Electric vehicle Racing Team and the streamliner they are building for a land speed record (183mph):
http://www.byustreamliner.com/homepage/tiki-index.php
View attachment Streamliner.jpg

400V of A123 cells from DeWalt 36V packs:
View attachment Streamliner_A123.jpg

...into a 3-phase AC motor:


After about four years in development, they are headed for Bonneville this summer...
Tks
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[wheelbender6]

I've always wanted to go to Bonneville for the speed trials. Good luck to BYU.

 

[DaveAK]

They couldn't get A123 cells directly? That sucks.

 

[johnrobholmes]

It was probably cheaper to get them from scavanged dewalt packs, plus you can use them as modules and save a bunch of labor.

 

[lutach]

I wonder if they tried to get A123 to sponsor them?

 

[Lock]

Dewalt did donate their battery packs... Yah, I believe they have other sponsorship also
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[michaelplogue]

'

Interesting - very nice front wheel drive system they have there!

.

 

[Lock]

http://www.youtube.com/watch?v=xKWBB6lspu8

Man does their motor sound awesome...
[youtube]xKWBB6lspu8[/youtube]

 

[Mudder]

Due to your voltage configuration, y'all might not be at risk, but y'all should be VERY CAREFUL with that A123 pack configuration if you're using a BMS!!!! If one of the cells fail, and the BMS leads are tied together across banks, the voltage difference between the cells will cause the metal spring wire to melt out of the plastic enclosure. This is ultra bad in your configuration because if two of the springs melt out, the packs will short out:

Again, this will only happen if all the BMS voltages are tied together:

This happens because the wires used by Dewalt have a very high path impedance and therefore sink a lot of power. I used an NI-4071 7.5 digit precision DMM and measured a 4-wire resistance of 84mOhm. This, coupled with the high current that we try to sink over the small BMS wires will cause a failure. Here you can see the failure mode being the spring from one container melting out of the black plastic housing and into the next battery:

I'd recommend you either use isolated BMSs that only look at one cell at a time or you change your battery design to a linear one.

 

[liveforphysics]

A land-speed vehicle isn't much a commuter, and it seems the need for a BMS is very low IMO. I would think it would be simple enough to just start with the cells in balance, keep the DOD <70% or so, and charge the string in series with no BMS involved. If slight balance differences develop, they would have plenty of time to correct them by manual charging when back at the shop.

 

[Lock]

Post from the team:
http://www.byustreamliner.com/homepage/tiki-view_blog_post.php?postId=44

http://www.youtube.com/watch?v=Ri1RDamt-Lw
[youtube]Ri1RDamt-Lw[/youtube]

Recent email:

Re: [EVDL] BYU streamliner crashes at 170 mph
Saturday, August 21, 2010 12:53 AM
From: "Kelly Hales" <ke llygha les@g mail.com>
To: "Electric Vehicle Discussion List" <e v@li sts.sj su.edu>
Thanks to David for posting all this for us, I guess I shouldn't use him as
my news service since I am on this list too! LOL

Anyway for just a bit more info, the car got loose at what the driver
estimates was about 170 and rolled onto the right side then the roof. It
stayed on the roof and slid to a stop (with the help of the parachute). As
has been mentioned the safety requrements are indeed pretty strict, and for
good reason. That is why the driver walks away. They say that there were
many more spins and crashes this year for some reason, but no serious
injury. That is a good thing for sure.

We will now be taking a serious look at many aspects of the design (duh) and
deciding what our course of action will be for the future. We don't have
the data out of the car yet, but we do have the on car video. I hope we
continue the project for sure, but it could be at least a year before we try
again. With our funding for the car about gone I don't know what will
happen. It has been six years to get this far, don't want it all to be a
waste. The hard thing about land speed racing is that you really have no
where to test, so you build and then test at the track.

On the good side, the drivetrain, batteries, chargers and all the safety
equipment worked flawlessly. Also of interest is Ohio States Buckeye Bullet
was there with a new battery system to replace the hydrogen fuel cells. The
were using the larger A123 cells (three thousand plus) and running about
650 volts. They hadn't run yet before we left today.
Kelly Hales
BYU Streamliner team

 

[liveforphysics]

I'm glad the driver is ok. Salt is such an awful surface to race upon. Slippery, unstable, high rolling resistance etc. I don't fault the driver for wrecking on that unstable slippery crap.

 

[Evoforce]

Yea and the more it is raced on the looser it gets.

 

[liveforphysics]

Yea and the more it is raced on the looser it gets.

Yep, very true. The only reason anyone races on salt is just becaue there is nothing to crash into for many miles in all directions, it's flat (and level), and there is nobody to complain about noise etc. Everything else about racing on salt totally sucks. Running on an a freeway with no/low traffic is a hell of a lot better surface to race on IMO.

Though I wouldn't want to do it in the rain on public freeways in traffic at >200MPH (>320km/h)

[youtube]SYLVhuGYjp8[/youtube]