Model S Battery/Motor: first impressions?

[shark2k]

Where did you hear that the battery pack is suppose to add structural integrity to the car? My thinking at this point is that what we are seeing is obviously the pack itself. When it does get installed into Model S it will probably be fitted into a bracket / housing / box, with all of the necessary connecting points to the chassis.

They said this is the CNET article:

Chief Engineer Peter Rawlinson explained to us that the battery pack also serves to help the Model S' torsional rigidity and safety. Cross members keep it from flexing much, and he anticipates that the Model S will lead its segment in rigidity, contributing to the car's handling. The pack also serves as a brace, helping to limit cabin intrusion during a side impact.

.

Also in the Wired article they talked about how the battery pack would increase rigidity because (from the computer model they created) the underbelly is perfectly flat, resulting in increased rigidity: http://www.wired.com/magazine/2010/09/ff_tesla/6/ under the "What's the disengage, force" bold part, end of 6th paragraph. Also in that paragraph it says that the battery pack sits in a 9-inch deep rectangular metal frame that's bolted onto the floor of the car, adding even more stiffness.

-Shark2k

 

[raymond]

If the 2600s are less than 18% more expensive than the 2200s then it is a no-brainer to use 2600s.

Maybe not so. 18% Less cells typically also means 18% less power. If you still want your 0-to-60 in 5.6 (or whatever the number these days is) you need a certain number of cells to give you that power. But then again perhaps the 160mi version has a higher 0-to-60. Could be.

Has there been any mention of higher 0-to-60 times for the 160mi version? It kinda seems inevitable, doesn't it?

 

[dpeilow]

If the cells are horiztontal, then the 8000 cell packs could have 3 layers and the 5500 cell pack could have 2 layers.

If they are oriented vertically, then just take cells away from the left and right edges in the same box.

 

[WarpedOne]

Has there been any mention of higher 0-to-60 times for the 160mi version? It kinda seems inevitable, doesn't it?

It seems inevitable yes unless they lower max battery current in lower cell count batteries and in this way reduce max available power. More cells means more energy and more mass but also higher max current with same current per cell.

 

[Cobos]

Playing with the numbers Tesla will be a force to be reckoned with as a battery purchaser.
Say a Model S pack on average has 7000 cells. They intend to sell 20000 cars each year.
That is 7000 * 20 000 = 140 million cells.
Gartner says there was 49 mill sales of mobile PCs in Q1 2010. So about 200 mill laptops for entire 2010. About 35 mill of those are netbooks with 2-3 cells and I suppose the rest has 4-6 cells and a few has more cells. Lets say 4,5 cells on average per laptop.
That means laptop use for the 18650 cells are about 900 million and Tesla will add another 140 mill on top of that.

That should easily put Tesla in the top 5 consumers of 18650 cells. That can't be anything but good for Tesla as their contract should definately carry some weight.

Cobos

 

[tdelta1000]

All very good questions / points.

Where did you hear that the battery pack is suppose to add structural integrity to the car? My thinking at this point is that what we are seeing is obviously the pack itself. When it does get installed into Model S it will probably be fitted into a bracket / housing / box, with all of the necessary connecting points to the chassis.

I myself am quite astonished by how thin this pack is. I was expecting at least double in thickness ~8" to 10".

Albern here's the direct quote: Chief Engineer Peter Rawlinson explained to us that the battery pack also serves to help the Model S' torsional rigidity and safety. Cross members keep it from flexing much, and he anticipates that the Model S will lead its segment in rigidity, contributing to the car's handling. The pack also serves as a brace, helping to limit cabin intrusion during a side impact.

That was pulled from the cnet article. here a link:Tesla Model S battery pack article

 

[WarpedOne]

Albern here's the direct quote: Chief Engineer Peter Rawlinson explained to us that the battery pack also serves to help the Model S' torsional rigidity and safety.

This does not mean that Model S falls apart without battery installed - it just means that battery frame is a stressed member in car chassis, especially when driven "hard."

 

[vfx]

I hope they will be well protected from big ungly things from below. Boulders, furniture, stray mufflers and road signs.

Am I the only one who runs over these things?

 

[vfx]

How much does this thing weigh?

 

[richkae]

Multiple points:
Output from a cell is expressed in its C rating. When you pull 1C from a 2200mAh cell you get 2.2amps, when you pull 5C you get 11amps.
It is most likely that you can pull 5C from a 2600 the same as you can from a 2200, meaning the 2600 can put out 13amps, which also means that power density increases at the same rate as energy density.

I found some LG-Chem cells on a website that have a 2200 mAh 18650 at 45g a 2400 mAh at 46.5g and an 2600 mAh at 48g
( A 6% increase in mass for an 18% increase in energy and power )
So 6831 of the Roadster cells is about 674 pounds.
Clearly the energy density improves in both volume and mass with the better cells.

The 42kW pack at 5C has 210kW available, but the 60kW pack at 5C has 300kW available.
The 42kW pack should be a lot lighter, it will be interesting to compare the acceleration between them.

Also I did some other poking around on some laptop websites and a lot of the 6 cell laptop batteries I found are most likely 2200mAh cells, but the 9 cell batteries I found were most likely 2600mAh cells.

 

[vfx]

Here's another article with more insights.

http://blogs.edmunds.com/greencarad...-reporters-unveils-model-ss-flat-battery.html

 

[stopcrazypp]

How much does this thing weigh?

Are you talking about the "one ton cap." in the picture?
Supposedly the 160 mi pack will be ~600lbs, while the others will be ~900. However, given 8000 cells in the larger packs and the 6800 cell Roadster pack already ~900lbs, the weight is probably a bit more.
http://blogs.edmunds.com/greencarad...-a-great-concept-but-now-the-wait-begins.html

 

[TEG]

On a side note, is it just me or are those Model S motor assemblies with an S on the case in that last pic? .

More close-up pic:
http://images.thecarconnection.com/lrg/tesla_100325173_l.jpg

 

[PopSmith]

I hope they will be well protected from big ungly things from below. Boulders, furniture, stray mufflers and road signs.

Am I the only one who runs over these things?

Yes, I'd never off-road in my car. :tongue:

On a more serious note, the pack isn't exposed to the ground so it shouldn't be much of a problem. However, we'll see what, if any, testing Tesla does targeting the Model S pack when it's closer to production.

 

[vfx]

http://images.thecarconnection.com/lrg/tesla_100325173_l.jpg
So these must be for the Model S' they are building for all the Tesla stores. 20 motors is about right.

Liquid cooled right?

 

[TEG]

I can't tell from those photos. I still think they could be Roadster Sport motors with enlarged air cooling fins.
Is there something you see in that photo that makes you think those are liquid cooled?
The big "S" could be "Model S" or "roadster Sport"...

 

[vfx]

...Is there something you see in that photo that makes you think those are liquid cooled?
...

Nope, I was just having fun speculating.

...The big "S" could be "Model S" or "roadster Sport"...
.

Yep, It sure could.


More battery info:

With regards to battery safety, there is an enormous amount of redundancy built into the battery pack. The firm has made efforts to eliminate the risk of thermal runaway. If a thermal runaway event does occur, the battery pack design incorporates multiple levels of fusing to ensure that it does not propagate. The sheer amount of battery testing done by this firm is impressive and has essentially made Tesla one of the leaders in battery reliability and blowing up batteries. The company showed video of the vehicle and its battery being crushed and engulfed in flames in a variety of different scenarios and conditions.

My naive non-automotive-engineer question would be to ask why a battery form factor used for laptops and toys is still being re-purposed for a luxury vehicle. It turns out that Tesla is buying custom battery cells for their pack, and Jim Dunlay, VP of Powertrain Hardware Engineering, insists that the volume-production of the 18650 form-factor has helped bring cost down and improve design.

 

[Doug_G]

I can't tell from those photos. I still think they could be Roadster Sport motors with enlarged air cooling fins.
Is there something you see in that photo that makes you think those are liquid cooled?
The big "S" could be "Model S" or "roadster Sport"...

Don't they look a little too big to be a Roadster motor? They look kinda fat to me.

I can't see any sign in the photo that they're liquid cooled, though. You'd expect there to be a couple of ports visible. Of course they could be on the other side.

 

[Todd Burch]

99.99% sure they're Roadster motors. Refer to this image:

http://www.teslamotors.com/roadster/technology/motor

 

[TEG]

Yes, indeed they have the big red "S" on that Roadster motor picture:
http://www.teslamotors.com/sites/default/files/MotorHero_0.jpg