Model S Battery/Motor: first impressions?

[TEG]

http://reviews.cnet.com/8301-13746_7-20018836-48.html

[Cobos]

So you guys think that is one or two cells stacked on top of each other? Do you still think Tesla has the blade concept where you can extract a limited number of batteries in case of a failure and not have to scrap the whole pack?

Cobos

[dpeilow]

If you work out the dimensions of 8000 * 18650 cells, it's got to be 3, possibly 4 layers of them. [EDIT] With CNET guessing 7 feet by 4 feet, it has to be 4 layers deep. That's still compatible with 4 inches deep.


Also, from here, and overview of the factory.




That story also claims that Panasonic are not the exclusive suppliers...

[T@oo]

That shape was to be expected. I think for the sake of simplicity and rigidity, they went for a single block. Not a blade design. But I think the pack it smaller than CNET suggests. At most 10cm high (4 inches). Although it's hard to judge from the pics.

I would really love to know how it gets filled with cells. I mean, by hand (and using just two seconds per cell) it will take more than four hours to fill the biggest 8000 cells pack.

Also, the coolant dock would perfectly fit under the rear seats. But on a second thought, it would be much better for it be in front (where the coolers will certainly be) and the power connectors to be below the rear seats, to keep the distance to PEM and motor low. No?

[WarpedOne]

I bet it is a single layer with cells standing upright. 18650 cells are 6,5cm long, add 2 cm for the bottom plate and 2 cm for top plate and you get 10 cm height. Cells are circular with 18 mm diameter, when stacked together in triangular pattern there is space for vertical connections and coolant pipes between them.

[dpeilow]

Yep, got to that conclusion myself. Packed together they need 2.6 m^2, which is almost the 7ft by 4ft they saw.

[richkae]

I wonder what cells will end up in each pack.
They will have a lot of choices in cells and I think it all comes down to how much those cells cost because I think the cost increases non-linearly with energy density.

Lets say the 160 mile pack is 42 kWh
That would be ~5300 2200mAh cells ~4500 2600mAh cells ~4000 2900mAh cells or ~3600 3200mAh cells.

If the 230 mile pack is 60kWh
That would be ~7500 2200mAh cells ~6400 2600 mAh cells ~5700 2900mAh cells or ~5200 3200mAh cells

If the 300 mile pack is 85kWh
That would be ~8000 2900mAh cells ~7300 3200mAh cells or ~5900 4000mAh cells

Here are my wild guesses:
The 160 mile pack will use 2600mAh cells.

The 230 mile pack will use cells between 2600mAh and 2900mAh

The 300 mile pack will use cells between 2900mAh and 3600mAh

[WarpedOne]

IIRC it was already mentioned that high-milage pack will use bigger format cells and will thus be non-proportionally more expensive. Mid and low-milage pack are supposed to use different number of same cells.

Another variable in this equation is DOD. Car never uses full cell capacity, even if you charge in range mode, only about 90-95%. Exactly how much is technical secret.

[vfx]

Quite a press Junket. More here:
http://www.siliconvalley.com/news/ci...nclick_check=1
and here:
http://gigaom.com/cleantech/how-tesl...come-big-auto/

[TEG]

IIRC it was already mentioned that high-milage pack will use bigger format cells...

???

Did they say "bigger format" somewhere? My assumption was that the 300 mile pack was still to use 18650s, just higher capacity per cell.

http://green.autoblog.com/2009/01/13...n-the-model-s/

...The top option will be a pack using cells with a more advanced chemistry that offers a 300-mile range...

http://www.greencarreports.com/blog/...echnical-specs

...BATTERY PACK: 8,000 commodity cells; standard 42-kWh pack gives 160-mile range; 230-mile (50-plus kWh) and 300-mile (70 kWh) packs to come later for rental or purchase; quicker to change than a gas tank. The 300-mile pack will use an entirely different cell chemistry than the other two...