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Discussion Starter #1
In reference to the article below:

http://www.gizmag.com/tesla-model-s/11386/

Tesla S wt=3825 lb with300 mile range pack, 8000 18650 cells, 70 kwh, pack wt=1200 lb

This means the car without the pack= 2625# (vs Volt=3100#)

for 160 mile pack, 5500 cells, 42 Kwh, calculated pack wt=825#

Therefore:

Tesla S with 160 mile pack=3450# (vs 3500# for the Volt)

0-60 MPH in 5.6 seconds.

Approx cost comparison 39900$ Volt, 57500$ Tesla (before 7500$ Fed rebate)
 

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70kwh and 8000 cells means 2.4Ah per cell, if they upgraded to the 2.9, 3.4 or 4.0Ah cells then they could boost the capacity in the same physical space. I think the smallest 18650 cell Panasonic makes is 2.5Ah.

Using the 4.0Ah cells would give you a 115kwh pack :)
 

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70kwh and 8000 cells means 2.4Ah per cell, if they upgraded to the 2.9, 3.4 or 4.0Ah cells then they could boost the capacity in the same physical space. I think the smallest 18650 cell Panasonic makes is 2.5Ah.

Using the 4.0Ah cells would give you a 115kwh pack :)
At 5 mi/kwh and 80% pack usage 70 kwh only gives you a 280 mile range. Interestingly, Prowler says that in range mode you are allowed nearly 100% of the pack in his Roadster. That must be what they are doing here in order to get the 300 mile range.
 

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At 5 mi/kwh and 80% pack usage 70 kwh only gives you a 280 mile range. Interestingly, Prowler says that in range mode you are allowed nearly 100% of the pack in his Roadster. That must be what they are doing here in order to get the 300 mile range.
I think Tesla has always quoted their range with full pack use (or at least very close to 100% - I think on their blog or used to be on Martin's blog the exact pack usage) so it's logical they would be doing the same with the Model S. However, the 160 mile pack numbers in comparison to the 300 mile pack don't bear this out. Just doing a straight line analysis, one would predict the smaller pack to be 37.33KWh (160/300 * 70KWh). Given that the pack is 375lbs lighter (only 375lbs? - I know some pack weight overhead isn't saved but...), the miles/kwh should improve not decline.

Given the 400 or so pounds of weight savings, the smaller pack version should have a bit more pep to it. I wonder how they are handling the weight differential with the suspension. It should be a big deal to engineer but it would interesting to hear their solution, especially if battery expansion is an option for trips or permanently adding capacity. I could see myself purchasing with 160 miles of range initially and then adding 8kwh at a time to maintain 160 miles of range (@120 real world) as the pack loses capacity. I could easily get 10 years of 150 mile average range with only adding one additional 8kwh module. I certainly believe that 8kwh will be significantly cheaper and lighter 4-5 years after the car purchase. Don't know if I'ld rent extra modules for trips, however. I'ld probably just use our second car.
 

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I could see myself purchasing [Tesla S] with 160 miles of range initially and then adding 8kwh at a time to maintain 160 miles of range (@120 real world) as the pack loses capacity. I could easily get 10 years of 150 mile average range with only adding one additional 8kwh module.
I have seen nothing to indicate that you can do this. The 3 packs are distinctly separate, not modular.
It also isn't clear from the above that there's only two physical packs - large pack with premium cells, and the smaller pack with either premium cells or lower capacity cells for the minimum offered range.
 

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I have seen nothing to indicate that you can do this. The 3 packs are distinctly separate, not modular.
It also isn't clear from the above that there's only two physical packs - large pack with premium cells, and the smaller pack with either premium cells or lower capacity cells for the minimum offered range.
The only thing I've seen on the packs is the different ranges ( I thought they mentioned 3) and that they were planning to make them swappable. George's details are new to me and I haven't read the Gizmag article yet. Has Tesla announced (leaked) more info?

I'm interested to see any info available.
 

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The only thing I've seen on the packs is the different ranges ( I thought they mentioned 3) and that they were planning to make them swappable. George's details are new to me and I haven't read the Gizmag article yet. Has Tesla announced (leaked) more info?

I'm interested to see any info available.
Three ranges - yes
swappable - yes
modular (additive) - not that I've heard.

There are 2 physical sizes of packs, one of them is offered with two different cell types to give 3 ranges.
 
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