I was considering battery improvements for upcoming Tesla models given JB Straubel's statement that batteries improve at a pace of 7-8% a year. This was primarily referring to the cost/weight per unit of energy.
The time between the Roadster release and the Model S was ~4 years (2008 to 2012). I suspect the battery chemistry was locked in well before that, but let's assume 1 year prior... so the the delta is still 4 years (2007-2011).
Four years of improvement at 7.5% per year is a 33% improvement. Yet it would appear that the Model S batteries improved by about 50% over the Roadster batteries in that four year span. The Roadster is understood to have 2.2Ah cells, and the Model S likely has 3.3Ah cells.
So JB's estimate holds and, if anything, may be conservative.
So if the Model S pack cells were selected in 2011, then we are are about to hit the four year mark. If cell chemistry has improved at a pace as JB describes, then in 2015 you could build a ~115kW pack for the same cost/weight. If the pace has been more like the 50% described above, that would be a 127.5kW pack.
All of the above is interesting timing, given the Model X release in later 2015. Of course the cells for a 2015 vehicle would have been selected some time prior to vehicle release... but with the platform & pack design of the X being the same as the S, one wonders if that lead time could be reduced from what it was between the Roadster and the S.
Just musings I had while walking my dog yesterday...
The time between the Roadster release and the Model S was ~4 years (2008 to 2012). I suspect the battery chemistry was locked in well before that, but let's assume 1 year prior... so the the delta is still 4 years (2007-2011).
Four years of improvement at 7.5% per year is a 33% improvement. Yet it would appear that the Model S batteries improved by about 50% over the Roadster batteries in that four year span. The Roadster is understood to have 2.2Ah cells, and the Model S likely has 3.3Ah cells.
So JB's estimate holds and, if anything, may be conservative.
So if the Model S pack cells were selected in 2011, then we are are about to hit the four year mark. If cell chemistry has improved at a pace as JB describes, then in 2015 you could build a ~115kW pack for the same cost/weight. If the pace has been more like the 50% described above, that would be a 127.5kW pack.
All of the above is interesting timing, given the Model X release in later 2015. Of course the cells for a 2015 vehicle would have been selected some time prior to vehicle release... but with the platform & pack design of the X being the same as the S, one wonders if that lead time could be reduced from what it was between the Roadster and the S.
Just musings I had while walking my dog yesterday...
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