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Battery Technology Improvement Over Time

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scaesare

Well-Known Member
Mar 14, 2013
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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...
 
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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).

Perhaps it's the difference between "industry average" and "Tesla specific".
 
My pet theory about the Model X delay has to do with Tesla increasing the capacity of the pack. I think they are working out those details. Releasing the Model X with a maximum 85 kWh battery seems like a let down, in my opinion, and if it doesn't present the same or better range than Model S I think there is going to be a lot of negative media and hits to the stock. I think it's quite obvious at this point that we are going to see a higher capacity pack towards the end of next year.
 
I agree that is a likely scenario. It would be awesome if the X launched with a battery pack option significantly above 85kW (100?) and at the same time the S got a higher power battery option to match the X. I do think they will keep the 60kW for the S so as to be able to promote the base S at a lower price point, but I don't expect the X to be available with the 60kW.
 
My pet theory about the Model X delay has to do with Tesla increasing the capacity of the pack. I think they are working out those details. Releasing the Model X with a maximum 85 kWh battery seems like a let down, in my opinion, and if it doesn't present the same or better range than Model S I think there is going to be a lot of negative media and hits to the stock. I think it's quite obvious at this point that we are going to see a higher capacity pack towards the end of next year.
You beat me to it:biggrin: , Initially once the secound delays was announced i was confindent that in part it was due to having a larger pack and cost production curves. In January Elon and straubel did a conference in norway Q and A style and Elon admitted that next year there will be a larger pack available. We have moved from the 1.9 mah for roadster to 3.1 mah for the model s and panasonic has confirmed that are testing 4.1mah batteries. I am not expecting a 60kwh for the Modelx rather 85 kwh and 110Kwh- DISCLAIMER FOR MEDIA SOURCES THIS IS PURE SPECULATION AND HAS NOT BEEN CONFIRMED.....
 
I would be very surprised if Tesla is not testing modules and possibly full packs with the expected gigafactory battery cell size and chemistry. They have 1 year to beginning cell production. They have 2 years to have high production output of the packs. These packs have to be simpler than today's tour de force packs. I am guessing water cooling on the bottom of the cells and electrical connections on the top. Much simpler than today's winding cooling tubing. We will see what the final configuration is, but they must be testing now.
 
By industry standards, Straubel introduced this image.

Battery Energy Density.jpg


It is very possible that Tesla can get a 110Kw battery by 2016-2017. That would get the distance to 400miles. The big problem with all EVs is the curse of range. Once we get close to 500 miles (wishful thinking), this problem will go away/reduce.

From the Tesla 10-Q Securities and Exchange Commission report,
"We plan to use the battery packs manufactured at the Gigafactory for our vehicles, initially for Model S and Model X, and later for the Model 3 vehicle, and stationary storage applications."

I guess we have to wait for this to happen.
 
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...

Keep in mind that the cells Tesla used for the roadster were not top of the line for their time. I am pretty sure 2800mAh cells were available by then.

On the other hand, the cells used in the model S were certainty top of the line when they were released, and they still are, all specifications considered.
The only cells with higher capacity are the B, the BF and the G, all of which under-perform the model S cell in impedance significantly.
The BD may offer lower impedance at near the same capacity, but it hasn't been verified in public....

I am speaking of Panasonic cells only.... their competitors don't really have anything that can compete at this time in terms of capacity, lifetime and impedance.
 
Do you have an authoritative source for this? I've seen several plausible cases for 3.3Ah cels for the S...
While the S was still in prototype stage, Tesla and Panasonic jointly announced a supply agreement for 3.1Ah cells:
http://www.engadget.com/2010/04/23/panasonics-3-1ah-batteries-to-be-used-in-the-tesla-model-s-hav/

However, given what we know about cell count (7104 in 85kWh pack, verified by pack dissection) it would appear Tesla has picked different cells for the production version.