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Discussion Starter #1
So, I've been doing some quick figures on the Model 3 and the likely battery pack size on the base spec.

The Model S:
275 miles / 70kWh
3.93 miles / kWh

The Model 3:
215 mile range
54.7kWh (at the same efficiency as the Model S)
It's smaller, lighter and has a better drag coefficient. Could that give us a 7% saving? If it did:
215 miles / 50kWh

If so, a 50kWh battery giving us 215 miles means upgrades would be:

60 kWh / 258 miles
70 kWh / 301 miles
80 kWh / 344 miles
90 kWh / 387 miles
100 kWh / 430 miles

Admittedly basic calculations, there will be some losses on the larger battery packs due to additional weight, so take it with a pinch of salt. Also, the smaller frame could lead to physical constraints on getting the larger battery packs in, maybe they can't even fit a 90kWh pack in...

Thoughts?
 

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Discussion Starter #3
430 mile range would finally bring complete equality with the ICE -- at a price!
Well, with double the weight in the pack it probably wouldn't be quite that high, but I'd guess you could still get it over 400?

That would be very nice!
 

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Discussion Starter #4
If they get better than 7% efficiency increase then we could be looking at a 45kWh pack, but that might be a bit too far at 18% more efficient than the Model S?

If that's the case, you can bump all of those numbers for the upgrades even higher! :)
 

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Discussion Starter #5
Just for fun, here are the numbers for upgrades if the base spec with 215 mile range has a 45kWh battery pack. That represents an 18% increase in efficiency over the Model S though!

215 miles / 45kWh

60 kWh / 287 miles
70 kWh / 335 miles
80 kWh / 382 miles
90 kWh / 430 miles
100 kWh / 478 miles
 

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Interesting figures - but I think you're using NEDC figures (which are highly optimistic) for your calculations, but I suspect Elon is using the USA standard, which is a little more realistic. Just look on the USA version of the Tesla website and you'll see what I mean - same model less range quoted.

So many variables - smaller car (so less weight), steel body (so more weight), higher density batteries (so less weight), less drag (more efficient), reduced electronics (less weight). At a guess 50 kwh will be the smallest size. I doubt it'll go to 100kwh in the initial launch.
 

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Discussion Starter #7
You're right! Adjusted figures:

The Model S:
233 miles / 70kWh
3.33 miles / kWh

The Model 3:
215 mile range
64.5kWh (at the same efficiency as the Model S)
It's smaller, lighter and has a better drag coefficient. Could that give us a 7% saving? If it did:
215 miles / 60kWh

If so, a 60kWh battery giving us 215 miles means upgrades would be:

70 kWh / 251 miles
80 kWh / 286 miles
90 kWh / 322 miles
100 kWh / 358 miles
 

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8 battery modules in the "3" versus 16 modules in the "S" wasn't it?

So, either they are using new format cells (loads of space wasted using 18650) or it's going to be 8/16 of 100kWh (the battery shortly to be fitted in the Model S, based on the hash someone found in the software).

I make that 50kWh ...
 

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Discussion Starter #9
Looking at the comparable EPA figures from the S/X, I'm not sure you could get 215 EPA from 50kWh could you?
 

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Does anyone know what a 60kWh battery pack weighs ?
Just wondering how much difference a 60kWh battery in a steel body versus a 70kWh battery with the aluminium body...
 

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So basically the model S is a bit obese then
Wonder if I could swap out the engine in my Ampera for a 60kWh battery.... Similar weights :)
 

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I originally thought that Model 3 would come in at around 50kWh.

Comparing this to the other Teslas (wikipedia):
60 weight 1961Kg range 224 (EPA) 3.75 miles per kWh
70D weight 2090Kg range 240 (EPA) 3.43 miles per kWh
85D weight 2188Kg range 265 (EPA) 3.12 miles per kWh

Adding the weight of a driver... then making some assumptions about the weight, lighter battery, smaller body, better materials I deducted 15% from the weight of the 60.

Following the trend line from the above, this would bring the miles per kWh of the Model 3 to an impressive 4.6.

Then add some improved aerodynamics, more efficient tyres/motors which all makes a big difference at 65mph. If the miles per kWh was 4.8 or better at 215 miles range, the battery capacity could be as low as 45kWh, half the size of the 90D. Coincidence?

They would need to work hard to get this level of efficiency improvement but it might just be do-able.

Upgrades could be...
55kWh 255 miles
70kWh 309 miles

Alternatively, given the Model 3 needs to exceed the 215 miles expectation, they may well plump for a 50kWh pack and reap the extra miles as a bonus, final range 220-235 miles (4.4 to 4.7 miles per kWh) depending on how the diet goes.

100kWh could become the main option for the S and X in 2017 bringing efficiencies of production and design by keeping the capacities a function of one another.
 

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You're right! Adjusted figures:

The Model S:
233 miles / 70kWh
3.33 miles / kWh

The Model 3:
215 mile range
64.5kWh (at the same efficiency as the Model S)
It's smaller, lighter and has a better drag coefficient. Could that give us a 7% saving? If it did:
215 miles / 60kWh

If so, a 60kWh battery giving us 215 miles means upgrades would be:

70 kWh / 251 miles
80 kWh / 286 miles
90 kWh / 322 miles
100 kWh / 358 miles
I'd say a 60kWh pack in the base Model 3 is a very good bet.

Also you can't then just multiply up ranges as the battery capacities get higher, because the cars also get heavier which reduces the gains.

The range of a 90kWh Model S is not 9/7 of the range of a 70kWh Model S. The usable capacity of the larger pack is ~30% greater but the range is only 20% more.

Comparing this to the other Teslas (wikipedia):
60 weight 1961Kg range 224 (EPA) 3.75 miles per kWh
70D weight 2090Kg range 240 (EPA) 3.43 miles per kWh
85D weight 2188Kg range 265 (EPA) 3.12 miles per kWh

Following the trend line from the above, this would bring the miles per kWh of the Model 3 to an impressive 4.6.

Then add some improved aerodynamics, more efficient tyres/motors which all makes a big difference at 65mph. If the miles per kWh was 4.8 or better at 215 miles range, the battery capacity could be as low as 45kWh, half the size of the 90D. Coincidence?
EPA range for S60 is 208 miles, not 224. Usable pack capacity is 58kWh so that's 3.6 mi/kWh.
EPA range for 85D is 270 miles. Usable pack capacity is 77kWh so that's 3.5 mi/kWh.

The trendline is hugely flatter than you think it is.

50kWh is too small for them to get to 215 miles EPA. It's all very well saying "ah but what if they can get 4.8 miles per kWh" but wishing for it doesn't make it true. The BMW i3 is the most efficient BEV ever tested by the EPA and it only gets 3.7 miles per kWh. You cannae change the laws of physics...

If you take the i3's effficiency, and the usable capacity of the Tesla S60 pack and multiply them together lo and behold you get... 214.6 miles :)
 

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So, I've been doing some quick figures on the Model 3 and the likely battery pack size on the base spec.

The Model S:
275 miles / 70kWh
3.93 miles / kWh

The Model 3:
215 mile range
54.7kWh (at the same efficiency as the Model S)
It's smaller, lighter and has a better drag coefficient. Could that give us a 7% saving? If it did:
215 miles / 50kWh

If so, a 50kWh battery giving us 215 miles means upgrades would be:

60 kWh / 258 miles
70 kWh / 301 miles
80 kWh / 344 miles
90 kWh / 387 miles
100 kWh / 430 miles

Admittedly basic calculations, there will be some losses on the larger battery packs due to additional weight, so take it with a pinch of salt. Also, the smaller frame could lead to physical constraints on getting the larger battery packs in, maybe they can't even fit a 90kWh pack in...

Thoughts?
The potential weight makes me think of Ettore Bugatti's comment on seeing the Le Mans Bentleys - 'fastest lorry in the world.'
 

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EPA range for S60 is 208 miles, not 224. Usable pack capacity is 58kWh so that's 3.6 mi/kWh.
EPA range for 85D is 270 miles. Usable pack capacity is 77kWh so that's 3.5 mi/kWh.

The trendline is hugely flatter than you think it is.

50kWh is too small for them to get to 215 miles EPA. It's all very well saying "ah but what if they can get 4.8 miles per kWh" but wishing for it doesn't make it true. The BMW i3 is the most efficient BEV ever tested by the EPA and it only gets 3.7 miles per kWh. You cannae change the laws of physics...

If you take the i3's effficiency, and the usable capacity of the Tesla S60 pack and multiply them together lo and behold you get... 214.6 miles :)
No need to change the laws of physics - take the above 85kWh example, 3.5 miles per kWh. Reduce the size of the car and battery and drop the kerb weight from 2188kg to around 1665kg. Bringing the weight down, improving the aerodynamics and efficiencies could lead to a gear change in energy consumption of 4.6-4.8 miles per kWh.

The first S60 was 1961kg so weight only needs to come down by 15% from there, not that much a stretch of imagination given the reduced size of the car and potential for reduced battery weight from improved density.

The Nissan Leaf 30 is 1516kg. Tesla battery packs are currently 544kg for 85kWh, around 6.4kg per kWh. Add 20 kWh to make a 50kWh pack and the Leaf 50 would be a comparable 1644kg. Come to think of it, replace the whole 30kWh pack with 50kWh Tesla batteries and the weight would not be much different to the start.

To sell a car for $35k, Tesla is going to need the cheapest possible battery pack, Why put in a heavier, more expensive 60kWh pack as the base option if they are not going to need this to meet the 215+ miles. The weighty 60D already achieved this range.
Tesla - Model S - 60D (60 kWh, 376 Hp) - Technical specifications, Fuel economy (consumption)
 

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Discussion Starter #19
I'd say a 60kWh pack in the base Model 3 is a very good bet.

Also you can't then just multiply up ranges as the battery capacities get higher, because the cars also get heavier which reduces the gains.

The range of a 90kWh Model S is not 9/7 of the range of a 70kWh Model S. The usable capacity of the larger pack is ~30% greater but the range is only 20% more.



EPA range for S60 is 208 miles, not 224. Usable pack capacity is 58kWh so that's 3.6 mi/kWh.
EPA range for 85D is 270 miles. Usable pack capacity is 77kWh so that's 3.5 mi/kWh.

The trendline is hugely flatter than you think it is.

50kWh is too small for them to get to 215 miles EPA. It's all very well saying "ah but what if they can get 4.8 miles per kWh" but wishing for it doesn't make it true. The BMW i3 is the most efficient BEV ever tested by the EPA and it only gets 3.7 miles per kWh. You cannae change the laws of physics...

If you take the i3's effficiency, and the usable capacity of the Tesla S60 pack and multiply them together lo and behold you get... 214.6 miles :)
It was just some fag packet calculations :)
 

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Why put in a heavier, more expensive 60kWh pack as the base option if they are not going to need this to meet the 215+ miles.
Because they are going to need this to meet the 215+ miles.

There's no such car as a 60D. It was briefly advertised by Tesla but none were ever built, and it was certainly never EPA tested.
 
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