Choose: Another 25 kWh or Performance?

[WhiteKnight]

And considering the huge margins they're getting on the performance upgrade (it's not as if the motor is any different), those are some lost profits on their end.

I agree with you the margins on the Performance version have to be way fatter than the margins on the extra 25 kWh. The only reason I can think that Tesla makes you go up to the highest capacity pack is that their competition (BMW M5, AMG E63, etc) are all priced up in the stratosphere.

But I also think they should not be bound by what other companies are doing and if they can unleash the performance of the 40 kWh or 60 kWh vehicles for $15K they should do that.

That would make your decision on range (160, 230, 300) completely independent of your decision on other options and upgrades.

[gg_got_a_tesla]

But I also think they should not be bound by what other companies are doing and if they can unleash the performance of the 40 kWh or 60 kWh vehicles for $15K they should do that.

That would make your decision on range (160, 230, 300) completely independent of your decision on other options and upgrades.

I think this has been discussed before. One plausible explanation for doing the perf addon only for the 85 kWh pack was the increased power draw from the pack for the perf - the 40 kWh for sure may not be able to handle that. Deferring to the battery experts here...

[AndrewBissell]

I think this has been discussed before. One plausible explanation for doing the perf addon only for the 85 kWh pack was the increased power draw from the pack for the perf - the 40 kWh for sure may not be able to handle that. Deferring to the battery experts here...

That is almost certainly correct. Note that for the non-performance models 0-60 times decrease with rising pack size.

This is because a larger pack can source more kW. Why? Think of each cell - it can source a maximum number of watts during discharge. If there are 4000 cells in the 40 kWh pack (made up number) and 6000 in the 60 kWh, then the 60 kWh can source 1.5 times more power. So as long as the motor is not the limiting factor, larger pack = more power = lower 0-60.

Now at the 85 kWh level I guess that the pack can source more kW than the motor or inverter can handle. Therefore at that level of pack they can offer an upgraded motor and/or inverter - a performance upgrade.

But offering the upgrade on a 40 or 60kWh car would deliver no benefit - the pack is limiting.

[drees]

Now at the 85 kWh level I guess that the pack can source more kW than the motor or inverter can handle. Therefore at that level of pack they can offer an upgraded motor and/or inverter - a performance upgrade.

But offering the upgrade on a 40 or 60kWh car would deliver no benefit - the pack is limiting.

Could be - but in the past the Roadster performance model was an upgraded motor (and PEM?) that improved performance without increasing load on the battery pack.

One has to imagine that the Performance package's electronics have significantly beefier electronics which can handle higher power with low loss - but without knowing the details it's hard to say for sure if the same performance package would also improve the performance of the smaller packs without also increasing load on them.

[onlinespending]

That is almost certainly correct. Note that for the non-performance models 0-60 times decrease with rising pack size.

This is because a larger pack can source more kW. Why? Think of each cell - it can source a maximum number of watts during discharge. If there are 4000 cells in the 40 kWh pack (made up number) and 6000 in the 60 kWh, then the 60 kWh can source 1.5 times more power. So as long as the motor is not the limiting factor, larger pack = more power = lower 0-60.

kWh is a measure of energy. Yes, the large packs provide more energy than the smaller packs but that's all you can say without digging deeper. The power required to accelerate at a given rate is the square of the current necessary to run the motor at the required torque times the impedance of the load. So despite a smaller pack size, it's certainly theoretically possible that they could source enough current to be able to accelerate at the rate necessary. You simply won't be able to do so as many times before draining the battery as you would with a larger pack (it's like using a smaller battery in an iPhone that can still provide enough current to operate all components of the phone, just that it won't last as long). But one thing to keep in mind is that the lower pack sizes have less batteries in parallel which will mean that there will be a higher ESR (equivalent series resistance) from the battery packs themselves, which means they are less efficient for the same current draw. It may very well be that Tesla has limited the current sourced by the lower pack sizes (and hence the acceleration rate) to reduce wear on the battery and be able to comfortably provide the sort of warranty they do.

[howabout2]

Given the hypothetical situation posed by the original poster, I'd opt for performance over range without a second thought.

Being a Los Angeles resident, range is simply not important to me over the 160 mile baseline. I hardly ever drive out of LA. When I travel, I head to our awful airport, LAX. If for some reason I wanted to visit San Diego or Santa Barbara, I would suck it up and rent an ICE.

I'd much rather enjoy the day-to-day fun of the extra performance compared to a daily squandering of the potential to have driven eight times as far as I actually drive each day. To say that another way: the extra range would be enjoyed once--maybe twice--a year. The extra performance would be enjoyed every single time I turn on the car.

In an ideal world, I'd be able to opt for a performance-spec 160 mile Model S.

So yes, performance, please.

[GSP]

I would go for the extra range. 5.3 seconds to 60mph is plenty quick enough for me. A 400-mile Model S would be so sweet, and really change the public perception of EVs. Heck, the soon to be launched 320-mile Model S, performance option or not, should have a huge impact on the automotive industry.

GSP

[stopcrazypp]

Here's some of the numbers to work out the likelihood of performance versions.

Battery size, battery power (@4C), motor power, 0-60 (0-60 Performance/Sport version)

Roadster
56kWh, 224kW, 225kW, 3.9 (3.7)
*Roadster changes added by request by brianman; only the motor power changed, battery and 0-60 remained the same.
Roadster Year, Version, Motor power (Sport)
2008, 1.0, 185kW (185kW)
2009, 1.5, 185kW (185kW)
2010, 2.0, 215kW (215kW)
2011, 2.5, 215kW (215kW)
2012, 2.5, 225kW (223kW)

Model S
40kWh, 160kW, 300kW, 6.5
60kWh, 240kW, 300kW, 5.9
85kWh, 340kW, 300kW, 5.6 (4.4)

Model X
60kWh, 240kW, 300kW, 6.5*
60kWh, 240kW, 450kW* (AWD), 6.5*
85kWh, 340kW, 300kW, 6.2* (4.9*)
85kWh, 340kW, 450kW* (AWD), 6.2* (4.9*)
110kWh*, 440kW, 300kW, 6.2* (4.9*) <- bottle neck here will be the motor/PEM so same as 85kWh pack
110kWh*, 440kW, 450kW* (AWD), 4.8* (3.8*)

*0-60 numbers from dividing Model S numbers by 0.9 (Tesla says Model X will be ~10% heavier and have ~10% less range than Model S).
*AWD has extra half-sized front motor; 300kW*1.5 = 450kW.
* Numbers for theoretical 110kWh pack figured by scaling the 85kWh pack's numbers.

For the models where the obvious bottleneck is the battery (battery power is much less than motor power), it's less likely there will be a Performance version. Tesla has indicated the performance version of the Model X will be AWD only and Elon has thrown out a 4.4 second 0-60 number for the Model X (supposedly non-performance).

If Tesla does offer a 110kWh pack for the Model X (although they have never indicated they will do so), there will be a second teir of battery where the battery power greatly exceeds the motor power (in the non-AWD case). Therefore Tesla can technically offer a "Performance" version for both the 85kWh and theoretical 110kWh pack. They can't do so for the 40kWh and 60kWh pack in the Model S because they are already battery limited.

[brianman]

@stopcrazypp - If you have the data, can you edit your post to include the various flavors (versions, sport/non-sport, etc.) of the Roadster? Thanks.

[WhiteKnight]

110kWh*, 440kW, 450kW* (AWD), 4.8* (3.8*)

I like it! An extra 25 kWh AND a Performance version. So who would pay $102,500 before options for a Model X with 330-340 miles of range and 0-60 in 3.8s (faster than a Roadster!).