Model S Test Drive

[NotTarts]

This methodology is wrong, because it uses the nominal physical capacity of the battery instead of the usable capacity. If you used the usable capacity, you'd find that the Volt's "inefficiency" is actually conservatism in SoC window, and the reason its battery may last ten or fifteen years (38/10.8 vs 73/20.4)

Thanks - I wasn't aware that that was the case with the Volt.

EPA also claims that the Volt uses 8.8kWh to drive 25 miles. That comes to something like 2.84kWh/mile, which is perfectly fine, but if you take the usable capacity of 10.3kWh you get 3.69 miles/kWh, which is way off the EPA estimate and on the tail of the i-MiEV (weighing nearly half of what the Volt does), which is a bit unbelievable IMO.

[DonC]

The EPA MPGe values are bogus, as any simple calculation will tell you. If you divide the EPA-tested range with the battery capacity you get the proper mile/kWh values, and the Model S stacks up properly in that case.

As Walter has pointed out to you, your method is flawed because you're using total battery capacity not usable capacity. You're actually making it more difficult than it is. Just use the EPA numbers for number of kWh/100 miles. That gives the overall efficiency and, considering that charging efficiency should be very similar, the efficiency of the car as well.

i-Miev --> 34 kWh/100 miles
Model S --> 38 kWh/100 miles
Leaf --> 34 kWh/100 miles
Volt --> 35 kWh/100 miles
Karma --> 65 kWh/100 miles
Roadster --> 30 kWh/100 miles

This seems right given the EPA cycles, the weight of the vehicles, and their overall efficiency. At the one end you have the Roadster and the other the poor Karma. For pure electrics you have the Roadster at the top and the Model S at the bottom.

The major point is that, despite what has been suggested, you can't safely use more than 80% of the pack. If you use more you're running a risk that the batteries will lose capacity and power quickly. You can, like GM has done with the Volt, use less, which makes these losses less likely. It's easy to separate the engineering wheat from the marketing chaff, so to speak, by simply looking at the battery warranty. Do they put their money where their mouth is? If the warranty is like what you get with the Volt, where the capacity is warranted, then the manufacturer believes in its engineering and its numbers. The marketing matches the engineering. When you see a battery warranty that doesn't warrant anything, like what you see in the Leaf and Model S warranty, then you know the company doesn't stand behind its numbers or its engineering. What you're getting is marketing hype without engineering substance.

[NotTarts]

Those figures make more sense - MPGe can die in a fire for all I care - but they still don't add up. At those values the Model S would need a battery with a usable capacity of slightly more than 100kWh to achieve the EPA-tested range of 265 miles, the Roadster a battery of 73kWh to reach 244 mi, and the i-MiEV a 21kWh usable capacity (in reality the total capacity of the battery is 16kWh) to get to 62 miles.

[saghost]

Those figures make more sense - MPGe can die in a fire for all I care - but they still don't add up. At those values the Model S would need a battery with a usable capacity of slightly more than 100kWh to achieve the EPA-tested range of 265 miles, the Roadster a battery of 73kWh to reach 244 mi, and the i-MiEV a 21kWh usable capacity (in reality the total capacity of the battery is 16kWh) to get to 62 miles.

EPA kWh per 100 miles includes charging losses. If the Model S battery sizes are usable kWh, as I've read suggested a couple times, instead of total, the ~100kWh/~20-30% losses is right in line the Volt experience (12-13 kWh for 10 usable.)

[NotTarts]

Completely forgot about the charging inefficiencies. Thanks, I finally understand.

I wouldn't be too quick to call out Tesla on their drag coefficient claims, though. According to that EPA data, the Model S is 70% heavier than the Roadster but only 25% less efficient, and 22% heavier than the Volt/8% less efficient. It probably has the highest efficiency per kg (if that makes sense) of any electric vehicle on the market.

[TeslaOwner]

It's very difficult to accept what you're saying ...

Don't believe me. Head over the the Tesla forum and talk with owners who have put many tens of thousands of miles on their cars over 3 or 4 years. Meet up with owners are their events, or stop by Tesla's Model S test drive events and talk to long time Roadster owners who are excited to be getting their next Tesla.

That would require believing that the standard 18650 Panasonic batteries will, when used in a Tesla, be magically transformed...

But, you really need to stop putting words into people's mouths. I didn't say the batteries Tesla uses are "standard." Tesla itself doesn't say they are "standard" - matter of fact they say the opposite.

The fact is, and you can see this from the specs released by Panasonic, that if you use 95% of the pack capacity the cells aren't going to last very long.

I said that the STANDARD charge uses 90% of 95% of the pack. That's about 85%. The RANGE charge uses more, but Tesla recommends against using that often. Panasonic hasn't released specs for the specific batteries Tesla is using. Neither you nor I know the specific batteries Tesla is using, but we've been told they're not the standard ones you and I can buy.

Loss of Battery energy or power over time or due to or resulting from Battery usage, is NOT covered...

Here's the Chevy Volt battery warranty:

Depending on use, the battery may degrade as little as 10 percent to as much as 30 percent of capacity over the warranty period. A dealer service technician will determine if the battery energy capacity (kWh storage) is within the proper limit, given the age and mileage of the vehicle. Your Volt battery warranty replacement may not return your vehicle to “as-new” condition...

What this says is that if, in three or four years, when you as an owner have tried to get the advertised range out of your Model S and now have a range of 55 miles and your 0-60 times are 16 seconds...

I guess you need to re-read the warranty, especially the part about "gradual energy or power loss with time and use." Dropping from 125 to 55 in 4 years is not gradual, and would be covered.

Perhaps more importantly, this situation you pulled out of your ear hasn't happened with Roadster owners and is even less likely to happen with Model S. The way Tesla has been treating its customers there is every reason to expect that a 55 mile range after 3 years (assuming start point was 125) will be covered since it means there's actually something wrong with the pack. Go read TMC where a few owners have had sheets in their battery packs replaced under warranty when they didn't even know they had a problem! Similarly, for your completely made up 16 second 0-60 time. Again, which Roadster owners haven't experienced. At all.

This is after all EXACTLY what Tesla did with the Roadster owners who bricked their packs...

Nice twist there. There's only one confirmed bricking, and that owner left his already depleted car unplugged for months, despite many warnings in the manual. And then instead of working with Tesla, he went out to attack them in the press.

Do something that your Volt manual repeatedly says not to do and see how well Chevy supports you.

As far as Roadster owners claiming they've suffered no capacity loss, if you want to believe something badly enough no doubt you can torture the data until it confesses.

This is well beneath someone who is supposed to be a Moderator. I did not say "no capacity loss" in any shape or form. I even specifically gave an example of normal degradation. Stop lying.

[sinnombre]

Thanks - I wasn't aware that that was the case with the Volt.

EPA also claims that the Volt uses 8.8kWh to drive 25 miles. That comes to something like 2.84kWh/mile, which is perfectly fine, but if you take the usable capacity of 10.3kWh you get 3.69 miles/kWh, which is way off the EPA estimate and on the tail of the i-MiEV (weighing nearly half of what the Volt does), which is a bit unbelievable IMO.

The EPA 2.84 miles per kWh estimate for the Volt is very low . The only time I use that much energy is when I step into a hot car and the A/C has to cool on max for the first few minutes . After that , I normally get 3.5 - 4.3 miles per kWh . Today I went to the post office and used 2.1 kWh for an 8.1 mile round trip . (3.8 miles per kWh)

Conditions : 103 degree heat , a few stops for signal lights , 43- 50 mph when not stopped .


My 2 cents on the Tesla 60 kWh and 85 kWh battery packs . They have one advantage that people are forgetting . They aren't going to be regularly drained to less than 30 % like the others because few people drive more than 120 miles on a daily basis .

[DonC]

I guess you need to re-read the warranty, especially the part about "gradual energy or power loss with time and use." Dropping from 125 to 55 in 4 years is not gradual, and would be covered.
...
This is well beneath someone who is supposed to be a Moderator. I did not say "no capacity loss" in any shape or form. I even specifically gave an example of normal degradation. Stop lying.

Tesla doesn't warranty the battery EXCEPT for defects. The warranty can't really be clearer. It explicity says that Loss of Battery energy or power over time or due to or resulting from Battery usage, is NOT covered under this New Vehicle Limited Warranty. Under the plain terms of the warranty, not only would a loss of range from 125 miles to 55 miles NOT be covered by the warranty, the warranty wouldn't cover the same loss of range over ONE year. Loss of capacity or power is covered ONLY if there is a defect which creates a sudden and dramatic loss of capacity. Since you seem resistant to accepting this fact, my strong recommendation to you is that, if you're considering buying a Model S, and you believe capacity and power loss is covered, that you consult with a lawyer so you understand what you are buying, or, in this case, what you are not buying.

If you want to see how this works in practice just look at the Leaf. The warranty for the Leaf basically says the same thing as the Tesla warranty in a slightly different way, and Nissan hasn't been bashful about pointing out that all those Leaf owners who have lost 40% of their capacity in a year do not have a warranty claim. This will not be a problem for me because unless a company is going to put their money where their hype is -- and warrant capacity -- there is no way I'm buying an EV from them.

BTW Panasonic has most certainly posted the specs on the Model S 18650 cells. Just do a Google search.

[DonC]

The EPA 2.84 miles per kWh estimate for the Volt is very low .

I think the estimate is pretty accurate. Keep in mind that there are many variables and a single number can't cover them all. Lots of Volt owners get only 25 miles of range during the winter but over 45 miles in the summer. The (now) 38 mile range seems about right for the average driver over the course of all four seasons.

[sinnombre]

I think the estimate is pretty accurate. Keep in mind that there are many variables and a single number can't cover them all. Lots of Volt owners get only 25 miles of range during the winter but over 45 miles in the summer. The (now) 38 mile range seems about right for the average driver over the course of all four seasons.

If the EPA rating is 35 miles and the usable energy per charge is 10 kWh , doesn't that calculate to 3.5 miles per kWh ?

I understand the need to not over estimate , but they need to show it's fair weather capabilities . Otherwise Toyota will continue the slaughter with the 70-80 mpg exaggerations of the Prius .