Available kWh in Standard and Range Mode for Model S?

[Wattson]

Hi all,

I'm new here and haven't yet been able to find the answer to my question through the forum search feature. If anyone has any info or could point me to the appropriate forum, I'd greatly appreciate it. I've also considered that the info might not yet be available. I feel that I can make a more informed buying decision in the future with this info.

When Tesla advertises 40, 60 and 85 kWh battery pack capacities, are those the absolute capacity of the pack or the available capacity?

I've learned via the forum that the Model S will have two charging modes: Standard and Range. What is the user available kWh charge in Standard and Range in each of the three battery packs?

Cheers,
David

 

[ckessel]

I've learned via the forum that the Model S will have two charging modes: Standard and Range.

Can someone actually confirm this? I've yet to see the car and not ever actually heard that the Model S will have selectable charging modes.

 

[Wattson]

I've seen it mentioned by several people in various threads. I found the best confirmation in this post.

 

[ckessel]

I've seen it mentioned by several people in various threads. I found the best confirmation in this post.

So, then the next question would be is 300 miles in standard or range mode? It feels a bit disingenuous to advertise 300 mile range (or EPA 265) if that range can only be reached by damaging the battery with range charging. If the listed mileage is only in range mode, that really cuts down effective range.

Take a 160 battery, use standard mode, freeway speeds, and give it a few years degradation and you get maybe 80 miles of realistic freeway range?

 

[Kevin Sharpe]

If the listed mileage is only in range mode, that really cuts down effective range.

With respect, isn't that the same as the Roadster?

 

[smoothoperator]

With respect, isn't that the same as the Roadster?

Tesla recently changed their position from there only being one mode (standard) on the Model S to two modes. They must have seen degradation in the battery (after multiple trips where the battery was almost depleted) when only having a single mode and legal probably made them add range mode to cover their butts with a disclaimer about "using range mode + longevity of the battery." It is a recent & sudden development that Tesla implemented an additional mode on the Model S.

 

[Doug_G]

To be fair, Tesla previously stated that they hadn't decided on charge modes yet. So there's nothing "sudden" about the decision to include Range mode... they've simply decided.

For the Roadster Standard mode gives you 80%, BUT since it actually charges to 90% and hides the bottom 10%, you can always access the bottom 10% by tapping the touchscreen - an extra 10% "magically" appears.

It is woth noting that the Model S apparently doesn't need a Performance mode, unlike the Roadster. That's nice to see.

 

[ckessel]

With respect, isn't that the same as the Roadster?

Yes, but 99.99% of the people that will buy the Model S (over the next few years) will never have seen or know how the Roadster worked. They, like me, will simply come in and go "Wait, you mean I can't actually get the advertised range without hurting the battery?" Then, hopefully, would be a flurry of questions (the other possibility is the customer just leaves in annoyance).

How often can I charge in range mode before it does damage? How much damage? What does that mean for the warranty? How does that impact my lease if I use range mode frequently? etc, etc, etc

I'm pretty much in Tesla's corner, but I'd thought all this time the 300 mile battery was with a standard charge. I, in part, sold the concept of Tesla to my wife with the idea should could regularly make the 240 mile round trip Portland->Eugene->Portland without much strain, or the coast and back, but it sounds like that might not be true if I'll have to charge in range mode each time. In short, if 300 (EPA 265) isn't a standard charge that has some impact on my perception of the car's overall value.

 

[smoothoperator]

To be fair, Tesla previously stated that they hadn't decided on charge modes yet. So there's nothing "sudden" about the decision to include Range mode... they've simply decided.

For the Roadster Standard mode gives you 80%, BUT since it actually charges to 90% and hides the bottom 10%, you can always access the bottom 10% by tapping the touchscreen - an extra 10% "magically" appears.

It is woth noting that the Model S apparently doesn't need a Performance mode, unlike the Roadster. That's nice to see.

Before the "Rainbow Event" Tesla "Geniuses" were telling customers that there would only be one mode.

 

[Wattson]

So one potential answer to my question is that Standard mode allows 80% of the battery capacity to be used. Somewhere else on internet.com or this forum, I've seen the figure 3.5 miles per kWh thrown out for the average Model S efficiency. Using these figures, usable range is:

40 kWh pack
32 kWh usable
112 miles of range

60 kWh pack
48 kWh usable
168 miles of range

85 kWh pack
68 kWh usable
238 miles of range

Again, these are just estimates based on assumptions of 80% charge available in Standard mode and an average efficiency of 3.5 miles per kWh.

 

[Wattson]

For the Roadster Standard mode gives you 80%, BUT since it actually charges to 90% and hides the bottom 10%, you can always access the bottom 10% by tapping the touchscreen - an extra 10% "magically" appears.

Doug or anyone... What percent of the battery is made available to the user in Range mode on a Roadster?

 

[Andrew Wolfe]

Come on now. Range mode doesn't "damage" the battery. It just uses it up faster. Just like driving at maximum specs uses up tires and brakes faster. Nobody complains that "If I accelerate 0-60 in 4.4 seconds every day then I only get 4000 miles out of the tires," but that is probably the reality of the situation. Admittedly, batteries are expensive and thus everyone is oversensitive about them - but if you drive at 90-100% of range every day then you are driving the wrong car.

 

[smoothoperator]

Doug or anyone... What percent of the battery is made available to the user in Range mode on a Roadster?

100% (10 char)

 

[brianman]

Come on now. Range mode doesn't "damage" the battery. It just uses it up faster. Just like driving at maximum specs uses up tires and brakes faster. Nobody complains that "If I accelerate 0-60 in 4.4 seconds every day then I only get 4000 miles out of the tires," but that is probably the reality of the situation. Admittedly, batteries are expensive and thus everyone is oversensitive about them - but if you drive at 90-100% of range every day then you are driving the wrong car.

As I understand it, Range mode can damage the battery. But the scenario is more specific: charge it to full in range mode, and then leave it sit at that full charge for a day. That does damage to the battery.

Charging it to ranged mode and driving it down to "normal range" within a few hours of reaching full charge shouldn't cause undue strain on it though.

That's how I understood it from the Roadster engineer(?) post a bit back.

 

[Doug_G]

Doug or anyone... What percent of the battery is made available to the user in Range mode on a Roadster?

Tesla specifies the Roadster battery pack at 56 kWh, but elsewhere have stated 53 kWh.

The consensus appears to be that the pack is 56 kWh nominal and 53 kWh usable (in Range mode).

Also Range mode does NOT damage the battery. The rate of cell degradation is slightly higher than normal while the car is fully charged or nearly empty. By using Range mode judiciously the additional degradation is tiny. If you charge to 100% and then immediately drive off the pack gets back under 90% in short order, so the time spent in the extra degradation range is tiny. (It's actually better for battery balancing to leave it at 100% for a couple of hours once in a while.)

 

[Wattson]

Thanks all for your speculative answers. It seems so far that official usable battery figures are not yet available.

As for the average Model S efficiency of 3.5 miles per kWh figure, it seems supported by the second graph in this Tesla blog post.

 

[Wattson]

The consensus appears to be that the pack is 56 kWh nominal and 53 kWh usable (in Range mode).

If 53 of 56 kWh is available in the Roadster, that would mean about 95% of the battery would be available in Range mode. Again assuming an average efficiency of 3.5 miles per kWh:

40 kWh pack
38 kWh usable in Range mode
133 miles of range

60 kWh pack
57 kWh usable in Range mode
199.5 miles of range

85 kWh pack
80.75 kWh usable in Range mode
282 miles of range

Disclaimer: The above figures are just some speculative math based on the context of Roadster usable battery charge and assumption of 3.5 miles per kWh efficiency for Model S

I'm a lot more comfortable with the numbers I've generated in this thread. The Standard and Range mode mileage estimates seem a lot more real based on facts available and reasonable assumptions.

 

[ckessel]

Come on now. Range mode doesn't "damage" the battery. It just uses it up faster.

What's the distinction between "damage" and "impacts long term battery life" (the wording from the Tesla screen shot)? We're just talking semantics?

If Tesla is warning about long term impacts of range mode, seems like that leads to those various questions I mentioned.

Edit: (having seen Doug_G's post) Sounds like Tesla needs to have a very clear specification about what "long term impact" means with range mode or a great many people are going to assume it's essentially all but verbotten to use range mode at all. In my mind, I'm wondering "So, 1% damage each time?" I have no idea, neither does 99.99% of the rest of the population. Sounds like it's an education issue Tesla needs to jump way out in front of.

 

[stopcrazypp]

"So, 1% damage each time?"

It doesn't work like that and it's not really possible to have a very clear specification to the general public (without them being willing to learn about the details of battery chemistry).

I'll refer you to wikipedia on lithium ion batteries. A laptop cell stored at 100% SOC loses 20% capacity per year. Stored at 40-60% SOC it loses 4% capacity per year. That's what Tesla means by long term impact.
http://en.wikipedia.org/wiki/Lithium-ion_battery#Disadvantages

What matters is not what happens "each time". What matters is how long the battery is stored at or near 100% SOC. So if you charge in Range Mode and use up the charge almost immediately, the long term impact is negligible. But if you charge in Range Mode and store the car for long periods of time (I'm talking about weeks, not just days) near 100% SOC, then the impact is huge. And it's very hard to quantify this in specific numbers (esp. because the relation is not linear).

And Doug G makes a good point that this is not "damage". This is just accelerated degradation (which happens even if you pamper the battery). You can think of it as extra "wear" (like Andrew's analogy). Damage is something like over-voltage or under-voltage (which would make the battery cell completely unusable, see the whole bricking controversy).

 

[ckessel]

It doesn't work like that and it's not really possible to have a very clear specification to the general public

Well, Tesla's going to need to find a way to make that discussion possible because people are going to want to know and they'll feel very uncomfortable and untrusting with vague answers.

What matters is not what happens "each time". What matters is how long the battery is stored at or near 100% SOC.

Then that sounds like the educational material Tesla needs to put together. I'm not trying to be a hardass here, people are going to want to know. George B even talks about how the stores are about educating people on EVs. This seems like a good fit of purpose.

And Doug G makes a good point that this is not "damage". This is just accelerated degradation (which happens even if you pamper the battery). Damage is something like over-voltage or under-voltage (which would make the battery cell completely unusable, see the whole bricking controversy).

This is just quibbling semantics. It all boils down to "I do X and the battery gets worse by Y". Very few people, including fairly technical people like me, are going to care about the technical classifications of why Y gets worse. You might argue they should care, but that's fighting human nature and that battle is lost before it's started.