Tesla cuts 60kWh Model S, entry-level Model S is now 70D.

[qwk]

J

What is also interesting about that pic is the way the pack has been opened.

If you look at wk057's thread:
Pics/Info: Inside the battery pack

You can clearly see that the cover is a simple pressed piece of sheet metal, with the ribs formed as part of the pressing.

The picture we see here has hinged metal bars forming the strengthening ribs of the pack cover.

The layout of the dummy cells is also bugging me. If we think how the pack manufacture would be automated, i.e. using a continuous process a bit like say a bottling plant, why are the dummy cells not missing in a contiguous block, or at least at the end of each strip of cells?

Then there is the issue of balancing individual cells, such a configuration would seem really hard for each strip to balance, or am I missing something?

Overall, it really does look like an early engineering test bed. Only when some third party like WK057 takes apart a production 60 pack and documents it in such detail as the 85 (big thanks to him btw, I found the thread fascinating,) will we truly know.

I have a niggling feeling it would have simplified production and inventory issues to have identical modules and to have simply absorbed the additional cell count cost on the small percentage of modules destined for 60 packs, software limit them to give a decent model differentiation and in the majority of cases recoup that back via Supercharging fees anyway.

That's a regular production pack. They did open it differently, but that is not relevant. Same pack cover. The two dummy modules are made of metal, but who knows what metal Tesla used. The 60kwh packs do use fewer cells per module. This isn't any secret.

One other thing to keep in mind, just because Tesla says that a pack is 85, 60, 70 kwh or whatever, doesn't mean that it is exactly that number. They(like everyone else) round up, and rate them in different ways. A good example is the Roadster pack, depending on what timeframe you look at, Tesla rated the same pack at both 56, and 53kwh. That is quite a difference.

Trying to get an idea of what cells Tesla is using from pack weight and kwh capacity, is pretty much impossible(unless you know some other details).

 

[smac]

Each module contains 6 sub-groups with 74 cell locations in it. These are connected in series for a total of 444 possible cells.

There appear to be 10 spacers per sub-group, so I expect you missed two, and the logical total is 60 spacer cells per module.

60 ties in with the "842" additional cells per module claim. (OK the real number of extra cells per pack should be 840, but studies have shown using non-rounded, or overly precise digits in 99.472% of cases makes a number more psychologically believable )

What I don't get from that pack is why some of the modules appear fully populated, some appear to have black spacers, and one has white spacers. The clustering seems a bit odd too, but without a layout of the cells wiring it could just be an artifact of how they are constructed. The "spacered" modules do seem to be consistent.

Again one could theorize this is an R+D pack and that one module is for investigating the impact of high resistance failure, one is for low resistance failure, and it's effect on the module overall (or more specifically the sub-groups within a module). I'm not sure it's the smoking gun that says 60's are really built this way in production, but has definitely been used as proof in many a discussion.

 

[JRP3]

Again one could theorize this is an R+D pack and that one module is for investigating the impact of high resistance failure, one is for low resistance failure, and it's effect on the module overall (or more specifically the sub-groups within a module). I'm not sure it's the smoking gun that says 60's are really built this way in production, but has definitely been used as proof in many a discussion.

It's a pack from a NHTSA crash test, which as far as I know is a purchased production vehicle.

 

[HankLloydRight]

One more thing I ran across on TMC.. there is a video/quote from Elon talking about optimizing energy density in small batteries, and that the 18650 isn't the optimal size/shape for maximizing energy density in a battery, and that the optimal size is only about 10% larger than the 18650. So if Tesla has been developing new production line plans for the GF over the last year, I would think that they are exploring this new optimal battery size (and chemistries), and not caring about any new battery chemistry in the 18650 form factor.

Maybe this new size will be engineered into the existing form factor for MS and MX packs, but I wouldn't expect to see that until the GF comes online. Until then, I still assert that there's no new change in battery chemistry in production cars today.

 

[JRP3]

On the other hand Panasonic has a lot of 18650 capacity production lines so I'd expect any denser chemistries to end up in those cells as well. In fact they already exist in the form of 3.4ah cells.

 

[Trev Page]

One more thing I ran across on TMC.. there is a video/quote from Elon talking about optimizing energy density in small batteries, and that the 18650 isn't the optimal size/shape for maximizing energy density in a battery, and that the optimal size is only about 10% larger than the 18650. So if Tesla has been developing new production line plans for the GF over the last year, I would think that they are exploring this new optimal battery size (and chemistries), and not caring about any new battery chemistry in the 18650 form factor.

Maybe this new size will be engineered into the existing form factor for MS and MX packs, but I wouldn't expect to see that until the GF comes online. Until then, I still assert that there's no new change in battery chemistry in production cars today.

Yes, they're said that on a few occasions. However the new form factor is really for the gen 3 platform as reengineering the current battery pack to handle any new form factor would be very expensive. Improvements in chemistry for the 18650 would help for the current packs.

 

[jvonbokel]

Again one could theorize this is an R+D pack and that one module is for investigating the impact of high resistance failure, one is for low resistance failure, and it's effect on the module overall (or more specifically the sub-groups within a module). I'm not sure it's the smoking gun that says 60's are really built this way in production, but has definitely been used as proof in many a discussion.

Source: NHTSA Opened Up the Model S Battery Pack - Pics

 

[vgrinshpun]

OK, the verdict is in.

According to the Car and Driver instrumented test (thanks to Anticitizen13.7 for posting) the weight of the 70D is 4608lbs, while the weight of now defunct 60D was essentially the same - 4597lbs according to the Road & Track data back from Oct. 9 article published right after the "D" event. This is consistent with my theory that the battery in 70D weighs the same as the battery in 60, contains the same quantity of cells, but each cell, due to higher volumetric and gravimetric energy density contains about 16.7% more energy. This is consistent with the conclusion that 70D contains new generation of the cells, due to show up in Model X, and, perhaps a little later in other variants of Model S.

Hello 300+ EPA range in Model S??

This information is coming from Tesla Store personnel, so should be taken with a grain of salt, but it is consistent with my theory of next gen battery cells in 70D. As posted by TMC member Martin Austin, according to the Austin, TX store employee 70D has a "denser" battery pack. "Denser" means higher energy density...

 

[Andyw2100]

This information is coming from Tesla Store personnel, so should be taking with a grain of salt, but it is consistent with my theory of next gen battery cells in 70D. As posted by TMC member Martin Austin, according to the Austin, TX store employee 70D has a "denser" battery pack. "Denser" means higher energy density...

In the thread you reference above, that post from Martin Austin was made on April 23. But in the same thread there are additional, more recent posts, including one from a new 70D owner who took his Model S to a supercharger and shared the numbers. The conclusions drawn by others in that thread after that were that the cells were not new, denser cells.

Did you not read that entire thread, or are you disputing that?

 

[vgrinshpun]

In the thread you reference above, that post from Martin Austin was made on April 23. But in the same thread there are additional, more recent posts, including one from a new 70D owner who took his Model S to a supercharger and shared the numbers. The conclusions drawn by others in that thread after that were that the cells were not new, denser cells.

Did you not read that entire thread, or are you disputing that?

I am not sure which post are you referring to - no link in your post. If you are referring to this one, I would like to see line of thought laid out to support *that* conclusion.

 

[Andyw2100]

I am not sure which post are you referring to - no link in your post. If you are referring to this one, I would like to see line of thought laid out to support *that* conclusion.

I wasn't referring to any one post in general. To be honest, all of this stuff is a bit too technical for me. But what I saw in that thread was many people posting after the real 70D supercharging numbers had been posted, (including some long-time users who are very well-respected and definitely do understand the technical aspects of batteries and charging far better than I do,) and none of them were questioning the conclusion reached in the post you linked to, while all of them seemed to be on the same page with respect to what they were saying.

So I, perhaps incorrectly, reached the conclusion that since the numbers were now available, the conclusion that seemed to be reached in that thread was generally accepted.

 

[vgrinshpun]

I wasn't referring to any one post in general. To be honest, all of this stuff is a bit too technical for me. But what I saw in that thread was many people posting after the real 70D supercharging numbers had been posted, (including some long-time users who are very well-respected and definitely do understand the technical aspects of batteries and charging far better than I do,) and none of them were questioning the conclusion reached in the post you linked to, while all of them seemed to be on the same page with respect to what they were saying.

So I, perhaps incorrectly, reached the conclusion that since the numbers were now available, the conclusion that seemed to be reached in that thread was generally accepted.

The only post I noticed commenting on the "more" vs. "denser" cells was the one that I linked. I do not know what was the thought process of the person who posted it, so I really can't comment further, except to say that I would like that person to lay-out his line of reasoning - his conclusion in the post is not backed up by any explanation.

 

[stopcrazypp]

What the posts above from superchargers confirmed is that there are 14 modules in the 70kWh and not 16 modules like in the 85kWh. It says nothing about the density of the cells in the pack. For the record, the 60kWh pack has been confirmed to have dummy cells inside the modules that if swapped out for real cells would easily give 74 kWh using the same cells as the 85kWh. It's unknown what those dummy cells weigh.

 

[jvonbokel]

according to the Austin, TX store employee 70D has a "denser" battery pack. "Denser" means higher energy density...

This could just as easily be interpreted to mean more cells, especially when we know that the 60kWh pack had spacers in it. In fact, that's how I would interpret it, if he says it has a denser pack, rather than denser cells.

 

[Gtoffo]

Looks like we still don't have definitive proof one way or the other. It might be that the spacers still weight somewhat, so by "filling them out" overall weight would not change much and we would have the impression of improved cell chemistry.

I see two scenarios here going forward:

• New battery chemistry. When X is presented 85kWh will be phased out in lieu of a 100kWh, leaving us with 70 and 100kWh for both S and X.
• Old batteries, but spacers have been filled out. When X is presented three battery packs might coexist: 70, 85, 100kWh if Tesla wants to ensure that Model X range matches Model S (do we have a source confirming this is their intention?)

We will see.....soon.