Tesla BEV Competition Developments

[techmaven]

I rated you funny because I think you're making fun of the estimated range of the Taycan. Is there anything know about the Taycan's efficiency yet?

Even if they would share the same powertrain (which I don't think), I don't think the eTron's and Taycan's efficiency are similar.

It isn't an issue of efficiency. It's that Porsche has said the Taycan has at least 500 km of range on NEDC scale. A rough conversion of NEDC to EPA is to take 30% off, so that's 218 miles. I rounded up to 225 then, making the assumption that with smaller frontal cross section, it will do better. Given the target curb weight of around 4,500 lbs, the Taycan isn't likely to do all that well on EPA or WLTP testing due to the high amounts of acceleration simulating urban and suburban traffic. The Model S/X do particularly worse at those tests since they are optimized for highway cruising and their AC induction motors are particularly inefficient for accelerating from stops. I am expecting a similar issue with the Taycan due to curb weight, that higher speed travel will cause less range penalty, but that won't show up in the testing. Furthermore, Porsche may restrict the useable capacity in the Taycan further than in the E-tron in order to protect cell degradation given the much higher charging c-rate. I wouldn't be surprised if they restricted 15% instead of the 12.5% in the E-tron. That means 77 kWh of usable capacity, or about the same as the original Model S 85 kWh. Add high performance, likely wider and sticker tires, poorer aerodynamics, and guessing about 225 miles out of the 90 kWh pack is reasonable until Porsche gives us more information.

 

[jbih]

Hm. I've been a huge Porsche fan for a long time and I wanted to believe that the Taycan will be different.

TSLA needs to go up so that I can afford a Tesla Roadster.

 

[pz1975]

English Translation of “étron” | Collins French-English Dictionary

Translation of “etron” from French = “turd”. Seems fitting considering the car’s specs.

 

[jbih]

Table with major manufacturers' explanation if they are profitable building EVs or not. Except for Tesla and Renault/Nissan, everyone says not or barely profitable.

Nafnlaus on Twitter

I think this is a great table to share with anyone talking about EV profitability. And it makes me afraid Tesla will have _no_ competition for quite a while.

 

[mongo]

Table with major manufacturers' explanation if they are profitable building EVs or not. Except for Tesla and Renault/Nissan, everyone says not or barely profitable.

Nafnlaus on Twitter

I think this is a great table to share with anyone talking about EV profitability. And it makes me afraid Tesla will have _no_ competition for quite a while.

Also available here (it's by KarenRei):
Tesla, TSLA & the Investment World: the 2019 Investors' Roundtable

 

[mikevbf]

I think this is a great table to share with anyone talking about EV profitability. And it makes me afraid Tesla will have _no_ competition for quite a while.

Audi and Porche share your concerns:

Tesla Model 3 cost surprised Porsche and Audi after reverse-engineering

choice quote from article:
"The e-tron as the first electric Audi is not only late. It does not reach some target values and has become far too expensive with more than two billion euros in development costs. The approximately 600,000 cars sold for the break-even are now regarded as an illusion."

 

[jbih]

Also available here (it's by KarenRei):
Tesla, TSLA & the Investment World: the 2019 Investors' Roundtable

I suspected it could be Karen because "nafnlaus" is Icelandic: nafnlaus - Wiktionary
Nice!

 

[wdolson]

Table with major manufacturers' explanation if they are profitable building EVs or not. Except for Tesla and Renault/Nissan, everyone says not or barely profitable.

Nafnlaus on Twitter

I think this is a great table to share with anyone talking about EV profitability. And it makes me afraid Tesla will have _no_ competition for quite a while.

It boils down to volume. With car manufacturing there are a lot of fixed costs. Factory space costs x per sq ft if you're building 10K cars or 500K cars. With high volume production, you amortize the costs of the R&D, facilities, and equipment over more cars. It's doable to make very expensive, limited production cars if there is a market for them and you can get away with charging a fortune. There is for Lamborghinis and Rolls Royce but there isn't for a mid-sized family car.

Battery supply is the big limiter for everyone today. Even Tesla might be a bit constricted by battery supply, but they have enough to mass produce a car and do mid-level production on two others. Nobody else has access to the kind of volumes that Tesla does and nobody else has access to batteries as cheap as Tesla.

Nissan had their own captive battery company for a while, but I believe they sold it, but they are the only company outside of China producing an electric car in volumes approaching Tesla. For everyone else EVs are not profitable right now, but you have to drill down to the why. It isn't that they aren't profitable ever period, it's that they can't make a profit on them right now at the volumes they can produce at a price point the public is willing to pay.

Some companies may be looking at what it will take to get to a point where they can produce a profitable EV and realize there is significant risk the company might go bankrupt before they get there going down the paths open to them today.

 

[renim]

Nissan's sale of their battery business is really more of a supplier swap. Nissan is reducing their ownership of the jv from 50% to 25%. NEC's 50% goes to the new supplier.

Factories change hands, but locations remain adjacent to Nissan.

Dont know if it went ahead, agreement between parties was OK, but government s were of various levels of unhappy.

 

[Oil4AsphaultOnly]

Taking this to the Tesla BEV Competition thread, since it seems more relevant.

Thanks but I think my grasp of the facts is more than adequate:

1. KarenRei supplied the figure of 270Wh/kg energy density for the Taycan cell, which I immediately took at face value.

2. Tesla's NCA 21700 cell specific energy density was calculated at 247Wh/kg by Jack Rickard in a teardown video, also yielding 240Wh/kg for the S85 cell. The 100D cells, which are upgraded with silicon, are presumably somewhat better than those in the 85kWh packs and claimed at 250Wh/kg in the link you provided.

3. My 590kg for S100D pack stems from Den, a site admin at EV Compare.io - Find the electric car which suits you best
Don't know how accurate that is but >600kg is a quite vague. How much closer is "much closer"?

4. The Audi pack is stronger by design for crash-resistance but we do not know for instance that it contains a lower proportion of net cell weight than the Tesla S100D pack. It could for example be that Tesla had to expend a larger percentage of its pack weight into cooling the NCA cells with higher internal resistance hence heat generation, such that non-cell weight for each pack could end up being roughly the same despite the differing constructions. This can only be decided once we have a full spec for the Audi cell.

5. The Audi NCM 622 is from LG CHEM and thus presumed to be closely related (chemically) to the Bolt EV cells, which are given in that same link with a comparable specific energy density but a volumetric energy density 61.6% that of the best Tesla NCA cell [100D]
View attachment 376258
6. I think from all that it is not unreasonable to infer that the Audi e-Tron cells have roughly the same energy density in weight terms as Tesla but are still considerably worse for volume, thus quite probably leading to a relatively bulky [and heavy] pack which is overall less energy dense than the S100D.

7. I agree that the Audi cells seem to be designed for a good balance of energy-density and power-density, at the expense of greater volume, compared to Tesla's NCA, which exhibits supreme volumetric energy density at the expense of lower specific power [==charge rate].
i.e. the old "you can pick any 2/3" rule: specific energy density, volumetric energy density or power density.
If this is case it tends to refute the false dichotomy of KarenRei that because Audi's cells are relatively energy dense they cannot be as power dense as Tesla's NCA and thus Audi must be frying their packs by design.

Ah right, I misread your 590kg as 500kg. My apologies.

Back to the point though, being within 110kg with much more crash support still doesn't support your point about a power-dense pack versus energy-dense. The gravimetric density is what's used to make that assessment, not the volumetric density.

One note about the bolt comparison, that battery pack has a max charge rate of 50kw. It's probably not the max that the pack is capable of, but that's what Chevy did to protect the pack.

At this point, I eagerly await Byorn's unembargoed test results (Audi blocked him from releasing that info until later).

 

[OPRCE]

First up, thanks for moving the discussion [start to end] over here where hopefully things can develop in a more calm environment than amongst the easily excitable investor types!

Ah right, I misread your 590kg as 500kg. My apologies.

2. No worries, it happens to the best.

The gravimetric density is what's used to make that assessment, not the volumetric density.

3. Yes, but if the Audi cell volume is as I suspect considerably greater for a roughly equivalent gravimetric energy density as Tesla NCA then those cells will also requires a somewhat larger/heavier pack to contain them, so there is some relationship there though it remains unquantifiable ATM.

4. From the look of the Audi pack illustrations available it seems to contain a fair amount of hollow space in the grid structure and side framing, so it is IMHO quite a bit more voluminous than a Tesla 100D:

... but how that translates into non-cell weight remains to be seen.

5. On further rumination it may be that the Audi engineers more or less made a silk purse out of a sow's ear as the saying goes: they had to make a bigger pack due to the lower cell volumetric energy density so decided to go ahead and also make it into a full value crash-resistant structure in order to at least recoup some of the weight/space disadvantage. Hmmn?

6. I am also impatiently waiting on that terrible slacker Bjørn

 

[Oil4AsphaultOnly]

First up, thanks for moving it to this tread where hopefully things can develop in a more calm environment than amongst the easily excitable investor types!



2. No worries, it happens to the best.



3. Yes, but if the Audi cell volume is as I suspect considerably greater for a roughly equivalent gravimetric energy density as Tesla NCA then those cells will also requires a somewhat larger/heavier pack to contain them, so there is some relationship there though it remains unquantifiable ATM.

4. From the look of the Audi pack illustrations available it seems to contain a fair amount of hollow space in the grid structure and side framing, so it is IMHO quite a bit more voluminous than a Tesla 100D:
View attachment 376315
... but how that translates into non-cell weight remains to be seen.

5. On further rumination it may be that the Audi engineers more or less made a silk purse out of a sow's ear as the saying goes: they had to make a bigger pack due to the lower cell volumetric energy density so decided to go ahead and also make it into a full value crash-resistant structure in order to at least recoup some of the weight/space disadvantage. Hmmn?

6. I am also impatiently waiting on that terrible slacker Bjørn

4. That "Fachwerkstruktur", even though hollow looks way too extensive to be light. And it should be interpretted as sitting between the cell modules (all 31 modules in the flat pack portion - the other 5 modules are in the "head" portion), with the housing cover sitting above it and the housing tray right below it.

Combine this with 5, where the battery pack is bigger (due to the lower volumetric density), are you agreeing that most of the weight difference between Audi's 95kwh pack and the Tesla's 100kwh could be due to the packaging and not the cells?

If we take Tesla's gravimetric density of 250Wh/kg, we get 400kg of cells in a 100kwh pack, which means over 190kg (I'm more inclined to believe 200kg) of the pack is packaging and cooling. The Audi pack weighing 50% more (due to a 33% lower volumetric density) isn't unreasonable, which then gives us essentially the same gravimetric density for Audi's pouch cells.

 

[OPRCE]

4. That "Fachwerkstruktur", even though hollow looks way too extensive to be light. And it should be interpretted as sitting between the cell modules (all 31 modules in the flat pack portion - the other 5 modules are in the "head" portion), with the housing cover sitting above it and the housing tray right below it.

Combine this with 5, where the battery pack is bigger (due to the lower volumetric density), are you agreeing that most of the weight difference between Audi's 95kwh pack and the Tesla's 100kwh could be due to the packaging and not the cells?

Agree on 4.

On 5., all things considered it seems likely.

If we take Tesla's gravimetric density of 250Wh/kg, we get 400kg of cells in a 100kwh pack, which means over 190kg (I'm more inclined to believe 200kg) of the pack is packaging and cooling. The Audi pack weighing 50% more (due to a 33% lower volumetric density) isn't unreasonable, which then gives us essentially the same gravimetric density for Audi's pouch cells.

Leaving volume aside for a moment:
By my calculations 102.4kWh/250Wh/kg = 409.6kg cell weight in 100D pack, from 590kg = 180.4kg packaging = 30.6%

Assuming Audi cell GED wcs is akin to Bolt @ 237Wh/kg so 95kWh = 400.8kg in cells from 700kg = 299.2kg packaging = 42.7%

In best case GED is the 270Wh/kg KarenRei quoted for the Porsche variant = 351.8kg cell weight = 348.2kg packaging = 49.7%

In either scenario the packaging [structure + cooling, etc.] of Audi is significantly heavier than seen with Tesla, by either 118.8 or 167.8kg, for a 7.4kWh smaller gross capacity.

Unfortunately ATM it is impossible to say what proportion of that increase is due to the structure versus cooling, cabling, BMS, etc, but I would guess that, as the added crash structure is mostly lowish-density aluminium profile and module boxes, at that total weight the cooling system must also be generously over-specced, which would tie back to the suspicion that no cells will be wilfully fried in this design.

 

[Oil4AsphaultOnly]

Agree on 4.

On 5., all things considered it seems likely.



Leaving volume aside for a moment:
By my calculations 102.4kWh/250Wh/kg = 409.6kg cell weight in 100D pack, from 590kg = 180.4kg packaging = 30.6%

Assuming Audi cell GED wcs is akin to Bolt @ 237Wh/kg so 95kWh = 400.8kg in cells from 700kg = 299.2kg packaging = 42.7%

In best case GED is the 270Wh/kg KarenRei quoted for the Porsche variant = 351.8kg cell weight = 348.2kg packaging = 49.7%

In either scenario the packaging [structure + cooling, etc.] of Audi is significantly heavier than seen with Tesla, by either 118.8 or 167.8kg, for a 7.4kWh smaller gross capacity.

Unfortunately ATM it is impossible to say what proportion of that increase is due to the structure versus cooling, cabling, BMS, etc, but I would guess that, as the added crash structure is mostly lowish-density aluminium profile and module boxes, at that total weight the cooling system must also be generously over-specced, which would tie back to the suspicion that no cells will be wilfully fried in this design.

Hmmm, so you're advocating enhanced cooling to counter heat from charging? That could work except that the cells are being cooled through two layers of packaging (module casing and housing tray) instead of directly, which is heavily inefficient.

This reeks of Nissan Leaf passive thermal management, which everyone by now knows does NOT work.

One of the articles I linked speculated on some sort of thermal management through the electrodes, but the Audi battery diagram doesn't support this speculation (unless you run the refrigerant through the aluminium crash structure?).

I agree with waiting for supporting data, but initial checks don't support the theory.

 

[JRP3]

Came across this paper looking at NMC cells charging at 6C rate and discussing ways to reduce plating. (These are obviously low density cells.)

Models were tuned starting from parameters collected under an earlier DOE Computer-Aided Engineering of Batteries (CAEBAT) program and updated using new ANL data for thin electrodes at charge rates up to 7C. The model predicts the baseline design can only sustain 6C charging to 60% SOC when electrodes are less than ~50 μm thick, which corresponds to an energy density of <115 Wh/kg during constant current (CC) charging. A small amount of lithium plating is predicted for this condition. To enable XFC, the initial study indicates the need to:Reduce electrode tortuosityImprove electrolyte transport propertiesUse electrodes with high surface area and intercalation kineticsOptimize electrode porosity for rate capability and energy density

The model predicts that CC charge capacity and achieved energy density during XFC quickly drop with an increase in electrode thickness/loading. This is a result of limitations due to relatively poor negative electrode tortuosity, low electrolyte diffusivity, and low electrolyte conductivity leading to electrolyte saturation/depletion, non-uniform electrode utilization, and lithium plating. The model also predicts lithium plating occurs at much lower charge rates with an increase in electrode thickness (see dot-dash lines in Fig. 5). For instance, at 42 μm thick (1.5 mAh/cm2) the model predicts only at a rate of 7C does plating start to occur. At 85 μm thick however, lithium plating is predicted to occur at rates as low as 2C. If the anode tortuosity alone could be reduced to that of the cathode by using spherized graphite, then the maximum electrode thickness that could achieve 60% SOC at a given charge rate improves by about 20%.

http://blogs.anl.gov/access/wp-content/uploads/sites/53/2018/05/XFC-FY18Q1.pdf

 

[renim]

The model predicts the baseline design can only sustain 6C charging to 60% SOC when electrodes are less than ~50 μm thick....At 85 μm thick however, lithium plating is predicted to occur at rates as low as 2C.

http://blogs.anl.gov/access/wp-content/uploads/sites/53/2018/05/XFC-FY18Q1.pdf

so for context, is this referring to anode electrode thickness only? and would 85 μm be about 1/2 the thickness of a typical Panasonic/Tesla equivalent.

 

[JRP3]

I believe that is correct.

 

[Brando]

Came across this paper looking at NMC cells charging at 6C rate and discussing ways to reduce plating. (These are obviously low density cells.)


http://blogs.anl.gov/access/wp-content/uploads/sites/53/2018/05/XFC-FY18Q1.pdf

Elon has mentioned the Li-Ion battery should be called Nickel Graphite battery as those are the largest components.
Suggest searching Jeff Dahn Lithium Batteries one example

and SLAC lithium batteries for fine technical details.

and look for information here Battery Discussion

 

[OPRCE]

Hmmm, so you're advocating enhanced cooling to counter heat from charging? That could work except that the cells are being cooled through two layers of packaging (module casing and housing tray) instead of directly, which is heavily inefficient.

This reeks of Nissan Leaf passive thermal management, which everyone by now knows does NOT work.

One of the articles I linked speculated on some sort of thermal management through the electrodes, but the Audi battery diagram doesn't support this speculation (unless you run the refrigerant through the aluminium crash structure?).

I agree with waiting for supporting data, but initial checks don't support the theory.

1. Not sure I'm advocating it but saying it looks like that is what must be happening, otherwise at a loss to explain what packaging diff of up to 167.8kg goes into.


2. Leaf was passive air cooled, i.e. without even a fan it's the worst/cheapest design imaginable. This Audi pack is more like the Bolt EV, active liquid bottom-plate cooling, only [I presume] beefed up in all directions. Which would be no surprise if LG CHEM had an input on the design. AFAIK the Bolt EV battery has proved relatively reliable in all climate conditions and no problems since Dec.2016 with premature degradation, a stark contrast to the Leaf's sorry record.


3. Continuing comparison with Bolt EV pack, described by WikiPedia as a "stressed member":

Weight = 440kg for 60kWh with cells of 237Wh/kg = 253.2kg in cells leaves 186.8kg in packaging = 42.5%
which is almost identical to the percentage packaging in Audi pack, assuming cells have same GED.


4. Also of note from WP:
"The Bolt's battery uses "nickel-rich lithium-ion" chemistry, allowing the cells to run at higher temperatures than those in GM's previous electric vehicles, allowing a simpler and cheaper liquid cooling system for the 60 kWh (220 MJ) battery pack."

Have not found information on what those higher temperatures actually are, or how they compare to Tesla-typical ranges, but in general a higher delta between heat source and coolant should tend to increase the efficiency of the cooling system, right?

The simpler and cheaper system refers to the bottom plate as opposed to the stacked inter-cell cooling seen in the Volt:

5. Audi e-Tron motors are rated for 300kW (peak) versus 150kW for Bolt EV, whereas the pack is less than twice the energy capacity, so it would appear the cooling system should be proportionately improved, or the chemistry improved to produce less heat output. I suppose the latter is less easy to achieve than the former.


6. Passive "tab cooling" inside the Audi modules could happen to some extent if e.g. thick aluminium cables conduct the heat out and there is then something else to wick it away, or the modules are filled in with an engineered cooling fluid which is electrically isolating but heat conductive, but it's most likely not part of this design as there has been no mention of it so far.
It may simply be a dual-function of the possibly quite thick aluminium module walls to act as intercalated passive heat conductors between the cell blocks to soak the heat down to the bottom plate.
From the schematic there is no indication of refrigerant running through the aluminium crash structure.


7. Something else that might help with cooling while charging is the battery configuration:

Bolt EV 288*208Wh cells, nominal 350V/3.65V = 96S3P at max charge 50kW = 143A /3 = 47.6A in each strand *3.65V = 174W
if 5% heating loss = 8.7W/cell, thus pack max heat load = 2.5kW

e-Tron 432*220Wh cells, nominal 396V/3.65V = 108S4P at max charge 150kW = 375A /4 = 93.75A in each strand = 342.2W
if 5% heating loss = 17.1W/cell, thus pack max heat load = 7.5kW

Here we see that the cell capacities are close [208 v 220Wh] but due to the electrical layout each cell charging at max produces waste heat (if assumption holds) at 8.7 v 17.1W, i.e. double for e-Tron, whereas the total pack heat load is tripled for e-Tron. Thus addition of 1 parallel path means the heat load per cell is more spread out, facilitating cooling.

[source for basic figures: Bolt EV, e-Tron]


8. Similarly for max discharge loads [if same 5% heating loss]:

Bolt EV pack supplies 150kW peak motor = 26.1W/cell, thus pack max heat load = 7.5kW

e-Tron pack supplies 300kW peak motor = 34.2W/cell, thus pack max heat load = 15kW

Conclusion: e-Tron pack has 1.58x capacity of Bolt but must eliminate triple the pack max heat load [which is double the cell max heat load] to avoid frying cells.


9. I'm not entirely sure any more what the original theory was! (apart from the frying batteries bit)

 

[mongo]

7. Something else that might help with cooling while charging is the battery configuration:

Bolt EV 288*208Wh cells, nominal 350V/3.65V = 96S3P at max charge 50kW = 143A /3 = 47.6A in each strand *3.65V = 174W
if 5% heating loss = 8.7W/cell, thus pack max heat load = 2.5kW

e-Tron 432*220Wh cells, nominal 396V/3.65V = 108S4P at max charge 150kW = 375A /4 = 93.75A in each strand = 342.2W
if 5% heating loss = 17.1W/cell, thus pack max heat load = 7.5kW

Here we see that the cell capacities are close [208 v 220Wh] but due to the electrical layout each cell charging at max produces waste heat (if assumption holds) at 8.7 v 17.1W, i.e. double for e-Tron, whereas the total pack heat load is tripled for e-Tron. Thus addition of 1 parallel path means the heat load per cell is more spread out, facilitating cooling.

[source for basic figures: Bolt EV, e-Tron]

Your X% of cell power might work for electrochemical losses, but you need to use the square of current for resistive losses. Double the charge current (47 vs 94 per string) means 4x the heat per cell due to resistance, assuming the same resistance.