Debunking Audi's ‘sustained power beats top power’

[afadeev]

If you subscribe to Audi's assertion that sustained kW is more important than peak kW or net km/hour charging, then sure, forget about the car and only talk about the battery.

I don't subscribe to anything.
Just trying to gather the facts and develop an informed opinion on the latest in battery chemistry and charging options.

However, the point of my post comparing ABRP results was that the current Supercharger network already allows all three Tesla vehicles to complete a full day's trip in less time than you can in an e-Tron with their allegedly faster charging system. Only the now obsolete Model X takes more charging time and total trip time than the e-Tron.

You are diverting the discussion from battery tech to vehicle preferences and brand affiliations.
I know this is a Tesla forum, but common, man !

a

 

[miimura]

Since I mentioned all three vehicles, I add the Model S 100D (2018) without recent efficiency improvements to the ABRP results.

Model 3 LR AWD: 00:59 charging, 07:58 total
Model S 100D (2018): 1:13 charging, 8:04 total
Model X (2019): 01:13 charging, 08:12 total
Audi e-Tron (mirrorless): 01:21 charging, 08:24 total
Model X (2018): 01:29 charging, 08:38 total

The S does the trip faster than the 2019 Model X because it only makes two stops instead of three.

 

[miimura]

You are diverting the discussion from battery tech to vehicle preferences and brand affiliations.
I know this is a Tesla forum, but common, man !

I am not saying anything about my preferences, I am just talking about vehicle performance. I don't see the point of talking about batteries and charging performance in a vacuum without considering the vehicle it is used in.

 

[sreams]

Sure, you could argue that. However, I think if you put an e-Tron next to a line of 3 / S / X and asked a lay person which vehicle is the most similar to the e-Tron, most would say the X.

True. Because lay people tend to judge a book by its cover rather than consider what it can actually do, unfortunately.

 

[sreams]

Since the point of the comparison is evaluating relative speeds of battery charging, what models those batteries fit into is kinda irrelevant.

It is absolutely relevant. We are also comparing how long it takes to add a certain number of miles of range. If Tesla can build a vehicle that can move just as much cargo and just as many people, but have it be lower to the ground with far superior aero as well as a more efficient powertrain, then they've altered how fast the vehicle effectively charges.

 

[Zoomit]

Here's another interesting take on the Audi presentation slide.

Correcting Audi: Tesla Model 3 Charges Over 2 Times Faster Than Audi e-tron | CleanTechnica

I updated my Model Y graph to be similar to the authors' mi/hr vs miles graph. They used some questionable Model 3 data, but it doesn't change the conclusions.

 

[XmUrF]

There is absolutely no point in comparing added miles per minutes as this includes other factors in the equation unrelated to charging! What should be looked at is average added watts per minute for the total duration of the charging.

However because of the Audi's battery reserve their 80kwh battery should be compared with Tesla's 90, but charged up to 80kwh.

 

[sreams]

There is absolutely no point in comparing added miles per minutes as this includes other factors in the equation unrelated to charging! What should be looked at is average added watts per minute for the total duration of the charging.

However because of the Audi's battery reserve their 80kwh battery should be compared with Tesla's 90, but charged up to 80kwh.

I totally disagree. How much energy a battery can store is meaningless if you don't know how efficient the thing using that energy is.

Example:

EV 1 can charge it's 100kWh usable battery capacity in 10 minutes. It can travel 1 mile on a full charge.

EV 2 can charge it's 100kWh usable battery capacity in 30 minutes. It can travel 300 miles on a full charge.

You'd have us declare EV 1 the winner, because there is "no point" in comparing added miles. The opposite, however, is true. How much energy is stored in a car's battery is meaningless. What a vehicle can do with a certain amount of energy and with a certain number of minutes charging is everything. It's the only thing that matters.

 

[afadeev]

I totally disagree. How much energy a battery can store is meaningless if you don't know how efficient the thing using that energy is.

You are totally missing the point.
This thread is not comparing cars. At all.
The article raised the prospect of optimizing total battery charging time by feeding a steady 140 kW+ rate vs. spiking to 250+ kW initially, then linearly decaying towards 50 kW as cooling system is struggling to remove excess heat.

If the observation is valid, there may be room for Tesla to improve charging times further, based on Audi's research, all else being equal.
Which it may not be, if battery chemistry and cooling approaches are different between Panasonic (aka Tesla) and LG Chem (aka Audi) batteries.

You'd have us declare EV 1 the winner, because there is "no point" in comparing added miles. The opposite, however, is true. How much energy is stored in a car's battery is meaningless

There is literally no point in getting defensive about Tesla, or arguing "oh, but I can driver further/quicker in car X vs. car Y".
No car is a "winner" here.
Knowledge of how to optimally charge the batteries is.

a

 

[SageBrush]

Just trying to gather the facts and develop an informed opinion on the latest in battery chemistry and charging options.

Keep on trying

 

[SageBrush]

The article raised the prospect of optimizing total battery charging time by feeding a steady 140 kW+ rate vs. spiking to 250+ kW initially, then linearly decaying towards 50 kW as cooling system is struggling to remove excess heat.

Do you own a Tesla ?
If so I hope you choose the V2 Superchargers and leave the V3 for people who want it.

As for your guess, we don't know yet how much of the taper is due to heat and how much due to SoC.
This is what I do know, based on the experience reported thus far: in my Model 3 LR I'll be able to start at a SoC of ~ 10% and add 150 EPA miles at an average 175 kW on a V3 Supercharger.

Arithmetic aside, do you really think that Tesla would not have set the V3 to peak at 150 kW if that made for faster charging ? Really ?! The combined genius of Tesla cannot calculate a high school level maxima problem ?

One last point: The Audi line is a sleight of hand because some 13% of capacity is unused. The SoC values use different scales which lets Audi display the start of taper at a higher SoC

 

[SageBrush]

What should be looked at is average added watts per minute for the total duration of the charging.

Good luck with that.

 

[XmUrF]

Good luck with that.

Well it is not that hard. All we need is the time needed to charge e-tron's battery up to 100% and the time it is needed to charge a tesla 90kwh battery pack up to 88%(let's say from 10%). Nothing else really matters.

If the Audi charges faster, then Tesla can only benefit from this information, if not, all is good and Tesla reigns supreme .

 

[XmUrF]

P.S.
Of course this cannot be done right now because there is no Model 3 with such a big battery and S and X with 90kwh packs cannot charge with 250kw.

 

[SageBrush]

Well it is not that hard. All we need is the time needed to charge e-tron's battery up to 100% and the time it is needed to charge a tesla 90kwh battery pack up to 88%(let's say from 10%). Nothing else really matters.

If the Audi charges faster, then Tesla can only benefit from this information, if not, all is good and Tesla reigns supreme .

You misunderstand my comment. Watts per time has no useful meaning in this discussion.

However, kWh is a useful unit.
Consider a graph that plots power on the Y axis and time on the X axis. The AUC is kWh.
Just eyeball the graph with one line drawn at Y = 150 kW and another line the V3 power output into a Model 3 LR
Can you identify the two congruent triangles ?

If all else fails just make a spreadsheet.

 

[sreams]

You are totally missing the point.
This thread is not comparing cars. At all.

It isn't for you to decide what this thread is about. The OP made a point that Audi (who put their battery into a car) is failing to consider charging speed as it relates to the thing being charged (a car). So the thread is exactly about comparing cars. And if you look at Audi's own chart, it compares... cars. Not batteries in a test lab.

 

[SageBrush]

It isn't for you to decide what this thread is about. The OP made a point that Audi (who put their battery into a car) is failing to consider charging speed as it relates to the thing being charged (a car). So the thread is exactly about comparing cars. And if you look at Audi's own chart, it compares... cars. Not batteries in a test lab.

I agree, but @afadeev has asked a tangential question whether a V3 Supercharger set to 150 kW ~ constant would be a faster charging time than the power curve Tesla has chosen. The answer for the Model 3 LR varies from no to hell no depending on start and end SoC.

 

[XmUrF]

It isn't for you to decide what this thread is about. The OP made a point that Audi (who put their battery into a car) is failing to consider charging speed as it relates to the thing being charged (a car). So the thread is exactly about comparing cars. And if you look at Audi's own chart, it compares... cars. Not batteries in a test lab.

If you really believe that then we must be reading different forum threads. The title clearly states that we are discussing different charging techniques, not cars. And no, Audi does not compare cars, it compares Audi's choice of charging method vs Tesla's choice. It has nothing to do with each car efficiency and mileage! You can't debunk Audi's claim that sustained power beats top power by insisting that Tesla's cars are more efficient and have better range. These are two separate things.

[QUOTE="SageBrush]You misunderstand my comment. Watts per time has no useful meaning in this discussion.

However, kWh is a useful unit.

Consider a graph that plots power on the Y axis and time on the X axis. The AUC is kWh.
Just eyeball the graph with one line drawn at Y = 150 kW and another line the V3 power output into a Model 3 LR
Can you identify the two congruent triangles ?
[/QUOTE]

Ah, I see what you mean . Granted, you seem more familiar with various units of works, but that is not the point. I am pretty sure you understood what I mean. We need to find average charging rate or total charging time for comparable batteries and the discussed here added mileage per minute is definitely not doing this. Audi's chart is much more representable for the case.

Also I am not sure I get your point about the chart. The claim is that if you charge with 150kw continuous instead of 250kw peak, it will be able to sustain 150kw for longer, thus achieving faster charging time. Audi claim they are doing just that but their comparison is flawed, because their battery is bigger and they charge it only to about 89%. That's why I said we need comparable batteries to find out whether they are right or not.

[QUOTE="SageBrush]I agree, but @afadeev has asked a tangential question whether a V3 Supercharger set to 150 kW ~ constant would be a faster charging time than the power curve Tesla has chosen. The answer for the Model 3 LR varies from no to hell no depending on start and end SoC.[/QUOTE]

Well, if you charge from 10 to 50%, obviously Audi's way is not better, but I don't think you have the data to claim that for charging to 100%. You don't know all the possible reasons behind the aggressive tampering in Tesla's case and you don't know whether it will be possible to sustain somewhat lower charge rate for longer period of time.

 

[sixela]

You can't debunk Audi's claim that sustained power beats top power

If a flat curve is all you want, just clamp the start of the curve and chop off the end by not allowing people to charge fully at low rates. Problem solved, except that the integral of power over time (i.e. energy to the battery) isn't any higher than it was before you nerfed the low SoC charging rate and the maximum SoC.

Seriously, the Audi e-tron charging curve is not too shabby (except if compared to Tesla V3 SC rates). In Europe, where there are already quite a number of E-Trons, the main problem is not the charging rate, since it's decent. It's making sure that your car actually charges at 150kW with third-party fast chargers --it doesn't always "just work"-- and it's the fact that it guzzles a lot of energy per km for the interior space you get (but the trunk space is excellent!) because of the form factor they chose, which makes the maximum range smaller (Tesla's Model X suffers from the same choices made, if you compare it to an S or a Model 3). And if you drop an E-tron to 0km, that's _really_ 0km: with repeated starts you'll manage to limp only one km further before the car refuses to budge.

Audio are limiting max amperage and disallowing customers to fill the battery completely because they value reliability and don't yet know how far they can push the battery -- it's new technology for them. That gives them a flat charging curve.

The rest, as they say, is spin. That spin, I would expect, is going to disappear as soon as Audi has enough experience to become less conservative. Just as the Model 3 early delivery model was panned by VW for years, but not anymore since for the ID.3 basically areplaying by the Tesla book ;-).

 

[SageBrush]

Well, if you charge from 10 to 50%, obviously Audi's way is not better, but I don't think you have the data to claim that for charging to 100%. You don't know all the possible reasons behind the aggressive tampering in Tesla's case and you don't know whether it will be possible to sustain somewhat lower charge rate for longer period of time.

I know from looking at the chart as I described it to you above (Power Vs time) that the Tesla algorithm handily beats 150 kW constant in any situation starting from 10 - 20% SoC going up to as much as 80% SoC.

You should also keep in mind that Tesla owners on long drives who know what they are doing preferentially stop charging when they have enough range + buffer to reach the next charging stop. So 10% - 60% Soc or thereabouts in a Model 3 LR is the most important part of the graph. Tesla long distance driving is an integrated system that takes the car and the Supercharger network into account.

Audi has to consider charging up to 80% SoC because their car has too limited a range otherwise. Don't constrain Tesla with the same baggage.

Regarding units of measurement: I will not guess at what you mean.