Debunking Audi's ‘sustained power beats top power’

[SageBrush]

Ah, I see what you mean .

Re: congruent triangles ?

Just in case we are talking about different things:
The blue and yellow triangles are equal area because the bases are set to be equal so in this case equal kWh
It follows that any charge session that starts no more to the right than the left side of the blue triangle and ends no further right than the right side of the yellow triangle cannot favor the constant power case.

 

[Leafdriver333]

Unless there is an intervention from an alien, any advantage in Audi's or Tesla's technology will not be large enough to sway my car buying decision.

(I charge at home 99% of the time after work and I don't have any inconveniences with my level 2 charging.)

 

[sreams]

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.

The title of the thread is "Debunking Audi's 'sustained power beats top power'. And the OP then goes on (in the thread he authored) to compare EPA miles in his chart. That makes it undeniably clear what the OP's intent is, and thus what the thread is about.

Beyond that... in the case of an EV, top power does beat sustained power in many cases, because most normal humans don't drive the entire range the battery allows without stopping. If you stop every 200 miles, the Model 3 LR will charge faster than the Audi, whether you measure in miles or in kWh.

 

[Leafdriver333]

"... Every 200 miles..."
That would be nice.
I have to stop every 140 miles with my SR+.
ICE freeway range is about 350 miles. For an EV to have similar range the battery size have to be about 180 kwh. (350 wh/ mile @ 80mph)
Will the battery even fit in a model 3? And what about the price? At $200/kwh, it will raise the price by $20000.
The roadster 2's 700 mile range is just unbelievable.

 

[CarlK]

Unless there is an intervention from an alien, any advantage in Audi's or Tesla's technology will not be large enough to sway my car buying decision.

(I charge at home 99% of the time after work and I don't have any inconveniences with my level 2 charging.)

Your decision should be swayed by number of chargers available outside your house though. In occasions you do drive somewhere else the difference between if there are chargers available or not would be huge.

The roadster 2's 700 mile range is just unbelievable.

I thougt it's 600 miles. Jugdging from that S could already get 370 mile range it's not that unbelievable anymore. People were thinking a 200kWh battery is needed but with still a year for improvement plus lighter weight and better aerodynamics a ~140 kWh battery could just be enough to do it.

 

[brianman]

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.

Then why are you clicking "Disagree" to all posts offering facts that don't align with your mental model?

Examples:
Debunking Audi's ‘sustained power beats top power’
Debunking Audi's ‘sustained power beats top power’

 

[Leafdriver333]

Your decision should be swayed by number of chargers available outside your house though. In occasions you do drive somewhere else the difference between if there are chargers available or not would be huge.

Yes. Supercharging network was the deal maker.

 

[Leafdriver333]

Your decision should be swayed by number of chargers available outside your house though. In occasions you do drive somewhere else the difference between if there are chargers available or not would be huge.



I thougt it's 600 miles. Jugdging from that S could already get 370 mile range it's not that unbelievable anymore. People were thinking a 200kWh battery is needed but with still a year for improvement plus lighter weight and better aerodynamics a ~140 kWh battery could just be enough to do it.

370 mile is not all freeway miles though. It will be good for may be 250 miles at 78 mph on I-5.

 

[CarlK]

370 mile is not all freeway miles though. It will be good for may be 250 miles at 78 mph on I-5.

Motor Trend has verified the range in mostly freeway driving with speed (intended to be) kept at between 65~70. Although the tester said it's hard to drive that slow on I5. There were some steep grades to climb on both end of the route too.

EXCLUSIVE: 2019 Tesla Model S Review: From SF to LA on One Charge? - MotorTrend

 

[chronopc]

This article does a good job of explaining what the OP is talking about.

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

 

[Zoomit]

This article does a good job of explaining what the OP is talking about.

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

As pointed out upthread, but be cautious as there are number of errors in their analysis. Specifically, their Model 3 conversion to mi/hr charge rate is off and their reference e-tron charge profile video is not an optimal charge session.

 

[SageBrush]

This article does a good job of explaining what the OP is talking about.

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

This tidbit from the article

Audi’s mysterious charging profile is a perfect match. What is striking, however, is that the data posted on Twitter was plotted on a non-equidistant horizontal axis. Notice that 28%, 30%, 40%, and 44% are spaced by the same distance on the chart while being different by 2%, 10%, and 4%, respectively.

was also discussed on reddit. Privater made a mistake with his spreadsheet by setting the SoC results as text rather than numbers. It is just irony that Audi got caught by propagating the error.

 

[Eno Deb]

This tidbit from the article

was also discussed on reddit. Privater made a mistake with his spreadsheet by setting the SoC results as text rather than numbers. It is just irony that Audi got caught by propagating the error.

Yes, they should have been more diligent in checking the data. But the mistake doesn't really change the gist of the argument. And we cannot fully rely on the available data for the Tesla v3 charger anyway since that was only observed on a single prototype station with early-access software and we don't know if they will use the same charging profile when they release v3 charging broadly.

What I'd be much more interested in is to hear some technical background from Audi. From what I can tell the bigger top-end buffer of the Audi battery does not entirely explain how much longer they can sustain 150kW. So what is it that allows them to do that? Cooling, battery chemistry, or just a willingness to risk more degradation?

 

[MP3Mike]

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

 

[Zoomit]

What I'd be much more interested in is to hear some technical background from Audi. From what I can tell the bigger top-end buffer of the Audi battery does not entirely explain how much longer they can sustain 150kW. So what is it that allows them to do that? Cooling, battery chemistry, or just a willingness to risk more degradation?

150 kW at 80% into a 95 kWh battery isn't groundbreaking from a battery perspective. The Hyundai Ionic Electric, which was first sold in early 2017, accepted 69 kW at 75% into it's 31 kWh battery. The Soul EV could basically do the same and was first sold in 2014. Scaling that up to the e-tron's 95 kWh battery would be 211 kW.

A Spark EV could do 47 kW at 80% into a ~20 kWh battery. It was first sold in June 2013. Scaling that up to the e-tron's 95 kWh battery would be 223 kW.

What's different here is the e-tron's battery energy density is quite a bit better than those earlier cars. The Spark EV battery weighs 474 lbs, whereas the e-tron's is about 1500 lbs. So it's only 3x heavier but almost 5x larger capacity.

 

[SageBrush]

From what I can tell the bigger top-end buffer of the Audi battery does not entirely explain how much longer they can sustain 150kW.

I wondered about this also.

I gather that the e-tron battery is 95 kWh nominal and ~ 81 kWh is usable, meaning "100%" charge is actually 81/95 = 85%
150 kW is sustained to "80%," or an actual 0.8*0.85 = 68% SoC. 150 kW at 68% SoC is higher than Tesla allows but not by much and not for long, so I mostly lost interest in the question once I factored in the extra heat from the higher charge rates earlier in the charge cycle.

Lost interest, as in I concluded that Audi does not have a superior chemistry, packaging, or heat dissipation engineering. Semi-quant, I estimate that my Model 3 LR will average about 175 kW from 10 - 60% SoC. If the battery resistances are similar then the Tesla pack will generate in excess of (175/150)*(175/150) = 36% more heat due to the higher power by the time the pack reaches 60% SoC. The actual answer is even more if I bothered to calculate the mean of the squares.

 

[XmUrF]

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.

This and your other post with power/time chart. The thing is, there is no power/time chart here. So if you are making your observation on the charts present here they are just guesses. From what I've found so far regarding V3 supercharging Model 3, you can get 80% charge in 40 minutes. From Audi's chart you can see that the tapering starts around 70% and it is very gradual, you can almost keep the same charging speed up to 80%. If you can average 140kw up to 80% that would be faster than the Tesla method.

The title of the thread is "Debunking Audi's 'sustained power beats top power'. And the OP then goes on (in the thread he authored) to compare EPA miles in his chart. That makes it undeniably clear what the OP's intent is, and thus what the thread is about.

No, it just means that the OP is trying to prove his point using the wrong arguments. His claim that because Tesla gains more mileage when charging(which I guess is true) means Audi's method of charging is inferior is wrong.

Having said that, It is true it's more complicated and depends on whether you are charging up to 80% or less. This also depends on a lot of things. I guess Tesla has optimized for faster charging times up to 50% which may seem more appropriate in some cases. However you also have to understand not all people live in US. Here in Europe there are plenty of countries with highway speed limits up to 140km/h(87mi/h) and this drains the battery really fast. Being able to charge fast for longer is important as well.

 

[XmUrF]

Seriously, why can't I edit my posts? This is frustrating.

 

[Eno Deb]

I wondered about this also.

I gather that the e-tron battery is 95 kWh nominal and ~ 81 kWh is usable, meaning "100%" charge is actually 81/95 = 85%

That assumes that the entire buffer is at the top end, which is unlikely. Also, has the rumored usable capacity been confirmed by someone knowledgeable?

 

[SageBrush]

That assumes that the entire buffer is at the top end

Good point.
Better then to think in terms of C rate