Discharging at High Speed (>100 mph)

[L@urens]

My E61 535d needed a fuel stop on a nightly 600km autobahn trip, so to assume you will never drop below 600km range in a 3l diesel is false, given enough empty autobahn. City trafic is even worse.

Also, a 3.0TDI only has 265ish hp, alot slower than the S in acceleration. Compare to the 2.7TFSI...

 

[Realist]

535i has a smaller tank than the A6. Anyway we are talking about mpg figures double the factory claims.

The biggest A6 TDI has 313hp and it will annihilate the Model S on any free Autobahn.

 

[widodh]

535i has a smaller tank than the A6. Anyway we are talking about mpg figures double the factory claims.

The biggest A6 TDI has 313hp and it will annihilate the Model S on any free Autobahn.

You however keep ignoring the fact that a Model S is just way more efficient then a A6.

One liter of diesel/gasoline holds roughly 10kWh of energy! So a Model S only has a 8L "tank" instead of the 60 ~ 70L.

It's just the laws of physics here, nothing wrong with Model S.

 

[Realist]

I don't ignore that, this is exactly what I wrote earlier.

It's a 8l tank weighting 500kgs.

 

[widodh]

I don't ignore that, this is exactly what I wrote earlier.

It's a 8l tank weighting 500kgs.

We can turn the same story around about weight The 3.0TDI including transmission weighs about 400kg, so that's not a big difference.

The thing we have to realize is that energy consumption of a EV will always spike upwards the faster you go.

At some point you might reach 1000km on a charge going 100km/h, but when driving 160km/h you'll get about 300km of range.

 

[brianman]

The thing we have to realize is that energy consumption of a EV will always spike upwards the faster you go.

Why the "EV" qualifier here vs. "any automobile tech currently available"?

 

[widodh]

Why the "EV" qualifier here vs. "any automobile tech currently available"?

I had to explain that better. A EV always runs on ~90% efficiency where a ICE runs at 25%, but it becomes a bit more efficient, going towards 30% the faster you drive.

So it doesn't spike up as 'badly' as a EV does, but that's because it was wasting all the energy in the first place.

 

[CalDreamin]

Sorry for incorrect numbers. The 55 mpg is for the far less powerful 2.0. Thanks for the correction.

No car that hasn't got a plug gets 55+ mpg in the EPA test cycle. Among cars with no plug, the Prius at 50 mpg leads in EPA testing. For the same car, the EPA test cycle yields substantially lower mpg numbers than the Euro NEDC test cycle.

The Audi A6 isn't sold in the US with the 2.0L TDI. But that drivetrain is available in the VW Passat TDI which is EPA rated for 34 mpg. The Golf and Jetta with the 2.0L TDI have similar EPA ratings. US owners of the 2.0L TDI generally report 36-40 mpg (see Fuelly.com). My 2.0L TDI averages 40-42 mpg, though it's rarely driven anymore since I got the Model S. While the TDI has better range than the Model S, by comparison the TDI's sluggish acceleration seems borderline unsafe when passing or doing simple lane changes on the highway.

I kept the TDI because I thought it might come in handy for long road trips. But every long car trip I've taken in the last 12 months has been in the Model S instead. The Model S is a much nicer road trip car.

 

[brianman]

While the TDI has better range than the Model S, by comparison the TDI's sluggish acceleration seems borderline unsafe when passing or doing simple lane changes on the highway.

It makes me smile to see someone praise acceleration ("speed availability") as a safety feature. It's a nice change.

 

[dsm363]

Realist: we understand the Model S isn't the perfect autobahn car. You've made that abundantly clear and I agree with you. You've probably figured out that most people in the world don't drive on the autobahn. I hope Tesla someday produces a car that meets your daily driving needs at 150mph while going to get the groceries but it will be a few years until they can make a car like that.

That doesn't mean anything is 'wrong' with the Model S, just that it isn't engineered to shine in that aspect of driving. It is extremely efficient at normal driving speeds and crazy quick acceleration. Does the 2L TDI move to 60mph in less than 5 seconds or have a lag when you press the accelerator in order to avoid an accident?

 

[Olle]

180km range is nothing and that is just the main weakness of the Model S.

At that speed and under these conditions with almost zero traffic any standard BMW 5 or Audi A6 gives you 500-1000km.

And it is a lot faster.

See table in the link how much you get on a BMW 5 series at 100-120 mph, 12-18 mpg depending on diesel or gasoline.
http://www.metrompg.com/posts/photos/gcc-autobild1.gif

So 12 mpg * 18 gallons (bmw 535) =221 miles.

Much further than an MS at that speed but a far cry from the 1000 km you are talking about

 

[rabar10]

I am living in Germany and have a normal Model S 85kWh. We use km/h instead of mph in Germany. Please note, that 1 mile equals 1,609 kilometers.

I waited months for a perfect time to drive my fully topped up battery empty at a very high velocity. There are no speed limits on German Autobahns.
Yesterday (Saturday 5:30am) was the perfect time. My requirements for such a day were:

1. Low traffic density
2. Dry Roads
3. Daylight
4. Temperature < 20°C (68F)

I started topping up the car at 3:30am. 100% was reached at 5:00am and I started at 5:35am. I wanted to race the car as fast as possible in safe conditions. These conditions were:

0. Safety! No illegal speeds or maneuvers. Keep safety distance (for 200km/h - 125mph: 100m - 110yrds)
1. Reach my destination.
2. Long term power consumption <= 80kW
(I wanted to lower the risk for the battery. Long term discharge current should be less than 1C)
3. Driving foresight-fully not braking too often.
(I had to slow down twice from ~160km/h (100mph) to 120km/h (75mph) using the breakes)
4. After reaching 100km (60mls) Typical Range, I reduce max. power to ~60kW
(Cell voltage will have reduced significantly then and the taken amps from the battery would otherwise rise above 1C)

The Results:
View attachment 52558
Average speed had been ~165km/h (102mph).
Average energy use was 410 to 430 Wh/km (660 to 700 Wh/mi) on the Autobahn.
With street works, few speed limits and change at Autobahn crossings the average energy consumption was 392 Wh/km (631 Wh/mi).

I reached a distance of 181,6km (112,8mi).

Very interesting was the amount of energy I was able to get out of the battery. 0 Typical Range was reached 100m (90yrds) in front of the garage. So the Zero Mile protection as well as the Block Protection were untouched. 71,2 kWh came out of the battery. With these 9 kWh protection the battery just gave 80,2 kWh (instead of 85 kWh).

This is normal, because Peukert's Law says, that higher currents result in more losses. I compared this high speed discharging with a typical discharging of mine at an average of 204 Wh/km (328 Wh/mi). I got more (74,3 kWh) out of the battery during slow discharging. I also calculated the Kapa of the Peukert Function. It resulted in a value between 1.03 and 1.04, which is significantly better than a standard Li-Ion battery (1.05). This shows the high end chemistry of the cells in our cars.

P.S.: Cruising along undisturbed at 200km/h (125mph) I was overtaken by a Nissan GT-R at roughly 300km/h (185mph). There are more maniacs under their ways on German Autobahns very early on weekend mornings :scared:

Thanks for the very technical and informative post. Sorry your thread got derailed.

 

[horst98]

The fuel consumption depends on the speed. Regardless whether its gas or electrons. The main influence have the aerodynamic drag coefficient and the front area of the car. Due to the fact that our car has one of the best drag coefficients, our fuel consumption does not rise as fast as for ICE cars.

BUT ICE cars use a lot of gas for overcoming friction and alike. Therefore the additional gas/Diesel needed for additional speed goes relatively down. I have an Mercedes CLS 350CGI as well and this car needs 16 to 18 litres per 100km in such an extreme drive (14,7 to 13 mpg). The range reduces to 350km (215mls). This is still much more than in our Tesla.

 

[rcc]

All correct. The Mercedes CLS 350CGI has a 21.1 gallon tank and is EPA rated at 30 mpg for highway driving.

So at more normal speeds, I would expect the 350CGI to have a highway range of about 850-950 km / 550-600 miles. High speeds (understandably) drops that range to about 1/3 of normal range.

So the Tesla does better in terms of % range loss because of its better aerodynamics and low rolling resistance. But its base range is less than 1/2 of the Mercedes (256 EPA miles vs. ~600) so not a surprise that the resulting high-speed range is lower even though the Model S loses less range at high speeds.

 

[Bookkeeper]

How will the results be with the current Model S 100D ? Anyone got some experience?

Next week I will drive my "normal" trip from Rotterdam to Leipzig. 680km

Normally I drive at an average speed of 130-140km/h for the whole track. This means 180-200km/h for some long parts of the trip.

Planning to stop at the following superchargers;

Rotterdam
128km
Zevenaar
136km
Kamen
173km
Staufenberg-Lutterberg
137km
Sangerhausen
85km
Nempitz
20km
Leipzig

Please let me know or anyone can tell me anything about the discharging at high speed and also about the do's and don'ts on a trip like this.

Thanks

 

[eschummer]

The app ABRP (A Better Routeplanner) can probably give you a pretty good idea. You can edit the assumed speed in the calculations, and it will estimate the rating charge at each of your proposed stops. I live in California, but on longer trips typically also drive at higher speeds where possible (averaging maybe 120 km/h). The tool gave me very good correlation to what I was actually experiencing.

 

[eschummer]

I meant "remaining" charge....

 

[Bookkeeper]

I will check it out. Thx @eschummer