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Coasting technique long trip - RESULTS

Already now: sorry, maybe too long, but I try to be thorough.

Trip: Home - pick-up friend and a LOT of luggage - Stockholm (S) - Norrköping (N).
Pause 5 hours, no charging.
Return: N-S - Airport.

I think this is relevant, since 100 miles of the trip is identical, but in opposite directions. Measurements in European standard [US within square brackets]

0610 Start from home. Range Charge 100%, finished 15 mins before starting trip.
4 degrees C [39 F]. Dry road. Pitch dark. Battery cold.
0630 Pick-up and pack. Trip A reset
0650 Entering freeway (heavily trafficked) Trip B reset.
0850 Reaching N. Temp 8 C [47 F]

Spent most of trip talking, not particularly concentrating on coasting, but it was used intermittently.

Consumption: Home - Pickup 16 km [10 miles] 2,7 kWh
Pickup - S: 15,2 km [9,5 miles] 2,8 kWh bumper to bumper traffic
S-N: 161 km [100,5 miles]: 26,0 kWh Heavy traffic, average speed 80 kmh [50 mph]. I did NOT upset traffic flow, but melted in.

Average Consumption Home - N 165Wh/km [264 Wh/mile]
S-N 162 Wh/km [259 Wh/mile]. Total consumption 191 km [120 miles]: 31,5 kWh

Energy Bar at 64% Energy App remaining Range 50 km [31 miles] Average: 243 km [162 miles]
Dashboard Typical: 237 km [158 miles] Rated/Ideal: 297 km [185 miles]

=====================

Return trip. 9 degrees [49 F]. Light half trip. Dry road. Alone in car, no payload. Here I "hitch-hiked" with a lorry that kept a steady 90 kmh [56 mph], but so far behind that I didn't use slipstream, and I made a conscious effort to drive cheaply, using coasting, while not upsetting traffic rhythm.

First a few km/miles to warm up Battery, then

N-S same 161 km [100,5 miles] plus another 39 to airport, together 200 km [125 miles] 29,6 kWh, or an average of 148 Wh/km [237 Wh/mile].

Total consumption Home-N-Airport 399,1 km [250 miles]: 63,1 kWh. Energy Bar at 26%. Remaining Range Energy Bar: 74 km [47 miles].
Average consumption whole trip: 158 Wh/km [253 Wh/mile]
Remaining Range Dashboard Typical: 74 km [47 miles]
Rated/Ideal: 93 km [58 miles].
Remaining Range Energy App 50km [32 miles] Average: 109 km [68 miles].

=========

Difference Dashboard Typical Range end first leg (N) to complete trip (237-74 km) = 163 km [102 miles]
Difference Dashboard Ideal/Rated Range end first leg (N) to complete trip = 205 km [128 miles].

REAL distance end first leg (N) to complete trip: 208 km [130 miles].

=================

Conclusions:

It would seem that driving the car with single occupancy in rather cold weather, with headlights on half the trip, and keeping an average speed of 90 kmh [56 mph],

using coasting technique actually consumes slightly less energy than even the Ideal Range setting.

The forecast about Range, using available data from the return trip indicate that the car, using coasting technique, averaging 90 kmh [56 mph], also in these semi-hard conditions, and assuming an available energy after reserves etc of 75 kWh (it is probably more) should be able to go exactly 507 km [317 miles].

QED and sorry for the length of this.

I just saw that in another thread "pgiralt" says that we get to use 81,1 kWh.

If that is true, the range with "my" coasting technique in the conditions given in the post above would be
548 km [342,5 miles],
assuming a warm battery. If not warm deduct 8 km [5 miles].

Of course, given 20 degrees C [68 F] rather than 9 [49 F] and no darkness, this would be even better.

The 81.1 includes the extra miles you get after hitting zero as well. From max charge to zero is 75.9 kWh. The rest is after you pass zero.

OK, so I was only 0,9 kWh off, and those go anyway to warm up the Battery.

Then I have proved to my satisfaction that I can easily go 500 km:s (some 320 miles) and STILL have about 20 miles in reserve, under rather adverse physical conditions, using my driving technique, on one Range Charge.
Fine - now I can let that subject rest.

Why the onboard computer cannot show this, according to the actual (MINE or whosever's) driving style, is inexplicable to me.

Odd that basically noone seems to be interested in this. I would have thought that range is one of the crucial matters when it comes to EV:s. I spent some time on this.

Nice to know.

Robert,

Maybe the reason is there are many people who don't care about range so much (like I don't). The MS will go the 50-100km I go by car a day easy, at any speed and temperature. I don't have the illusion to be able to plan a trip longer than this with such small margins. A large traffic jam with the aircon/heating on, larger diversion, just about anything can blow that out of the water. So I would not run the cars battery down that far, I also don't let my ICE get lower than a quarter tank which is around 100km before refueling. With the density of charging stations in Germany (without even waiting for a supercharger if you can settle for 22 kW) there is not issue with that. But honestly, distances larger than that I use the train so I can work and not tie my hands to the wheel.

Cheers,

Robert

Robert,

Not sure why you say the car cannot show range based on your specific driving style. That is precisely what the energy app does. Push the Average button on the top right and it will show your expected range based on the last 5, 15 or 30 miles. The car doesn't know if the next 30 will be driven in the same style, but you do, so that average will be accurate if you plan to keep driving that way.

@triss1

Only problem - the figures don't match up. At all. Of course I have tried that. Why would I make such a fuss about this, if that actually worked. (sorry, question mark doesn't work on this airport computer).

@RZippel

I can only wish and hope for the time, when we have charging stations at all, not even to talk about 22 kW. The very few there are, are 230 V 1-phase, and those charge a royal 13 km/hour. There is a limited pleasure in sitting in a roadside café, waiting to get the next 100 km - some 8 hours or so....

Wir haben einfach total unterschiedlichen Voraussetzungen...ich muss einfach beruflich die etwas längeren Strecken - mit Last - fahren.

Sorry, I forgot myself - I said that we simply have totally different situations - I have to be able to go the "long hauls" with a lot of recording equipment - hundreds of kilos. Not so easy on a train. And I am damned if I ever go back to an ICE. I just won't!!!!

@robert@bis.se: Thanks for sharing the results of your test.

@ robert@bis Thanks a million (almost literally; rough price in kr) for sharing your experiment. This goes a way towards relieving my Angst and domestic resistance concerning actual range in Swedish conditions. So it might be almost possible for me to use a MS85 for my regular "beruflich" travels of about 480 km, even before the Superchargers charge into Sweden. Hmm. Now, if only my TSLA shares would appreciate some more ... ;-)

Going to Copenhagen in a few weeks with family, and plan to sneak them into the Tesla show room there. Hammering away reluctance bit by bit.

@Lessmog

480 km? Like a breeze, with 19-inch Summer tires in plus degrees C.
That is, if you learn the coasting technique.
I have now shed my doubts and proved to my satisfaction that this is entirely possible, keeping a realistic speed and not accellerate hard.

I just saw a Tesla ad in the Airport train in Norway. There Tesla adcertised 504 km range. I find such ads quite dangerous (especially so, since the car shown had 21-inch wheels).
Rather better to advertise a realistic range for people driving "as usual" and let those who can learn another technique be positively surprised. Without coasting technique, there is no way a Tesla with 21-inch wheels can do any 504 km in Norway.

What is this "coasting technique"?

It was thoroughly explained in another thread. The short of it is that, as soon as feasible (meaning downslopes or when you see in the blue yonder that you have to reduce speed) you put the car in Neutral and coast along.
If you need to further reduce speed, just put in Drive and regenerate. If you need to accellerate or keeping the same speed, likewise. The car has such little air resistance and rolling resistance that you can roll "for ever", especially if it goes slightly downward.
I have now really checked this, and I have a saving of at least 10%, without breaking traffic rhythm, without risking anything (the gearbox is a marvel). It is just a matter of "reading" the topography, the traffic situation and adjust your free-rolling accordingly. For me the possibility to go for 330 miles or so on one charge is of crucial importance in a country that has absolutely no infrastructure for EV:s.
The other thread gives you further arguments and legal answers.
Tesla have given the green light for this "modus drivingensi".

Yes, please describe the coasting technique that was used by the OP. Thank you.

Look at "Energy-efficient driving" just below this thread. I just bumped it.

In that thread I hoped for 260 Wh/mile.
In a real test over 200 km (125 miles) in cold weather and with headlights on for half the trip, I got it down to 237 Wh/mile, keeping with the traffic flow with an average speed of 56 mph. Not bad, if I may say so myself.

Thanks Robert, great post!

I tend to drive in this fashion as well, preferring coasting to regen whenever possible, and I also get better than ideal range. In fact, I used this technique driving 50 miles back from the service center a couple of weeks ago, most of it freeway, and I got my energy usage to about 250 Wh/mi while driving 70 MPH most of the trip.

@robert, I do the same as you have done and generally get the same results as you. I have done this for years with my Roadster. The only thing I want to point out that a trip to and from a place is not necessarily the same. A few things that can be different and can skew your results are: Elevation (start and end aren't identical), wind direction (Huge impact on results if more than 5 mph head/tail wind.)

So although I totally agree with your premise since I have the same results, your methods of proof could easily be shown to be incorrect.

Like you I would also like to have an easier way to implement this but I doubt Tesla will ever provide a means as far too many drivers would not use it correctly which (in the US at least) would create lawsuits for Tesla.

@Theresa

I have already been castigated (in a friendly way) that I write too verbously, and there's something in that. So I cut away a few sentences:

1) The altitude of start and halfway finish in my trip yesterday is the same - sea level. Lots of hills in between, though.
2) There was no wind yesterday, at least none that I noted.

I have studied statistics at University level, and I am aware of factors that can skew the results. Those two did not, but I am the first to acknowledge that this was in no way a scientifically adequate experiment. The multitude of hills, for example, didn't look like sinus curves, in one direction some could be quite steep uphill, but a very low gradient downhill for a longer distance after the top. That also influences results. As I said from the outset, I wanted to prove a tendency and a technique rather than absolute numbers, and I have proven them to my own satisfaction. That's enough for me. That you get basically the same results just strengthens my assumptions about this way of driving, which, if done intelligently and with foresight on the traffic situations, vastly further reduces environmental impact and increases range.

@robert@bis.se | NOVEMBER 1, 2013: The short of it is that, as soon as feasible (meaning downslopes or when you see in the blue yonder that you have to reduce speed) you put the car in Neutral and coast along. If you need to further reduce speed, just put in Drive and regenerate.

I just wanted to point out, as you are probably aware, that you can just leave the car in Drive all the time and modulate the regen using the accelerator pedal. There will be a spot where there will not be any power used and the car will effectively be in neutral. Another technique that is useful is to set the cruise control below the speed limit when going up hills and above the speed limit when going down hills.

@Alex, Robert and I both know this but my hypothesis of the whole matter is that even when coasting along with the car still in drive you cannot modulate nearly as well as just free wheeling can do so you get some regen and acceleration (too small to note on gauges) that affects your range. Both Robert and I have had very similar results which lends itself to supporting my thought.

I am also assuming there are some magnetic losses to just keep the motor spinning which would also increase the losses.

Something which physics does not support is my experience with my Roadster in which I have found that increasing my speed quickly (but not drastically quickly) tends to get me better efficiency too. And I have also seen that if I speed up to ~ 10 mph over the limit and let the car drift (in coast mode) to ~ 5 mph below the speed limit and keep repeating I also get better efficiency than just holding a constant speed.

I agree this doesn't sound correct but I have over 30000 miles under my belt with the Roadster to support this.

@robert, Thanks for adding the extra info. Since you hadn't included it I didn't want to make that assumption and so just posted my thoughts. I am glad you didn't take offense to it as that was not my intent either.

Your average speed of 56 was within a hair of the EPA 55 mph standard. If there aren't too many speed "anomalies", your Predicted and Ideal would show P

Ahhkk. Forgot to use HTML display coding:

.. show P<I, a rare occurrence in variable traffic.

Good luck with any "Elk Avoidance Adventures".

@Brian H

Yes, true, however, the EPA Standard is on a flat track, without other traffic, hills, in a temperature much more convenient for the Battery, without headlights, without A/C - heating, without condensation issues inside the windshield that need to be "blown away".

My - better than EPA - results stem from real traffic, real roads, real driving under less than ideal conditions - and with one absolute rule: DO NOT DISTURB THE TRAFFIC RHYTHM. That's why I couldn't drive like Theresa says, with a constant speed change, unrelated to ongoing (rather heavy) traffic of some 15 mph - that would create a big disturbance for the traffic flow. My idea is to look for the small downslopes and coast on them, scanning the traffic situation far ahead to predict, when I am going to have to reduce speed anyway and do it earlier than usual by coasting (also upslope)(how I hate those who accellerate towards the red light and then stand on the brake in the last moment - WHY?????). It works, doesn't disturb anybody, and it is second nature to me anyway. Ultimately I think it is also better for the car and the tires mechanically, since it is a smoooooth style of driving. Also much easier to implement in the States, with the multilane freeways. In Sweden the motorways are 2-lanes in each direction, other roads mostly 3 lanes total, the middle one being used for the ones that have upslopes. Try to drive with variable speed on a single-lane road with barriers each side of the lane, and you'll see some rather unhappy drivers (I am putting this very mildly) in the queue behind you.

You are incorporating basic hypermiling techniques that have been mastered years ago by hybrid drivers. Prius hypermilers get close to 100 MPH if they do it correctly. Basically you coast as much as possible, accelerate slowly, and slow down on upslopes while regaining your speed on the downhill portion. If you see a red light two blocks away, start coasting and slowing down well ahead of the light. They key is not to apply your brakes or regen at all, so by the time you get to the light with some remaining forward momentum, the light will have turned green and you can continue on your way.

Search the internet for hypermiling techniques, you can use them with the Model S to significantly increase your range. However, it will also require that you drive in a way that may annoy those behind you who don't share your love of efficiency. :)

@Theresa

Tesla does not use permanent magnets in motor, so there is no
magnetic losses while coasting. Motor always spins with wheels,
because there is no clutch.

Where do coasting saves come from? Regeneration can only return
perhaps 60% to battery (?). Brakes of course waste all. So avoiding
those saves energy. Lower average speed saves energy.

If drive train has max efficiency above power needed for normal
driving, then accelerating to +10 mph and coasting to -5 mph would help.

If that's true, then 4 wheel drive could improve efficiency. Battery
limits acceleration, so 4 wheel drive would use 2 smaller motors. In
normal drive only one would be used. Another would be 'coasting'.

Some have seen, on long consistent rises, as much as an 80% recovery (up a mountain, and back down). So that 20% is what you have to work with.

I don't believe that.

Energy flow:
battery -> inverter -> motor -> kinetic energy -> motor -> inverter -> battery

efficiency = e(inverter)^2 * e(motor)^2 * e(battery)

Motor efficiency peak is 0.92. Energy goes through it twice so that alone
makes 0.8464 or less. Battery charging voltage is always higher than
output V. Inverter efficiency is not 100% either.

Reported max recovery on some group trips reported here.

It has been proven that at 24 mpg the S85 will go 400 miles. So what? Hyper-miling is fine for those without lives.

Communal answer to Amped Realtor and Pungoteague_Dave:

I don't need to search the Internet and, yes, I have used that technique for two decades now, with only one deviation from your post (and written with upper case as well):
I WILL NOT DISTURB TRAFFIC FLOW. That's a given, because doing otherwise would lead to angry overtaking and far increased risks.

To PD: does it make you very happy and content to be so rude?? I have a very rich life, and the Tesla is enhancing it further. I would say that, should everyone THINK a bit more before letting their devils loose as soon as they get behind a steering wheel, this planet wouldn't be in anywhere near the situation it is now. Traffic is a very major part of the emissions, and, using 10-20% less gas to get the same distance with basically the same speed would have saved innumerable million tons of oil, quite apart from the fact that the cars would have much less mechanical repairs. It isn't like we're going to have a choice in the end - remember 1973 and the oil shortage?? I will not sink to your level of writing, so I shall not say what I really feel about posts like that.
And, before Brian H gets to it, you do mean mph, don't you? The Tesla doesn't deal with gallons. And, while I'm at it, Amped Realtor is the opposite, you do mean MPG, don't you?


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