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Calculation of Rated Range

Calculation of Rated Range

A short while ago, there was a discussion in one of the threads regarding the calculation of the "Rated Range" number that appears on the speedometer. I can't find the thread, so I am starting a new one.

The issue, in brief, was whether driving style affects rated range. Here is the text of an email message I sent to Ownership:

Hi,

I wonder if you could settle an argument? In forum discussions, some people claim (and have been told by Tesla reps) that the "Rated Range" number that appears on the speedometer is partly determined by the way the vehicle has been driven recently. Others claim that the number is based on the battery's state of charge and a fixed energy consumption rate of approximately 308 watt-hours/mile. Still others claim that the number is based on state of charge, a fixed consumption rate, and certain other variables such as battery temperature -- but not driving style.

Could you please clarify how this number is derived? If you are uncertain, could you please find out from someone who knows?

My own personal view is that Rated Range WAS based on a fixed consumption rate prior to software version 4.3, but now includes other parameters such as battery temperature, but that driving style does not affect the way that the number is computed (although driving style obviously affects energy consumption, and hence the number of rated miles remaining at any given time). It would be nice to get an authoritative answer.

Thanks for any information you can provide.

Regards,

Doug

Here is the answer I received:

Hi Doug,

Thank you for reaching out to us at Tesla Motors, and for patiently awaiting a response from us. I was delighted to get a clear reply from our powertrain systems architect. He states, with regard to how Rated Range is calculated:
Rated range = the car’s estimate of remaining energy / a fixed whpm. The fixed whpm is different for different vehicles (85kWh / 60kWh) and in different markets based on the regulatory test for that vehicle in that market.

Further information he would not elaborate on, but I hope this aids in ending the discrepancy regarding how we achieve your range predictions.

As always, please reach out to us again if there is anymore hash you need settling.

Kind Regards,

Peter

This is actually a simpler calculation than I had thought, although I had not anticipated that TM would use a different fixed whpm for each market. It does not explain why the relationship between rated miles used and whpm (as determined by the trip meter) seems to vary for a single vehicle. In any event, it does not appear that rated range is at all based on driving style.

Since it took about a week for Peter to get back to me on this question, I assume he got his answer from a fairly authoritative source.

jnb | 11 June 2013

Based on a week of driving (i know, its a small sample size), it appears that the Rated calc is based on 300 wh/mi. That is where the "Rated" line is on the energy app and when i happened to hit that as my average, the projected range (based on average, not instant) was exactly what the rated range was. i have a p85+.

elguapo | 11 June 2013

If I remember correctly, general consensus on the previous thread was Rated miles had nothing to do with how an individual drove the car but was a set formula (as indicated above). The Energy App in the car was the only measurement that estimated range based on driver specific consumption.

amirm | 11 June 2013

There was a separate thread on battery degradation and how it is reflected in Rated miles when fully charged. Since many of us see a gradual reduction in rated miles after a charge, some argued that Tesla told them that it is related to driving style. based on the answer you got it looks like that answer was wrong. When new my MS60 showed 190 miles after charge and now it's down to 184 after 6K miles. If this reduction is a reflection of battery degradation we have a problem...

Brian H | 11 June 2013

Maybe the P85+ got the Rated back up from 265 to 300?

drp | 11 June 2013

Sometimes a cigar is just a cigar

rsusi | 12 June 2013

Concerning rated miles. I picked up my Model S last Friday and then on Saturday did an extended trip from northern Virginia to Virginia Beach. I set the charge to max range on Friday night. The max charge I got was 270. Drove to Virginia Beach and again wanted max range for the return trip, and again all I got after a nights charge was 269. Have it reset to standard charge now, which is giving me 236, which is fine for local driving. I was under the impression that you could charge it to 300 under the max range setting. Do I have a software problem?

Theresa | 12 June 2013

No you don't have a problem. The original estimate of range was Tesla's statement of 300. Now that they have the EPA rating of 265 that is what they have the display showing as the rated range. It is still the same kwh rating.

info | 12 June 2013

to Rsusi:
I may have misunderstood your question, but it is my understanding that if you change the settings from rated to "Ideal" you will get your 300 miles.

info | 12 June 2013

And,
I'm not sure Tesla's answer is correct. If you drive hard, the rated range goes down faster. It also goes up if you are on an extended downgrade. This means that your driving style affects the rated range. I think the initial rated range is what you should get with a usage of 308 kw/m. If you exceed that usage, the rated range shrinks accordingly and conversely if you stay below it, it increases.

I check this by adding the rated miles to my odometer. Once I have that figure, I continually add the two numbers. If I drive very conservatively, the number increases, if not, it decreases.

Example. My odometer says 6,000 and my rated range is 240. This means that at the end of my charge I my odometer should read 6,240. After 40 miles (indicated on the odometer) my range should be 200. If after 40 miles, when I add the rated range to the odometer it is (for example) I get 6,235, then I know that in 40 miles, I've actually used 45 miles of charge. I know I'm driving over the allotted kw/m. If I slow down, when I add the numbers, I will get over my expectations.

With this being said, your rated range at START UP is what Tesla said it was, but the rep didn't understand your question. The instantaneous range display DOES use your driving to tell you how much has been used BUT the remaining amount is still based on the 308/kw/miles. So the answer is Slow down to increase range and speed up if you're near a supercharger or home.

mbergman | 12 June 2013

THe answer that I got from Tesla a few days ago when I asked this question is the same as that received by DouglasR.

So at any given point in time, the rated range is computed by dividing the energy remaining in the battery by 300 (or 308 or whatever number the EPA or other agency in other countries initially used to compute rated range). Projected range is computed by dividing the energy remaining in the battery by your usage over the previous 5,15 or 30 miles.

That being said, I don't see any real value in knowing the Rated range since it is computed using a number that may bear no relationship to how you currently are, have been or will be driving during a trip.

Can somebody explain why rated range is something worth knowing?

jnb | 12 June 2013

mbergman, i think that you are totally right. And you raise a very good question. Its a pretty good guesstimate of remaining battery for those days when you won't be cutting it short. Other option would be to display the battery left in terms of percentage or kwh, but that wouldn't mean anything to most people.

Another good question is: why doesn't the energy app when displayed on the left of the speedometer tell you your projected range? it provides the entire chart and the average usage, but no projected range!

Brian H | 12 June 2013

No.
Ideal is the old EPA standard, 2-cycle test. 300 miles.
Rated is the new EPA standard, 5-cycle test. 265 miles.
Projected takes account of your driving style, and varies. The other two do not.

jnb | 12 June 2013

Brian,

We are having a bit of a disconnect. You are right too. We are talking about how the 300 miles and the 265 miles is calculated. Those tests that you refer too come up with a number for the watt hours the car uses per mile (Wh/m). For the "rated" 265 miles, you divide the charge in the battery that is available for driving by 300 wh/m (or 308 wh/m or whatever) which is the result of the 5-cycle test. That is how the remaining rated range at any time is calculated.

mbergman | 12 June 2013

But Jnb, if I am not cutting it short, who cares how much battery I have left? And if I am cutting it close, range-wise, and I'm trying to decide if I need to slow down, etc., wouldn't projected range provide me with the most meaningful information?

Neither rated range nor percentage of battery remaining take current energy consumption into consideration, so both seem pretty irrelevant compared to projected range.

I guess I am wondering why projected range isn't more prominently displayed than rated range, or to take it to the extreme, why rated range is displayed at all.

mbergman | 12 June 2013

OK, I can see having rated range displayed when you turn the car on, but it becomes more and more meaningless the further you drive, no?

jnb | 12 June 2013

mbergman, I agree with you. It does get more irrelevant the more that you drive. And it would be nice if it adjusted as you drive. Which is why i don't understand why the projected miles are not displayed in the instrument panel when you have the energy app open.

As far as what it is supposed to be, though, I think of it as a "battery remaining" number that is expressed in miles, instead of percentage or hours. Think if it like the battery indicator on your phone. If it says 100% you know that you have a full battery but no idea how long it will last based on your usage. Same for when the battery is at 50%. Here, same idea, but it shows you the remaining battey life in something that is just a bit more useful, miles, although still an estimate. I tend to look more at the green bar that the miles frankly.

DouglasR | 12 June 2013

@info

I think the rep I corresponded with understood my question just fine. Of course the way you drive will affect the rated range you have remaining at any given point -- I even specified this in my question when I said, "although driving style obviously affects energy consumption, and hence the number of rated miles remaining at any given time."

However, the question had to do with how that rated range number is calculated. As it turns out, that computation is very simple, and does not involve your driving style. The car estimates how much usable energy remains in the battery and then divides by a fixed number. That fixed number depends on the tests used by the jurisdiction responsible for monitoring energy efficiency, but it would be the same for all U.S. cars. So, for example, let's say the fixed number is 308 whpm under the EPA's five-cycle test. Assume further that the usable energy in a full battery is 81,620 watt-hours (81.62 kWh). If you divide 81,620 by 308, you get 265 rated miles. Under the EPA's older two-cycle test, the assumed consumption would be lower, say 272 whpm. Divide 81,620 by 272 and you get 300 rated miles.

Now these numbers are somewhat hypothetical. We don't know the precise number of usable kWh in a full 85 kWh battery. We don't know how TM deals with the 10 or so miles a car can be driven after "rated range" goes to 0. The fixed numbers -- 308 whpm for the five-cycle test and 272 for the two-cycle test -- are basically just estimates. But the principle is the same: all U.S. cars use a fixed divisor to compute rated range from the car's estimate of energy remaining in the battery.

You asked why this matters. For me, it is helpful to know how closely the actual range of the car is reflected in the rated range displayed on the speedometer. I can control energy consumption to a degree by how fast I drive and what accessories I run. If I can keep my average consumption since the last charge to around 300 whpm, then the rated range displayed on the speedometer will tell me exactly how far I can go before the battery is completely depleted.

Longhorn92 | 12 June 2013

I actually like seeing and use both rated and projected ranges.

Rated is a nice standard (overall, if I drive fairly conservatively, no fast acceleration, keeping my speed no more than 5-10 mph over the speed limit), then I do seem to stay somewhere close to the rated range. Some of us may need to adjust up or down slightly, but I feel rated range is a good average driving statistic (sort of like a gas gauge). It shows that, if I go back to fairly normal driving, then I roughly know what my range should be. In addition, rated also helps me see how my battery pack is doing over time since it is a consistent number, so I can compare rated miles over time when I am fully charged to see how much capacity I am losing.

When I need to focus on how I am currently driving (which may be different than my normal driving style), then I look to projected range (5, 15, or 30 miles depending on how long I have been in a certain driving style). For example, if I am traveling on a longer trip (highway driving with more consistent and/or faster speeds), then I look to projected miles to make sure I will get where I am going at my current speed and adjust accordingly.

I agree that having projected displayed on the instrument panel energy graph would be a useful addition.

DouglasR | 12 June 2013

@mbergman, the reason I don't rely on "Projected Range" displayed at the right side of the energy app is that it is rarely accurate. The instantaneous number is so variable as to be practically useless. If I use a 30 mile average, it is better, but it still varies widely as I drive. However, the trip meter showing consumption since the last charge provides a pretty stable number. If I can't get it under 300, I know I need to plan a stop within the rated range.

mbergman | 12 June 2013

Yeah, ok, what everybody is saying makes sense. The most important thing, I think, is to understand exactly what these numbers represent. I, for one, didn't understand how rated miles was computed until a few days ago, and I am sure that as I put more miles on the car, I will get a better feel for the relative importance of the rated vs. projected numbers.

MarkV | 12 June 2013

@DouglasR

I think you have the a good grasp on the issue. The rated range is based on the EPA estimated consumption rate. The 85 kWh battery consumption rate is slightly higher than the 60 kWh battery. I presume because to the difference in weight of the vehicle. Anyway what shows on the dash under the speedometer is an estimate of how many miles are remaining IF you consume power at the rate of the EPA test for that vehicle. What shows on the touch screen is the "projected" miles remaining if you continue to consume power the same as the average of the last 30, 15,or 5 miles (if you display the average). I am not sure what length of time or distance is used for the instantaneous values.

All that said, the car does not know what lies ahead so you as the driver have to use some common sense and know to adjust the estimates based on your destination. For example my commute to work is a net downhill so my consumption averages in the 230 Wh/mile range while my commute home averages about 335 Wh/mile for a round trip average of about 283 Wh/mile. My projected range on the way to work is higher than the rated range and vice versa on the way home. Once again neither of those numbers are correct predictors of the future, they are based on the past and you have to take that into account.

Rod and Barbara | 12 June 2013

@ DouglasR – Thanks for this thread and posting the answer from Ownership. It answers a question I was trying to explore in another thread (Need Help from 60 kWh Car Owners) – the Rated Mile Wh/M is a different value for the 85 kWh and 60 kWh cars. This, of course, makes sense since the 60 kWh car is about 200 pounds lighter than the 85 kWh car.

You mentioned, “It does not explain why the relationship between rated miles used and whpm (as determined by the trip meter) seems to vary for a single vehicle.” I have collected a few data points on Rated Miles used. In addition to significant scatter in the Wh/M vales, I found that Rated Miles appear to be “used up” at a faster rate than they are predicted. On one trip, after driving 151 statue miles, the total energy efficiency on the trip display was 308 Wh/M, but we had “used up” 165 Rated Miles. I have exchanged emails with Ownership on this topic and they hope to have an explanation for me sometime next week. I will post the answer here when I hear back from Ownership.

DouglasR | 12 June 2013

Let me give you a concrete example. A few months ago, I wanted to drive with a friend to Paradise on Mt. Rainier, elevation 5400 feet. The route from my house in Seattle to his in Kirkland, and up to Paradise is about 121 miles, or 242 miles round trip. I was never worried about running out of charge, since I would be passing plenty of public charge stations as I neared Seattle on the return trip. But I wanted to do it on a single charge because my friend is not well, and stopping would be inconvenient.

On the way up the mountain, I could see that my average consumption was quite high, around 400 whpm as I recall, and of course the Projected Range numbers were way too low to get me home. On the return trip, the Projected Range numbers were unrealistically high, and consequently unreliable. However, my average consumption began dropping from over 400 whpm to around 325 whpm at the bottom of the mountain where the terrain began to flatten out. Thereafter, my average consumption continued to drop, but much more slowly. By the time I got to a point where public chargers were available, my consumption had stabilized to under 300 whpm, and my rated range matched pretty closely with the actual number of miles I needed to travel to reach my home. I therefore did not feel the need to stop, and I arrived home with about 18 rated miles to spare, having consumed about 246 rated miles to travel 242 actual miles.

As it turns out, I didn't need to stop. But suppose the trip home had been 30 miles longer, and stopping to charge would have been necessary. At 50 miles from home, consuming energy at an overall average rate of 300 whpm, my Rated Range would have been about 40 miles at the point where I first encountered the charge stations. My Projected Range, however, would have been about 60 or 70 miles, based on the previous 30 miles of (downhill) driving. Had I relied on that too-optimistic Projected Range estimate, I might have skipped a charge and run into trouble.

DouglasR | 12 June 2013

@Rod & Barbara

Our posts crossed. But I agree with you about the unexplained variability. In the case above, for example, my total actual miles was 242, rated miles was about 246, and yet my average whpm was UNDER 300 (this is from memory, but I think pretty accurate). So clearly the rated miles here had a consumption rate less than 308.

DouglasR | 12 June 2013

Edit: and of course, my examples involve an 85 kWh car. With a 60 kWh car, the numbers for rated and ideal range will be less than 308/272.

Bob W | 12 June 2013

@Rod and Barbara wrote:
"On one trip, after driving 151 statue miles, the total energy efficiency on the trip display was 308 Wh/M, but we had "used up" 165 Rated Miles. I have exchanged emails with Ownership on this topic and they hope to have an explanation for me sometime next week."

According to this summary of EPA testing procedures, "EPA tests for fuel economy do not include electrical load tests beyond climate control, which may account for some of the discrepancy between EPA and real world fuel-efficiency."

Not counting the motor, the Model S has a higher electrical load that most ICE cars. Headlights, radio, heater, A/C, display screens, computer cooling fans, etc. all drain the battery, and this could easily reduce actual range over the EPA estimated range by 10%, as you observed. 32 watts steady load for accessories is 32 extra wH/mile. For a full charge, 81620/(308 + 32) = 240 miles, instead of 265, or for a 150 mile trip you would use up 10% more energy than estimated = 165 miles of rated range used.

Does anyone know if the Model S instrumentation (trip meters and Energy Graph) actually counts energy used by everything or just the motor? You can be sitting still with the A/C or heater on "full", but the center dial seems to read "0 kW" used, and the Energy Graph "Instant" or "Average" number won't move much except to reflect the slowly decreasing state of charge.

With the new 4.5 "shore power" feature, you can see the car draw 1 to 2 KW from the wall when the A/C is running and you're sitting still.

DouglasR | 12 June 2013

@Bob W

You make a good point. The trip meter does NOT show any energy usage when the car is stationary. It is certainly possible that when the car is in motion, it records ONLY the energy used by the power train. That could easily account for the variability in whpm consumed across a rated mile.

Evidence against that theory is anecdotal: turning on various accessories seems to result in higher energy consumption as measured by the trip meter. I admit, however, I have never looked at this question systematically. The way to do it would be to take two trips under the same conditions (as far as possible), but turning on all accessories, bright screen, etc. for one trip but not the other.

TikiMan | 12 June 2013

My P85 Sig (w/ 12k miles), is only showing a 'Rated Range' of 240 after a full-charge. I was told by three different service advisors at Tesla, that our 'Rated Range' is based on our driving habits (battery usage, etc), and will vary greatly depending on average speed, grade, etc.

I regularly drive in the HOV lane at speeds of 75-80 MPH on fairly flat roads on a daily bases, with the a/c on. Thus, I assume this explains why my 'Rated Range' is so much lower than some others here.

cerjor | 12 June 2013

How does Tesla measure the energy left in the battery? Is it simply a measurement of the voltage and compared to a full battery?

DouglasR | 12 June 2013

@cerjor - It is apparently quite difficult to do reliably. http://liionbms.com/php/wp_soc_estimate.php

@TikiMan - The service advisors may be right, but "the powertrain systems architect" sounds pretty authoritative. What is your average whpm?

Bob W | 12 June 2013

I made at least two mistakes in my previous post here.

First, looking closely at the instrument panel, the power meter actually does move up slightly when you turn on the A/C (parked). It's pretty hard to see because it's only 2 kW on a scale that goes to well over 320 kW. So now I'm thinking that the Model S does include A/C (and maybe heater) power consumption when recording the energy graphs.

Second, 32W of accessory use for a solid hour is 32 Watt-Hours (wH), but not 32 wH per mile, unless it takes you an hour to drive one mile (1 mph)! At 60 mph, the 32W load adds only 0.53 wH/mile, which is insignificant. However, 2 kW of A/C plus accessories for one hour at 60 mph is 33.3 wH/mile, which is about 11% of the 308 wH/mile number being used to translate state of charge to EPA rated range.

Finally, note that the rated range displayed by the instrument panel does not change by 11% if you turn the A/C on or off. Do you think it should?

A friend showed me how his Ford Focus EV increases the estimate range displayed when you turn off the A/C. I guess it's far more important to consider the impact of A/C in a car that has such a limited range.

What does the Nissan Leaf do?

TFMethane | 13 June 2013

Excellent idea to reduce the rated range displayed when the A/C is turned on.

The rated range appears to be a static calculation based on the battery's remaining energy (voltage, or %) times a fixed, per-mile energy consumption multiplier (the "rated" Wh/mile number). Tesla states that different regional governments require them to use different Wh/mile conversion factors. This conversion factor is not adjusted based on driving habits and conditions. Habits and conditions cause such a wide swing (as the mountain driver's post attests), that factoring them in would make the rated range a meaningless momentary number.

Tesla wants this to be the equivalent of a "fuel remaining" number in an ICE. Anyone who ever saw the "remaining range" calculation in an ICE knows that it has never been reliable in any car.

However, since the A/C creates such a predictable and constant drop, it might make sense to factor it in with a simple multiplier. It wouldn't be perfect, since the relative drain caused by the A/C peaks at 0mph and lessens with increased speed, road grade, headwind, etc. But, it would give a slightly more realistic number that might prevent a few people from getting stranded once in a while.

Brian H | 13 June 2013

Projected Range swings widely, but Rated and Ideal are simple conversion factors applied to remaining charge.

merijn | 13 June 2013

Why not make customizable rated range settings for different drivers (or circumstances)? For example 250 wh/mi for my wife and 400 wh/mi for me. ;)

DouglasR | 13 June 2013

My preference would be to go the other direction, and not try to predict actual range, with all the variables that go into it. Since rated range is basically just a surrogate for battery state of charge (SoC), I would like to have the car estimate the number of kWh remaining in the battery, and let me determine how far I can go on that. It would also be useful to have a gauge showing the instantaneous m/kWh (as opposed to whpm). I made this suggestion in the Prioritized Software Enhancement List a long time ago.

While the power draw from accessory usage may show up on the orange wedge of the speedometer, as well as on the Energy App, there is still the question of whether it is considered in the "kWh consumed" or whpm displays of the trip meter. Note that the trip meter shows NO kWh consumed when the car is stationary. It is therefore quite possible that the trip meter records ONLY the energy consumption from the power train. If that is the case, then I would like to see a meter showing kWh consumed from all sources, as well as an average whpm that includes all accessory usage.

As I think about it, there appear to be two possible causes of the apparent variability in computing the rated range of a given car. The first is the possibility, discussed above, that the trip meter energy consumption display is not counting accessory usage. This alone could explain why I have observed the fixed energy consumption multiplier to occasionally be lower than the assumed 308 whpm.

The second cause may be the inherent uncertainty in estimating the car's SoC and any point in time. If, for example, the car overestimates its SoC at the beginning of a trip, but then corrects the estimate by the end of the trip, the rated miles used will be greater relative to the actual miles traveled than if the estimate had been accurate for the entire trip.

TikiMan | 13 June 2013

DouglasR,

My average watts per mile use is usually between 340-385 depending on traffic. My daily commute is about 140 miles round-trip. I'm currently charging it to the highest setting for daily driving (which currently shows around 220-225 miles 'rated range' when I leave in the morning). I typically have about 65 miles of 'rated range' left when I get home.

DouglasR | 13 June 2013

I don't put on as many miles as you (4,500 miles), but my average consumption since getting the car in early December is 346 whpm. Before version 4.5 I was getting 242 rated miles on a standard charge. Now I have it set to the middle of the daily range, so it is much less. Maybe others with higher average whpm can weigh in on how their battery is holding up.

djm12 | 15 June 2013

For those mathematically challenged, "rated range" is the result of dividing a calculated estimate of the remaining charge (the numerator) by a fixed number (the denominator). Because the amount of remaining charge is constantly changing, the rated range will go up and down occasionally and of course will go down as the battery is discharged. In their software updates, Tesla may also be making subtle changes to how the battery is conditioned and maintained which may affect the battery voltage level.

Rated range is intended to provide a more accurate depiction of the distance remaining because it does not take driving behavior into account. It's then up to the driver to judge if he/she will outperform this number.

Baer | 15 June 2013

Has anyone else noticed a decrease in the Wh/mi on the highway with 4.5 installed? I was getting about 370 Wh/mi before 4.5 and now I'm seeing about 335 Wh/mi on the highway. I usually drive about 75 mph. I'm wondering if Tesla tweaked the monitoring or if they've actually tweaked the way the car is functioning....of if I'm dreaming....

jat | 17 June 2013

@Baer - I have seen no difference at all.

willardb | 17 June 2013

After installing 4.5 there seems to be a DIFFERENCE in RATED RANGE ON THE DASHBOARD AND THE IPHONE APP. My dashboard changed from maximum of 265 to 300, but the iPhone app showed 277.

Could 4.5 have changed the calculation method? The iPhone not? Why two different readings? A difference of 33 miles might get me into trouble since one trip left me with barely 12 miles rated range left.

Could there be bug in 4.5?

Brian H | 17 June 2013

willardb;
As long as you continuously watch your usage and keep remaining range above your actual miles, you will always make it. The actual drive will not differ from previous trips; only the display will behave a bit differently (range should drop more slowly).

SCCRENDO.Ca.US | 17 June 2013

Wiilarb I think you are making the same mistake as I was. If your max range is 300 you have your car set to ideal range not rated range. The I phone is set for rated range even though it says ideal range. . I changed my settings on the car control panel to rated range and it now matches the iPhone. It is a lower number but more realistic to my driving. going to work i go uphill and a little faster so i burn 360 wh/ mile and home i burn well under 300 wh/mile. Still burn off more miles than the rated range but realise with more cautious conservative driving could match the rated range (308 wh/ml). I standard charge to 228 which is about 258 ideal miles and was around 270 ideal miles before the update.

willardb | 17 June 2013

Tesla called me about the range problem. Apparently, the showing of 300 miles is because in SETTINGS, UNITS, I am set up for IDEAL RANGE which means the mileage I might get if I drive at 55 mph. Rated range is a calculation based on other factors. It was good of Tesla to call me. I have had nothing but very pleasant experiences with everyone at Tesla that I have met.

Vicelike | 17 June 2013

Has anyone actually run out of charge? How does the car react during the running out process? Does the car still have miles left when the indicator shows zero? If so, how many?

Brian.C | 18 June 2013

This is actually a big point of contention for me. When I first got my car in March I could get more than 240 miles rated range on a standard charge and now I am lucky to get 225 miles after <3000 miles of driving.

My friend is a systems engineer at Tesla and he told me that this is not normal since it corresponds to >5% change in capacity.

I tried taking it into service and the service advisor was quite adamant that the "rated" range changes based on driving habits saying my friend is "100% incorrect".

So what is the deal with this? Why is there such a disconnect with service and what is actually going on?

Rod and Barbara | 18 June 2013

@ Brian.C - The service advisor is wrong. Rated Range following a charge cycle is not based on driving habits. I recommend speaking to the supervisor at the service center, contacting the service headquarters in Palo Alto, and/or contacting the Ownership Experience team about getting the correct information to the service advisor. As for your difference between 240 rated miles and 225 rated miles, if you recently installed software v4.5 that could account for much of the difference. In v4.5 there is no longer a Standard charge setting. Instead there is a daily charge setting that can be set anywhere between 50% and 90% of battery capacity. In my experience, in pre-v4.5 a Standard charge was about 240 rated miles charged to about 93% battery capacity. In v4.5, my daily charge is about 230 rated miles charged to about 90% battery capacity.

Bob W | 30 June 2013

Together we can figure out what magic number is used by the Model S to translate your current state of charge to an EPA rated range. It seems to be slightly different for every car. For mine, the magic number seems to be exactly 300 Wh/mi, every time I've checked.

Magic No. in Wh/mi = Avg Wh/mi * Projected Range (AVG) / Rated Range (Instrument Panel)

Per a suggestion from @Rod and Barbara, I am using this thread, rather than this other thread, since this thread has a much more appropriate title.

Rather than fill this thread with responses that are difficult to summarize, I've created a short Unofficial Tesla Model S Rated Range Survey in Google Docs, where you can enter the numbers displayed by your Energy App. and your instrument panel (and optionally, your trip meter).

After you submit a response, you can see a summary of all the other responses that have been reported. Bookmark that results page to see the updated results in the future. With enough responses, we can figure out what Tesla is doing to calculate your rated range, and how it compares to real-world driving, and whether the tire type makes any difference in rated range (it should, but it may not).

Be sure to tap the Average button in the Energy app. before reporting any numbers, the app. it resets itself to "Instant" every time you restart the car!

Rod and Barbara | 29 July 2013

On 6/12/13 I posted in this thread:

“I have collected a few data points on Rated Miles used. In addition to significant scatter in the Wh/M vales, I found that Rated Miles appear to be “used up” at a faster rate than they are predicted. On one trip, after driving 151 statue miles, the total energy efficiency on the trip display was 308 Wh/M, but we had “used up” 165 Rated Miles. I have exchanged emails with Ownership on this topic and they hope to have an explanation for me sometime next week. I will post the answer here when I hear back from Ownership.”

Please see the new thread “Important New Information About Rated Miles and Projected Miles” for additional information on this topic.

Vichinpuri | 2 November 2013

Hi,

I got a MS85 just last week. Did my first trip from Nashville to Memphis -213mile
I did a full charge got a rated milage of 265. When I got to memphis i had 17 rated miles remaining

213+17= 230 miles Average speed was about 63mph average consumption 332whpm
So I got 35 miles less than the initial projected
kinda scary it wasnt a fun drive towards the end

I agree that projected miles with everything going on should be displayed(cabin energy expenditure + driving style). Its less mathematics and guessing when you drive and less stress especially on routes that dont have any supercharger. Charging at level 2 stations are time consuming.

I have to drive back tomorrow

Cheers

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