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1 week owner - concerned about mileage

Hello All: I got my MS85P+, Red, PanoRoof on 6/28. It's exhilarating! However, I am concerned about the discrepancy between the rated miles and the actual miles I am getting. Two nights ago my wife accidentally toggled the charging from standard to max on the iPhone app. My car charged to 274 rated miles. I have not charged it since, and I noticed that the actual driven miles from last charge are 67, but the rated miles remaining are only 183 (I should have around 207) – where did the 24 rated miles go? I have been concerned about this ever since I got the car, and I have called Tesla twice. The first guy told me to change from the ideal miles that my system was set to miles, which he said are accurate to within a few miles. When this did not seem to be the case, I called again, and I was told to just drive the car for 2 weeks, and the computer will “learn” my driving habits, allowing the rating calculation to become more accurate. However I have read on this forum that that is actually not the case. I don’t see how I can take this car on a long trip if there is around a 10+% discrepancy between traveled versus expected miles. I have deliberately been laying off the pedal, coasting without using the brakes, and I have the climate set to extended range. Please give me your thoughts.

Two thoughts:
vampire loss to be addressed with SW update
what's your Wh/mile avg?

After driving a leaf for a year and a half before getting a Tesla, I learned to watch the energy meter more than the estimated distance. It is like watching the gas gage rather than the estimated distance based on the last so many miles driven. The Leaf had 12 bars instead of Tesla's 10. I knew how many bars it took me to get to work downhill and how many bars it took for me to get home uphill. For the Tesla I also watch the number of kWh consumed since the last charge, though it isn't really an issue around town now that I have so much more range. I have heard they are refining the software estimating range to take into account well traveled inclines. Having 274 rated miles is weird though. I think it is supposed to max out at 265 for an 85kWh.

These factor will decrease mileage:

- AC usage
- Change in elevation
- Lead foot, e.g. quick acceleration, speed > 60
- Extra cargo / passengers
- Vampire power drain ( can be up to 12-15 miles loss per day)

If you feather the accelerator pedal and keep the speed under 55 consistently then your will get expected / ideal miles.

The same factors will affect ICE cars also but it is more noticeable for EV.


If I understand correctly you have not plugged-in your car in around two days.

Unfortunately, the Model S eats up battery even when not it's parked. That's why Tesla recommends you leave it plugged-in all the time, even when it's full.

Other than that, the rated miles when you first charged assume you drive at a specific 55mph and not any quick accelerations, etc. That number is a calculation but never exact, could be more, could be less.

Anyway, most people here can confirm about the "vampire losses", the miles lost while parked. Surprised that the Tesla did not bring this up when you called them.

I meant to say "the Model S eats up battery even when it's parked."

It's no different than a regular internal combustion engine car, when the trip computer tries to calculate range for you based on average mileage and fuel remaining. Its only going to be so accurate. In fact the Model S is far more accurate, or at least gives you far better tools to estimate your mileage yourself.

It takes a little while to get the hang of it but its really pretty easy.

One simple rule: if you're averaging 300 wh/mi, that will give you approximately the rated range. If you're averaging higher you will get less range, lower you'll get more range. As with any car its based on how fast or aggressive you drive, if you hit stop and go traffic, and so on.

I find that in warm weather, if I keep it around 65, avoid lots of needless accelerations, that usually gets me the rated range or better. In fact sometimes I get that driving 70+.

Until you get used to it just leave yourself a mileage buffer. Maybe 20%, 30%, just until you get the feel of it?

And know that if it gets tight, just slow down.


Why are we calling it "vampire drain"? The problem he has isn't what you guys refer to as vampire drain. Losing 24 miles forever isn't vampire drain. Losing 10% overnight on your cell phone battery; Is that vampire drain? If so, then why hasn't this word been in mainstream yet?

I've owned a cell phone for 20 years, and they all discharge some battery overnight, if not plugged in. In fact, if I have lots of apps running, it will lose significant battery life, like 40-50%. However, I've never heard called it vampire drain. Laptops, same thing.

I guess what I'm saying is that I take offense to the term "vampire drain", because 1) vampires are scary by definition 2) drain is scary 3) You're coining a word to make it something bad, when it's just what people already expect when they own something that runs on batteries and has to be plugged in to charge! Imagine Mitt Romney saying "vampire drain" when he called Tesla a loser. How offended would you be?

Oh and then there's 4)You guys are potentially scaring away uninformed people who might otherwise buy an S. Fellow investors and fans, please read that last sentence again. All because of the vampire drain boogie man that will get them while they sleep, literally ! Protect the babies! Bad, bad Tesla enthusiasts! :)

Now that I've said that,

"Where did the 24 rated miles go? I have been concerned about this ever since I got the car..."

-So you got it on 6/28, but this happened two days ago. By my calendar is 7/3. So you mean that before you got the car you thought this might happen? You should read "The Secret". You gotta harness the good energy, block the bad. Oh and remember, it's all in the hips.

"....allowing the rating calculation to become more accurate. However I have read on this forum that that is actually not the case. "

-I'm not sure what thread you're referring to, unless you mean the vampire drain related threads? Link?

Please keep us informed, this sounds like something might actually be wrong! Otherwise congrats on your new S, that's awesome you got it in time for July 4th! I'm sure you probably sold a Model S or two during the holiday with friends and family showing it off! Did you take a nice road trip? :)

P.S. sorry everyone my posts seem to be getting longer and longer lol.

You will still have to drive pretty conservatively to match rated miles -- I have only done it when I needed to drive 240mi on a charge, otherwise I am driving a lot faster and using more energy.

What you will get used to doing (at least until the Supercharger network is built out) is to watch the Wh/mi number on the trip meter since last charge. Figure out what you need to make to reach your destination with the margin you want, and then adjust your speed so you make it (to hit rated range, you need to achieve 308Wh/mi).

+1 stimeygee
@eye, you just got the car, you need to relax a bit. The rated miles are just estimates, and it changes based on how you drive. you will figure out what your range really is after you have some miles under your belt. If you drive short trips, you will use more miles than long steady trips on the freeway, a hard acceleration can eat some miles up, And it does use battery when the car is parked, it is normal to see 10 miles down if you do not plug in overnight, just plug it in like Tesla said in the manual unless you are at the airport or somewhere other than home
@mvannah it is NOT weird to see 274 rated miles! I have seen it in my car, and I am sure I am not alone. But that only happens when you use max range.

just try to keep the average wh/m close to 300 if you can to have the rated miles closer to your expected actual., but since you have a P+, I doubt you would be able to drive slow! mine is about 350 wh/m over than 6000+ miles!

Coasting? Laying off the brake pedal? RU sure you're driving a Tesla? The brakes are almost never used, and you get regen braking backing off the "goose pedal", not coasting.
Projected miles uses recent driving to generate a number. Rated miles is a fixed ratio of the EPA 265 mile range calc'd from remaining charge.

Your post makes no sense.

He said he was laying off the pedal, as in spirited acceleration, not the brake pedal. He's a legitimate poster, perhaps not well-versed in the vernacular of the forum.

oh Brian, a little slack, he says he just got his car on 6/28, old terminology!
btw, what 's his name that ran out of charge and had two tow trucks, kids throwing rocks in the fountain, etc. never posted again did he?

Do you have Regen set to Low or Standard? In Standard you recover more energy, and achieve longer range on a charge.

Vampire drain is likely the issue. His maximum miles haven't decreased 14mi, just the current estimated after not charging for two days. 14 sounds reasonable, especially in less than perfect temperatures. The term has been around for awhile and isn't new , nor scary and also isn't residual discharge during no-draw periods; it's the slow drain from maintaining nominal power to systems for quick start up (term originally coined for household plug-in electronics that draw low amounts of power while turned off). Your cell phone analogy holds true though (cell phones stay camped on a pair of frequencies or PN Offset to monitor for incoming calls or new network data, and thus draw power). The term shouldn't cause any more fear than the applets in your computer task's unavoidable, though we're still seeking to minimize the amount of drain.

Supposed to return to the 2 mi/day level once the buggy 4.1 deep sleep version is fixed and re-released (at the expense of slower system start-up).

I first want to say that I love this forum – you guys are great - and I'm glad you enthusiasts take the time to answer. I asked a question last night as a new owner and woke up with 16 replies!! This is an awesome part of the ownership experience. I was even reprimanded by Brian H for making “no sense” – just like joining a frat and being hazed – thanks brother. Jonesxander – here is the link that indicates that rated range is not related to driving style:; CalDreamin – yes I have regen set to standard.
In any case, you folks have set my mind at ease that what I am experiencing seems to be normal – now I can be less paranoid and enjoy!!

Be careful, too, because you just might know someone around here. I've found several old friends lurking here. Had to creep because of your email address--we have several stomping grounds in common--Albany Med, Brown U and Wilmer, just to name a few. My BIL is a cop in West Chester, not that you'll be needing any favors! Congrats on an amazing choice--my-P85+ arrives later this month.

Here's a link that pretty much matches your observations...

I agree with what Matthew said above. I have not had any problem matching the rated miles and occasionally do find ideal miles even being beat ideal by my driving style. I have driven 11,000 miles and have the 21 inch wheels and I drive a P 85. There are a few "sweet spots" for speed, at least in my particular vehicle. It certainly does like 55 – 58 mph and also 63 mph and 73 mph. Lead foot and use of heat is particularly problematic but I have found less of a problem with air conditioning for some reason. I do plug my car in almost every night and keep it plugged in when it is parked, although not at the office during the day. Ambient temperature is also a very large factor.

Bighorn - wow that's really neat. Please e-mail me at the above address - I'd love to know what years you were at Brown, Albany Med, and Wilmer. When you come to visit your BIL in West Chester - in your P85+ of course - let me know and I'll take you out to lunch.


Vampire load is actually a very common expression. There is even a wikipeda page for it :) So I don't really see the FUD factor here.

Your cell phone analogy is not very compelling. A cell phone loses charge overnight because it is switched on. It is continuously communicating with the network to respond to incoming calls. It is keeping an internal clock so if you happen to have set an alarm, it will wake you up. Etc. Switch off you cell phone and I can assure you that it will not lose charge.

First, in order for your Rated Range Miles to equal your actual miles driven, you need to average about 308 Wh/mi. Why this number? It is obtained by taking the energy (Wh) in a full batter (minus a couple of kWh so that you don’t fully drain the battery) and dividing by the EPA 5-cycle estimate of miles: 265. Round up to 310 Wh/mile if you like. If you average about 310 Wh/mile, you will actually be able to drive 265 miles on a full charge. Average under 310, and you will be able to drive more than that, average over, and you will get less.
But another important point is to realize that there is measurement error in the system that is unavoidable. The actual measurement that the car makes (to ultimately determine Rated Range) is a voltage difference across the battery pack terminals. This is the direct measurement. Unfortunately, it is difficult to take this direct measurement and “guess” what that means in terms of how many miles you can drive. So several calculations have to be done to convert the voltage distance into Rated Range Miles.
First, this voltage difference is then turned into an energy storage amount, in kilowatt hours (kWh) by an empirical equation that was developed using measured correlation between voltage differences and kWh used. Then another empirical equation is used that calculates Rated Range miles from the energy (in kWh) that was calculated from the direct voltage difference measurement. What do I mean by an “empirical equation”? An empirical equation is an equation that is developed by measuring the responses of one variable to a range of values of another variable. So it is based on measured data, rather than on physics. In the first example, they would measure a voltage difference, then put a load on the battery (i.e., drive the car), monitor the current used to drive a certain distance, from that, they could directly calculate the energy (kWhr) used. Then they repeat this many times to get a “data set”. This data set allows them to determine the exact form of the empirical equation and the parameter values that go into it. Can you see where we are going here? There is lots of room for variation! What was the temperature when doing the measurements? Is there a way to correct for temperature? These measurements were done in a lab (car probably on an ergometer, that is the drive wheels were turning a device that measures distance, speed, torque, etc). The real world is a lot more variable than the lab. The bottom line is that there are lots of sources of uncertainty and measurement error. Let’s summarize:
So here are the steps of uncertainty:
1. On a given day, your battery may accept more or less charge, depending on temperature and other variables.

2. There is measurement error in the process of measuring the voltage drop across the battery.
3. Potential error or drift in the empirical equation that calculates energy storage (kWh) from voltage drop - the equation was developed from measured data that was subject to specific temperature conditions which may not be the same.
4. Further potential error in calculating Rated Range Miles from energy storage.
The bottom line is not to get too worried about, well, let's say about plus or minus 5% of the maximum rated range. So, about +/- 15 miles. Differences of less than this are most likely not "real", but just due to the measurement/conversion process.

By the way, I'm a retired Professor of Geophysics.
Steve Wheatcraft, Reno, NV

Dang, that's battery, not batter!!

Thanks and check your email. , jonesxander & Andre-ni

As a Leaf and Tesla owner, I think I know why there is a drain of the battery when parked. The car is always running something, e.g. the 3G antenna, GPS, etc.. And unlike the Leaf, The T does not have a lead-acid battery (connected to a solar panel) as a backup supply that runs auxiliary functions of the car.

Tesla (Elon) should clear this up, because it will scare away potential sales for most of the ICE drivers out there don't really understand the trade-offs when one owns an EV.

I just pulled this from the Model S Facts page (the link to which seems to have disappeared from Tesla's Model S pages):

  • "The Model S battery will not lose a significant amount of charge when parked for long periods of time. For example, Model S owners can park at the airport without plugging in."
  • So… ?

    I believe there is a sleep mode which was buggy that did limit charge loss, but it's been temporarily disabled as improved software is developed.

    wheat-craft, flour, batter.
    It all makes sense now! Add water, yeast and then bake.

    I just pulled this from the Model S Facts page (the link to which seems to have disappeared from Tesla's Model S pages):

    •"The Model S battery will not lose a significant amount of charge when parked for long periods of time. For example, Model S owners can park at the airport without plugging in."

    This is BS. It is time for TM to fix this.

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