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Rated Miles, Projected Miles, and Actual Miles

Rated Miles, Projected Miles, and Actual Miles

We took a drive yesterday from Seattle to Bellingham and back. The display showed 230 rated miles when we left, and 30 rated miles when we returned. The projected miles jumped around some, but because I was driving conservatively, projected miles generally tracked within about five miles of rated miles. In any event, I returned with about 30 projected miles left also. However, the odometer showed that we had traveled 180 miles, not 200 miles. So what do people use to determine how many "actual" miles they may have left? Clearly both the rated and the projected numbers were overly optimistic.

skymaster | December 16, 2012

How fast was your "conservative" driving? Did you have anything else on like heat? What was the outside temp.? Battery range is affected by many different various things.

jat | December 16, 2012

The problem is they can't predict how you are going to drive and whether you are going on surface roads or the interstate. Driving my LEAF, I find % interstate makes the largest difference. I don't pay much attention to the computed range -- instead, I know that the way I drive, each bar of capacity is about 8 miles on surface roads and 4 miles of 80mph interstate driving, and compute it myself.

DouglasR | December 16, 2012

@Bsbomber,

I'm not complaining about the range I got (I was driving under 60 and got reasonably good range). I'm just pointing out that you can't rely on either rated miles or projected miles to predict how far you will get. I might prefer to have a raw number such as "state of charge percentage," rather than a derived number such as rated miles or projected miles. I guess you could consider rated miles to be a reasonable surrogate for state of charge percentage.

anthonytesla | December 16, 2012

As @jat mentioned, I too drive a Leaf and you start to understand your range depending on how you're driving, hills, freeway, surface streets, AC, etc. I always joke with friends that ask about range anxiety that I find myself driving very conservative to my destination and "who cares, I'll make it home" when I'm driving home!. The Leaf has a much more limited range than the Tesla (and its for the wife) but eventually you figure it out. Regardless, driving without gas, heat and noise is simply the best.

My (wife's) Tesla arrives very, very soon...

Volker.Berlin | December 17, 2012

Rod and Barbara have tried a systematic approach to understand what's up with all these different kinds of miles:
http://www.teslamotors.com/forum/forums/rated-miles-and-predicted-miles

ylyubarsky | December 17, 2012

Battery Percentage is A MUST feature

stoked | December 17, 2012

@DouglasR Sorry for the off-topic questions but I live in Vancouver, BC and am interested in the Model X. Which battery version do you have on your S and did you have the heat/radio on for your trip? I'm hoping the 60kW Model X can make it from Vancouver to Seattle on a single charge in any conditions and without having to conserve energy.

Thanks.

DouglasR | December 17, 2012

@stoked, I drove slowly (60 mph or less), and the car is configured for "range driving mode" (i.e., the fan is somewhat restricted and seat heaters are used more). However, I also had the sound system going, it was raining quite a bit so the wipers and blower were on, and the cabin was kept comfortably warm. I have the 85 kWh battery, but remember: I went to Bellingham and back on a single standard charge -- i.e., not a range charge. You should have no problem getting from Vancouver to Seattle in a 60 kWh car, but I would think about getting supercharger support for added flexibility.

jat | December 17, 2012

@stoked - note that the Model X is going to use more power to cover the same distance because it has higher CdA and weight. I don't think they will know for sure yet, but I think the estimates were around 260mi range rather than 300, so I would expect an EPA range for the 85kWh battery at more like 230mi.

Of course, battery technology may have improved enough by then that speculating now is a waste of time.

stoked | December 17, 2012

@DouglasR Thanks for the details. Hopefully the 60kWh X has somewhat close range to the 60kWh S.

@jat@jaet.org I figured as much, I guess I'll have to wait to see what the range is for the 60kWh X.

gagliardilou | December 17, 2012

I too am not sure of the actual range I can drive. I drove 82 miles today on a standard charge (started out at 238) which should leave 156 but I ended up with 120. So running the heat, radio, etc.. took 36 miles of range? Seems like a lot.

I have had my car a week. It has surpassed all my expectations but if I had to say one thing, it would be that I am surprised at how much mileage the heat, radio, or whatever else uses the power takes from the projected mileage. So even though in the morning it says 238, in reality, it may be truly only 160 miles. Just glad I got the 85KWh battery.

It is the nicest car I have ever had and I truly enjoy it!

jat | December 17, 2012

@lgagliard - the speed you drive also matters a lot -- the 300mi range is based on constant 55mph. The EPA figure is based on a mix of driving, so if you drive nothing but interstate at 75mph you will get less.

Timo | December 18, 2012

Speed has by far the biggest effect on range. Everything else is secondary. If you think you can't make the distance, slow down. Range sweet spot is around 25mph.

Mark K | December 18, 2012

BTW - wouldn't simpler nomenclature help reduce confusion?

Actual, Projected Range ===> Range

Rated Range ===> Max

I know the current terms are born of layers of engineering subtlety, but most consumers need a more common sense handle for what these numbers mean to them.

I think "Range" and "Max" convey it more simply.

Software updates are a beautiful thing.

Timo | December 18, 2012

Rated range is not max range. You can go quite a lot further than that. Similarly Projected range doesn't match actual range, it is estimation based on your driving behavior that far.

IMO you should not have "rated range" in display at all, it just confuses people. Just projected one (maybe change word "projected" to "estimated").

loewenberg | December 18, 2012

The new software update is not good. It is much more important to know your projected range based on your driving habits than some imaginary number which may or may not bear any resemblance to what you actually get.

Brian H | December 18, 2012

The Rated Range provides a standard, a measure to tell you how much you could get if you're prepared to drive "by the book". I'm sure that's how most drivers would view it, and why it's valuable.

DouglasR | December 18, 2012

As I understand it, Rated Range uses EPA's new 5-cycle standard, and is based strictly on the State of Charge, i.e., independent of your driving style (when Rated Range drops to 0, SoC is greater than 0, however). Rated Range after a full range charge should be about 265 miles in mild weather.

There is a new setting called Ideal Range, which I cannot seem to get my car to display. This measure uses a hypothetical driving style more conservative than the EPA standard, a steady 55 mph on a level surface with no climate controls or other accessories running. Ideal Range after a full charge should be about 300 miles in mild weather. Again, this measure is independent of your actual driving style.

You can choose to have either Rated Range or Ideal Range display on the instrument panel under the speedometer (this is my understanding; I cannot seem to get Ideal Range to display). Projected Range, by contrast, displays on the right-hand side of the graph on the Energy app. Projected Range does depend on your actual driving style, and you can choose to have it computed based on your last 30 miles, 5 miles, or 0.1 miles of driving.

None of these measures, of course, is guaranteed to correspond with your actual range, as determined by your odometer. I find it useful to monitor Projected Range while on a long trip. It provides the feedback I need to modify my driving style in order to achieve the range I will need to reach my next charging opportunity. So, for example, on a recent drive I was able to keep Projected Range within about 5 miles (+ or -) of Rated Range.

What I think would be most useful would be an app that takes into account all of the relevant variables: outside temperature, road type and terrain on the planned route, number of people in the car, etc. (think of combining the tools found on http://www.teslamotors.com/goelectric#range with those found on http://www.jurassictest.ch/GR/). The idea would be to plot a course that gives you a fairly accurate estimate of how much energy will be required to reach your destination, and then to modify the controllable variables (speed, accessory use) to match that estimate on a continuous basis. Maybe as I get more accustomed to driving this car, I will internalize these calculations, and they will become second nature. But until then, I think the more information, the better.

shs | December 18, 2012

I was in a Tesla store yesterday having a very similar discussion with the Asst. Mgr. As a fair amount of the driving we do is in the mountains/foothills, I would be more than happy to enter my destination into the Nav system, even if I knew how to get there, if the Nav system would look at the route and elevation changes and calculate projected energy usage and then compare that to what is available, etc.

MichaelHMB | December 18, 2012

Without having paid too much attention to it, in my daily commute of +/- 60 miles I'm using up closer to 80 rated miles.

DouglasR | December 18, 2012

Two points:

First, I called Ownership, and finally learned how to set Ideal Range to display: it can be found in Controls/Settings/Units & Format. I guess I could have found it if I had searched the Owners Guide for "ideal."

Second, according to the TM rep, and contrary to what I stated above, there is in fact some relationship between actual driving style and Rated Range. I could not get a clear answer as to how that is different from Projected Range, and frankly, it does not make sense to me. The solid horizontal line on the Energy app displays something under 300 Watt-hours per mile for the Ideal Range rate and something over 300 Watt-hours per mile for Rated Range rate. I have not seen any change in the Rated line in the week I have had the car. I'm wondering: do others have this line at a different level, and have you seen it change over time? In any event, until I get some clarification on this issue, I cannot stand by my earlier assertion that Rated Range is unrelated to actual driving style.

Brian H | December 18, 2012

Where does the rubber hit the road? You want to know how much you need to "restrain" your fun-driving to reach your destination. Comparing projected to Rated or Ideal helps you do that. What's the problem?

Timo | December 18, 2012

I see the problem as ideal or rated are both useless facts that do not actually tell you what to do.

I would like to see car give you actual real time usage as number and tell you how much power you should be using to get that usage in power meter. Maybe even show you your desired range from navigation info and how much power you can use to get there. IOW "don't go above this line and you are safe" -info.

Something like:

340Wh/mile or less needed
360Wh/mile current usage !!!

(both numbers change as you go, power usage or energy usage both work)

Maybe even with programmable safety margin (choose between 5-20% battery state)

July10Models | December 19, 2012

+1 Timo
The car can warn you that your current energy usage exceeds the usage to reach your destination

RZitrin1 | December 19, 2012

While I have also found this confusing - and the small dashboard display is so small - I think they'll get it sorted out. My understanding - I'd love to be corected:

Rated range: Driving the EPA way
Projected range: How far you can go driving the way you have been for the last (SELECT ONE) 5, 15, or 30 miles
Ideal range: The "max" range you could possibly squeeze out.

None are precise. If you are driving from Tahoe to Sacramento, you could get more by going 55 and regenerating like crazy.

I am hoping that in the next several months we'll get a better explanation.

Richard

Brian H | December 19, 2012

rzitrin;
+1

Rod and Barbara | December 20, 2012

@ DouglasR, et. al. – If a Tesla rep told you Rated Range is related to the way you drive, the rep was wrong (unless he meant the rate at which you use up Rated Range is related to the way you drive). Your 12/18/12 description was correct.

Rated Range is based on the EPA’s 5-cycle test. So after a Max Range charge with a nominal battery (note that most people will have a above or below nominal battery) will result in 265 miles of Rated Range. The power usage of a Rated Range mile is approximately 307 Wh/Mile (empirically determined value from my test data) and does not change based on your driving style. It is correct to say that the Rated Range miles and battery SOC are linearly related and in a perfect world (car) any SOC value would always display the exact same Rated Range miles. However, the SOC and Rated Range values appear to be calculated using independent algorithms so their linear correlation isn’t always precise.

The new setting called Ideal Range is based on driving 55 MPH on a flat road. It should behave exactly like Rated Range, just based on a different power usage. I don’t have enough data to say what the Ideal Range miles for Max Range and power usage are, but my guess is that they are about 300 miles and 270 Wh/Mile.

Predicted Range is displayed on the Energy app and is computed based on recent driving experience. 30 miles, 15 miles, 5 miles, or 0.1 miles can be selected as the recent driving experience distance for calculation. Each time the car is shut down this selection defaults to the 0.1 miles selection.

The advantage of Rated Range and Ideal Range is that they are predictable and constant, not affected by your driving conditions, and therefore always provide a reliable estimate of the useful battery capacity remaining in the car.

Lets return to your original question concerning the round trip between Seattle and Bellingham where you drove 180 miles but used 200 Rated Range miles. If your Projected Range and Rated Range had matched precisely throughout the trip, then your distance traveled should have matched precisely the Rated Miles used. You said the Projected Range and Rated Range matched within 5 miles plus or minus throughout the trip. Since Projected Range is only based on recent driving experience it may agree closely with Rated Range at some point in the drive and hide the fact that the driving experience older than the selected Projected Range was worse than the Rated Range standard. One method to try is to reset one of the trip odometers when you begin a trip and note the Rated Range. Monitor the Wh/Mile on the trip odometer – if it is below 307 Wh/Mile you will do better than the original Rated Range value, if it is higher than 307 Wh/Mile you will do worse than the original Rated Range value.

You asked, “what do people use to determine how many ‘actual’ miles they may have left?” I don’t think there is any single gold-standard formula. If you are familiar with your driving style and the route ahead you will have a good feel for whether Rated Range will be right on, pessimistic by x% or optimistic by y%. If you know the route ahead will be fairly constant and you will use a consistent driving style, then Predicted Range should give you a good answer. If there are lots of unknowns then you need to build in an appropriate fudge factor and if things get tight, slow down.

DouglasR | December 20, 2012

Thanks, Rod and Barbara. That explanation makes perfect sense to me. And yes, you are right that on my trip, I probably started out with my energy consumption fairly high, but then drove more conservatively when I realized that I needed to stretch out those electrons. I was probably keeping Projected Range close to Rated Range only for the second half of the trip out and for the whole way back, but lost those 20 miles during the first part of the journey. That was easy to forget, since Projected Range covers only a 30-mile average. However, it is good to know that Projected Range will equal actual range for the REMAINDER of the trip if I am able to match Projected and Rated Range for that segment. After all, what matters is not how far I've gone, but how far I need to go to reach a charging outlet.

One person did comment, however (in a different thread), that the line on the Energy app graph representing Rated consumption changes as he drives. I agree with you that it does NOT appear to change, and 307 watt-hours per mile is just about where it appears to be (hard to tell because the x-axis does not show fine gradations). Now I'm thinking he misunderstood, and was actually saying that rate at which he uses up Rated Range depends on his driving. I will find his statement and report it back here, but I would be interest whether anyone else thinks that this rate varies.

DouglasR | December 20, 2012

Ok, the comment was by Klaus in this thread: http://www.teslamotors.com/forum/forums/full-300-mile-recharge-issue

And he did expressly reference the flat line on the Energy app graph. I will pursue this further, but not right now. Dinner calls.

Brian H | December 20, 2012

Yes, both Rated and Ideal are standards that you can reference and "compete" with, on brief stretches or the whole trip. Your predicted actual mileage will be your own SWAG from observing the difference -- whether better or worse.

dahtye | December 20, 2012

I also found that the heater/AC with fan running takes up quite a bit of juice. Just sitting at a stop light, my energy consumption (orange part of the speedometer) in non-zero by a large amount - maybe 2 or 3 KWHr. So, depending on how long I spend in the car, I could be using up precious energy. If I spend 4 hours driving, I could use between 8KWHr and 12KWHr of battery - which would equal between 26 and 39 of rated range (assuming 307 watts/mile). Using the driver's seat heater on the highest setting, 3, does not move the orange dial at all.

Also, has anyone noticed that a standard charge in cold weather does not yield the normal 240 or 241 rated miles? I've noticed that since it's gotten colder in the SF bay area this week that I can get only about 237 rated miles on a standard charge. I hope that when it gets warmer, my standard charge miles go back to around 240.

DouglasR | December 21, 2012

@dahyte, I've never gotten 240 on a standard charge. I typically get around 233-235. My highest, as I recall, was 237, and my lowest was 231. I'm in Seattle. It's been cool here, but mostly in the mid-30s at night, and mid to upper 40s in the day.

dahtye | December 22, 2012

@Douglas, so that makes sense then. There is an external temperature dependency on maximum standard charge. My early experience was consistently 240 or 241 miles when charging at about 65F to 75F in the SF Bay Area. Recently, temps have dropped to between 48F and 53F during charging, and I'm seeing 237 miles range on a standard charge. It's also likely that external temperature has a bearing on our actual range when driving - perhaps the battery does not hold its charge as well in the cold?

DouglasR | December 22, 2012

@dahtye, I don't know how they determine the Rated Range number that appears on the instrument panel -- i.e., whether the car monitors external temperatures or whether it measures the charge level in kWh rather than in percentage of a full charge. However, the lower number in cold temperatures is certainly consistent with the actual mileage we should expect. Take a look at the little calculator on the Go Electric page: ideal range drops from 301 to 287 when you drop the temperature from 70 to 32, even without turning on the heat.

Klaus | December 22, 2012

@Douglas, After rereading my post, I mispoke/typed concerning rated, ideal, and projected range. I normaly, on a standard charge, will see 240 miles rated or 275 miles ideal. These don't seem to change more than 1 or 2 miles, probably dependant on temperature. Here in Florida the overnight lows have gotten in the high 40s. The projected range is the dashed line. That's the one I can ocassionally get below the ideal (solid line) and routinely get below the rated (also solid when selected).

My average wh/mi has been slowly dropping and is currently at 308 for over 3500 miles. My driving habits have definately gotten better and I expect my average to drop below 300 eventually. I still enjoy kicking it up a notch on the freeway, but most of my driving is around town at 35-45 mph.

Ron5 | December 22, 2012

I have been getting *very* close to rated range here in warm South Florida. I don't think you need anecdotal numbers to figure out the rated rage Wh/mile. I believe it's just 85000 / 265, which works out to around 320.75. Or am I misunderstanding it?

DouglasR | December 22, 2012

@Klaus, But you agree with me that the solid line on the app, whether set to Rated or Ideal, does not change with your driving style? I know the dotted line -- average watt-hours per mile over 5, 15, or 30 miles -- does change with your driving style. But I'm pretty sure that the solid line is the same for everybody: as Rod & Barbara said, about 270 watt-hours per mile for Ideal and 307 for Rated.

DouglasR | December 22, 2012

@Ron5, not exactly. The numerator is something less than 85000 because the car is designed to use less than the full capacity of the battery for driving. The last 5% is to protect the battery when it gets low. So if you take 85000 watts times .95 and divide by 300 (range charge), you get 269. Similarly, if you divide by 263 (standard charge) you get 207.

DouglasR | December 22, 2012

Oops, I got that wrong. First, I meant 307, not 207. And this was referring not to range v. standard charge, but rated v ideal range. Sorry.

Ron5 | December 22, 2012

@DouglasR, good point regarding the 95%, but I'm talking about rated charge here. So I believe the denominator would be 265 for range charge, not 300. 95% of 85000 is 80,750. 80,750 divided by 265 is almost 305. So to me that means I need to average 305 Wh/mi to match the rated miles for a range charge.

Brian H | December 22, 2012

Cooler air is denser and harder to push out of the way. Like driving up the Cd a bit in its effect or moving to a lower altitude.

Klaus | December 23, 2012

@Douglas, agreed.

HansJ | December 23, 2012

It would be nice to have a customizable "Personal Miles" display that would be just a simple Rated Miles number with a fudge factor that each driver can input. If you are an aggressive driver then you could put 0.7 as your multiplier and your Personal Miles display becomes your own special Sport Miles range. If you are an ultra conservative driver then input 1.1 and you get your own custom Hypermiler Miles display.

DouglasR | December 24, 2012

While I understand that Projected Range/Average should change when you select 5, 15, or 30 miles, I just noticed that Projected Range/Instantaneous also changes when you select each of these three distances. That leads me to think I have been misunderstanding the Instantaneous tab. I thought it was an average over 0.1 miles, but that would be inconsistent with being able to choose 5, 15, and 30 miles.

So can anyone give a cogent explanation of what the "Instantaneous" tab is measuring?

jkirkebo | December 25, 2012

"Personal miles" is a good idea, but no need for a "fudge factor". It's much easier to just be able to input your usual Wh/mile number. So if you usually do around 405Wh/mile, input that and the "Personal miles" should indicate ~200 miles from a range charge or ~175 miles from a standard charge.

drp | March 3, 2013

This is from.........

Klaus | DECEMBER 22, 2012
@Douglas, After rereading my post, I mispoke/typed concerning rated, ideal, and projected range. I normaly, on a standard charge, will see 240 miles rated or 275 miles ideal. These don't seem to change more than 1 or 2 miles, probably dependant on temperature. Here in Florida the overnight lows have gotten in the high 40s. The projected range is the dashed line. That's the one I can ocassionally get below the ideal (solid line) and routinely get below the rated (also solid when selected).

My average wh/mi has been slowly dropping and is currently at 308 for over 3500 miles. My driving habits have definately gotten better and I expect my average to drop below 300 eventually. I still enjoy kicking it up a notch on the freeway, but most of my driving is around town at 35-45 mph.
..............

So far in the 1 1/2 days that I've had the car, my experience is very similar to what Klaus has experience. However, I am in Illinois and the temperature has ranged between 25° and 36°. I am getting a standard charge that shows rated miles well below the ideal miles but I have only been paying attention to the ideal miles which are around 277 ideal miles. I have been practicing my drive that is coming up tomorrow and hope that I can make it round-trip 165 miles in the cold temperatures. The car will sit out for about six hours at my destination. I am going to be really wimpy and just drive 55 mph or 57 mph mostly on cruise control. However, I also find that it is best to disengage the cruise control when going downhill because there is some regeneration that occurs. Otherwise, it just cuts back on the kilowatts use.

drp | March 3, 2013

Just to clarify in the above, My comment starts after the dotted line in the middle of the post. I just want to know what other people are experiencing. This kind of information could be really useful to me and I hope other people could benefit from it as well. We can make this private if you want, just let me know.

drp | March 3, 2013

I'm not talking about software, I'm talking about real practical experience from those people who have driven the car under various conditions.

KevinR.co.us | March 3, 2013

In my experience you will see more energy use on a cold day to warm the battery & the cabin at the start of each leg of your journey. Your "rated miles" will actually increase once the battery is warmed. Your rated miles should be a good estimate for you once your battery is warmed. Your rated miles when you park the car for 6 hours should help to reassure you for the trip back. If you have concerns you could always plug in to a 120 outlet to keep the battery warm during the day--but I don't think you will find it necessary.

DouglasR | March 3, 2013

@drp

You should be OK, but to be on the safe side, why don't you do a range charge the night before, and set your amperage so that the car finishes charging just at the time you want to leave. You should have about 270 rated miles (I would ignore "ideal" miles, because you won't get close to that consumption rate).

Driving slow is also a good idea, at least until you know what kind of consumption you are getting. If, on the way home, you see that you will have many miles to spare, then you can speed up. Remember, you can use fewer miles if you turn off climate control and use the seat warmers instead.

I would also use Recargo or one of the other sites/apps to scope out where you can stop to pick up a charge if you get into trouble. Of course it would be much better if you could plug in during the six hours you will be at your destination.

The Go Electric page on this site shows that an 85 kWh battery can go 233 highway miles or 211 city miles at 60 mph, with temperatures of 32 degrees, using the heater. It does not take account of your six hours sitting in the cold, which could cost you another 10-15 miles. So you should make it no problem. But it never hurts to plan ahead, and to have a backup in case things don't work out as planned.

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