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Tesla Real HWY Range and EPA COMBINED Range.

Discussion in 'Model S: Battery & Charging' started by No2DinosaurFuel, May 20, 2015.

  1. No2DinosaurFuel

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    I have been obsessing over the max range of the model S for some time now. The only reason is I would like the model S to replace my ICE car and want to make sure it can meet most of my needs. I want to drive the model S the same way I drive my ICE car now.

    Over this website I found out the usable capacity the Model S has for the 85KWh is 76KWh. It might be more or less this number, but lets make that assumption.
    Tesla Model S Buyers', Delivery and Owners' Guide

    This equates to roughly 90% of the battery. Being knowledgable about lithium batteries, I can conclude this is really where you want to use your battery anyways (worst case). 5% bottom and 5% top to maximize battery life.

    Given this data, the capacities for the different model S batteries are:

    85KWh - 76.5KWh
    70KWh - 63KWh
    60KWh - 54KWh

    Using this EPA website, I calculated the HWY miles I can get. HWY is really what I care about anyways because in the city, I would most likely be near a charger of some sort and can easily charge. On the Highway when moving from city to city I might find it difficult to charge and charge quickly.
    Gas Mileage of 2015 Tesla Model S

    Using ONLY the HWY mpge and the 33.7KWh in 1 gallon equivalent of gasoline I arrived at the following numbers for the following Model S:

    Model S85D - 76.5KWh/33.7KWh * 106 = 240.6 miles
    Model P85D - 76.5KWh/33.7KWh * 98 = 222.46 miles

    Model S85 - 76.5KWh/33.7KWh * 90 = 204.3 miles
    Model S70D - 63KWh/33.7KWh * 102 = 190.68 miles
    Model S60 - 54KWh/33.7KWh * 97 =155.43 miles


    This is the MAX range you will get on the HWY. The first thing I don't understand is why the P85D, despite being more efficient, have lower EPA total range, 253 miles, compared to the S85 which is rated at 265 miles and less efficient. I think EPA changed their method of range rating and hence why the overall lower EPA range for the P85D. My point is, not to worry about the EPA COMBINE range, but look more at the HWY and CITY EPA range and do your calculation on those numbers.

    In real life HWY driving, the P85D will get more range than the S85 despite EPA rating the P85D at overall lower total EPA range.

    Now to the point of degradation.
    Assuming 5% degradation over the first 4 years or so (generous) , we are looking at:
    Model S85D - 240.6 miles * 0.95 = 228.57 miles
    Model P85D - 222.46 miles * 0.95 = 211.37 miles

    Model S85 - 204.3 miles * 0.95 = 194.1 miles
    Model S70D - 190.68 miles * 0.95 = 181.15 miles
    Model S60 - 155.43 miles * 0.95 = 147.66 miles

    This will be your HWY range for the first 4 years of driving. The reason I am looking at this number is most likely when you do take road trips, you will want to use a number you can count on, not the max your battery is providing at the time.

    Now factor in 10% of that range is what we typically leave in before really panicking to finding a charge:
    Model S85D - 228.57 miles * 0.9 = 205.7 miles
    Model P85D - 211.37 miles * 0.9 = 190.23 miles

    Model S85 - 194.1 miles * 0.9 = 174.69 miles
    Model S70D - 181.15 miles * 0.9 = 163 miles
    Model S60 - 147.66 miles * 0.9 = 130.2 miles

    Obviously these numbers are probably what you would get worst case condition, i.e. headwind, raining, AC on, going 70+mph, etc. Yes I know many of you on the forum would complain you get much better range than these numbers. But keep in mind, this is what the range you would get if you drive your Model S like you drive your ICE car in any typical condition. Again apples to apples comparison.

    After looking at those numbers, the S85D would be the only car that would comfortably do 200+ miles. This makes my decision on which model to get much easier.

    GET THE S85D!

    Going on these numbers, the model 3 must be much more efficient or have a much bigger battery than most will anticipate if it going to legitimately get greater than 200 miles on one charge with AC on like Musk has said. But then again, who knows what trick EPA plays to get these BEV combined range numbers. I am not dissing EV cars, but I feel the EPA sometime hacks the numbers to make it look more favorable compared to ICE cars.
     
  2. apacheguy

    apacheguy Sig 255, VIN 320

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    Folks have certainly pulled > 76.5 kWh out of an 85 pack on a single charge.
     
  3. stopcrazypp

    stopcrazypp Well-Known Member

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    A couple of big assumptions you made throw your numbers way off.

    1) no one knows the actual usable kWh in the pack, so don't rely on that. The 76 kWh is just a guess that may not be correct.
    2) The EPA MPGe numbers factor in charging losses. Therefore you cannot use the MPGe numbers with the usable kWh number (which you are guessing only in the first place) to convert to a range number unless you know the charging efficiency of each model.

    The proper way to do this is to scale the official EPA combined range number with the MPGe combined/hwy/city numbers to find out whichever one you want. Any other way throws in too many assumptions.
     
  4. dennis

    dennis P85D

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    While the P85D is slightly more efficient at certain highway speeds, it is overall less efficient because it weighs 300 lbs. more than the S85. This really shows up in the EPA combined number, which has more that 50% slower speed and start/stop driving. Check out JB Straubel's blog post from late December on the Tesla website.

    The EPA has not changed their method of rating range.

    My P85D is 1%-2% less efficient thus far than the P85+ I previously owned, as measured by lifetime wh/mi.
     
  5. No2DinosaurFuel

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    Most people will not completely drain their battery every charge. Moreover, most people will want to leave enough to feel comfortable and safe. Sure they might drain more than the usable 76.5KWh, but will they keep driving if the indicator states 0 miles? I think the numbers I used are good.

    1) I think the numbers I used is a good starting point when no one knows the exact numbers. In fact, I would think that is the number tesla use to rate your 0 miles range.
    2) What do you mean by charging loss? You mean EPA read out what you put in at the charger and not after the charger? If so then that explains the huge discrepancy. I will have to redo the numbers. I think we can generously say the charging efficiency would be 92%. Most 240V Lithium chargers are rated at this rating. Though some are higher, I think we should use the lower number to "Boost" the Model S range.

    Lifetime wh/mi does take into account many things. I would like to see someone who drives their model S like they drive their ICE car on the HWY in typical conditions, i.e. AC on, maybe some wind/rain, etc to see the wh/mi. Using this number would be more accurate as oppose to using lifetime wh/mi. Again the goal is to give people who don't know about how to properly drive a BEV a realistic range they can expect.


    So assuming 92% efficiency conversion, we are looking at HWY mpge:
    S85D - 115.2 mpge
    70D - 110.9 mpge
    P85D - 106.5 mpge
    S60 - 105.4 mpge
    S85 - 97.8 mpge

    Using these new numbers, the range of the following cars are:
    S85D - 261.51 miles
    P85D - 241.76 miles

    S85 - 222.01 miles
    S70D - 207.3 miles
    S60 - 168.89 miles

    The usual 5%:
    S85D - 248.43 miles
    P85D - 229.67 miles

    S85 - 210.91 miles
    S70D - 196.94 miles
    S60 - 160.45 miles

    And the usual 10% buffer before people get scared and search for charger:
    S85D - 223.59 miles
    P85D - 206.7 miles

    S85 - 189.82 miles
    S70D - 177.25 miles
    S60 - 144.41 miles

    Better... But it looks like the S85D is still a much better. I think these are the numbers the road trip thread is telling most people to expect anyways.
     
  6. dennis

    dennis P85D

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    Since you live in California, with superchargers every 100-150 miles on major routes, you may be over analyzing the problem.

    Aggressive drivers, going 80 mph on the freeway, use up to 400 wh/mi. That yields a range of 2.5*75=187 miles.

    Moderate drivers, going 70-75 mph on the freeway, may use around 350 wh/mi. That yields a range of 215 miles.

    Conservative drivers, going no more than 65 mph on the freeway, may achieve 300 wh/mi. That yields a range of 250 miles.

    All of these will be reduced by cold weather, hills and rain. But again, you are in an area that is well-served by superchargers, especially after the one in San Diego opens in the next few weeks. The only time you will have to think about where you might have to charge is on a road trip that takes you 100 miles or more out of the range of a supercharger.
     
  7. stopcrazypp

    stopcrazypp Well-Known Member

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    According to your linked article the empty point is at 81 kWh and recent firmware versions had people reporting that they ran out of charge immediately after reaching 0 (no zero buffer). And given you already assign a 10% range buffer in the bottom of your post, I think you are double counting here (doubling the buffer on the bottom).

    The EPA test reads the usage at the AC charging source. They don't put a probe in the battery and read the DC energy. This also makes the number more useful for calculating costs for operating the car (the primary reason for EPA ratings).

    Using a direct scaling between combined/city/highway and the combined EPA range number, I come up with very different numbers from you.

    VERCOMCTYHWYCOMCTYHWYCharge kWhnameplate / charge
    85D1009510627025728691.00.934
    S85898890265262268100.30.847
    P85D93899825324226791.70.927
    70D10110110224024024280.10.874
    S6095949720820621273.80.813
    I think the core difference is I made absolutely no assumptions other than that the combined MPGe number corresponds with the combined range number.
    Here's all the assumptions you are making:
    1) The nameplate rating is actually the pack capacity (not necessarily true)
    2) Usable capacity is 90% of pack capacity (this likely double counts if you want to assume 10% range buffer)
    3) All packs have the same percentage of usable capacity (this can even be different between P85D/85D/S85 since the P85D has a different pack version number)
    4) Charging efficiency is 92%
    5) All versions have the same charging efficiency (unlikely to be true, see below)

    I have added another row to illustrate the charging kWh (calculated by using combined MPGe / 33.7kWh * combined range), and also nameplate kWh/ charging kWh (rough estimate for charging efficiency, ignoring usable capacity). Keep in mind the S60/S85 numbers are unchanged from 2012/2013 model and so likely reflect charging efficiency of the older versions. That's likely why their numbers are so much worse (the charging kWh numbers will also be affected by any changes in usable capacity).
     
  8. Ed Chan

    Ed Chan Member

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    I really thing your calculations are off somehow... I've driven from Barstow to Kingman (209 miles, around 7000 ft of up and down elevation changes) and had 20 miles to spare driving an average of 70 MPH in my S85. I didn't take any extreme measures to save energy, AC was on comfortably, music blasting, etc. etc. The key to getting there without worry was to keep the speed reasonable. Now, the big pain in doing that drive was waiting for a full charge in Barstow, which took > 1 hour!
     
  9. David99

    David99 Active Member

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    That's how Tesla advertises Superchargers conveniently drawing a 250 mile circle around each Supercharger, but that's really unrealistic. I have 8 Superchargers withing a 100 mile radius from my home, yet there are many situations where I have to keep an eye on my range. For the most part there is no Supercharger when I drive. And of course I have to make it back again as well.

    I think his numbers are very realistic. That's kind of how I would calculate as well and I think a good guide when you are new to a Model S. Achieving 'rated range' is very hard in reality. I had to do it a few times on trips to make it at all and man it was painful and embarrassing.
    The 10% buffer is absolutely needed. Any missed turn, or missed exit on a freeway can quickly cost you many miles. An accident or blocked road can require a detour. You have to allow for a buffer.
     
  10. No2DinosaurFuel

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    Right but when i use this car, chances are i will be outside of california.

    I am specifically ot worried so much when i am in california.

    This is why i think the range anyone who owns a tesla cares about is the highway range. And this number should take into mixed weather conditions.
     
  11. JohnQ

    JohnQ Active Member

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    Look for people's experience on road trips. It will give you the best numbers. For example, I drive to Boston at least once a month. 170 miles each way, 160 miles is highway driving, some stop and go traffic for about 10 miles. I drive a steady 75mph on the highway through rolling hills. Ending elevation is within 300 ft of starting elevation. I've done in 90F weather and 0F weather. Rain, wind, you name it. With 32k miles on the odometer I range charge to 249 miles in an S85.

    Tuesday's drive there, no wind, in 55F temps left me 50 miles on arrival. So, 18% above rated miles. In the winter with single digit temps I arrive with about 20-25 miles. About 32% above rated miles. Wind and rain play havoc, they just need to be accounted for.

    I have a feel for what I can get based on terrain and weather, and I know if I need to drive 200 miles in the wind and rain I can do so as I've done it before. It just means slowing down. If you don't want any compromises, want to drive like an ICE and charge anywhere, anytime, don't get an EV. It will not meet your expectations. With minor adjustments and planning, however, you probably can get what you need.

    There's a Stones song buried in that last sentence ....
     
  12. mspohr

    mspohr Active Member

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    You have done an impressive amount of work and come to the right conclusion.
    However, you should be aware that this is an EV and you won't drive it the same way you drive your ICE car now.
    It is faster, has better performance, is more comfortable. You will drive it more. You will learn how and when to charge and all of the averages you have calculated really don't mean very much. The bottom line is that there are lots of charging opportunities (Superchargers, Level 2 and Level 1) available. Electricity is ubiquitous and you will always be able to find a charge.
    We have put 9,000 miles on our 85D in less than three months. I didn't drive my ICE car that far in a year. We have done trips (all over California and Arizona) with lots of Superchargers and been able to drive 80+MPH forever. We have also done trips (Eastern Sierra Rt. 395 through Death Valley) with only one Supercharger and made it work by using destination charging (L2) and driving carefully (my mantra... if you're worried about range, slow down, you'll go "forever").
    Don't overthink and overanalyze this... just get the car and enjoy it. It will work out fine.

    - - - Updated - - -

    You have done an impressive amount of work and come to the right conclusion.
    However, you should be aware that this is an EV and you won't drive it the same way you drive your ICE car now.
    It is faster, has better performance, is more comfortable. You will drive it more. You will learn how and when to charge and all of the averages you have calculated really don't mean very much. The bottom line is that there are lots of charging opportunities (Superchargers, Level 2 and Level 1) available. Electricity is ubiquitous and you will always be able to find a charge.
    We have put 9,000 miles on our 85D in less than three months. I didn't drive my ICE car that far in a year. We have done trips (all over California and Arizona) with lots of Superchargers and been able to drive 80+MPH forever. We have also done trips (Eastern Sierra Rt. 395 through Death Valley) with only one Supercharger and made it work by using destination charging (L2) and driving carefully (my mantra... if you're worried about range, slow down, you'll go "forever").
    Don't overthink and overanalyze this... just get the car and enjoy it. It will work out fine.
     

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