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Amazed, yet confused by range

Discussion in 'Model S: Battery & Charging' started by deonb, Jul 5, 2015.

  1. deonb

    deonb Active Member

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    First the amazing part. Today I was able to achieve 282 Wh/mi...

    That in itself is not impressive.

    What's impressive about it is that I was able to achieve that while going over a 4000 ft mountain pass... Twice!

    All the while, with the temperature outside at 95 degrees, A/C on lowest setting all the time (not range mode), carrying 700 lbs of passengers and doggies. Going speed limit all the time (55 to 65). I was expecting to be getting around 370-ish, so 282 was quite a shocker.


    The part that I'm confused about though is that my distance travelled and remaining rated range is 159.8 + 94 = 253.8 miles. I charged the car up initially to 257 mile range. I thought that we achieve rated range at 290 Wh/mi though, so I expected at 282 Wh/mi, that the two range numbers would add up to over 257?

    You can tell from my trip meters below that I don't often get down below the 300's, so quite surprisingly (after 2+ years of ownership), this is new to me. I basically left the 'P' of my 'P85' at home today, hard as it was.

    I'm still super impressed that I was able to get 253.8 miles range going up 8000 ft of elevation though! Just curious about the calculations wrt. the 290 wh/mi.

    282kWh.jpg
     
  2. Sosius

    Sosius a.k.a. Uptown Frunk

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    Interesting and impressive. Some people have said recent software updates may have increased efficiency.
     
  3. tomas

    tomas Traded in 9 rep bars for M3, used to be somebody!

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    A couple of reasons for not getting 257+: 1) vampire loss. How many times did you stop? For how long? I suspect that's a big part of it. 2) it seems "par" wh/mi is not consistent across batteries or software releases. You are assuming 290 as par. There was thread about this, I forget name. Various members calculated their "par" and the numbers varied from the 280s to the 290s.
     
  4. imherkimer

    imherkimer Member

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    In my experience, rated range is achieved at about 273 Wh/m average
     
  5. porshuh

    porshuh Member

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    #5 porshuh, Jul 6, 2015
    Last edited: Jul 6, 2015
    I'm still trying to think of a good analogy for the whole thing. I come from about 5 years in the NiMh cell world.

    How about this one - it's like looking at a large backyard pool and saying "I can tell you that exactly 257 kids can all fit in this pool and have a great time". In reality, you don't know if one of those kids is a bully and will take up more of the pool than he/she should. Are they all fat kids? Will one piss the pool and send all the others screaming out of the pool to safety?

    I think most of us agree (besides the fact that that is a pretty horrible analogy) that Tesla has a pretty robust battery charging and monitoring system. But even with that...there are just way too many variables to accurately put a mile count on a battery pack's capacity. And I'm not even talking about driving habits. The battery itself is hard to judge down to the mile. Think about the common scenario where miles don't add up and someone asks where their two miles went. 100% / 257 miles * 2 miles ... That's less than a 1% variation. Hell, I'm impressed to see anything lower than a 5% variation (which is a whopping 12 miles) on a complete pack containing so many individual cells.

    I'm not harping on anything or anyone - I'm just saying I think Tesla has developed a pretty badass battery system to be able to predict range as well as they do.

    That being said - I, too, love to hypermile and see how my actual range compares to what the car predicts at the start of the day. My last set of vehicles included a 2002 Honda Insight and a Chevy Corvette. I would hypermile and nerd out in the Insight, and then have some sports car fun in the Vette. Now with the MS, I can do either one (decided by my right foot, of course).
     
  6. supratachophobia

    supratachophobia Active Member

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    I suspect under high ambient temps, some of the reserve "leaks" into the calculations of the car.
     
  7. travwill

    travwill Member

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    It does seem also that based on the Tesla site range calculator, that 90 degrees is a temperature where the batter performs the best, start to go over and loose some range or under as well.
     
  8. FlasherZ

    FlasherZ Sig Model S + Sig Model X + Model 3 Resv

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    At any portion of the trip, were you sitting in the car with it in "P" or "N", or at 0 mph while in "D" or "R"? During these times, the power consumption isn't factored into the "since last charge" power meter but is factored into the rated range. This is what prevents you from having strange graphs, e.g., a graph showing 2,000+ Wh/mile after sitting for 4 hours at a drive-in movie theater with the climate control operating the entire time in summer heat or a graph showing that much power consumption after being pre-heated while on battery.

    While I do the mental calculations of rated range + miles driven since last charge as a comparison to Wh/mi - because I tend to be a numbers guy - I can't say that I trust them at all. On my recent trip, I found myself looking at, and trusting, two numbers - the Wh/mi number over the past 15/30 miles and the projected arrival SOC from the trip mode in the energy app.
     
  9. Zextraterrestrial

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    #9 Zextraterrestrial, Jul 6, 2015
    Last edited: Jul 6, 2015
    274.25 :smile:
    but that might have changed with newer firmware. this # was from last winter

    updated my data and get
    272 lifetime (but looking at a chunk of later #'s it is much lower like 260 something and since I switched to % vs mi I don't have recent trip stuff added)
     
  10. David99

    David99 Active Member

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    The confusion is that the rated range is calculated from a 100% charge down to when the car shuts off to prevent the battery from being damaged. It is NOT from 100% to 0 (zero). This difference between zero miles on the battery gauge and where the car actually shuts off can be quite a bit (depending on how you drive and temps and so on). I've driven 11 miles beyond zero once which is is about 3 kWh. That's about 4% more energy compared to the usable from 100% to zero. Rated range is calculated based on 300 Wh/miles and from 100% to shut-ff. Now if you subtract the 4% from that you get 288 Wh/mile. In other words, if you want to get the full rated range within the 100%-to-zero, you have to drive at 288 Wh/miles.

    That's why people get confused when they can't get rated range when they drive exactly 300 Wh/mile. The difference is they assume it's to zero, yet it is to shut down.
     
  11. deonb

    deonb Active Member

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    I'm aware of that. I was driving at 282 Wh/miles though.


    Well yes, I was waiting at a few traffic lights. So while waiting at a traffic light your range decrease without it affecting your Wh/mi? That doesn't seem like the right thing to do...


    I had a single 30 minute stop, but the range before and after the stop was the same. However, even at the time of the stop, the math was already off by a couple of miles.
     
  12. FlasherZ

    FlasherZ Sig Model S + Sig Model X + Model 3 Resv

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    The alternative is to have *huge* peaks when you pre-condition the car on batteries, or while you sit at stoplights with the heat running. Tough call for Tesla to make, whether to appease the scientific, make-it-come-out-to-5-significant-digits crowd or to make it look reasonable for the average person who wants to know how his driving style is measured.
     
  13. porshuh

    porshuh Member

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    Here is another way of putting it:

    Tesla Model S Buyers', Delivery and Owners' Guide

    scroll down until you see the mostly black graphic with a green battery on the left portion of it. That might make it a bit clearer for some.
     
  14. RyanT

    RyanT Member

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    #14 RyanT, Jul 6, 2015
    Last edited: Jul 6, 2015
    I can back up what people are saying about the use of the climate control not factoring into the trip meter for some cases. This weekend I went up to the mountains and camped. I used about 40 miles rated range while camping with the car "on" and climate control on the whole time. It showed the usage in the graph when I started going the next morning (it showed a huge spike for awhile) but I got back with 280 wh/m showing on the trip meter. That can't be right when I burned 40 miles camping on a 200 mile trip.

    P.S. The car does do great up on mountain roads around PNW. I've been very happy with the P85 in that regards. It seems like that's where I get my best efficiency.
     
  15. dalamchops

    dalamchops Member

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    my experience is that it takes account of AC when the car is in Drive, but does not when the car is in idle or "off" mode.
     

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