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sad - because I don't understand battery performance

Discussion in 'Model S' started by hypermails, Sep 26, 2019.

  1. hypermails

    hypermails Member

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    hi

    I got me a pre-owned 2016 P90D. it drives great - but I don't understand the battery performance at all.

    rated at 100% is 257 miles (per google)

    I charge it every week or so to 90% and it shows 231 miles.

    I use a mix of 110, 220 and supercharging as available to me / when available to me,

    but when I start driving everything go to crap

    it should technically give me 2.5 miles per 1% of battery (I don't expect that)


    it uses about 345 - 375 wh/mi
    • make sense = 90KW / 257 = 350

    But in reality - I get 1 road mile for every 2 battery mile

    Or about 1.2 to 1.5 miles for 1% of battery.

    I drive about 6 miles a day (each way). All inroad - no free way. In Sunnyvale - so slow road. I have range mode on.

    Any suggestions - how to understand if the car is being inefficient or losing range ?

    thanks

    upload_2019-9-26_9-56-49.png
     
  2. mswlogo

    mswlogo Well-Known Member

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    Your battery condition is great !!

    What's 90% of 257? 231

    Almost to good to be true.

    Your efficiency looks lousy though (not sure how a P90D should do).

    Make sure your tire pressure is correct. Set HVAC to only what you NEED. Go easy on the foot.

    The tires on a Performance car might not be the most efficient and can make a big difference.
     
  3. zanary

    zanary Active Member

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    The Wh/mile look accurate compared to my previous 2016 Model S P90DL with 21". I'm around the same with my Model S P100DL with 21" Arachnids.
     
  4. .jg.

    .jg. Member

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    I have never bothered with Range Mode. Your issue is probably the short trips of six miles. Rather like an ICE engine, the battery pack takes a while (and some energy) to get to an efficient operating temperature. On a trip of six miles, your battery pack may never reach an optimal operating temperature and the aircon/heating may also be taking a chunk of energy to get the cabin to a comfortable temperature.
     
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  5. hypermails

    hypermails Member

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    @mswlogo yes, it is too good to be true - but every day I check - and then with a few miles - it looks dumb. I am not sure if the numbers are real or if some calc function is converting 90% to Miles.

    There was one week between updates I was getting 295 Wh/Mi - but since then everything is around 350 or so.

    AC is on only in the evenings.. when the day is hot. I don't do freeways - but I did one time 60 mile trip on freeway - but that didnt really alter anything much.

    wheels are original. but I can't imagine losing that much to wheels ?

    the 1.5 miles per % battery does not make sense.
     
  6. Huachipato

    Huachipato Member

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    I could be wrong - but aren't the rated miles closer to 300W/H a mile?

    I think there is a buffer in the batteries - so the 90KWh in the "90KWh/257" calculation is probably not accurate. Reality is you have a 90KWh pack - but there is portion of it that is used as a buffer and you don't have use of. Please correct me if I am wrong....
     
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  7. kavyboy

    kavyboy Active Member

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    What @.jg. said. I average around 280 Wh/mile overall. On short trips of a few miles, I've seen it be as high as 900+, and there's no rhyme or reason that I can see why exactly.
     
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  8. demundus

    demundus Active Member

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    rated is like 245 or some comically low number. non-grandma driving will yield numbers the OP is showing. unless you intend to drive 45 MPH everywhere you go with VERY gentle accel patterns you'll average closer to 300, which is higher than rate, and accelerates the battery usage (source: 150K miles of tesla driving)
     
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  9. ewoodrick

    ewoodrick Well-Known Member

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    The rating is good ONLY when you are driving about 55 mph on a flat road. Also, the first 15 or so minutes are spending energy on other things, so they can't be counted.

    Get on a road and watch the energy graphs.
     
  10. Chaserr

    Chaserr Hyperactive Hyperdrive

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    The EPA rating requires you to use less than 300 watt hours per mile and drive no faster than 55 with slow acceleration. If you look in the Energy app on the center screen it will have a line showing your energy use (jagged orange) and rated (flat grey). If you want to get every mile of rated charge you have to drive with that line matching your average.
     
  11. Pale_Rider

    Pale_Rider Member

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    Very likely the short drive. AC will be running full just to get to your set temp by the time you get to your destination. Start stops eat a fair amount as work. You’ll see closer to expected when you go a decent distance at a constant reasonable speed on the interstate. I had a X90 for two years and on the highway I could comfortably get 200 miles or so, I could maybe push that to 230 if I went 60-65. My short trips around town often match exactly what you are seeing.

    Someone just tested the X Raven LR (which I just traded for and will have my first road trip in this weekend), which has a rated range of 325 miles. Going 60ish they could have gotten 340-350 miles. Going 75 that drops to almost 250.
     
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  12. hypermails

    hypermails Member

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    I have never had a 300 wh/mi ever. I think there was one week when I was under - but I am sure that was a software bug.

    I am not sure how to improve efficiency ? in the current usage pattern - I essentailly only have a little over 120 miles of range (between 90 and 20%)
     
  13. Science fan

    Science fan Member

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    I have a 2016 S75 and have average 270 watt hours/mile for the past 17,000 miles using Michelin tires. The original tires were replaced at 22,000 miles and I averaged 263 watt hours/mile on them. My S is not a performance model and I have the 19" tires. Tire pressure is very important and I keep mine around 47 ppsi cold (45 is recommended). Lots of fairly short trips. I try to not use the brakes too much. If your range does not improve on a long trip at moderate speed then, clearly, this problem needs to be looked at while you are still under warranty.
     
  14. pgkevet

    pgkevet Member

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    I have a 100d. On twisting country roads and hills I can get as bad as 450wh/m driving sensibly.. hoof it on the straights and it's a lot worse. On UK motorways in the summer on the flat and at a steady 70mph and its under 300 wh/m
     
  15. gaswalla

    gaswalla P4201/85/airsusp/pano/19i

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    #15 gaswalla, Sep 26, 2019
    Last edited: Sep 26, 2019
    the watts/mile for a 3 and a 75D will be different from OP's P90D.
    In other threads: 300 watts-h/mile is the known rated calculation for a P90D
    OP needs to start looking at watts-h/mi and amount of miles obtained per kwh... looking at miles/percent battery is a bit inaccurate.
    Also there is a buffered, unusable portion of the battery, and the 90 battery had pretty much nearly the same capacity as the 85 (unfortunately). So, your 257 rated range gives you usable capacity of about 77.1 kwh. If you drive using 350 wh/mile, you'll get an effective range of 220
    For degradation: look at mile range at a given state of charge and convert to 1000%... your 90% range looks great.
    For efficiency: look at the watts-h/mile after each day of driving to see if you can keep getting that number lower. Honestly, 346 isn't bad at all.
    Also, the size of the tires are critical - do you have 21's?
     
  16. SSedan

    SSedan Active Member

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    Use range mode only when you need it.
    Also are you lumping in vampire losses or cabin overtemp protection?
    What tires are on it?
    What pressure are they at?
     
  17. mswlogo

    mswlogo Well-Known Member

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    I get my best wh/mi on short trips (under 200 wh/mi Model 3 AWD, 230 wh/mi Model X Raven).
    My commute is "short" 5 miles. It's highway that wh/mi goes up on.
     
  18. kavyboy

    kavyboy Active Member

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    For me, first 10 minutes and speed over 70MPH are big consumers. Over 80 MPH is crazy - the exponential aspect of the drag curve really becomes obvious about there.
     
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  19. hypermails

    hypermails Member

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    @Science fan Not a chance to get 270 !!! I don't use the brakes - becuase of the range anxiety I try to get the regeneration going as well -as much as I can. I will check tire pressure today for sure.

    HOW do I ask Tesla for information ? Last time (when I got the car) - I got a report that battery decay was in line with car of the same age.
     
  20. hypermails

    hypermails Member

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    I have opened a telsa ticket. let's see what happens
     

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