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Battery performance in this heat

Discussion in 'Model S: Battery & Charging' started by MrOteece, Jun 29, 2013.

  1. MrOteece

    MrOteece Member

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    With the massive heat wave covering the western US, wondering how the battery life is faring for everyone. I noticed a decent drop during the time it was parked in the heat, but I wasn't paying that much attention to give accurate numbers. I know the AC is hitting it hard, but curious what you guys are seeing.
     
  2. djp

    djp Roadster 2.0 VIN939

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    If possible, you should lower the battery's state of charge to protect it from the heat.
     
  3. brianman

    brianman Burrito Founder

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    Funny you should ask. It was 89F when I arrived at Bellevue with 2mi. rated today coming down I5 South from Burlington. I cheated a bit (turned off AC, switch to venting only and was going as low as 48mph in a 60mph for some of the hills) but pretty darn good consumption for the "vertically varied" terrain.

    SouthboundI5ToBellevue.png

    The 5 mi chart Avg was 158, but that includes a mile of off-freeway travel that skews the data a bit.
     
  4. Blurry_Eyed

    Blurry_Eyed MS Sig #267, MX Sig # 761

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    Living dangerously Brian! :smile:
     
  5. brianman

    brianman Burrito Founder

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    Yah, it was closer than I planned. I took the wrong exit because I was tired and had to adjust course. I hate waking up early.
     
  6. gaswalla

    gaswalla P4201/85/airsusp/pano/19i

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    you should actually get more miles/kwh in the warmer weather. As for battery "life"...putting my trust into Tesla's battery/temperature management system.
     
  7. jomo25

    jomo25 P4398

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    Not sure if I am following you on this one. If you are talking about the extreme heat (i.e. 110+) its going to have a negative impact. Yesterday, I noticed I used about 10% more Wh/mi in 119 degree weather than I average on my daily commute driving essentially the same way. Im attributing it to the TMS and AC working harder.
     
  8. ZBB

    ZBB Emperor

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    #8 ZBB, Jun 29, 2013
    Last edited: Jun 30, 2013
    Being in Phoenix, I had been wondering how the battery/ energy drain would be due to the heat.

    I've had my car 3.5 weeks now. Temps have generally been mid 100s for the high. I have a ~60 mile commute -- with a ~1500 foot elevation change. I was seeing ~70 miles in range loss over my commute -- with 6 miles due to vampires while parked.

    On Friday, I drove 82 miles. But lost 104 of range. The morning part of my commute was about normal -- all downhill and i used just over 200 wH/mile. But it was well over 115 on the way home (high was 119) -- and the drop in range was noticeable, especially in the first 15 min while the interior cooled down.

    So my takeaway is that heat does have an impact -- but it's marginal unless the temp is above ~110. At that point it's noticeable, but maybe a 5-10% impact...
     
  9. jerry33

    jerry33 S85 - VIN:P05130 - 3/2/13

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    About what I expected to see (hasn't been quite that hot here yet). However, you should be able to mitigate that by starting with a higher temperature setting and then lowering the setting as the drive continues. That is adjust the temperature until only one or two fan blades show (it will still seem cool compared to outside) and then reduce the temperature setting every so often. (Note this is assuming you are someplace where you can't plug in and cool using shore power.)
     
  10. gaswalla

    gaswalla P4201/85/airsusp/pano/19i

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    ok... at extremes of heat, there may be some efficiency losses.. however, along a normal range of temperatures (eg: 30degrees to 90 degrees), warmer temps result in increased range. Tesla even includes this in their range estimator: http://www.teslamotors.com/goelectric#range
     
  11. jomo25

    jomo25 P4398

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    OK, sorry, yes, I agree on expectations in that temp range. I thought you meant the extreme temps, since the OP references the current heat wave. LV, PHX, and parts of CA are all experiencing 115+ temps.
     
  12. Al Sherman

    Al Sherman It's about THIS car.

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    Yes, living dangerously. However quite awesome! Very impressive to see real world "mile milking." In the airlines if we beat the flight plan we used to say we were "making gas.":smile:
     
  13. jomo25

    jomo25 P4398

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    Any thoughts on best charging behavior in such heat? I.e. If I get back home after being out and about, should I do anything different w.r.t. charging? (In my garage where the ambient temps will be higher than usual, but not like sitting in the sun.) Should I lower the amps? Wait before plugging in? Will being plugged in help with continued battery management in the higher ambient temps? Etc?

    I'd think not, since in theory, the battery is already being "managed" while I was driving, so plugging in immediately shouldnt be an issue. Just wondering if anyone knows.
     
  14. ZBB

    ZBB Emperor

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    That's probably only needed if range is an issue. I used about 10-12 miles more of range on Friday than normal -- but still took the car out to dinner on Friday evening and got home with plenty of range to spare.

    And I did pre-cool on shore power yesterday before going out -- although I only drove a couple miles... I glanced at the dash a couple times -- it was initially drawing 20 amps and later dropped to 10. Sounded like both heat pumps were on at first, then only the cabin one after the battery had cooled down in a couple minutes...
     
  15. djp

    djp Roadster 2.0 VIN939

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    Plugging in as soon as you get home is best. On the Roadsters you need to start a charge cycle to cool down the battery so some owners drop the amps to force the BMS to start cooling without adding much charge. I'm not sure if the Model S does a cool-down immediately on plug-in or only during charging, either way you're better off being plugged in to drive HVAC from shore power.

    The worst possible thing you can do to the battery is let it sit at a high temperature and high state of charge. During a heat wave you can help protect the battery by dropping the charge level to 50-70%. Also avoid charging at 120V in the heat since there's less power available for cooling and the BMS will let the battery run hotter.
     
  16. Stoneymonster

    Stoneymonster Active Member

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    Not sure it works that way on the S. I always plug in when I park, and I never see it draw shore power for cool down. Not even yesterday when it was easily 105. I am on timed charging however, maybe that prevents it from occuring. If I sit in the car with the AC on for long enough it will start drawing power, but not as far as I can tell just to manage the battery.
     
  17. djp

    djp Roadster 2.0 VIN939

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    Sounds like it's similar to the Roadster then, where battery cooling only happens in extreme heat (above 105) or during charging. If you start a charge cycle do you notice the AC compressor comes on?
     
  18. tdiggity

    tdiggity Member

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    with the rest API there's a status indicator that tells you if pack heating is on when you get status of the car. I didn't see one for pack cooling, so I bet the pack heating setting indicates heating or cooling. In California, my car doesn't get hot or cold enough yet to see that indicator change, but it could be useful for you guys.
     
  19. tbleakne

    tbleakne Member

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    I am surprised you have seen no battery cooling turn on while parked with daytime temperatures reaching 105 F. How cool are your overnight temperatures now ?
    The battery pack has a high heat capacity, so the average day/night temperature is relevant.

    My garage is reaching 95 F in daytime, high 70 s F overnight. I am going to flying out for a few days, so the average temperature could be in the high 80s or even low 90s. Is it true no one with average temperatures like this for a parked Model S is seeing the battery cooling system turn on ?
     

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