TMC is an independent, primarily volunteer organization that relies on ad revenue to cover its operating costs. Please consider whitelisting TMC on your ad blocker or making a Paypal contribution here: paypal.me/SupportTMC

HVAC behavior when car off but doors opened

Discussion in 'Model S: User Interface' started by tomp, Mar 17, 2014.

  1. tomp

    tomp Member

    Joined:
    Dec 3, 2013
    Messages:
    386
    Location:
    Durham, NC
    Hi,

    I've noticed that my MS will turn on the HVAC (or continue to run the HVAC) even when the car is off.
    For example, I get to my destination and exit the car. Then start to unload - my son, bags, etc - and the HVAC continues to run.
    Similarly, it turns on as soon as I open the door in the morning and begin to load (son, bags, etc).

    It seems more natural for the HVAC to not turn on until the car is turned on. Part of my concern is that during these times (load/unload), doors are open and so running the HVAC is very inefficient.

    Is there any way to adjust this? (Other than manually turning off HVAC when I am about to exit the car?)

    Thanks!
     
  2. jerry33

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

    Joined:
    Mar 8, 2012
    Messages:
    12,753
    Location:
    Texas
    In the morning (assuming your pre-warming). I always make sure to turn it off with the App so that won't happen. Otherwise, turning it of manually is the only way.
     
  3. cinergi

    cinergi Active Member

    Joined:
    Sep 17, 2010
    Messages:
    2,169
    Location:
    MA
    Though the amount of energy used to run HVAC for a few minutes while loading/unloading the car is relatively negligible...
     
  4. tomp

    tomp Member

    Joined:
    Dec 3, 2013
    Messages:
    386
    Location:
    Durham, NC
    I had thought HVAC was a big eater of battery, although you're probably right that for a few minutes it's not a big deal. I had noted on my way home from work yesterday that I had an energy usage of 900Wh/mi for the first little bit, which I'm assuming was because of the HVAC while not moving. That did make it hard to get my average Wh/mi down to even less than 400 for the trip home. Anyway - I'm still learning how to manage the battery and learning how various things impact remaining range.
    Thanks!
     
  5. tezco

    tezco Sig P85

    Joined:
    Nov 9, 2012
    Messages:
    818
    Location:
    Colorado
    When the battery is too cold you will also notice a huge energy spike from the pack heater. Shoots your average to heck.
     
  6. cinergi

    cinergi Active Member

    Joined:
    Sep 17, 2010
    Messages:
    2,169
    Location:
    MA
    Worst-case scenario (heater going full blast, battery heater on), it's roughly 1 mile of range lost per 1.5-2 minutes of HVAC runtime.
     
  7. tomp

    tomp Member

    Joined:
    Dec 3, 2013
    Messages:
    386
    Location:
    Durham, NC
    Thanks! Great point, and I noticed that today. Today I turned HVAC off for the first several miles and the energy use was still quite high. Then I turned HVAC on and happened to note my energy use went down. I'm almost sure its' because the battery was warmed up by then.
    - - - Updated - - -

    Thanks! Do you know if HVAC takes more or less energy to heat the cabin versus to cool it? I'm wondering if I could test that while parked by simply running it on max cool and max heat?

     
  8. cinergi

    cinergi Active Member

    Joined:
    Sep 17, 2010
    Messages:
    2,169
    Location:
    MA
    Cooling the car takes significantly less energy than heating it.
     
  9. tomp

    tomp Member

    Joined:
    Dec 3, 2013
    Messages:
    386
    Location:
    Durham, NC
    Great to know. Especially since in NC, cooling is the feature we'd use more than heating.
     
  10. strider

    strider Active Member

    Joined:
    Oct 20, 2010
    Messages:
    2,918
    Location:
    NE Oklahoma
    This is one of the best parts about driving electric. In the morning as we are loading up the kids in the garage w/ the garage door closed the car begins heating so it's warm by the time we're ready to drive. Likewise in the summer when we open the doors the car immediately starts cooling while we are getting the kids strapped into their car seats, stroller in the trunk, etc.

    In the morning just leave the car plugged in while you're loading and it will pull power from your house so your range is not impacted.

    As for unloading... a few moments of A/C is a trivial amount of energy. But if it bothers you just turn the HVAC off before you get out.
     

Share This Page