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Two minor oddities

Discussion in 'Model S' started by tinm, Jul 20, 2015.

  1. tinm

    tinm 2013 S85 Owner

    Joined:
    May 3, 2015
    Messages:
    1,136
    Location:
    New Mexico, USA
    Two things I've never understood about my Model S. One happens nearly every day, and one just happened for the first time over the weekend.

    (1) Sudden change to battery charge number.
    What happens is, I walk out to car in the morning. Just walking by the car wakes it up, unlocks the doors. I always look in to see what the battery charge is on the dash as I'm unplugging the plug and rolling the cord back up to hang on wall next to HPWC. I usually charge to 90% and for my car, 90% means around 232, 233, 234, never quite know what it'll be. Lately it's around 234 a lot. BUT.... what I usually see is 228, 229, 230, or 231. Sometimes within minutes of the charge to 90% completing. And as I'm pondering this with some audible grumbles, climbing into the car and seated in the driver's seat, when I press the brake pedal to start the car, the 228 or 231 or whatever will suddenly change to 233 or 234. Happens nearly every day. So the question is, why does it do that?

    (2) Mystery re-charge that wasn't even accurate.
    Saturday night I had the car charging on the HPWC, and it finished at 21:42. Ok fine. I was watching a movie at the time, and my phone app buzzed. "Charging completed at 21:42 with battery at 234 mi" it told me. Nothing odd about that. What WAS odd was that my phone buzzed AGAIN at 22:01, saying "Charging completed at 22:01 with battery at 231 mi". I immediately took a screen shot:

    twhat.png

    Why did it do that? I went out to check, and the dashboard said 234 miles. So why the heck did it send out a second notification to my phone, when charging had stopped nearly 20 minutes earlier? And why the wrong reading?
     
  2. caddieo

    caddieo Member

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    Location:
    Palm Coast, FL
    Do you have your car set to charge as soon as you plug it in (unscheduled charging) or do you have it programmed to start charging at a specific time (scheduled charging). If it is unscheduled, then it will resume charging as soon as vampire loss reaches a certain level which is what I believe is happening in your situation. I have mine on scheduled charging to start every night at 12:15 AM so when I wake up, I have two notifications - one for the starting time and range and one for the ending time and range that I have chosen/programmed on the slider. If I do not use the car for some time after charge completion, the range will have drifted slightly lower than that reported on the notification due to vampire loss but the car will not charge since it is programmed to do so only at 12:15 AM. During a 5 week absence, I got a regular notification every 3 days regarding charging which was always the same for the starting time although the starting range would vary from 10-13 miles below ending range-- but the final notification always had the same ending range even if the ending time varied by a minute or two.
     
  3. ddimit

    ddimit Member

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    Sacramento, California, United States
    thats a classic notification of vampire loss and the car starting to charge again
     
  4. tinm

    tinm 2013 S85 Owner

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    Right, but... why would there be "vampire loss" within minutes of a successful 90% (234mi) charge?

    Note the second (one on the top) notification came in 19 minutes after the previous notification, and these are notifications indicating COMPLETION of charge.

    If the car started vampiring right away, then shouldn't the car have sent me a "Charging Started at..." notification? It usually does. So it was weird that the car started charging right after it finished charging, and then also weird that it notified me 19 minutes later it finished charging again --- BUT the second time it'd lost 3 miles and it still considered itself done. It usually takes many hours for my battery to lose 3 miles due to vampire loss.

    In my universe, none of that makes any sense at all. I assumed and still assume it's a bug.
     
  5. bollar

    bollar Disgruntled Member

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    Battery cooling or predictive A/C? It has been warm lately.
     
  6. tezzla

    tezzla Member

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    Location:
    SoCal
    I think if you have range mode on; it adjusts +3 miles when it starts (something like that anyway).
     
  7. ThosEM

    ThosEM Space Weatherman

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    Dec 13, 2013
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    Location:
    Annapolis, MD
    This is just the downside of using range as a quantitative measure of the energy in your battery, with three digits of precision. It's based on a calculation based on a number of factors, and isn't solely determined by the amount of energy in the battery.

    I find that switching to "Energy" units (% of full charge) in the preferences alleviates this kind of angst in two ways. First, it is a measure that is intended to be purely proportional to the energy content of the battery. Second, it reduces the number of digits to two, which eliminates most (but not all) digital fluctuations (round off errors). 1% is about 4 km of range for an S85, so it's easy to translate it into range if desired.

    Voila. I get a 90% reading every time I charge to 90%! Offline energy use does erode that to 89% after a day or less depending, but now I don't get so obsessive about the range numbers as I once did, and I let the Nav energy system worry about whether I'm going to make it to my destination, based on my recent consumption.
     

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