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Car needs to warm up after being parked?

Discussion in 'Model S' started by Hairdryer, Jun 12, 2019 at 8:40 AM.

  1. Hairdryer

    Hairdryer New Member

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    I have a 2019 S100D. After parking the car for a while (not charging, on street), e.g. at work and driving off, consumption seems to be quite high and performance a bit restricted.

    I'm seeing approx 600Wh/mi instead of say 300-400 normally, for 5-10 miles whilst the car 'warms up'.

    Ambient temps of 10-15c.

    Is this normal?
     
  2. Bill_75D

    Bill_75D Member

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    Yes.
     
    • Disagree x 1
  3. bishoppeak

    bishoppeak Member

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    It's been doing the "vampire" drain thing while parked and adds that usage to your drive usage for a short distance before the average catches up.
     
    • Disagree x 2
  4. drklain

    drklain Member

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    What you are seeing is not vampire drain but a cold battery. If the battery is cold, the battery heater will be turned on when you first start driving until it gets up to the normal operating temperature range. At that point (unless the outside air temp is REALLY cold), the battery heater turns off and your power utilization drops down to a more normal range.

    Thing you can do to prevent this (aside from parking the car indoors in an insulated/heated facility) is to have it plugged in and charging where the charging generates heat and keeps the battery warm. In my case (in winter) I have my car to start charging at 5 am so that it finishes charging shortly before I plan to leave the house and thus the battery is already warm. When I'm parked outside somewhere, nothing I can do but live with that for the first 10 minutes or so of a drive.
     
  5. mswlogo

    mswlogo Active Member

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    #5 mswlogo, Jun 12, 2019 at 9:31 AM
    Last edited: Jun 12, 2019 at 9:44 AM
    It does not do that. It only accumulates what is used while in drive.

    Getting the car moving from 0 mph is expensive, but you have no other data accumulated to average into. So it starts high and does not last that long. But it takes a little while for the running average to come down (with some efficient driving accrued in). Later on when say you stop for a red light, it's just as expensive to get going as when you first left but your adding to a running average that has some efficient data accumulated.

    Watch the energy chart. When you create that first big peak your "average" is based on that one big peak. Later when you stop, say at a red light, it is based on all the data accumulated (big peaks and lot of efficient driving stretches).

    I also think when you first start the car it may "prime" all the fluids in the system until it sees all the temps are in check before it starts regulating the pumps. Similar to when you turn on some computers the fans run full blast then once it's up for a minute they ramp down. Also if Heat or AC is on it may initially run high too until the cabin reaches desired temps.

    So the very first peak on the energy chart might be one of the worst peaks and you're basing all the wh/mi stats on that one expensive peak.

    Try looking at a trip computer that has the last 50 miles accumulated. You'll see your "start" has very little influence. But if you start with zero accumulated data (a reset trip computer) and the first thing you do is very expensive it's gonna be disproportionally high.

    After 10 minutes of driving try hitting reset on the trip computer at a red light. You'll see the same high value for a while. Also try the opposite, try resetting the trip computer at 40 mph going down a long incline. Now your trip computer will be disproportionally low for a good while.

    That's basically how a running average works.
     
    • Like x 1
  6. Silicon Desert

    Silicon Desert Active Member

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    While I generally agree, I'll just say that it must be extremely cold for the battery heater to come on when starting off the drive. In the last 3 winters up here where it typically gets down to 15-20 degrees F in the morning, I have never seen the battery heater come on (in log files) when I start driving or even until I get back home. The only time I've seen the battery heater come on in my MX is when starting a supercharge in a cold environment. Even then, it is only on for about 10-15 minutes.
     
  7. whitex

    whitex Active Member

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    Not true. Go ahead and turn on pre-heat/cool before you drive, better yet heat the car up to MAX and then cool it off to comfortable temperature, then get in the car and observe the Wh/mile for the first mile - it will be off the charts. I have in the past heated my car for a long time, that really spikes the initial Wh/mile.
     
  8. mswlogo

    mswlogo Active Member

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    Perhaps Model S's do that. Model 3 does not.
    Folks that preheat would be going through the roof if they saw what they really use.
    It also complicates things. Should it accrue the same if it's preheating plugged in or not?
    It's actually a complaint by many that Tesla does not include it and cheats a little.

    ICE cars don't either. If your in park with the heat running the MPG meter does not change.

    It does not take much to spike it. If you did just ran max heat or something, it might run something to cool it down at the start.

    Like I said to OP. Just reset the odometer at a stop light and you'll see the same spike. Much easier to test.

    The watt hour per mile only applies to when the car is in state that can do miles.
     
  9. 4EVar

    4EVar Member

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    You do realise this a Model S thread, right? Lol
     
  10. mswlogo

    mswlogo Active Member

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    I highly suspect it’s exactly the same.

    Model 3 also starts out high and gradually comes down. Mine might be 400-500 and come down to 230.

    That is why a lot folks also measure from the wall outlet to get the true cost of operating. Using the wh/mi does not give you all the numbers. Charging losses, Sentry mode, cabin cooling, dog mode, vampire drain, preheating are not accounted for in the TRIP computers. And shouldn’t be. But it would be nice if it kept a separate tally for the grand total.

    And the OP’s 600 wh/mi would not be even close to covering preheating etc. It would be in the 1000’s of watt hours.

    Let’s say I use Sentry mode all day. And lose 10 miles. Now that alone would be 11 miles of battery in the first mile of driving. If that was factored in it should read 3000 wh/mi in the first mile. Preheating uses way more juice than Sentry does. And you’d have to drive a 100 miles before that Sentry mode hit was less than 1% if it was factored in.

    Lol, your right about that.
     
  11. whitex

    whitex Active Member

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    I might vary between the 400+ different generations of Model S (Elon told us Tesla improves hardware every 2 weeks). I did careful experiments in my 2013 Model S, and realized that HVAC was probably not factored into the Wh/mile, as it seemed like there was a hidden 1,000W average drain while driving, i.e. the rated miles were disappearing faster than use Wh would suggest (accounting for brick buffers, etc). The behavior of my 2015 sometimes showing first mile at over 1,000Wh/mile when pre-heating shows up on the 2015. I never bothered doing the experiment on my wife's 2018 which has the new MCU, which would the same as the Model 3. Long story short, Tesla accounting of Wh is not exact, and likely varies between cars even of the same "Model".

    It's really not a big deal though, after a while of driving an EV you stop obsessing over Wh/mile, rated range, etc. If it suddenly was to jump by a lot over many miles, I would notice, but small variations and initial miles I don't worry about.
     

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