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Unexpected Charge Time

Discussion in 'Model S: Battery & Charging' started by BertL, May 15, 2016.

  1. BertL

    BertL Active Member

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    I've had my MS 90D set for charge or top-off at 12AM for months, since delivery. My MS has been plugged-in to my HPWC and not driven for a couple days, when my MS last topped-itself off to 90% beginning at 12AM on 5/13. It's only had normal daily vampire drain since then. In the past, MS has always, without exception, began any charging activity to top-off per my set schedule at 12AM. When I keep MS plugged-in and not driven for a few days, it tends to skip a day or sometimes two before topping-off, but has always begun what it wants to do at the scheduled 12AM.

    This morning, I hear two charging alarms on my iPhone first at 4:01AM that MS charging had begun, starting at 242 RR miles, and another alarm when it ended a few minutes later (at what's normal for me as 251 RR miles @ 90%). As you'll see in the 3rd photo below of my 17" CID, scheduled charging remains set at 12AM. Temperatures over night are well above 60-degrees here as they have been for weeks. Power was not off in my home this morning, and again, as the 17" CID photo shows, power is flowing properly from my HPWC -- there were no charging interruption messages that came through on my Tesla app. I've had 7.1 2.17.37 installed since 4/26 with 3 previous scheduled charging sessions taking place at 12AM as I expected.

    Why would my MS decide to charge itself off-schedule?

    IMG_0617.jpg IMG_0618.jpg IMG_0621.jpg

    Other Recent Oddities Related to Power?

    Always Connected ON Not Utilized
    While it may not be related, the other recent oddity is I went to check status of my Tesla via the Tesla App on my iPad earlier this week. For the first time ever, I received the message saying my Tesla was being waken-up, and that I should set Always Connected ON if I don't want to wait next time... BUT, I do have Always Connected ON and have had for months. I went out to my MS and it immediately rebooted and woke up from deep sleep. (I have Energy Saving ON, Range Mode OFF.) I verified Always Connected was checked, as it always has been. This has not repeated, but it's also strange, isn't it?

    Sleep after <10 minutes
    The other thing that has been happening more frequently in recent weeks, perhaps since 7.1 2.16.17 is my MS sometimes takes longer to come to life when I open the door... I can sometimes run a quick errand, be gone for no more than 10 minutes, and when I come back the infamous "wait until MS powers-up" message comes up on the IC, or my IC or CID may initially be blank before displaying the Tesla T and then coming-to-life. Something has changed, but it's not repeatable enough for me to consistently describe, or even report it to Tesla quite yet.
     

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  2. scaesare

    scaesare Active Member

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    Interesting.

    I had charged to 90% yesterday , and ended up not driving the car at all. This morning I saw the car decided to top itself off from 87 back to 90%.

    That's also not something I've seen previously...
     
  3. cpa

    cpa Member

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    BertL.

    This is strictly a guess on my part.

    I set my car to charge at 04:15 each day. I have noticed that if I unplug, drive, return home and plug in later that morning, that the car starts to charge even though it is 09:00 or so.

    Maybe the set time has a window to charge -- say six hours. So, if at your appointed time the car does not sense a need to charge (like the vampire loss is only a couple miles) but during the next six hours the vampire loss drops the state of charge for the automatic top off, that the car will initiate charging anyway.

    Just a thought. . .
     
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  4. BertL

    BertL Active Member

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    THANKS. Have you noticed this charging-off-schedule happening only recently, or for a longer period of time?

    I ask because I've not had my MS ever start charging off my 12AM schedule (except when I manually override via 17" or Tesla App) before this morning, since taking delivery in October. I have been tracking and logging my charges every day since early November, so I would have noticed this happening before now. I almost always plug-in when I get home, and charging has always waited to begin at (the next) scheduled 12AM if it needs it, no matter what SOC I have. Also, one of the reasons for charge scheduling is to use any low TOU rates an owner may have (like me with SDG&E from only 12-5AM each day), so it would seem contrary if Tesla's design didn't abide by that setting except perhaps in some emergency situation where the MS/BMS thought there might be damage to the battery if the charge were not initiated -- but none of that applied to my situation early this morning, at least that I know of. Maybe something will show in my logs.

    I went ahead earlier this afternoon and sent a note with detail to my Service Center, asking if they could explain from my logs why my MS initiated its charge off-schedule for the first time. If I hear anything back, I'll be sure to post here.
     
  5. mblakele

    mblakele radial cross member

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    From the manual:

    If, at the scheduled time, Model S
    is not plugged in at the location, it will
    start charging as soon as you plug it in as
    long as you are plugging it in within six
    hours of the scheduled time. If you plug in
    after six hours, Model S does not start
    charging until the scheduled time on the
    next day.
    Based on your experience the actual behavior is a little more complicated, but the six hour window seems to be correct.
     
  6. BertL

    BertL Active Member

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    Thanks for the clarity ...but as you say, my situation is a little different. My MS was plugged in for well more than 6 hours before the scheduled start at 12AM, but it skipped charging at 12AM as it should have, and began at 4AM instead.
     
  7. animorph

    animorph Member

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    Probably just hadn't reached the proper SoC for a top-off until 4 AM.
     
  8. mblakele

    mblakele radial cross member

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    Right. My guess — just a guess — is that the system doesn't care about plug state alone but also checks state of charge. At 00:00 the state of charge still counted as "ok" per the limit you'd set. But by 04:00 it had dropped just enough, and it was still inside the six hour window, so it decided to top off. Based on the numbers you provided, the minimum drop for that might be somewhere around 3-5%.
     
  9. BertL

    BertL Active Member

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    Thx. Yes, I now see your POVs ...although it just blows my mind that this would be the first time in more than 6 months it may have occurred, and logically, if I was that close to the BMS (or whatever) logic wanting to pull my charge up to my (90%) setting, why does it really makes sense to still do that later within some 6-hour window? Rules or design points are just that, but if I were managing it by hand, or programming it myself, I'd let my 90D wait until the next scheduled time to start the incidental "top-off" charge -- the handful of miles difference would not make that much of a difference. Maybe if I was still programming things, and considered an original 40kWh model, the logic makes sense, but not for 85-90kWh or more models that dominate the roads today. Perhaps it's just legacy code that isn't as contemporary as it could be, biting me in the rear again.

    I'll report back if I hear from the SC. THx again.
     
  10. Boatguy

    Boatguy Member

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    That's my guess as well. Vampire didn't drop it enough to trip the "top up" charge until 0401.

    I can imagine some programming loop like:

    Begin charge window processing
    If SOC < Charge Limit - X% Then Charge now
    Else wait Y minutes

    It is odd that it's never happened before in six months, but it could be the result of some s/w update in the last six months, even as recently as 2.16.17, so that the actual time that it took for this set of circumstances to occur is much less than six months.

    In any case, it charged when needed and you were ready to go in the morning!
     
  11. pdx4s

    pdx4s Member

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    my P85 had a similar glitch a week ago, when arrived in my home garage plugged in the car and it started charging imediatly, when looking at the charge control screen it changed it from delayed start of 03:15 to no delay, asked TM to investigate why it changed the setting by itself. I suspect GPS location was telling the algorithm it was not at home yet.
     
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  12. BertL

    BertL Active Member

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    @pdx4s, our situations are a bit different, but I'm glad I'm not completely alone with this latest oddity. Thx for the post.

    FWIW, I went on a short trip yesterday morning of just over 30 miles; Returned home and plugged-in to my HPWC as always; the MS charging screen popped-up that charging will begin at scheduled 12AM; ...and sure enough, as it has always done (except yesterday), my MS topped-off beginning at 12:00AM as it should have. :confused:

    Only difference here is MS clearly needed a charge last night to pull it back up to my set 90%... It had not been sitting for a couple days where vampire drain would become the trigger for charging as was the situation the day before and described back in Post #1.
     
  13. scaesare

    scaesare Active Member

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    My experience was also outside the norm... I've had it for nearly 3 yrs and it hasn't done this...
     
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