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Charge on Plug-in - charges automatically after 48 hours?

Discussion in 'Roadster' started by smorgasbord, Jul 27, 2013.

  1. smorgasbord

    smorgasbord Active Member

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    With charging available at work, I've now set my car to "Charge on Plug-in" even at home. I have current set to 13 amps via OVMS. When I get home, I let the car charge right away at 13 amps to cool the battery down. After about 20-40 minutes, I manually stop charging. The next morning I drive to work and do a full Standard charge.

    For two weekends now, I've noticed that on Sunday the car starts charging all by itself. That is, I parked the car at home and plugged it in on Friday night, let it charge for about a half hour, then stopped the charge. Then, without doing anything, the car decided to charge itself on Sunday night, probably after 48 hours of being parked, plugged-in.

    I'm assuming this is Tesla logic. Has anyone else noticed this? What was odd for me was that with the car set to start charging at a certain time of day, the car would kick on at that time every day and try to charge. So, I wrongly assumed that charge on plug-in would only charge on plug-in and not try again later. And, it doesn't seem to try until 2 days have gone by. This isn't the end of the world for me, but I would like to understand more about it.

    TIA
     
  2. Raffy.Roma

    Raffy.Roma Active Member

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    @smorgasbord

    I think that Tesla logic is good. This way you could leave the Roadster plugged-in at home for one month (if it is needed) without being afraid of damaging the battery for loss of charge.
     
  3. smorgasbord

    smorgasbord Active Member

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    Raffy.Roma, I wasn't questioning the logic: Just trying to understand it. Is it a 48 hour wait until charge, or is it something else? And, why does the car wait about 48 hours - why not kick it in after only 24 hours have gone by?
     
  4. Raffy.Roma

    Raffy.Roma Active Member

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    @smorgasbord

    I have not (unluckily) the Roadster but I suppose that on a long time period it's ok for the Roadster to be charged each 48 hours to insure that the battery does not suffer a fatal loss of charge. In my opinion it would have been good also a 72 hours period until charge but I think that Tesla designers wanted to be very conservative in the purpose of protecting the battery.
     
  5. Brit4864

    Brit4864 Member

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    I was away for 5 days recently and left the MS plugged in at home. I noticed it seemed to do a top up charge every other day. I think it might work when a certain % of charge, say when 7% is lost based on whatever normal charge range you are using (90% or full). Given the vampire loss is about 8 miles a day, 2 days would equal approx 7% loss from the normal 90% charge setting (240 miles). Page 25 of the manual states:

    "When plugged in, Model S wakes up when needed to automatically maintain a charge level that maximizes the lifetime of the Battery. There is no advantage to waiting until the Battery’s level is low before".

    I seem to remember somewhere else it says it does this at a pre-determined point (7%?). I'm assuming v4.5 without the sleep mode enabled. It might be different with the sleep mode?
     
  6. laalan

    laalan Member

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    Where is sleep mode. My 4.5 doesn't seem to have it
     
  7. Raffy.Roma

    Raffy.Roma Active Member

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    @Brit4864 and laalan

    Maybe the Model S charge logic is different with respect to the Roadster.
     
  8. pharma5

    pharma5 Roadster F#25

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    Hi Smorg,

    I've seen the same behavior routinely in my Roadster, since I don't use it as a daily driver. Usually does it between 24-48 hr. There are cases where I've left the Roadster closer to 50% charge, set to "charge on plug-in", and stopped the charging as you did. I usually expect it to wake up and resume charging at 24+ hr. If I stop it again it will wake up approx. the next day to resume.

    P5
     
  9. hcsharp

    hcsharp Active Member

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    I've noticed that it will top up every 48 hrs even if you don't drive it and even if you stopped the last charge. At first I thought it was strange but don't think about it anymore. The other thing that always seems odd is if you are programmed to charge at say 6 AM but aren't home, and get home at, say, 10AM, it won't wait until 6AM the next day. It will start charging right away at 10AM. But if you get home at say 7PM, it will wait until 6AM.
     
  10. brianman

    brianman Burrito Founder

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    Model S software/firmware changelog - Tesla Motors Club - Enthusiasts & Owners Forum
    Model S software/firmware changelog - Tesla Motors Club - Enthusiasts & Owners Forum
     
  11. mknox

    mknox Well-Known Member

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    My experience exactly. According to my home energy monitor, it consumed exactly 5 kWh every other day while I was away on vacation.
     
  12. hcsharp

    hcsharp Active Member

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    This is a roadster thread but thanks for your post b/c it's interesting to note the MS does the same thing.
     
  13. mknox

    mknox Well-Known Member

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    Oops! That's what I get for logging on to the forums past my bedtime :redface:

    I do recall that when Model S deliveries first began that there was much consternation over the so-called "vampire losses" and some Roadster owners were saying this didn't happen with their cars. I was left with the impression that Roadsters continuously "trickle charged" to keep the battery topped off.
     
  14. sethr

    sethr CPO Roadster #1089

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    My experience is that my 2.5 Roadster initiates charging every 24 hours when in standard mode. But: If you set it to charge at a specific time, it charges 24 hours later at the charge start time. However, it starts charging at the same time the charging session ended the previous day when set to "charge on plug in".
     
  15. Doug_G

    Doug_G Lead Moderator

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    I've noticed that when the Roadster is in Storage Mode, it still wakes up at the scheduled charging time. The charge port lights up, the pumps start running, it whirrs for a while, and then it shuts down again. I guess it's running some system checks.
     

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