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scheduled charging glitch

Discussion in 'Model S: Battery & Charging' started by David99, Oct 26, 2014.

  1. David99

    David99 Active Member

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    To use the off peak rate I only charge at night between midnight and 6 am. As recommended by Tesla I keep it plugged in all the time. The so called vampire drain is kind of high so even though I keep it plugged in, the state of charge drops after the charging has finished.

    I watched the car and noticed the battery management is definitely active when the car is just sitting there without charging. Every once it a while it seems to turn on the heater or cooler for the battery or maybe just circulating the coolant. Each time it does that it gets the power from the grid (I can see hear the main switch and the UMC shows the power flow.) Despite that the state of charge drops over time. It's usually not a big concern until I noticed that if I don't use the car for two days or more it won't start the scheduled charging at night even though the state of charge has dropped noticeable. It seem that schedule charging triggers the charging process only once. It won't start again the following night!

    For example I had the schedule charge set to 76 %. It finished two nights ago. Now, two days later, the state of charge as dropped to 73 %. If I just let it sit, it would drop to 0 % in 25 days. All while it's plugged in. It's kind of odd that the scheduled charging only triggers the charging process once. Does normal charging do the same thing? Will it start charging again once the state of charge drops beyond a certain level?
     
  2. stevezzzz

    stevezzzz R;SigS;P85D;SigX

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    In my experience leaving the car plugged in without scheduling a charge, it wakes up roughly once every 24 hours and charges back to the level you set.
     
  3. andrewket

    andrewket 2014 S P85DL, 2016 X P90DL (soon 100)

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    #3 andrewket, Oct 26, 2014
    Last edited: Oct 26, 2014
    This is close to my experience. It wakes up at the scheduled time every 24 hours and will charge, but only if the current SOC and desired SOC is off by more than 8 rated miles or so. This usually means my car charges every other day if I let it sit plugged in with the conserve energy mode set to on.

    I have never seen the EVSE relay engage outside of the schedule time, except when the compressor is turned on by cabin heat/cooling.
     
  4. David99

    David99 Active Member

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    Thanks for your replies. That's what I would expect, but that's definitely not what my car does. I tried it several times and the logs from Visible Tesla show the charging never starts again. I have a service scheduled next week. I will bring it up with them. Hopefully they can find the problem.
     
  5. rdrcrmatt

    rdrcrmatt Member

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    I've heard it takes 5-10% drop for the car to top itself back up.

    I wouldn't sweat it.
     
  6. shelbri

    shelbri Member

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    I was away on business for a week and checked on the car every night remotely. I also schedule charging at night. I watched the range drop 1-2 miles in range each day. After 4 days, I checked again and it was topped up.

    I agree that it probably has to drop a few % before it tops up.
     
  7. David99

    David99 Active Member

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    Thanks! I will see what it does when I let it sit for a few days (not sure when I will ever not need my car for more than 2 days LOL).
     

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