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Question concerning timing the end of my first 100% charge

Discussion in 'Model S: Battery & Charging' started by Andyw2100, May 15, 2015.

  1. Andyw2100

    Andyw2100 Well-Known Member

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    I am going to charge my P85D to 100% for the first time early tomorrow morning. I'd like to time the charge so that it ends just before I plan to leave, as the less time I leave my pack at 100% SOC the better. I'm sure a lot of you will feel the need to come and post to tell me that a few hours more or less at 100% SOC isn't going to make a lick of difference in the big picture. I'll save you the trouble and tell you I understand that. I'm still interested in timing things as optimally as I can.

    So, that being the case...

    I have read that people believe the pack management software may do some interesting things at the end of a 100% charge that it doesn't ordinarily get to do when charging to a lower SOC, and that these things take time. I know there is debate about whether it is pack balancing or not, etc., and I'm not trying to open that can of worms. All I am trying to find out is how much additional time I should factor in for whatever it is the pack management software might like to do this first time I am charging to 100%. I'll have about 8000 miles on the car at the time. We ordinarily charge with pretty deep cycles, and charge to 90% almost every day. A typical day has seen anywhere from 100-190 range miles being driven, depending on the weather and the day.

    My plan is to charge to 90% before I go to bed, and then set a timed charge for the last 10%. I'll be charging at 56 amps, and that last 10% or approximately 30 miles would ordinarily take approximately 45 minutes or so. I want the car ready to go when I need to leave in the morning. How much more time, over and above the 45 minutes it would normally take, should I allow for whatever it is the pack management software will want to do?

    Again, if you are inclined to tell me to just set it to 100% tonight, and not worry about it, please don't. I fully understand that I could do that. I'd just prefer not to.

    Thanks!
     
  2. Zextraterrestrial

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    #2 Zextraterrestrial, May 15, 2015
    Last edited: May 15, 2015
    truth is that it really depends on the imbalance of your pack. (and balancing possibly changed in some firmware versions a while ago)
    what is your 90% charge in rated?

    I have tried this long ago and had more than 20 minutes sitting at 100% but not done at my house

    recently I did a 100% at a SC and it was quicker at the end - from 91% charging at 33kW to 100% took 16 minutes but I was still charging at 16kW. 4 more min at 100% and I was still at 12kW & unfinshed when I left. But SC charging in DC voltage matching the battery is really different.
     
  3. Andyw2100

    Andyw2100 Well-Known Member

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    Thanks.

    Recently my 90% charge has been 226 in rated miles, with range mode off. When I turn range mode on that kicks up to 228 or 229.
     
  4. Zextraterrestrial

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    my 90% is 228 currently but was 226 before my 100% (P85 though so #'s will be different a little)

    I'd expect at least 15 min at 99 or 100%



    :wink::tongue:
    or 4 hrs
     
  5. deonb

    deonb Active Member

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    One data point:

    My last range charge was about a month ago, and it took 4 hours after it reached 255 to tick onward to 257. I left it overnight from that point on, and it stayed at 257.

    The car has always charged to 257 max on range (since day 1).

    So the 'balancing act' - whatever that is, can take at least 4 hours.
     
  6. Andyw2100

    Andyw2100 Well-Known Member

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    Thanks.

    I know there is some benefit to whatever it is the pack management software is going to do, so the last thing I want to do is have to leave before it finishes, since my charging to 100% is likely to be such a rare occurrence. I'll certainly leave extra time. I'm just trying to get an idea. 15 minutes is very different than an extra couple of hours, so thanks!

    Edit: I had typed the above before seeing this:

    That changes things quite a bit.

    Now I'm thinking I might just need to let it go, and have it possibly sit at a high SOC for hours.

    Edit number two--By the way, deonb, did the charge not actually complete after you left it those four hours, and then overnight? I mean, did you never get the "Charge Complete" status message?
     
  7. wraithnot

    wraithnot Model S VIN #5785

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    At least with my car, it generally takes something like 30 to 45 minutes to top off the battery if I haven't done a 100% charge in a while. It takes less time if I've done a 100% charge more recently.
     
  8. Andyw2100

    Andyw2100 Well-Known Member

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    Thanks!

    Since this is my first one, your experience is another argument for starting it early.
     
  9. Cottonwood

    Cottonwood Roadster#433, Model S#S37

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    I've see the time at the end take from 15 minutes to a couple of hours. Because you have not done a 100% charge before, I would add at least 1 to 2 hours to your expected time to complete to give you a 99% chance of completing the charge.
     
  10. Andyw2100

    Andyw2100 Well-Known Member

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    Thanks. I definitely want to make sure the charge finishes, but I also don't want the car sitting at 100% SOC much longer than it needs to. Decisions, decisions.
     
  11. Great Dane

    Great Dane Member

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    you Could also charge to 95 percent .
    have it finish at 5 am and when you get up,
    on your smart phone, slide her the rest of the way
    While you get ready in the morning eating breakfast
    so will the car.
    Btw
    will be in Brooktondale NY in 3 weeks
    15 miles east of Ithaca
     
  12. Andyw2100

    Andyw2100 Well-Known Member

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    Thanks.

    The difference between the 90 and 95% is irrelevant, though, since I can predict exactly how long that 5% should take. What I can't predict is how long the car will take to go from the time it should have reached 100% charge to actually completing the charge, and that doesn't change whether I start at 90%, 95%, or 50%.

    What will be bringing you to Brooktondale?
     
  13. omarsultan

    omarsultan Active Member

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    So, I regularly max charge (usually twice a week)--I have noticed the last couple of miles of range takes FOREVER. That being said, I would not sweat the timing too. I kick off charging a few min after midnight and the car is always ready to go by 5am. When they say don't let the car sit at 100%, I think they are talking about days at a time, not a couple of hours.

    I have 55K on my S85 max charging twice a week and it still max charges to 257 +/- 2 miles.

    O
     
  14. Andyw2100

    Andyw2100 Well-Known Member

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    So I started the max charge at 11:00 PM, and had expected to go to bed before it finished and wake up to a fully charged car. But I wound up staying up later than I expected to, and then since I was getting close to the time Visible Tesla was showing that the charge would be completing, I decided to watch to see what would happen.

    Over the last thirty minutes or so the rated miles inched up to 251.6, and the % inched up to 100%. The amps have been decreasing during this time, and are now down to 12. For quite a while the time remaining was decreasing more slowly than what it was promising, and it stuck at 4:00 for quite a while, but it did recently move to 0 minutes remaining. The car is still charging though, currently taking 10 amps. Since it may continue on this way for quite a while, and I'm getting up fairly early, I am going to finally go to bed, and trust that it will complete charging some time in the next six hours or so.

    Just wanted to report back. I'll follow up again with how it turned out, but probably not first thing in the morning.
     
  15. Andyw2100

    Andyw2100 Well-Known Member

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    #15 Andyw2100, May 16, 2015
    Last edited: May 16, 2015
    So Cottonwood wins the prize for best prediction. The charge completed fifteen minutes after I posted the message above, at 1:35 in the morning, 2:35 after I had started it. I was only adding about 90 miles, so that would ordinarily have taken about two hours. Had I allowed for an extra two hours, I would easily have been fine.

    VT showed 251.6 as the rated range when the charge finished, as per the email it sent me. When I got in the car this morning, the rated range showed as 253 miles.I thought that discrepancy was odd, so I exported the VT data, and found something really odd. Check this out:

    C_VLTC_AMPC_ESTC_SOCC_ROCC_BAML_PWRDate
    2435251.6110032.72.4-15/16/15 01:31:41
    2435251.6110032.72.405/16/15 01:35:41
    00251.611000-0.205/16/15 01:35:41
    00251.611000-0.205/16/15 02:39:49
    00251.611000005/16/15 05:55:02
    00253.5510000.105/16/15 05:55:03
    00253.551000005/16/15 05:59:03
    00253.5510000.105/16/15 06:03:03
    00253.5510000.105/16/15 06:07:02








    (Many lines removed. Lines around significant lines included.)

    At 5:55 this morning the rated miles increased by almost 2 miles, with nothing else going on!

    Anyone have an explanation for this? Note that this has nothing to do with range mode being on or off. When I got in the car (at around 7:45 AM) and turned range mode on the car then displayed rated range as 255 instead of 253.

    Also, I expect the answer to this is "No", but is the car supposed to do anything funky, like shut itself down after a range charge, to save vampire loss until the drive starts? I say I expect the answer is "No", because I've never read about anything like that, and I've read a lot. I ask because when I entered the car this morning, my 17" display was off. Stepping on the brake resulted in the message pictured.

    Car Off May 16.jpg

    I then waited a while, as instructed, and the message never cleared. I tried a scroll wheel reset, and almost simultaneously stepped on the brake again, and one of those two things got everything straightened out.

    Thoughts?
     
  16. gzerninplatz

    gzerninplatz Member

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    Maybe the system re-calibrated itself, as range charging is supposed to bring about?

    By the way, thanks for doing this....I'll be going on a long, somewhat non-supercharger trip soon (Oregon desert), and really want to understand the nuances of what range charging is all about....
     
  17. Andyw2100

    Andyw2100 Well-Known Member

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    Yes, I guess that could be what happened. I just would have expected it to happen immediately upon the completion of the charge, not several hours later.
     
  18. Cottonwood

    Cottonwood Roadster#433, Model S#S37

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    Another behavior that I have seen sometimes is to be able to drive the car for 2-3 miles after a 100% charge before seeing the first rated mile go away.
     
  19. Todd Burch

    Todd Burch Electron Pilot

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    Data point: Charged to 100% (or tried to) for the second time in 13,000 miles yesterday. When I got to 261 mi rated, the car was still charging at something like 240V, 28A for over 5 minutes without increasing to 262. I finally had to go, but this illustrates there's definitely some uncertainty toward the end. I ended up driving about 4 miles before dropping below 261 mi.

    On my previous S with about 30,000 miles (also with rare 100% charges and usual charging to 80% which I no longer do), I remember it staying at 240V, 2 or 3 A for 15-30 minutes toward the end of the charge.
     
  20. mackgoo

    mackgoo Member

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    I just did the 100% last night. Started at SC 1901 with 31%. 1934, 80%.completed 2049, 100%. It sat at 100% for at least a half hour with the message "calculating time remaining". This was the 2nd time in 30000 miles I completely charged to 100%.
     

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