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wierd thing about regeneration breaking

Discussion in 'Model S: Battery & Charging' started by blackscraper, Sep 15, 2017.

  1. blackscraper

    blackscraper Member

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    Model S 90D, about 40K KM. Running fine. The day before yesterday, I ran the SOC down to 4% and then charged it back to 90% using mobile charger. I did not drive it yesterday so the car sat in the garage. Local temperature is at 21C. However this morning, when I drove my son to school I noticed my regeneration was limited to somewhere between 40-50KW and just now i saw the regeneration braking was still limited. This has never happened to me. I made a call to Tesla support, the agent looked through the logs and saw nothing wrong. He later on told me when state of charge was higher than 90%, regeneration braking would be limited. Unless the SOC goes "way lower" than 90% (somewhere 85%) will it come back to normal. Does this sound right? I know when SOC is very high (>95%), it will be limited regardless of temperature and I personally observed the BMS behaved like 95% was the threshold, but I don't know 90% is actually the threshold and it never happened to me. Anyone can shed light on this?
     
  2. brkaus

    brkaus Active Member

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    I’ve noticed a little bit of regen limiting at 93%. Not much, but it was noticeable.
     
  3. Tevvy

    Tevvy Member

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    Funny you talk about this. I picked the car up a couple of weeks back and at first the regen braking was really strong, but when driving home tonight I thought it was less so. I put it down to the fact that I'm just getting used to it, but maybe not now I've read this thread.
     
  4. scaesare

    scaesare Well-Known Member

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    Hmm, I don't recall ever seeing regen limiting at 90%. I charge regularly to that level for weekends.
     
  5. artsci

    artsci Sponsor

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    Did your regen break?:)
     
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  6. Brass Guy

    Brass Guy Member

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    I've only seen limited regeneration in the high 90% SOC, or in much colder weather - like below 5C.
    It sounds wrong to me.
     
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  7. blackscraper

    blackscraper Member

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    yeah, same with me until today...... I will give it another try. I did observe, during the short trip to school this morning, the yellow dotted line faded away a little bit. Seems the coolant is flowing during acceleration. i will ask the technician to check it up during annual service next week if I can still drive it.
     
  8. David99

    David99 Active Member

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    Regen is still limited at 90%. The cars won't show the limiter dotted lines but it's limited anyways. Regen is almost completely limited at 100% and the limitation gets smaller as the battery level does down. At about 85% it is at fully functional. Temperature also plays a part. The cooler the battery the more it is limited. Both factors can add up.

    The Regen limit is reported on the CAN bus. I can see the limit (kW) go up and down depending on state of charge and temperature.

    Interestingly the Regen limit is 100 kW in ideal conditions. I have never been able to get 100 kW regen, though. Maybe 70 kW when going over 100 and letting go of the pedal.
     
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  9. David99

    David99 Active Member

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    Btw I noticed when the regen is limited to say 40 kW it won't regen as usual up to 40 kW and then limit there. It kind of scales the entire range down. For example at speeds that would normally produce 30 kW of regen it is only 20 kW.
     
  10. blackscraper

    blackscraper Member

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    Well, the battery now has been consumed to 387km rated range (393km when charged to 90%), the yellow dotted line seems to fade away. The only thing that baffles me is I haven't seen this behaviour untill now. There were numerous times I charged it to more than 90% while the yellow dotted line only existed when higher than 95%.
     
  11. jerry33

    jerry33 S85 - VIN:P05130 - 3/2/13

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    Regen limiting is caused by battery SOC and/or temperature. When it's close to being not limited, you'll only notice it at speeds ~60 km/h and higher (at least that's how my S behaves). I'm not sure what the reasoning was behind having the limiting bar go away before the limiting stops, but it has always been that way.
     
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  12. Cosmacelf

    Cosmacelf Active Member

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    I charge my S and X to 90% all the time and don't see regen limiting unless it is cold outside or the car is very hot. I would definitely have Tesla check it out, it could indeed be an indication of low coolant levels.
     
  13. Knightowl

    Knightowl Whovian

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    exactly the same
     
  14. SmartElectric

    SmartElectric Active Member

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    Our early 2013 S85 has the original "A" battery pack specification, and is charged to 90% daily, and a few times per week (yes 2x per week or more) to 100%, sometimes leaving it at 100 for a day at a time if we forget to reset the charge slider. (still charges to 97.5% original capacity BTW).

    Typically see yellow dotted line on regenerative braking until battery warms up if left at 90% overnight, and like everyone else, no regen at 100%, and scaling regen until around 85% SOC.

    We also get yellow dotted line show up under hard acceleration often at the start of a drive, even if the SOC is above 60% we see it depending on the length of time the car has sit idle.

    If you select range mode (which we rarely do), the yellow dotted line shows up more more often, likely due to battery temperature.

    My Smart ED has a similar indication, but it's very coarse, only 3 "bars" on a little gauge at the bottom right of the display.
     
  15. tnt1971

    tnt1971 Member

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    I saw regen limited at lower states of charge in very hilly areas after doing some hills with very moderate temperatures (60ish Fahrenheit). There is a temperature limit (at both ends of the spectrum) in addition to a SOC limit.
     

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