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Winter Capacity, in KWH.

Discussion in 'Model S: Battery & Charging' started by randvegeta, Jan 25, 2017.

  1. randvegeta

    randvegeta Member

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    Got back home last night with around 6km rated range remaining on my 2014 Model S 60. That's around 2% charge.

    My car stopped charging at 98% (not sure why it wont go to 100%), and it reports exactly 50kwh of additional charge. This suggest that 100% would be around 52kwh.

    I know there is some reserve, so the actual usable capacity is actually around 58kwh (rather than 60). So does that mean I've lost 6kwh of capacity or is this just the Winter Capacity?
     
  2. Tam

    Tam Active Member

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    How many hours did you notice that it remains 98% -> 98%?

    Too see how much your battery has, charge it up to 100% then drive your car down to 0% and see your trip consumption report of how many kW it spent.
     
  3. Andyw2100

    Andyw2100 Supporting Member

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    It's really not good for the battery to be as low as a 0% SOC. You're suggesting that he potentially damage his battery just to determine its capacity with a little more accuracy.
     
  4. Tam

    Tam Active Member

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    There have been reports of owners who run all the way down to 0 miles.

    I myself did twice down to 0 miles and dozens of times with less than 20 miles remained and my battery is still very good after 85,000 miles.

    It may not be good because the battery is stressed but I am not sure about the word "damage".

    The only documentation of doing repeated full depth of discharges is you get less Discharge Cycles (another name for pre-mature degradation):

    [​IMG]
     
  5. Andyw2100

    Andyw2100 Supporting Member

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    #5 Andyw2100, Jan 26, 2017
    Last edited: Jan 26, 2017
    If "premature degradation" isn't damage, I'm not sure what is.
     
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  6. Tam

    Tam Active Member

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    Ok! You got me!

    Put it in another way, for Tesla battery, if you keep doing full discharges, it's likely you'll be able to drive your car in 8 years regardless of how many miles you get.

    However, if you plan to continue to drive continuously 24/7 beyond 8 years, you might want to avoid doing full discharges due to pre-mature degradation.
     
  7. Andyw2100

    Andyw2100 Supporting Member

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    Some of us try to treat our batteries as well as we possibly can so that they remain in as good condition as possible. If you want to run your own battery down to 0%, just to see what the real capacity is, feel free. My concern was with your suggesting that someone else do it, without any indication whatsoever that it could be bad for the battery.
     
  8. Tam

    Tam Active Member

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    Ok! You got the point. That is fair enough. I apologize.

    I should have have placed a disclosure clause that it "may shorten your battery life."

    Thanks.
     
  9. apacheguy

    apacheguy S Sig #255

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    Depth of discharge is a slight concern, but in my view as long as the pack is charged within a reasonable time the degradation will be negligible.
     
  10. Andyw2100

    Andyw2100 Supporting Member

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    That's all well and good, though you should note that in @Tam's advice he failed to mention that the battery should be recharged immediately.

    The OP joined TMC a month ago. As members with more experience, we shouldn't be advising newbies to do anything that could harm their cars at all, without warning them of the potential risks. That's all I was doing.
     
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  11. randvegeta

    randvegeta Member

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    Hello all!

    Interesting responses. I have been getting a little worried over the number of times I've already done a full 100% charge (6 or 7 in the last month).

    Just a follow up on the situation.

    So yesterday I head out with a 98% charge (as mentioned before.. it won't seem to hit 100%), and 275km of rated range on the dash. I returned home after doing exactly 213km, and consuming 45.9kwh (according to the dash). My remaining range was 10km. I added 50kwh to the battery the night before, suggesting there should be AT LEAST 4.1kwh of remaining charge, assuming 50kwh is my total capacity.

    I did another '100%' charge last night, and this morning again found it had stopped at 98%, with a rated range of 275km, and 49kwh of energy put into the battery.

    I'm not sure what to make of this.

    Perhaps it is important to note that I had left the car parked outside (temperatures of around -5c) for around 3-4 hours. I also had climate control on, which at times was drawing 5-7kw. But I did not pre-heat the car.. CC was only on when I was actually inside the vehicle.

    Is my battery in very bad shape? Or maybe it's just the cold sapping away the capacity?

    I will probably avoid this full charge/discharge type of driving from now on and either drive slower or stop for a quick top-up at the Chademo charger on the way home.

    Since there is no Tesla presence in Lithuania, and I therefore have no way to claim on warranty, I am looking to maintain my battery as best I can. Sadly, if I want to keep my SoC in the 10 - 90% range, particularly if I only have a 50kwh usable capacity, that limits me to only 40kwh... which is only 212km of range. Far less than what I had initially expected when deciding to buy the vehicle...

    Now I am just hoping that some capacity will come back as the weather warms. Hoping for a summer capacity of 56kwh, which would be enough to get me to the seaside!
     
  12. Tam

    Tam Active Member

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    I myself only count on miles. When my 85 was new, it got 265 rated miles and 300 ideal miles with a full charge.

    Of course I knew from the first day that I would never get 265 nor 300 miles on real roads but I use that as a reference for my battery health.

    I've never paid attention to kWh at all in the past 4 years. So I have no idea whether mine is a real 85 kWh battery or not.

    An MS 60 would have 210 rated EPA miles or 375 NEDC km

    98% of that is 205 miles EPA or 367 NEDC km

    Your 275 km seems to be lower than 98% NEDC range (75% of 367 NEDC km).

    When was the last time you could get 100% charge an what was its range in km?

    I am not familiar with cold weather so I am not sure why yours couldn't charge to 100% in -5C if it could charge all the way up to 98% already.

    It's possible that it already reached 100% while you were sleeping and it gradually went down to 98% in cold weather and that's what you see when you woke up.
     
  13. randvegeta

    randvegeta Member

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    210m = 338KM. So 275km = 81%, so I appear to have lost 19% of my range.

    You know I'm not sure it's really ever been to 100%. I believe it was 100% but the difference between 98, 99 and 100 may not be noticeable when you only view the charge level in terms of rated range, rather than as a percentage. But I believe it was around the time I bought the car, just over a month ago. I think I was getting around 280 - 285km. I have never seen it above 300, that's for sure!

    Yes that is possible.

    What I am really trying to determine here is how much of my battery capacity has been lost to the cold, and how much has been lost to degradation.

    If we assume that the charge indicator (the one that tells you how many extra miles/km/Kwh is shoved in the battery) is both accurate, and NET of inefficiencies, then all indications point to a battery capacity of approx 52kwh. I am basing this on the following

    With a range of 275km, and a rated consumption of 188wh/km, you get 51.7kwh.
    When discharging to 6km of rated range, I was able to add an additional 50kwh of charge overnight
    When discharging to 10km of rated range, I was able to add an additional 49kwh of charge overnight.

    With a usable capacity of around 58.5kwh, my batter appears to have lost around 6-7kwh of capacity, or around 11-12%.

    Now there is still some discrepency over how many kwh was charged and discharged. The car only reported 45.9kwh of usage yesterday, and yet I was able to add 49kwh of charge to my car. So there seems to be 3.1kwh missing.

    So.. is my 11-12% lost capacity during charging explained at least partially by the cold? Or is that degradation?

    And is that 3.1kwh that is unaccounted for.. was that lost to the cold while it was parked outside for 4 hours? Or was it consumed by my car heating itself, but not counted in the car's meter when displaying energy consumed since last charge?

    Overall I have around 17% of my batteries capacity missing, and it has me somewhat worried.
     
  14. andrewket

    andrewket Well-Known Member

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    Are you sure it stopped at 100%? How long after it stops charging is it before you look at the meter? The vampire is always going.
     
  15. randvegeta

    randvegeta Member

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    A few hours.

    But the thing is I cannot even restart the charge to continue. I've never seen it reach the full 100%. 98 or 99 is all I ever see.
     
  16. Rocky_H

    Rocky_H Active Member

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    Ah, that part at least, I can answer for you. The meter in the dash in front of you only measures the energy used while the car is in Drive. Any use outside of that time while it is parked will not show in that display, even if it is "since last charge", and you have done several shorter trips without charging. So yes, that is very common that there will be a few kwh of energy that just seems to go missing, where it needs to be refilled, but it doesn't show on that energy used table.
     
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