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Draining close to empty

Discussion in 'Model X: Battery & Charging' started by RVD98072, Mar 27, 2018.

  1. RVD98072

    RVD98072 Member

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    Is it bad to run the battery down close to empty all the time?

    On ICE, I'm used to driving until the red light is on for awhile and using an EV I usually drive until I'm down to <20 miles range left on the Tesla and <10 miles range in other EVs (e.g. Leaf, etc.).

    Is it bad to run it down that low? I don't run it to empty but usually the car is complaining about low charge, etc.

    On the other end, I charge up to 80% or 90% only and never up to 100%.
     
  2. TexasEV

    TexasEV Well-Known Member

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  3. RVD98072

    RVD98072 Member

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    Ok I'll stop...maybe.
     
    • Funny x 1
  4. TexLaw

    TexLaw Member

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    Are you charging at home? If so, there really isn't much sense in letting the battery run down. If you are not, I suppose there could be some convenience in running it down, but it isn't particularly healthy.

    If I recall correctly, it's best for the battery pack health to keep it at or above 20% on the low end.
     
    • Helpful x 1
  5. Cowby

    Cowby S E X C R

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    If u plan to keep the car for a long time then battery life optimization is from 30-80%, otherwise drive it like you would ice cars.
     
  6. AZ Desert Driver

    AZ Desert Driver Rare combination

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    It seems like the idea of draining came from the old NiMH operation and the user has not evolved to the more modern chemistry that does not have Memory.
    Now, if I was in the market for a used car, how could I tell if the battery was abused? What price penalty should apply here?
     
  7. lymex2018

    lymex2018 Member

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    One way is to look at the current full pack value (in kWh) and compare it to the "normal" value to see if it deviate a lot.
     
  8. RVD98072

    RVD98072 Member

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    fwiw, i charge up to around 90% and then drive off immediately and it's always at 264 miles (I have a MX 100D). I haven't noticed any decline since I got the car (roughly 7000 miles in right now).

    i charge at home sometimes but mostly charge out at urban chargers while i'm on the road.
     
  9. IdaX

    IdaX Member

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    You shouldn't feel bad about using your entire range if you're on a trip and need an aggressive leg to get to a charger or something. But as a routine matter of course, no need to get below 25% or so.
     
  10. AZ Desert Driver

    AZ Desert Driver Rare combination

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    So this shows how the battery operates on its TOP. Would its bottom look the same?
     
  11. lymex2018

    lymex2018 Member

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    I'm not quite sure what this bottom mean. The full pack is the full pack energy when charged to 100%, but the BMS can estimated when not charge to full. On the other end, when draining the pack to 0%, then there will be zero.

    However, another parameter to look at is the internal resistance, the smaller the better.
     
  12. AZ Desert Driver

    AZ Desert Driver Rare combination

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    So if I understand the above....when shopping for a used Tesla, take the car to a charger and fill it to 100%. Note how many miles the full pack reflects. Compare that to what a new pack should be. Divide A by B and see how much degradation has happened. If that number is better than 90%, don't discount for abused battery. If the number is 70% - choose another car. At 80%, assume the car has been abused but not ruined and discount by How Much?
     
  13. lymex2018

    lymex2018 Member

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    Yes. And the "normal" value can be found here. You can select mileage or age to see of it is above the average or below.
     

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