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Proper way to charge

Discussion in 'Model S: Battery & Charging' started by DHG., Jan 22, 2017.

  1. DHG.

    DHG. Member

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    Reading over the threads I noticed questions about battery degradation. What is the maximum the pack should be charged to 100% or 90% or less or somewhere in between? What causes battery degradation? What are the best ways to prevent it?
     
  2. randvegeta

    randvegeta Member

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    For the longevity of your battery, try to keep the SoC between 50 and 80%.

    90% is OK, but 80 is better. Dont keep your SoC at 100% and only charge to 100 just before a long trip.

    Similarly, try not to let your SoC drop below 10%.
     
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  3. bob_p

    bob_p Active Member

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    I've had a P85 for 4 years, and have always charged to 90%, leaving the car plugged in overnight and whenever I'm home. And have only used 100% a few times, and quickly started driving after the car hit 100%, so it wasn't at a full charge for very long. And, when driving the car has been below 10% only a few times - and only for brief periods at the end of a drive before reaching a charger.

    At home, for most of the time I charged at 80A with my dual chargers - charging at home at the fastest possible rate.

    And I've only lost around 5% of the original charge, which is consistent with what other owners have seen.

    I've been at the 5% level for quite a while now. It seemed like the car lost that charge level and then stabilized, and haven't seen any further degradation (at least so far).

    Losing 5% over a several year period is much better than I expected - so it's not clear, at least from my experience, that it's worth worrying too much about the charging practices, as long as you try to keep the charge level between 10-90% almost all of the time.

    And, for software-limited 60's (which are really 75's), you may be able to charge up to 100% without any risks, because you still have the extra 15 Kwh of capacity that hasn't yet been unlocked.
     
  4. NovemberXray

    NovemberXray Member

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    I only charge to 60% when at home because I spoke with a guy who has a roadster, model S, and model X, and by only charging to 6 he claims even after 5+ years he's only lost 2% capacity...
     
  5. TexasEV

    TexasEV Well-Known Member

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    You could have saved a lot of money and just bought a 75 if you only need 60% of your range. Why would you even care about another 1or 2% of range after many years in that case?
     
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  6. NovemberXray

    NovemberXray Member

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    I only need 60% at home to drive around town for the day. I charge to 100% on road trips, and wished for even more range a couple times last summer on our 9000 mile cross country trip. And of course there's remote places it would be nice to get to. I am just saying at home, unless you have a long commute, there's no need to keep it charged so full all the time.
     
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  7. jerry33

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

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    First, much of "battery degradation" isn't real, it's caused by imbalance and Tesla messing with the rated range algorithm. Use ideal miles to check as they seem to mess with this less.

    Second, the balancing circuits are activated at 93%, so charging to that level once in a while keeps the pack in balance. Charging to 90% (maximum on the daily slider) reduces the rate at which the pack becomes unbalanced.

    Third, there is little evidence to indicate that Tesla batteries degrade faster at 90% than at 80%. Setting the slider to 50% (but plugged in) when the car will be idle for an extended period is recommended (how much of a practical difference this makes isn't known).
     
  8. WannabeOwner

    WannabeOwner Active Member

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    My only additional thought is to charge the car immediately, after stopping, if SoC is below 10%. I very rarely get home with that little charge, but at home I have scheduled charging for Off Peak [midnight to 7AM] and I deliberately override on the odd occasion when i get home "low on juice" so the battery doesn't sit in that state. How much difference a few hours makes, a couple of times a year, I don't know - probably next to none, but its better for my soul :)
     
  9. Zooomer

    Zooomer Member

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    The science of batteries would say that optimally do not fully discharge, do not fully charge, keep a high SOC time at minimal (use scheduler to make battery peak before you leave instead of charging right away), keep temps low, esp if high SOC, do not got WOT constantly.

    Having said that, someone was nice enough to gather real world info here:
    MaxRange Tesla Battery Survey
    I modified the sheet to narrow to users with higher mileage who've owned the car for a while. Then I broke down all behaviors to find any patterns in higher degradation. Only one thing seemed to make any measurable difference. 100% charging daily. Even then, the difference after 100k+ miles was like 2% additional degradation. Keep in mind, this is in older Model S vehicles and battery chemistry is improved constantly. Guys are seeing like ~5% loss after 100k miles depending.

    Moral of the story is this. Do what you want, just try not to charge over 90% except when you need to. The minor details aren't worth the stress of being 100% optimal so you can have 1% less loss after 7 years... By then you'll want a new car or pack anyway.
     

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