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Does this charging strategy make sense?

Discussion in 'Model S: Battery & Charging' started by pbleic, Feb 23, 2014.

  1. pbleic

    pbleic Member

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    I have read that keeping the battery as low as possible will extend its life. My S85 will have dual chargers. My commute is 17 miles round trip. Would it make sense to keep it on the "low" side (maybe 60 miles) when I know I am not planning to go anywhere after work. In case I needed more, I could pretty quickly add more with the HPWC (during dinner, if I was going out in the evenings).

    For those who have the car and have lived with it for a while, is this too severe to maintain? Would it be worth it? Or should I just charge to 50% every day?
     
  2. Andrew

    Andrew Model S #6151

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    Tesla repeatedly says that you should plug in your car anytime you're not using it (assuming it's near a plug). Just plug in every night, and keep the charge level set to 50%.. and then don't worry about it. :)
     
  3. Todd Burch

    Todd Burch Electron Pilot

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    Pbleic,

    First, I cannot stress this enough: you don't want to do this. Some day you will have something unexpected come up where you'll need the mileage.

    Story: a few months ago I was at work and my wife called me, saying she was taking my 3 year old son to the ER. He was fine in the end, but I sure am glad I had the miles to drive to the children's hospital and then home afterward. You would've been stucking looking for a ride at a low state of charge.

    Second, you're overthinking the battery thing. Seriously, just charge it somewhere in the daily range and don't worry about it. I'd recommend 70-80%. That way you will have extra range on that day when you need it.

    Low states of charge mean that you'll have less power available. This is a sporty car. Take advantage of that power.

    Finally, being at low states of charge isn't great for the battery either. You may find yourself using the heater on a cold, wet, windy day and be bringing the battery close to zero.

    Tesla has the "Daily" range for a reason. Use it, be happy, and drive :)
     
  4. efusco

    efusco Moderator - Model S & X forums

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    Agree, see above. Don't over think this thing.
     
  5. jerry33

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

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    Agreed. 50% is for storage--if you're going to be gone for over a week, then fine set to 50%. Otherwise there really is nothing wrong with 70 or 80% (that's about 180-210 rated miles).

    It's actually better for the battery to be driven when the charge is over 50%. Under 50% heats up the battery more for any given power level. There is a big difference in battery life between leaving the car sit at 100% and leaving it sit at 90%, much less difference between 90% and 80%, lower than 80%, the difference is small but measurable. If you set the timer so that the charge finishes about the time you leave for work, then it will be lower than when it finishes. Charging up to a high (over 90%) doesn't hurt, it's leaving it sit at very high levels that causes the deterioration.
     
  6. Jason S

    Jason S Model S Sig Perf (P85)

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    Tesla Motors has many patents on battery care. They take care of the battery so you don't need to think about it. Charge to 70-80% and don't worry about it. Anything higher is considered unneeded but the battery is still warrantied, again because Tesla takes care of the battery for you.
     
  7. slipdrive

    slipdrive Member

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    I personally think these paks are going to last a long time, and it will be a very long time if the extremes are avoided when practical and convenient. Jeff Dahn's research group at Dalhousie is pretty confident it is the hot temps and high SOC that is to be avoided. So the issue they believe is cumulative time spent at high (>4.0)v especially combined at high temperatures. It's the nuisance reactions in the electrolyte which can accelerate at high voltage and temperature. While we don't know for sure, they believe 4.0v corresponds to about 75% SOC in the Tesla paks of "special" 18650 cells. So without much trouble, the use of scheduled night charging to finish at say 7am, to minimize time higher voltages may help. Everyone is different on daily need and preferred "cushion". Personally, I have gotten progressively more comfortable staying in a "working range" of 60-160 mile on the P85. But easily used the phone app and range-charged Sat am early to 266mi and took off for the mountains.
     
  8. brianman

    brianman Burrito Founder

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    My 90% is approaching 210 rated miles... :(
     
  9. spentan

    spentan Active Member

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    On an 85kW?

    Mine is Dec 2012, 13000 miles and getting between 259-262 miles on a range charge.

    For the last 3 weeks or so I've been charging to 100% as I don't have home charging. Hence why I don't have a 90% figure
     
  10. brianman

    brianman Burrito Founder

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    Yes.

    (BTW, I'd be impressed if folks are getting 210 rated miles at 90% on a 60 kWh battery.)
     
  11. stopcrazypp

    stopcrazypp Well-Known Member

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    There's diminishing returns. The biggest return in life is avoiding SOC near 100%. I highly doubt the advantage below 50% is noticeable enough to be worth the effort in maintaining it.
     
  12. djp

    djp Roadster 2.0 VIN939

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  13. jerry33

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

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    When I Supercharged for the first time last Sunday, I stopped the charge at 260, and it looked as if I had kept going it would have gone to 265 though I can't be sure. I then drove the 115 miles home. So 210 is about 80%.
     
  14. mknox

    mknox Well-Known Member

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    My 85 kWh non-performance car hit 20,000 miles last week. I see 215 miles at 90%
     
  15. AmpedRealtor

    AmpedRealtor Active Member

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    Keep the car charged in the 50%-60% range and plugged in when at all possible. That is more than enough to cover your daily commute. On those days when you need more miles, add them with the HPWC. This is exactly the routine that I use. After six months and 5,500 miles I am seeing no battery degradation. Since the charge slider does not go below 50%, I'll assume that Tesla felt there was no benefit to keeping the car at a lower state of charge. Also, when you drive at a low state of charge, your battery throws out more heat. I've read that it's actually preferable to drive at a higher state of charge rather than lower due to the thermal stress. But it's all guesswork anyway.
     
  16. brandonmbeard

    brandonmbeard Member

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    UM have you notified service of this? Thats more than 10% degradation in less and 1 year!
     
  17. ElSupreme

    ElSupreme Model S 03182

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    I am also at 215 miles on 90%. I rolled over 23,000 last week.

    I think it is battery balance, or 90% selection not really equating to 90%. I still got 26x miles on 100% charges.
     
  18. mknox

    mknox Well-Known Member

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    I'm getting 215 at 90% and 245 at 100%. I haven't talked to service about it since it seems to be fairly consistent with what other are seeing at similar age/mileage. I am just over 20,000 miles and at just about 1 year.
     
  19. glhs272

    glhs272 Unnamed plug faced villian

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    Is 245 miles at 100% after balancing the battery?
     
  20. 100thMonkey

    100thMonkey Member

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    at any given time, give yourself plenty of wiggle room and drive the car the way you need/want to, charge to 100% when needed, drive to zero when needed and don't stress out about it... having fun driving!

    that said, I'm aiming for a no stress way to maintain peak performance as long as reasonably possible. I have the dual chargers and a 20 kW station which helps create convenience and flexibility, I also have super chargers to the north, south and east along our major routes here, which takes the pressure off as well. On a daily basis I leave the slider at 50% and always have it plugged in, which meets the vast majority of my needs. If you need more regularly, then no sweat, adjust upwards as required. I use the phone app to top up to whatever I need. If I know I will want a max charge the next day, I charge to 90% and top up the last bit in the morning. I think it's worth creating some good habits, but definitely not worrying too much about it.
     

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