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Questions of battery degradation over the years, warranty coverage, and battery pack

Discussion in 'Model S: Battery & Charging' started by carrerascott, Nov 21, 2012.

  1. carrerascott

    carrerascott FUEL FTR

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    I've read a lot and searched but didn't find these answers, if anyone knows, or has a link to an appropriate thread I'd appreciate it!

    First, what is the expected battery degradation over 8 years of ownership? IE if we are expecting 260-300 miles per charge in year 1, how much less should we expect in years 2-8?

    How does the 8 year battery warranty cover this degradation? Is there an expected %age that is or isn't covered by the warranty? If I'm only getting 100 miles by year 3, would that be covered by warranty?

    And lastly, after 8 years, what's it going to cost to put a whole new battery pack in this car? $20k? We'd hope battery prices would come way down, but who knows I guess. That would certainly kill 8 years of fuel savings. And really, really hurt resale!

    I have my deposit down, but my brother-in-law apparently was told by Tesla (he may have misunderstood...) to expect 25% per year battery degradation. He immediately went out and bought a Lexus Hybrid after hearing that (and I can't blame him if that's true...). That would mean

    Year 1 -- 300 miles range
    Year 2 -- 225 miles range
    Year 3 -- 168 miles range
    Year 4 -- 126 miles range
    Year 5 -- 94 miles range
    Year 6 -- 70 miles range
    Year 7 -- 52 miles range
    Year 8 -- 39 miles range

    I'm hoping and assuming this is way off, but would certainly like to hear clarification, and also just what the battery warranty covers.

    Thanks!
    Scott
     
  2. dsm363

    dsm363 Roadster + Sig Model S

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    I think it must have been a misunderstanding or a very misinformed Tesla employee as they've never stated anything like that. They wouldn't have any sales if that were close to being true which fortunately it isn't. The warranty doesn't cover degradation (which is normal) but is an 8 year unlimited milage (on 85 kWh pack with the smaller packs also having 8 year warranties but not unlimited miles). It would certainly cover a situation like you stated about with a 25% decrease per year. Tesla has said in the past that they expect the pack to have around 70% capacity after 8 years I think (something like that) but many Roadster owners are seeing about a 1-2% decrease in range a year at most. There are many factors involved though (number of range chargers, number of cycles on the pack, miles driven....etc).
     
  3. richkae

    richkae VIN587

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    I think it is very likely that the Tesla employee intended to say 25% after 8 years. Either it was misheard or mispoken.
    I think that is probably a good number to use in planning because it is at the extreme edge of what is likely.
    I am seeing about 3% loss after a little more than 3 years, but i am only at 27000 miles in the Roadster.
    I am expecting about 1% loss per year ( so 8% after 8 years ) but am emotionally and financially prepared for the 3% that would lead to 25% after 8 years
     
  4. Discoducky

    Discoducky Active Member

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    I'm prepared for 28% after 8 years and 125K on my 60kWh :wink:
     
  5. richkae

    richkae VIN587

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    I will add that from the tiny amount of data we have, the battery degradation correlates most highly with miles driven and not with time. Since I drive less than 12k miles per year, I am expecting to do better than average.
     
  6. carrerascott

    carrerascott FUEL FTR

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    Thanks all for the input. His numbers didn't sound right. I'm seeing my brother in law tomorrow at Thanksgiving, so I'll have to break the news to him that he made the wrong choice in buying the Lexus. ;)
     
  7. richkae

    richkae VIN587

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    He can return it within 3 days of purchase and get his money back!
     
  8. carrerascott

    carrerascott FUEL FTR

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    Pretty sure he bought it longer than 3 days ago -- my sister just mentioned it to me when I brought up the Tesla... sucks for him. ;)
     
  9. Doug_G

    Doug_G Lead Moderator

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    Uh, no. 25% after 8 years maybe. Nowhere near 25% a year.

    My Roadster is only down a few percent after more than 2 years.
     
  10. strider

    strider Active Member

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    I am down 4% after 2 years and 24k miles - I use my car as a daily driver ~50 miles/day. Your brother definitely misheard or that Tesla person needs to be taken in for "re-education" :)

    No one in the industry warranties capacity (except I think Renault but they only lease their batteries), they only warranty performance (can the pack output enough power for the car to achieve it's specified performance). The way it has worked in the Roadster is this.... The battery is broken down into a series of sheets and bricks. If all of the sheets/bricks lose capacity together, that is not a warranty issue. However if one drops more than the others they will replace that sheet/brick as it is failing due to some defect. Does that make sense?
     
  11. NigelM

    NigelM Recovering Member

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    2-5%, not 25%, per annum.

    P.S. After 20 months with the Roadster (now on 10k miles) I have experienced zero degradation.
     
  12. steve841

    steve841 Active Member

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    Nigel, that makes you a good model to outline your charging process vs driving habits. Care to elaborate ?
     
  13. swegman

    swegman Member

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    As an asidde, I read an ad fom Hyundai today for the Sonata hybrid. That car has a lifetime wearranty on the battery to the original owner. The ad did not give any more info than that, so I don't know what the warranty actually covers.
     
  14. mknox

    mknox Well-Known Member

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    Lifetime warranties to the original owner are a gamble by the manufacturer who looks at averages and figures most buyers will sell or trade in 3-5 years. Funny story: I bought a replacement battery for my mother's 1987 Chrysler Lebaron in about 1990 or so. She still drives the car today, and I think I have received at least 6 free replacement batteries for her!
     

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