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Is it worth getting the 85kwh battery to extend the time before the bank is replaced?

Discussion in 'Model S: Battery & Charging' started by craby, Jan 25, 2013.

  1. craby

    craby New Member

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    Brisbane Australia
    Hi,

    This is my first post, so sorry if I'm doubling up. I have looked for an answer to this question for awhile, and I haven't found much discussion on the issue.

    I'm currently waiting for the Tesla S price to be announced in Australia. Unfortunately we don't get any govt incentive, so tossing up between the 60 and the 85kwh battery bank is going to be part of the equation unless the govt comes to the party soon.

    What I'm interested to know is whether or not anyone else has bought the 85kwh battery, with the view of increasing the time before the bank is to be replaced. My thinking is that if the 85kwh battery will loose about 20% (or so) of its charge at about 8-10 years, then that puts it around the 60kwh level. I could then continue driving the car for another year or so, before it possibly went down to 40kwh, thereby giving several more years of serviceable life to the bank, and effectively meaning a substantial chunk of the upfront cost has been paid for by the fuel savings.

    I currently use a stand alone home solar power system (with 1500AH battery banks). My understanding is that towards the end of their serviceable life, they'll gradually stop holding as much charge, but will still be good for years as I only tend to use about the first 10-15% of their capacity. I'm assuming that the tesla battery bank will be much the same.

    Does anyone have any thoughts on this? I'm tempted to push out to the 85kwh battery bank on this basis alone, although the 60kwh battery is probably in the sweet spot for my usual holiday driving range and affordability.

    Thanks very much.

    regards,

    craby
     
  2. Jason S

    Jason S Model S Sig Perf (P85)

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    Rocklin, CA
    The main thing you'll lose to decreased battery capacity is range, at least as I understand it. So the usefulness of the car as limited by range is the differentiating factor.

    So how much of the range will you need in 10 years? Will the reduction from ~240 miles to ~190 miles make some trips less convenient? (It does in my case) If using the 60 kWh instead, does ~190 miles reduced to ~150 miles make a large enough difference to justify getting the 85 kWh instead?
     
  3. meloccom

    meloccom Moderator Aus/NZ

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    #3 meloccom, Jan 25, 2013
    Last edited: Jan 25, 2013
    I'm in the same position as you craby, I have a 160km trip from Sydney to Bundanoon every two weeks. The 60 kWh model should get me there and back without charging, so long as I range charge, but not after a few years when some capacity is lost.
    The 85 kWh battery would do the trip comfortably on a standard charge, so I would rarely ever need to range charge which should be better for battery life.
    I would like to go with the 85 kWh but the cost will be the final decider.
     
  4. ElSupreme

    ElSupreme Model S 03182

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    Pack longevity was a very large part of my decision to get the 85kWh pack. I fully expect to have this car for at least a decade and I don't want pack degradation, and possible replacement, to come up and convince me to get another car. This reason also pushed me to the premium sound, and panoramic roof. Get everything you want now so you aren't tempted in 6 years to buy another car.

    But if you plan on getting another car in 5-6 years I think the decision is much different.
     
  5. mknox

    mknox Well-Known Member

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    My reasoning exactly.
     
  6. craby

    craby New Member

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    Thanks very much for your replies. I'm definitely now leaning towards the 85kwh pack. The range of the 60kwh seems to be about right for my needs, but the 85wkh should buy me more time in the long run, plus being a bit more convenient all around.

    Even though it is a ton of money more, I guess the old saying remains true. 'Buy the best, and you only cry once'.

    regards,
     
  7. blakegallagher

    Joined:
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    so now it seems it would make sense to get the 60kw battery ... in 3 to 4 years (or 10) you can buy an upgraded battery with a 400+ mile range or just a new cheaper 300 mile range battery ... if battery capacity 4+ years out is your only issue it would seem to make sense to wait for next gen battery chemistry and then upgrade
     

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