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Warranty on S85

Discussion in 'Model S' started by MassX1317, Jan 17, 2014.

  1. MassX1317

    MassX1317 Addicted to TMC

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    I have been going over the cost of upgrading my current ICE vehicle to an S85, one savings that is impossible to quantify but definitely going to be impactful is keeping the S85 long term vs trading in my ICE every 3-4 years.

    I drive quite a bit. I used to drive 30-35k miles per year, now it's more like 20-25k. I like knowing that any major repairs will be covered and generally a low mileage car has less of a chance of breaking down when I'm 2 hours from home (at least they make me feel that way).

    So here is my question, if I buy an S85 and put 200-250k miles on it over the next 8 years, am I fully covered under the 8 year/unlimited miles warranty? In this same time with an ICE car, I will probably have 3 purchases and 3 hits on that initial drive off the lot depreciation.

    I figure in 8 years I will save about $30-35K+ in fuel vs. electricity if prices for both stayed the same. If I buy an $85k Tesla, less fuel, the break even cost for an ICE is now about $50k, but in my case that $50k could be for 2 cars. If the warranty is truly unlimited, it seems like a no brainer for me as long as I keep the Tesla though the end of the warranty.

    Am I using funny math to support my argument or is this truly a no brainer?
     
  2. deonb

    deonb Active Member

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    The warranty doesn't cover normal battery degradation though. So in 250k miles you may end up with a car with a range of only 160 miles (or could be 200 - who knows).

    But then again in 8 years you'll have 1000s of SuperChargers over the country. So 160 miles may not be that bad.

    I'd be more concerned that if you drive 25k per year that your daily trips would be very close to the charge limits (e.g. you drive 200 miles per day without a charge in between). In that case it may become unusable to you in a few years.
     
  3. tom66

    tom66 Member

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    You can get really long lifespans out of a lithium ion battery.

    For example, the NCR18650A cells that Tesla use a modified variant of are rated around 1,000 full 95% to 5% discharges (i.e. standard mode, ~220miles), which gives you 220,000 miles to approx 50% capacity. This assumes linear degradation and everything like that so actual mileage will probably be 10 to 20% less, but still around this figure.

    Now, if you baby the cells, and say, drive only 100 miles to work, recharge at work, then drive 100 miles back, a 50% depth of discharge (DoD), you can get over 3,500 cycles, which is about 350,000 miles to 50% capacity.

    If you do just 50 miles, recharge, then 50 miles, 7,500+ is possible... which is 375k miles (it's clear that the payback drops off on this, though, compared to the difference between 90% and 50% DoD.)

    So it's easily possible to get very high mileage from a Model S, much more than the average ICE.
     
  4. yobigd20

    yobigd20 Well-Known Member

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    this. +1
     
  5. Gizmotoy

    Gizmotoy Active Member

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    Interesting stuff. My typical commute is about 30-40 miles round trip, and I don't have full-time access to a charger. I usually charge up to 80% once I get to around 90 rated miles of range (40%), which is every few days. Is there something I should be doing to increase battery life? Charge to less than 70%? Something else? Charging every day isn't really possible since I share with 4-5 other EVs, but every other or every third might be doable.
     
  6. tom66

    tom66 Member

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    Li ion like to be at less than 100% if stored for a long time, so it's ideal to keep your car parked in standard mode, shore power connected to about 80 to 90%... remember Tesla don't use the full 85kWh or 60kWh, there's around 8% in reserve. So 100% isn't really 100%. It's about 95%. But if you're using your car a lot, it's more depth-of-discharge that's important to lifespan than storage charge levels. Discharging the pack to "Charge Now" is a bad idea for long term life, especially on range charge. If you only do 50% DoD each time between charges, range is halved but lifespan is tripled or quadrupled.

    Charging even at just 120V at work could help increase lifespan significantly, so if you have that facility available, I would really use it, sitting 8~10 hrs out at 3mi/hr charging could make up most of your work usage, reducing the cycles, though, as you can see from my figures (which are general figures for li-ion not Tesla-specific as only Tesla has that data) can increase life, the pay off in extra life decreases significantly beyond less than 50% DoD.

    This is why Tesla says that plugging in at night is the best option. It's simply the most convenient solution for most and also extends the lifespan.
     
  7. David_Cary

    David_Cary Member

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    Of course the warranty is battery only and there maybe significant repair costs for everything else. There may not be - it is a big unknown. Surely there are less parts than an ICE but that doesn't mean there are zero.
     
  8. tom66

    tom66 Member

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    Things like suspension, hydraulics, steering will have about the same failure rate.
     
  9. MassX1317

    MassX1317 Addicted to TMC

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    Do you know what the warranty is for non-wear and tear items. I am having trouble finding it on the site.
     
  10. lolachampcar

    lolachampcar Active Member

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    tom66,
    It will be interesting to see. I was surprised at how robust the MS suspension is. I think the engineers realized that, if there was any weakness at all, they would get nailed as a new car company. I think they added extra margin of safety to everything they designed to compensate. Of course, there are still all those rubber bushings which will be painfully expensive to deal with unless Tesla starts making the bushings available by themselves (instead of only in full assemblies).
     
  11. Gizmotoy

    Gizmotoy Active Member

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    My case is pretty unusual, and I suspect this wouldn't really work for me. If I want 120V I have to pay $1k installation (insane, I know), and pay for electricity. If I use the 3 shared 208V/32A chargers, it's completely free. The drawback, obviously, being that I have to share it with 5 other EVs so I don't always get a spot and don't want to come off like I'm hogging them. I usually just charge maybe twice a week from 40% to 80% at 15A (so it finishes overnight). Sounds like that's pretty decent, but not quite ideal. I'll take it, though.
     

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