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Realistically, How Long Can We Expect a Model S to Last?

Discussion in 'Model S' started by robby, Sep 28, 2014.

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  1. robby

    robby Member

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    #1 robby, Sep 28, 2014
    Last edited: Sep 28, 2014
    My wife and I are considering a Tesla. A major part of my thinking is that EVs will far outlast their ICE equivalents, redefining the life expectancy of a car with fewer headaches along the way and with significant cost-savings over decades of ownership, even for those who buy the highest end models. I've put together a spreadsheet/model that I believe validates this; more on that later.

    Maintenance and gas savings are easy to calculate; I would like to address some less-talked-about points relating to drivetrain and structural lifespan. Please assume for the sake of this discussion that the goal is to drive the Tesla for as long economically beneficial, thereby minimizing the "cost per mile driven" over the lifetime of the car. So the question is: just how far can a Tesla be driven at a fixed cost, and can it go even farther with small enough variable costs that the cost per mile driven continues to go down?

    I began this process by thinking about what stops an ICE from going. I think there are two main culprits:

    1) The frame rots, and thus it is either unsafe or it requires regular welding to keep it safe.
    2) Expensive repairs combined with the possibility of more expensive repairs makes people hesitant to do the needed work.

    On point #1, the Tesla S has an aluminum frame rather than a steel one. Thus it isn't susceptible to rusting and should last indefinitely, subject to accident avoidance.

    Point #2 is the more common problem. It's not that you may need to spend $2,000 on a new transmission at 200k miles that causes you to give up on your car; it's that after you spend that $200k, you might need to have the timing belt done, or the engine rebuilt, or the water pump replaced -- all of which are looming and you don't know exactly when disaster will strike. And so there is a fear that you are throwing good money after bad because of the risk of the unknown, so you sell it or donate it and move on for a newer vehicle that is a safer bet.

    Tesla seems to address, this problem, too. There are two expensive repairs that I can foresee looming over an old Tesla -- the motor and the battery. A worst case is that both fail, and so it should be a bit less nerve-racking to replace them on an older vehicle because unlike an ICE, once they are replaced, you have an entirely new drive system.

    Assuming degradation is acceptable, and based on Tesla's once-marketed 10-year battery replacement cost, I think it is a reasonable bet that in 15-20 years, you'll be able to buy an 85kW replacement battery for ~$10,000. It is possible the battery will last longer than 20 years, or shorter, but that seems like a reasonable lifetime before catastrophic failure if the degradation is acceptable.

    The motor is more difficult to judge. Obviously any moving part has a lifespan, but a brushless motor is so simple and efficient that I can't personally imagine what that lifespan is. I can't foresee anything that would cause it to fail at its core. Even with Tesla's early drivetrain woes, the problems were mainly in the angle of the gear shaft, not in the core itself. When discussing the 8-year unlimited mile warranty, Elon once said that Tesla has a car in a lab with 500,000 miles on it, making the point that he doesn't think anyone will be able to "kill" the battery or drivetrain assembly.

    I made a spreadsheet, which I link to below. It compares several 4WD cars to a Tesla S to calculate the cost of each car per mile driven. As mentioned earlier, I assume a new $10,000 battery at 200k-mile intervals. For the motors, I assume it will need $4,000 of gearing work at 200k-mile intervals. If I put in Elon's 500,000 mile lifetime figure, the Tesla blows everything away. If I use 300,000 -- more than ICEs but much less than Elon's number -- the Tesla is still cheaper per mile driven than all but the Subarus -- and those costs include MA's very high electricity costs.

    But can any car really last for 300k miles, let alone 500k+ miles? All of my thinking and calculations convince me it can. But because EVs are so new and so much is merely lab-proven rather than road-proven, I want to do everything I can to question this belief before making a purchase decision.

    Questions that would help me are:
    Do you see any flaws in my logic?
    Are there factors that limit how long a car can realistically run for that I've failed to address?
    Are there major expenses I've failed to account for?

    Here is the cost per mile driven as calculated by my spreadsheet:

    Tesla S 85: $0.48
    Tesla S 85 Performance Plus: $0.51
    Subaru XV Crosstek: $0.39
    Subaru Outback 2.5i Limited: $0.43
    Audi Q3 Prestige: $0.58
    Toyota Highlander Hybrid: $0.57
    Honda Odyssey EX-L: $0.48
    Mercedes GLK-350: $0.49

    Here is my spreadsheet: Google Sheets - create and edit spreadsheets online, for free.
     
  2. TesAus

    TesAus Member

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    Can you clarify the logic of comparing a model S against AWD/4WD cars, surely it is more appropriate to compare it to medium/large sedans or wagons or even minivans if trying to replicate the 5+2 kid seats capacity?
     
  3. robby

    robby Member

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    Great question. We are looking for a 4WD/AWD vehicle. The Tesla S is rumored to have that as an option soon, and the X will be available next year at a comparable price point. But I thought it would be easier to do this exercise against an in-production car than a theoretical one, so I based it on the current Model S since the same longevity issues should apply.
     
  4. Evbwcaer

    Evbwcaer Member

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    I have a few thoughts, use them how you wish:

    -A fair number of diesel trucks, like those with the 7.3 Powerstroke, go beyond 500,000 miles. Steel construction, ICE, transmission, all the complexities.

    -Compared to what it costs to fuel a gasoline/diesel vehicle, the cost to fuel an EV should continue to fall. Gas could be $10/gallon retail when a Model S hits 200,000 miles.

    -It is my opinion that many of the reasons, beyond complexity and usually steel construction, that ICE vehicles start to have issues is because of the hot/cold cycles, vibrations, leaks, and deferred maintenance. EV's have much less/none of these factors. It should be said that there are many ICE's that I would bet will see 200,000 miles with any reasonable care, any Honda to start.

    -You should save on brakes.

    Finally, and I think this is at least one consideration for all of us when considering an EV, fossil fuels cost more than their retail price. We can debate how much more, what are/will be the costs of climate change, the geopolitical concerns, etc. You simply can't deny that there are costs associated with fossil fuel consumption that are not represented in the retail price. Just because you don't pay it, or you only pay for part of the difference, it should be included in any honest price comparison. I suggest doing your own research and using a cost that you think is realistic. EV's can, in many circumstances, be fueled renewabley, and if not, still represent a reduction in fossil fuel use, in most cases, through their inherent efficiencies.
     
  5. physicsfita

    physicsfita Member

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    For what it's worth, my 2007 Prius will hit 300,000 miles next month. The only pricey (nearly $700, thanks to Toyota seriously gouging on the price of the two assemblies involved) repair was for malfunctioning buttons on the steering wheel that I had taken care of just this month. My mechanic thinks that I should readily hit 500,000 miles before I have to start worrying about anything major. I do have some rattles in the dash, but given the constant shaker platform that passes for Michigan's roads, I don't think I should be too surprised about that. I have no problem with corrosion, either, despite getting heavy salt spray for 4 or so months a year.

    Modern cars are much more reliable than they used to be. I share your thinking that essentially deleting about 90% or so of a Prius' powertrain should mean way fewer things to break, so if I do end up getting a Model 3 (the S is way out of my price range), I'm hopeful it will hold up for way longer than my Prius.
     
  6. nwdiver

    nwdiver Active Member

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    Well... consider this... the MS is basically a VFD (Variable Frequency Drive) motor on wheels. Where I work we have MANY MANY 3 phase synchronous motors driven by VFDs that have been operating continuously for over 3 years... that's >20k hours with very few failures. How many miles would you have traveled after driving for 20k hours?
     
  7. nleggatt

    nleggatt Member

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    Roughly 1,000,000 (tongue in cheek)
     
  8. robby

    robby Member

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    All great points. Thank you.



    This is all weighed heavily; it's just not quantified in the spreadsheet. Neither my wife nor I has ever owned a car that cost over $20k new, and the only other ICE we will consider is a Subaru, for the price point, so we're certainly prepared to pay some unwritten costs and vote with our wallets.



    Nice work. No problems with they hybrid battery after that many miles?


    I am currently driving a '96 RAV4 that's a bit shy of 200k. The engine itself is in great shape, but the frame has started to rot where one of the struts is held (18 New England winters haven't done it any favors) and the ABS controller has malfunctioned. Both fixable but my mechanic insists it's time to move on.



    Depends whether I'm at the wheel or my wife is at the wheel but either way... I'll take it. ;)
     
  9. Bardlebee

    Bardlebee Member

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    You seem to have all the major expenses plotted out. One thing I will note however is that I truly believe the car will last 20 years, but no one knows. No one can really tell you for sure. I have heard as well that Tesla has a 500k Model as well in their laboratory. But, here is the thing we've had several people have varying degrees of battery loss in this forum. Most of them are minor. For me I only have 5k miles on the car and only 1 mile of loss that I've seen. I am not really concerned about it however and here is why.

    You speak about in 15-20 years the battery pack may be 10k, but I thought the cost of the battery now was somewhere in between 10-20k? Maybe I am wrong, I don't have citation. Anyway, I think it will be less, but if its not think about what that 10k will get you. Likely it won't be 265 miles like it is now, it'll like garner you 400 miles or more. I think 400 miles is conservative of me, but its a fair assessment. So for 10k 15-20 years from now, you have a new battery with what I can only assume would be a new warranty, because why not warranty something that has proven track record, as in the previous 15-20 years, of being solid? That is how I think about my purchase. I am a very frugal person, the Model S was... uncharacteristic of my historical spending habits and I in fact have a few threads that were opened trying to judge whether this was a right move for me financially long term.

    If I had to do it again? I would have done it in a heart beat, but I would have gotten the parking sensors too! :) I can never go back. From a future perspective of how our automotive industry and a present perspective. Every morning I wake up and I don't have to waste my time at a gas station. I smoke most other cars, even though I am not a car person I can still appreciate the acceleration. And, for the one time I needed service, it was the most exceptional car service I ever had. If you'd like I can indulge in that story about service if you're interested in that aspect.
     
  10. physicsfita

    physicsfita Member

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    Not a lick of trouble with the hybrid battery, and my mileage is the same as when it was new. :biggrin:

    I have to admit, that was the thing that scared me the most (and I almost backed out of the purchase) -- since MI is a non-CARB state, they only guaranteed the battery for 100,000 miles (can't remember the years -- with my driving habits, those numbers go in one ear and out the other). CARB states were guaranteed for 150,000 miles for some legal reason. That made me afraid that the battery would crap out after 200,000 miles or so, so I budgeted for a replacement at that interval and still found the TCO better than other cars I could afford. Since then, the price has dropped a lot (over 50%, if I recall correctly), and it turns out that replacements are very rare -- if you check the Prius forums, you will regularly hear of taxis that were retired after 500,000-700,000 miles still on their first pack.
     
  11. ArtInCT

    ArtInCT Always Learning

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    Robby:
    Nice Spreadsheet.... a few questions however....

    1) Insurance rates per vehicle appear to be ignored... in real life are they the same? I would suspect that insuring a $100K car vs. a $40K car would have some sort of difference?

    2) My state/town has a personal property tax which is the current mill rate X the insurance underwriters blue book value of the car. Again the higher the value of the auto, the greater the annual tax. Not trivial.

    3) Have you forgotten the Long Term Maintenance Plans, their cost and also their effect on annual maintenance? For example my Volvo XC60 has cost me $0 in maintenance since I purchased it 3 years ago. Bumper to Bumper, tires, wipers, oil, you name it....

    Thanks
    Art
     
  12. jerry33

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

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    Mine is about $20 more per six months than the Prius. Insurance is based on driving location, safety, and the driver. The car's selling price has little to do with it. Note that you have to shop around, there have been some insurance companies that gouge Tesla owners.
     
  13. ArtInCT

    ArtInCT Always Learning

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    Jerry, Good to Know! thanks.
     
  14. J1mbo

    J1mbo Member

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    Some observations:
    • You missed the air suspension and Pano roof in the list of expensive-to-repair components.
    • Tesla will charge for data from year 4 (iirc), nav updates from year 7.
    • Minor fixes at Tesla labor rates are expensive.
    • No third party provider for Tesla components.
    • The battery estimate seems way too low - would budget for north of $30k unless they introduce some kind of recycle scheme.
    • Electricity prices may go up over the next 20 years, i.e. to compensate for loss of fossil fuel tax revenue or to pay for renewable projects.

    Sorry if this seems overly negative, just trying to cover all the bases!
     
  15. Kbsilver

    Kbsilver Member

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    A good train of thought.. I have a few items to toss into the mix. I believe we all expect that the cost of batteries will continue to go down while the capacities go up over the upcoming years due to various factors, thus battery cost estimate could actually be high. Recycling is not only expected but will be a must to prevent waste generation. Mechanically the Tesla is quite simple and should be easy to keep on the road. The one item that concerns me, which is the same for modern ICE vehicles, is all the electronics in the car. While electronics are not moving parts, they are still subject to failure. This is the exact reason I obtained the extended warranty on my BMW, not so much for the engine, but for all the electronics in the cabin.

    I will guess there are dozens of electronic assembles in the Tesla that can fail and be replaced. As long as 20+ years from now Tesla keeps the parts available, especially as affordable refurbished exchanges, then keeping the car on the road for a very long period of time is easily achievable. I believe regulations require that car manufacturers make parts available for 10 years after production of the model has ceased. I'm not saying that electronic failure is imminent, just that it is possible. How may 20 year old computers to you know of, the car essentially being a computer with a motor. On the other hand my home stereo is 45 years old and still working fine (with component upgrades over the years from LP, reel to reel to cassette to CD, and soon MP3).

    To comment on J1mbo's remarks as friendly discussion - While Tesla will charge for Data after 4 years, most other car manufacturers charge from after the 1st year, and most also never give NAV updates for free. I am not a owner yet thus do not know what the actual labor rates are, but I know for the BMWs I currently drive $125/hr is the lowest I can find. And yes that is one difference with ICE vehicles, there are independent's to turn to, but I have found any of the ones that are good, end up being the same price as the dealer. Electricity prices is really the true crystal ball item. There are more renewable sources coming on line all the time, as well as fracking making cheap abundant natural gas. I tell people an electric car is a more efficient way to use natural gas. Instead of a 35% efficient ICE running CNG, electric is 90+% efficent. On the other had there are constantly increasing regulations and possible carbon tax coming.
     
  16. Skotty

    Skotty 2014 Model S P85

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    I think the biggest potential issue that could end the life of a Model S will be electronics issues as the car ages.

    My general predictions are:
    Various old age issues start at around 15 to 20 years. (certain parts rust, plastic parts might break, flexible trims and seals harden and crack, increased drivetrain wear issues, electronics failures)
    Battery degradation becomes an issue at 25 years.
    If not totaled by expensive electronics failures or accidents, end of life at 40 years.
     
  17. donv

    donv Member

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    Cars can last indefinitely if they are maintained. It may be that maintenance isn't cost effective, or that new technologies cause them to be less usable than before, but there are plenty of cars still running which were built 100 years ago-- and those cars were far less reliable than any modern car!

    I suspect that a push for fully autonomous vehicles will reduce the usefulness of a Model S long before the car itself is no longer serviceable.
     
  18. JohnQ

    JohnQ Active Member

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    There were previous posts comparing Model S serviceable life to aircraft. The airframe stays usable but the subsystems (avionics, engine, interior, etc) get upgraded. I believe that this is possible but not necessarily economically wise. New aircraft are incredibly expensive, even a simple 172. It is usually better to refurbish an older aircraft, provided the airframe is sound, than to purchase new. Those same economics may not work for the S. If it costs me $40,000 (arbitrary number) to refurbish an S (new battery, motor, upholstery, etc) then I'm likely to buy new, particularly to get new features or more powerful electronics.

    Someone mentioned that aluminum doesn't rust. While true, it does corrode (rust is just the specific corrosion of iron alloys such as steel).
     
  19. Olle

    Olle Member

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    @OP: Great post.
    How about coolant leaks? More or less repairs than ICE cars?

    Regarding the Aluminum bodywork I wouldn't agree with "infinite" lifetime. While it will probably last much longer than a steel ditto, you can observe plenty of corrosion on old Land Rover alu bodies.

    While electronic components will eventually fail, which is the case also with ICE cars, I am more hopeful for Tesla. Elon says that he doesn't want to make exuberant profits on spares and service. What kills the economy in repairing many old ICE is that they charge 50 times cost for some unique components that you can't find at generic parts outlets.
     
  20. seanahan

    seanahan Member

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    The other factor I would consider is that in 10 years, the replacement battery is likely to be significantly better performing that the current batteries. This is all hypothetical, not practical, so:

    Question: if you drove a 60, and the battery went bad, could Tesla just swap in an 85kW batter with no other changes? (Obviously at some cost)

    Question 2: With the *hypothetical* battery replacement technology, could one swap out a 60kW for an 85kW, say for a long road trip?

    For the short term, if they do introduce a larger battery for the Model X, could be pay to get it upgraded into the Model S?
     

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