Cars

Published on May 18th, 2015 | by James Ayre

68

Battery Degradation Level In Tesla Model S Only 5% After 30,000 Miles?

May 18th, 2015 by  


Originally published on EV Obsession.

The Tesla Model S looks to be on track to match (at the least) the battery longevity performance of the Roadster, based on a recent survey of 80 European Model S owners.

While you might be saying, “well, 80 owners isn’t much of a data pool,” it’s all that we’ve got to go on for now — and it is promising. Altogether, on average, the data show that Model S batteries have only degraded by around 5% after ~30,000 miles (50,000 kilometers). Interestingly, battery capacity loss seems to level-off somewhat (though probably not as much as the graph bellows shows) after that mileage milestone — though, there’s not much to go on there (yet).

image14-e1431849359184

I’m going to take a wild guess here and say that the outliers with regards to greatly minimized battery capacity loss are mostly in Norway — though I’m open to being proved wrong. Given how ridiculous some of those outliers at the top look, I’m actually kind of curious — only 4% loss after 60,000 miles (100,000 kilometers), who’s car is that? And what are their driving habits? (Perhaps these outliers are a result of a misunderstanding concerning replaced battery packs, though?)

Electrek provides more:

The information collected in this particular survey was self-provided by European Tesla Motors Club members. Each owner surveyed provided the current range and mileage of their vehicle. 95% of the vehicles surveyed had the larger 85kWh battery installed. All vehicles were manufactured between 2013 and 2015.

One possible negative finding by the survey was the rate in which early battery packs may have been replaced. All owners were asked the question “Do you have a replacement battery?” and 8 respondents out of 80 (10%) marked “Yes. Don’t Know.” It appears that all 8 remarks are true “yes” answers as they all also answered the question “at what km did you replace the battery?” All 8 battery replacements took place in 2013 vehicles with the latest delivered in November 2013. The replacement occurred in nearly 20% of surveyed 2013 vehicles.

It’s probably worth mention here those that replaced their batteries did so under Tesla’s 8-year warranty (no mileage cap) — so, despite the inconvenience, direct costs were non-existent or minimal.

Reprinted with permission.






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About the Author

's background is predominantly in geopolitics and history, but he has an obsessive interest in pretty much everything. After an early life spent in the Imperial Free City of Dortmund, James followed the river Ruhr to Cofbuokheim, where he attended the University of Astnide. And where he also briefly considered entering the coal mining business. He currently writes for a living, on a broad variety of subjects, ranging from science, to politics, to military history, to renewable energy. You can follow his work on Google+.



  • Thanks for the graph. 100.000 km and 96% looks quite good from a user perspective.

    For a battery person it would be good to know much more details such as DOD%. Say this pack was driven in a taxi. Every day two 50% DOD cycle. 200km each. It’s about 500 shallow cycles in less than a year and within 10 to 80% region. Very doable with NMC. Actually I would consider the formation process be completed in the first 150 cycles during which the usable full 100% DOD capacity would increase about 5%.

    The thing is heat and time kills the cells (usually) more than cycles. NMC cells can have easily 10 year lifespan if treated right. LFP and other low voltage chemistries are doing better. Oversized (500km) LFP pack in similar use would provide easily 15 years and probably would serve the lifespan of the vehicle it self (+20years). Our test cars got unreliable from the electronics side before cells got bad. This was after 10 years on-road.

    • Teo

      Jukka, I added more charts to the google spreadsheet, including capacity vs cycles and capacity vs age. Link is in my previous message.

  • Joe Viocoe

    There was also something on the Nissan Leaf that showed a similar curve.
    Battery degradation is not linear… and it tapers off instead of accelerating.

    • ROBwithaB

      Except when it approaches so-called “calendar life” limit.
      And nobody really knows for sure about that one. Giant experiment going on at the moment with EV batteries. Time will tell…

  • Steve Grinwis

    We have a Smart Electric Drive that just went in for it’s two year maintenance, which is really just a suspension / tire / HVAC type of test.

    It came out with battery scores consistent with a brand new battery.

    The interesting part to me, in that graph, is how steeply it levels off after 5% battery wear. I wonder what is causing that?

    EDIT: We being ‘Club Smart Car’.

  • heinbloed

    How much ‘power’ or fuel do petrol cars lose?
    Or Diesel cars parked for weeks in the summer sun ?

    • Oil4AsphaltOnly

      If your fuel cap isn’t closed, probably all of it?

      Alternately, after 2-3 weeks, the 12V starter battery will probably be dead depending on the age of that battery.

      Now since there’s fuel at the airport, why isn’t there an evse in the parking garage, as there are in many international airports now? Then this mental exercise would be completely moot.

      • heinbloed

        Are there research papers on the issue “evaporation from petrol and Diesel cars”?

        B.t.w.: in the Scandinavian countries it is common on payed parking lots (airports, train stations, shopping centers etc.) to have a power supply for each car. The owners want the power for heating the cars.

        • Oil4AsphaltOnly

          I assume you mean for the 12V battery right?

          GREAT! Then you’ve agreed with my last point and answered the “potential” bricking problem.

  • sjc_1

    A problem could occur if you drive a long distance to the airport, then leave the car for 2-3 weeks. The term is “bricking” and it is a permanent loss of the battery pack.

    • Bob_Wallace

      Bricking has, I believe, been softwared away.

      Best I can determine bricking happened exactly one time. Some guy who parked his Tesla with the batteries pretty much at zero and went away for awhile.

      • Andre Needham

        And that was a Roadster, not a Model S. Here’s Tesla Motors’ blog entry that dealt with the “bricking” issue: http://www.teslamotors.com/blog/plug-it

        “The earliest Roadsters will take over two months to discharge if parked at a 50 percent charge without being plugged in. From that starting point, Tesla has consistently innovated and improved our battery technology. For example, a Model S battery parked with 50 percent charge would approach full discharge only after about 12 months. Model S batteries also have the ability to protect themselves as they approach very low charge levels by going into a “deep sleep” mode that lowers the loss even further. A Model S will not allow its battery to fall below about 5 percent charge. At that point the car can still sit for many months. Of course you can drive a Model S to 0 percent charge, but even in that circumstance, if you plug it in within 30 days, the battery will recover normally.”

    • Oil4AsphaltOnly

      WHY would you drive over 200 miles to an airport instead of going to one near you?

      As others have noted, you’d lose about 1% per day, so 3 weeks is ~21%. So to brick your battery, you’d have to use at least 78% (~200 miles for a s85) of your battery. And if you’re deliberately driving this far to make a point, you would’ve fully charged the car before leaving right?

      • newnodm

        Many people live 200 miles from an international airport. But few of those people own a model S.

        • Oil4AsphaltOnly

          And many more people live less than 200 miles from an international airport or live within supercharger range of an international airport or live within 200 miles of a regional airport from which they can “hop” to an international one.

          sjc_1’s potential problem is a non-issue, because a driver in that niche case isn’t going to be interested in the current pool of BEV’s anyway.

          • sjc_1

            Start with a 50% charge, drive 100 miles to the airport, let it sit for 2 weeks.

          • Bob_Wallace

            Drive your Porsche with no oil in the crankcase.

            Obviously one can find a way to mess stuff up if they look hard enough.

    • Ken

      Wrong. The Model S can not ‘brick’.

      Software prevents that. It is not an issue.

  • Dag Johansen

    That sounds about right. The Tesla probably has pretty slow degradation since it is such a big pack that it is rarely deeply discharged.

  • Tesla RoadTrip

    After 65,790 miles my Model S charges to 100% @ 250 miles. Thats only a 5.66% range loss!

  • Jouni Valkonen

    This is very interesting. We should also have time and average temperature dimensions for data points so that we could see which is stronger factor for battery degradation, storage and hot ambient temperature or the cycling of battery. Of course the sample size too limited for multivariable data analysis, but this is a good start that we soon are starting to see what will be the total expected lifetime of electric car batteries. This is important especially considering the logistics where levelized fuel/maintenance costs matters and high capital cost of EV batteries matters less.

  • Babam

    If you parked the Tesla in long term parking at the airport and gone for two weeks, how many kWh would you lose starting from a 80% state of charge?

    • Ivor O’Connor

      Long term parking lots need to supply charging! Hopefully this will be such a sought after feature soon.

    • Tom Capon

      Not as much as you would if it were hydrogen! (you would lose all of it)

      • Bob_Wallace

        Are FCEVs leaking H2?

        • Tom Capon

          Well, it’s one of the questions I’ve heard that Toyota execs like to dodge. From a physics perspective, H2 is virtually impossible to contain for long periods of time. Liquid H2 slowly boils in even the most insulated vacuum flask, requiring a pressure release valve to prevent the flask from exploding. Gaseous H2 can literally dissolve through metal.

          The only potentially stable storage mechanism I’ve heard of is using a metal nano lattice structure, which is likely heavier than a plain tank and less dense than liquid H2. Toyota is apparently using carbon-fiber pressurized gaseous H2 tanks, which are probably good but certainly not perfect, and they have not given a number for how long it takes all the hydrogen to escape.

          • Bob_Wallace

            I haven’t heard anything about FCEVs leaking H2. But if they even sometimes to that’s a big problem.

            Park in a garage that has been sealed up to fire containment standards and one could end up with a nice puddle of H2 along the ceiling. Push the garage door opener button and it could get exciting.

          • Dag Johansen

            They better not leak. Those explosions at the Fukushima nuclear plants? Hydrogen explosions.

          • Radical Ignorant

            It’s super escapous gas. Yes, it leaks virtually every possible tank. But the same means it won’t sit in one place to became dangerous. So it’s much more a matter of waste than danger.

          • Philip W

            I’ve heard from a former automotive engineer that H2 diffuses out of the tank because the molecules are so small.
            But I have nothing to back that up right now.

            Maybe somebody else has more information.

          • Ronald Brakels

            Philip W, yep, that’s it in a nutshell. Or rather, not in a nutshell since hydrogen will diffuse right out of it.

          • Ronald Brakels

            The good news is that hydrogen doesn’t have much bang per liter, so if the interior of your car filled with an explosive mix of hydrogen and oxygen and detonated, you’d probably be very surprised but would survive if you didn’t plough into something. But if there was enough hydrogen to displace the oxygen, you would black out almost immediately. It’s a peaceful death and it’s how I want to go. After my armies are crushed.

            We rarely suffocate or blow ourselves up with our LPG powered cars in Australia, but hydrogen is a bit more problematic in that it displaces a lot more oxygen than LPG per joule of energy. A kilogram of propane gas is about half a cubic meter at one atmosphere, a kilogram of hydrogen is about 11 cubic meters. And an interesting thing is it is really good at sucking the heat out of you. So if you pass out from a lack of oxygen but there is still enough available to keep you alive, you could potentially die from hypothermia if you lie there long enough.

          • I doubt a garage would contain Hydrogen. If a specially designed tank leaks, the garage materials will be like a sieve.

          • theUnhandledException

            Very slow leak. Remember if it leaks out of a sealed tank it is going to leak out of an unsealed garage even faster. The rate of leak is extremely low so it never reaches explosive concentrations. Now if you had a defective tank that would be bad but once again the permeability of H2 is a good thing in this case as it will quickly dissipate so the danger zone is very small.

          • Bob_Wallace

            “But if they even sometimes to(do) that’s a big problem.”

            I’m talking about a defective tank. Or a loose fitting. Larger than normal leakage.

            Something like getting a leak in your ICEV gas line that puddles gasoline on your garage floor and vapors up the air. Right up until the time your tankless gas water heater kicks on….

          • Michael G

            I got a little lost here. On the one hand H2 is impossible to contain but on the other you need pressure release valves to allow it to escape? I thought H2 is super deadly and can escape from any known containment vessel except home garages where they build up forever and explode as soon as someone enters.

            More seriously: “In 2001, researchers at the University Of Miami’s College of Engineering set fire to the hydrogen in a tank mounted in an SUV and later punctured the fuel line on a conventional gasoline-powered vehicle and set the leaking gas on fire. The burning hydrogen versus gasoline test showed that flames caused “severe” damage to the gasoline vehicle, whereas the hydrogen vehicle was undamaged because the burning hydrogen gas vented up and away from the vehicle.”

            For another look at the issue:
            http://www.fuelcells.org/base.cgim?template=hydrogen_basics

            Apparently, H2 would be a vast improvement over gasoline in this regard.

          • Tom Capon

            “I got a little lost here. On the one hand H2 is impossible to contain
            but on the other you need pressure release valves to allow it to escape?”

            Oh, you don’t need a release valve for the hydrogen to escape. You need a release valve so that you don’t get hit by shrapnel from the tank when it does.

          • Joseph Dubeau

            Oh Dear,
            Shouldn’t someone warn those folks at SpaceX about leaking hydrogen?

          • Bob_Wallace

            Why would leaking hydrogen be a problem for SpaceX?

          • Joseph Dubeau

            I believe they use hydrogen. Elon said it great for rockets.

          • Bob_Wallace

            Don’t think so.

          • Joseph Dubeau

            can’t get back to article. Get a 504 server error.

          • Bob_Wallace

            Give this a read –

            http://www.nasaspaceflight.com/2014/03/spacex-advances-drive-mars-rocket-raptor-power/

            (I was getting 504s for a while. Seems to have cleared up.)

          • Joseph Dubeau

            “The initial choice of liquid oxygen and hydrogen for Raptor was an interesting one. ”
            http://motherboard.vice.com/read/spacex-wants-to-send-a-positively-massive-rocket-to-mars

            The Meril 2 use liquid methane.

          • Bob_Wallace

            I believe all flights to date have been kerosene based. Future flights may move to methane.

          • Ken

            Wrong – again.

          • Ronald Brakels

            It’s okay. Rockets that use cryogenic fuel never sit around for long with fuel in the tank. Otherwise in humid weather they end up looking like phallic icebergs.

          • Ken

            No. They don’t use hydrogen.

          • Steven F

            Helium and hydrogen and other light gases can pass through materials. The rate depends on the pressure in the tank, the thickness of the tank wall, and the material the tank is made of. I work in the semiconductor industry and we use a lot of helium and a little hydrogen gas.

            The gas is delivered in large steel cylinders of 1/4″ thick steel at a pressure of 3,000 PSI or more. We can store these cylinders for months with no detectable pressure loss. The reason there is no loss is because the steel is very thick and dense. Hydrogen and helium have a very hard time getting through it We don’t even see losses in stainless steel tubing with 1/16″ thick walls. In contrast it is well known that helium balloons loose pressure and after a couple of days no longer float. The rubber is thin and not dense making it very easy for the gas to get out.

            If you park a fuel cell vehicle at the airport and come back a week later the care will still have most of its fuel left. the main issue with high pressure storage tanks is insuring that valves and pressure regulators are well deigned with dense , thick,plastic, rubber seals to insure very little hydrogen gets out. Storing hydrogen for long periods is not impossible it just takes careful design.

            The only reason at nano lattice structure tanks is that they can in theory store a lot of hydrogen at low pressure. It takes a lot of energy to store hydrogen at 5,000 to 10,000PSI. Reducing storage pressure would reduce the enegy cost of high pressure compressors.

          • jeffhre

            I read that H2 storage over the long term will enter steel tanks and cause them to become brittle…

          • That’s super interesting.

      • GCO

        [citation needed]

    • Bob_Wallace

      Apparently the ModS owner’s manual says 1% per day. So a 14% or less loss for two weeks.

      One owner is reported a one mile per hour loss which is about 12% per day prior to Tesla implementing a ‘sleep mode’.

      http://my.teslamotors.com/fr_CH/forum/forums/battery-losing-1-mile-hour-when-parked

      Here’s a more recent experience. A ModS parked for 27 days in cold temps lost about 20% range. Less than one percent per day.

      https://transportevolved.com/2014/01/21/vampire-drain-how-much-power-a-tesla-model-s-really-loses-in-almost-a-month/

      • Ronald Brakels

        Surprisingly high. I suspect they have some vampire loads they could cut further when the car is not going to be used for an extended period of time. …And I see Andre has mentioned below it’s been fixed.

    • No way

      https://www.youtube.com/watch?v=JEPBkjmS2uE

      Thanks to Bjørn Nyland you don’t have to wonder. But it’s 4 weeks and during norwegian winter. Then it lost about 100km in range or about 26 percentage points of charging.

      So you should have about 70% left then (any maybe even more).

      • newnodm

        Every time I see the tesla dash I start to rationalize why it would make sense to buy one.

        • No way

          Realize, you mean?

          • newnodm

            Realize, then rationalize, then return to my senses 🙂

        • Philip W

          Got the money? Don’t rationalize, just buy one. I’m confident you won’t regret it 🙂

        • Hahaha, understand that. 😀

    • Dag Johansen

      Don’t know. The Model S apparently initially had some bad vampire drainage but newer updates have addressed the problem a bit. I think they do still drain a bit too much though.

      • James

        I would really love to have a Tesla, but I agree that the vampire drainage is still too much. I have left my Leaf at the airport for two weeks and did not notice any vampire loss. Being the Leaf has only a 70ish mile range any loss would be noticeable.

        To put this issue into perspective a 1% rate for vampire loss per day is about 2.5 miles in lost range. That is not bad at an individual car level, but think in terms of the loss being across the fleet. With 75k Teslas on the road that is a total loss of 187k miles per day. This is still not bad when compared to the losses associated with driving an ICE, but it will have to get resolved when Tesla has a million cars on the road and is competing with other EVs which do not exhibit this level of vampire loss.

        • The Model S is thermally managed while the LEAF isn’t. My guess is that some form of battery management is going on in the Model S that causes a higher vampire loss compared to a LEAF for example.

          I’ve left my LEAF for over a week at an airport without any noticeable losses.

          • James

            Interesting! I hadn’t considered the battery management system. I guess I just assumed that BMS would not be active at night unless it was extremely cold outside. I always assumed that the vampire issue was due to keeping the main computer active.

            It should be noted that the Leaf has half a BMS. There is a battery heater that prevents the batteries from getting too cold on winter nights or freezing days. I have noticed a little loss one day when it dropped down to the mid-20s. However, the Leaf has no effective controls for preventing batteries from getting too hot.

    • Ronald Brakels

      About 1.

    • PeOO

      Not that much, Model S has a deep sleep mode. No need to keep it plug for long term parking

      • While you may not “need” to plug in the Model S while parked for a longtime, one might “want” to plug it in. It will keep the battery from getting too hot or cold. For example in the winter there will little to no mileage loss due to extreme cold as the battery pack will be kept relatively warm.

        • PeOO

          No one want to keep the battery warm for weeks long of storage in the winter. It’s wasteful.

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