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Transportation Power

A Real-Life Tesla Study Shows Durability of EV Batteries 124

Posted by EditorDavid from the charged-topics dept.
Slashdot reader Rutabaga8 is the CEO of a web site conducting in-depth research on personal finance topics. They recently contacted Slashdot to share "some surprising results" from their analysis of a nonprofit advocacy group's seven years of data on Tesla batteries: By seven years of age, the typical car could still deliver around 93% of the original range on a full charge. That means a Tesla battery typically loses around 1 percentage point of range each year on the road.

Of course, cars that put more miles on the odometer are likely to get faster battery deterioration, because it's the number of charges that really impact battery degradation. However, the data showed that by 150,000 miles Tesla cars still achieved more than 85% of their original range when they were charged to full capacity.
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A Real-Life Tesla Study Shows Durability of EV Batteries More

A Real-Life Tesla Study Shows Durability of EV Batteries

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  • They've got all the data. It'd be useful if they'd publish it.

    • They've got all the data. It'd be useful if they'd publish it.

      Uh... they pretty much have. And the fact they offer an 8 year unlimited mile warranty pretty much says they are not worried about batteries failing at all.

      • And the fact they offer an 8 year unlimited mile warranty pretty much says they are not worried about batteries failing at all.

        8 years is two years shy of what Hyundai offers, on cars most people can actually afford. It demostrates Tesla is more worried about the batteries/electronics degrading due to old age than due to wear and tear.

        Obviously, this doesn't matter to people who get rid of their cars before it ever becomes a problem. But we can already see today with the oldest Nissan Leafs what happens to EVs when it's no longer cost effective to replace the battery. Tesla may take a bit longer to get to that point due to their

        • Hyundai is the only company to offer 10 years, and they don’t offer it everywhere. Over here they offer 5 years, and 8 years on EV batteries, same as Tesla. Most other manufacturers offer much shorter warranties; the 7 year warranty that Kia offer (which was once the longest) is still considered to be very generous. All this doesn’t prove that auto makers trust ICEs more than EV drive trains; it shows other manufacturers have the same faith in EV batteries as Tesla does.

          As for the Leaf, what

        • Many of y'all seem to forget the cashiers, burger flippers, and (in my neck of the woods) theme park employees, need to be able to get to/from work, too.

          And you seem to forget that those people can't afford to pay for gas, oil,
          or mechanical repair bills where EV owners never do,
          Y'all.

  • Well... color me mildly surprised! I'd figure these EV batteries would have deteriorated by at least 20-30% if they are at least 4 years old, similar to current smartphone batteries.

    Perhaps there is some hope for EVs in extreme conditions.

    • Smartphone batteries use cheap chemistry.

      • Re: (Score:3)

        by Octorian ( 14086 )

        And good EV batteries also have sophisticated battery management systems, which wouldn't be practical or cost effective in a smartphone.

        • It would be simple enough to have some software in the smartphone that avoids full charge/discharge, which would already help a lot.

          • Apple does this in current iOS [macworld.com]:

            In iOS 13, Apple's introducing a new feature called Optimized Battery Charging that should help slow the rate at which the battery in your phone wears out. It's not going to help your battery last longer on a single charge, but it's going to help your battery hold the same amount of charge over the years you own it.

      • Re:Mild Surprise (Score:4, Interesting)

        by Solandri ( 704621 ) on Sunday November 24, 2019 @02:51AM (#59447856)
        Nope. The chemistry is the same. EVs just have the luxury (and designers who are cognizant enough about their limitations) to carry around excess battery capacity. The lifespan of a Li-ion battery depends on its depth of discharge [batteryuniversity.com]. The closer you charge it to 100% and the closer you discharge it to 0%, the more quickly its capacity drops with use. EV designers get around this problem by putting in a larger-than-necessary battery, and limiting its charge cycles to between 20%-80%, or 15%-85%. (Those are the figures I've seen for Toyota, GM, and Nissan EVs.)

        Smartphone designers OTOH seem determined to make the battery as small as possible, which forces them to use their full capacity (100% to 0% depth of discharge) to give you enough battery life to make it through most of the day. This kills the battery within several hundred cycles, which for most phone users is 1-2 years. This is why a lot of us have been campaigning for user-replaceable batteries, or phones with enough battery capacity to last 2-3 days. The battery on my previous phone (Nexus 5) died after just 13 months of me using it heavily from 100% to about 5%. Google replaced it under warranty, and I was careful not to charge the second one over 90% whenever possible, and to always recharge it before it dropped below 25%. That one lasted 3 years without any appreciable drop in battery life.

        Unfortunately, Tesla won't say how deep their discharge depth is. Which makes the stat given in TFA kinda useless. Without knowing the depth of discharge, we have no way of determining if their batteries are performing the same as those in other EVs, better, or worse.
        • This is exactly why in my phone I would rather start with a battery roughly three times of what I will ever need, so that I don't have to worry about things like battery deterioration and charging a specific way. Something I an very happy to say my Note delivers. This is something I will be waiting a long time to see in EVs.

    • Teslas batteries are pretty well managed by the sounds of it. Their discharge, charge, temperature and voltage are all carefully monitored/controlled. Your smartphone, laptop and even some other EVs do little if any of this which results in drastically decreased lifespans. Imagine if your car engine was air cooled (no radiator) and you routinely revved it till it hit the limiter, that is a little like what it is like for a battery pack that is ran from 0 to 100% regularly, charged at full power every-tim

  • Let's see hours of actual usage and number of charge-discharge cycles.

    Plus how much of their maximum achievable charge/discharge you charge/discharge them.

    • No. The real number is mileage. That determines most important aspect.
      • Wrong. Its all about the number of charge-discharge cycles, as he pointed out. Not sure how you could have made it to 2019 without learning the issues of high capacity rechargeable batteries, but you managed it. Congratulations for the extreme ignorance.

        • Re: (Score:3)

          by vakuona ( 788200 )

          No, you are wrong. Car buyers won't measure the car battery life in discharge cycles.

          If a would be car buyer goes into a dealership, they would enquire about the discharge cycles before they might have to replace the battery. They would want to know how long in years, or in miles driven, it would be before they might need a new battery, which would give them an idea of the cost per mile, or per year, of the battery.

          If you want blank stares, ask a random phone user about battery discharge cycles.

  • Metric might be, if we assume a linear decay. Is that for every 10,000 miles there is a 1% loss in battery range. This would, in fact, a person who has a commute to work, for instance, would lose about 8 percent of their range in 5 years or a full 10% in the average of 7 years that people keep cars.

    So a 40,000 dollar model three will have a range of closer to 200 miles that 300 miles in 7 years, given the real world test put the new range well below 300 miles. This is likely not an issue if you can charge

    • Re:More useful (Score:4, Informative)

      by whoever57 ( 658626 ) on Saturday November 23, 2019 @08:32PM (#59447232) Journal

      Metric might be, if we assume a linear decay

      Data collected for Teslas suggests that your assumption is not valid. Most data shows a drop in capacity of about 5-7%, over the first 50,000 miles, followed by very little drop in capacity over much longer distances travelled.

    • Re: (Score:3)

      by bbn ( 172659 )

      Actually you can charge a Tesla Model 3 LR from 10% til 60% in just 12 minutes at the Ionity 350 kW chargers (although the car only charges at 200 kW). 20 minutes will get you to 80%. You will not charge to more than that if you want to go fast.

    • Re: (Score:2)

      by ledow ( 319597 )

      Would it be a linear decay if you're using percentages?

  • After 2 years my phone battery is maybe 80%, and 3 years maybe 40%.

    Don't even get me started on an electric razor's lifetime. First one I had lasted maybe 20 years (2 blade replacements). It's replacement, about 4 (0 blade replacements). It's replacement is less than a year old and it's battery lasts 3-4 days (wish I'd kept the receipt).

    • Re: (Score:2)

      by jiriw ( 444695 )

      Phone batteries get charged to almost maximum capacity, so much that any more may let them burst into flames. And sometimes that actually happens ;). Also they are allowed to be discharged until they are on the point of unsalvability (you can ruin your Li* batteries by discharging them too deeply). And that all in sometimes abominable conditions (too hot or too cold... too fast). This probably is because in the eyes of regular consumers, time for 'untethered' operation, fast availability if you have to cha

      • Re: (Score:2)

        by GuB-42 ( 2483988 )

        I'd like to see a "safe charge" mode for phones, optimized for longevity. For example, only charge to 70%, slowly. I think some laptops have that but I don't know about phones.

        That would sufficient 90% of the time. Only enable full charge when needed.

        • Also, when you do need full charge, allow user to set the time. For instance, if you charge your phone at night, and your alarm is set at 7:30, it could first charge it up to 80%, and then keep it there until 7:00, and then top it off.

  • ... it can go very very bad. Local police report this afternoon of a Tesla not apparently involved in any collision that caught fire on a country road not far away. "1000' plume of smoke" reported. The occupants got out. The car melted down (fire dept couldn't do anything but watch and keep nearby brush wetted down) and took the pavement with it (was the smoke plume from the car or the asphalt burning?). Cleanup request was for a wrecker that could transport a "melted Tesla" and keep it at least 50' away fr

    • Can you provide links to the report? Or pictures? It's not that I don't believe you, I'm just curious on how this was reported and what the melted car looked like.

      • Was at a real-time dispatch log web site maintained for the media, and I saw it after they had already called the tow, so it's gone by now. http://cad.chp.ca.gov/ [ca.gov] Not a news story. Was on Fry Road/Lewis Road, east of Vacaville CA (Golden Gate dispatch center, also showed up in the statewide "hot spots"). FWIW, I also saw in passing a collision not too far away from this incident, where a Tesla was involved in a multi-vehicle collision on I-80; there was no fire (as is usual, which is why the fire report w

    • False impressions from news selection bias.. (Score:5, Informative)

      by jjo ( 62046 ) on Saturday November 23, 2019 @09:47PM (#59447424) Homepage

      The problem with this is that Tesla fires are rare, so they are news, while gasoline car fires are common, so they aren't news. So if you judge by number of news reports, Teslas have a bigger problem with fires, even though this is completely the opposite of reality.

      • Been driving on one of the busiest commutes in the US for 20 years. Only ever seen 3 car fires.
        Common isn't the word you're looking for.

        • I have seen 3 too, that already makes 6 total. I'm sure we can find a few more people.

          • We can- like the other 274,000 cars that passed the fires on those 3 days.
            Let's do some quick math.
            Let's say 3 car fires in 20 years is a normal rate of fires for a person to see.
            Let's say that the standard Seattle morning/evening commute people (274k vehicles... significantly more people, but we'll stick with vehicles) saw these same 3 fires.
            That's 3 fires out of 1,424,800,000 commutes, or 1 fire every 47,493,333 commutes.
            Now I'm not sure where we need to draw the line for rare, but 1 fire every 1,234
        • thats only on one route.
          17 gas car fires per hour [businessinsider.com]
          • Yes, that's only route.
            So you then use *all* routes to highlight... what exactly?
            Your argument can be used to say that being hit by lightning is common.
            At a large enough scale, all things are common.
            If current Tesla car fire statics were extrapolated to 275 million Teslas on the road making as many commutes as car drivers make, Tesla fires would be "common" by your definition of that word as well.
            • the point being that gas cars catch fire more often than you think
              From 2012 – 2018, there has been approximately one Tesla vehicle fire for every 170 million miles travelled. By comparison, data from the National Fire Protection Association (NFPA) and U.S. Department of Transportation shows that in the United States there is a vehicle fire for every 19 million miles travelled.
              • My point being it's not that often.
                1 fire every 19 million miles traveled.
                All things being equal, and extrapolated- that's 2 Tesla fires per hour instead of 17. It's absolutely better. I never intended to argue that it wasn't better.
                My point was that's not common.
                And futher more, 1/8th of common certainly isn't "rare"
                OP was making a sales pitch, not an informed observation.

        • Re:False impressions from news selection bias.. (Score:5, Informative)

          by thegarbz ( 1787294 ) on Sunday November 24, 2019 @05:40AM (#59448022)

          181000 cars catching fire per year isn't the definition of rare either.

          • Relying on the law of large numbers to make an argument that something isn't rare seems kind of silly to me.
            How many of those commutes involved no fires?

        • 'Only ever seen 3 car fires.'

          "Each year, from 2014 to 2016, an estimated 171,500 highway vehicle fires occurred in the United States, resulting in an annual average of 345 deaths"

          https://www.usfa.fema.gov/down... [fema.gov]

          • Yes, and every year 100 billion commutes take place that involve zero fires.
            You're using the law of large numbers to argue for the commonality of a thing, and that's ridiculous.
            Perhaps we should expand it hypothetically to the entire Universe?

    • So what you're saying is gasoline powered cars never catch fire?

    • You think that's bad, my dad's ICE car caught fire, and he was daft enough to drive into a petrol station. Fortunately he had the foresight not to park near the pump, and only needed to grab the extinguisher. He nearly became a statistic of the number of petrol stations to burn down. Instead he became one of these statistics: https://www.statista.com/stati... [statista.com] specifically one of the 395000 cars to catch fire in 1996.

      But we've gotten better. Only 181000 cars caught fire last year in the USA.

      1000' plume of smoke

      In related news,

      • His though-process might have been along the lines of :
        "If anybody knows how to put out a petrol-fire, it's gas-stations - right?"

        • Along the lines of a truck on fire pulling over beneath an overpass. At least one of those, in LA, resulted in enough damage to the bridge to require it to be demolished and rebuilt.

      • FWIW I was looking at a police media log, not a news report.

        As for ICE fires, yes, there are lots of them. Far more than there should be, even considering the vastly larger number of ICE vehicles around compared to battery (or Tesla). But road damage isn't common for gasoline fires, nor is a melted car. Burned-out hulk, yes, but not melted, unless the fire gets help from vehicle contents or something else involved in an accident (a diesel truck?). OTOH, diesel fires do produce meltdowns and road damage - th

  • In "real life", Nikola Tesla didn't have a battery, so Edison, in his 1931 Pierce Arrow.

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