Despite Capacity Loss, Today’s Entry-Level Electric Cars Can Meet 85% of Driving Needs, Says DoE Scientists

No matter what the manufacturer, all electric cars slowly lose range as their battery packs age due to the chemical changes that take place in a battery pack with continued charge and discharge cycles.

With early examples of modern electric cars like the Nissan LEAF and Chevrolet Volt more than 4 years old, there’s a growing interest in the automotive industry and the mainstream press on how healthy the battery packs of those cars are after tens or even hundreds of thousands of miles.

Even with range loss, most low-end electric cars like the Nissan LEAF can still meet most American commuting duties.

Even with range loss, most low-end electric cars like the Nissan LEAF can still meet most American commuting duties.

Some of that attention has been focused on the cost of eventually replacing battery packs as they age and lose capacity. Some of it has been focused on how useable those vehicles are as daily drivers after losing ten or twenty percent of their original capacity.

Thanks to companies like Nissan, which now offers LEAF and e-NV200 electric van drivers the option of buying a replacement battery pack for a set cost (€5,000, $5,500) when their car’s battery packs have lost significant capacity, the former is less of a concern than it once was.

Now a study from the Department of Energy’s Lawrence Berkeley National Laboratory has proven quantitatively that the latter shouldn’t be a big concern either for the majority of Americans in a study which it says is the first of its kind.

As it detailed yesterday in a blog post on its website, scientists at the Lawrence Berkeley National Laboratory analysed the effects of battery loss on electric car battery packs and plotted it against real-world driving patterns across the U.S.

Our staff car backs this study up, managing a 100-mile commute with a top-up despite having 20 percent capacity loss.

Our staff car backs this study up, managing a 100-mile commute with a top-up despite having 20 percent capacity loss.

Its discovery? Even in an aged, limited-range electric car like a 2011 Nissan LEAF — whose new EPA-approved range was just 73 miles per charge — a battery capacity loss of 20 percent still means that it can meet the daily travel needs of more than 95 percent of all U.S. drivers.

Even with a capacity loss equivalent to 50 percent of the original battery pack, more than 80 percent of U.S. daily travel needs — both weekday and weekend — could be met. This disproves the old theory held by many non-electric car drivers that electric car battery packs would become useless for everyday use once they had lost more than 30 percent of their original battery capacity.

“There are two main reasons people are hesitant to buy an EV: first, they’re unsure it will satisfy their mobility needs, and second, they’re afraid the battery won’t last the whole life of the car and they’ll have to replace it for a lot of money,” said Samveg Saxena, leader of a vehicle powertrain research program at the lab and coauthor of the study. “We show that, even after substantial battery degradation, the daily travel needs of most people are still going to be met.”

In total, more than 160,000 real-driving itineraries taken from the National Household Travel Survey by the Department of Transportation were studied and analysed. The data set covered 24-hour periods and included tracking when the car was parked or driving over both weekend and weekday periods.

The study bears true for any limited-range electric car with a LEAF-like range.

The study bears true for any limited-range electric car with a LEAF-like range.

Assuming those itineraries were travelled in a vehicle similar in specifications to a Nissan LEAF, a car with about 24 kilowatt-hours of on-board battery storage, the researchers then fed the data into its custom-built simulation tool V2G-Sim. As the name suggests, V2G-Sim is designed to model and quantify second-by-second energy use and charging capabilities for a plug-in vehicle, and allowed the researchers to plot battery draining and recharging for any given moment in each 24-hour period. In total, more than 13 million daily state-of-charge profiles were computed, taking into consideration different charging profiles and usage scenarios, including driver speed, weather conditions and weather the air conditioning was on or not.

The results speak for themselves.

As the graph shows, even with a 50% capacity loss, a car like the Nissan LEAF could still meet 80 percent of most American's driving needs.

As the graph shows, even with a 50% capacity loss, a car like the Nissan LEAF could still meet the daily driving needs of 80 percent of Americans.

“People have commonly thought, ‘if I buy an EV, I’ll have to replace the battery in a few years because I’ll lose the ability to satisfy my driving needs, and it’s not worth it,’” Saxena said. “We have found that only a small fraction of drivers will no longer be able to meet their daily driving needs after having lost 20 percent of their battery’s energy storage capabilities. It is important to remember that the vast majority of people don’t drive more than 40 miles per day on most days, and so they have plenty of reserve available to accommodate their normal daily trips even if they lose substantial amounts of battery capacity due to degradation.”

Running flat just doing daily driving is unlikely.

Running flat just doing daily driving is unlikely.

Here at Transport Evolved, we’ve owned and operated several Nissan LEAFs in our staff fleet, with Hiro — the Gordon-Bloomfield family LEAF — having covered more than 72,000 miles since new four years ago. Even with an estimated capacity loss of around 20 percent, it is still happily handling a 100 miles per day round commute, with a top-up charge during the day at a public type 2 charging station.

While range is certainly less than it was when new, it can easily drive more than the 40 miles of an average daily commute on a single charge.

If you’d like to read the report for yourself, there’s an abstract available with open access at Sciencedirect, or you can view the report in full in Volume 282 of the Journal of Power Sources, which is published on 15 May.

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  • vdiv

    This is what the majority of Americans really love, some DoE scientists telling them what they need.

    • mortisier

      They are not telling them what they need, they are telling them what they are missing out on.

  • Richard Glover

    11 bars on my wagon and I’m still rolling along, 56k miles covered, the Teslas are catching me but I am singing a happy song.

  • Martin

    I realy like and support EVs but I’m not happy with the graph shown in the report. With a bit of interpretation of the wording on the y axis I think that I can work out what the graph shows. However it does not show that 80% of Americans can still do their daily driving with a battery degraded to 50% of its new value as the text under the graph says.nThere are a group of Americans who can not get by with an EV with out some form of charging during the day. The graph should therefore have started at this figure I’m not sure what it would be and then show an increasing number of people who cant manage without a charge during the day as the battery degrades. The figure who can manage with a 50% battery will be some thing less than 80%nAs charging oportunities at work or at shops, etc increase over time the number who cant manage at all would drop for the initial case and then increase as the battery degrades over time.nHowever the build out of charging infrastructure could more than offset the loss of capacity over time in some areas. Also many vehicals have more than one owner over their lifetime. The second hand market still has some way to go to be established and the third hand market is not likley to have had any significant impact at the moment but many people would be able to make use of a second car which only needs very short range for school runs, shopping trips etc. So there are other routes to restore the usefulness of an EV with a degraded battery other than the purchase of a replacement battery.

  • jeffsongster

    Seems right. I figure that both of my LEAFs will still be useful even when all I can do with them is drive to the train station and grocery stores. nAs the charger nets improve so goes the usefulness of small battery EVs. I still fail to understand why the CHAdeMO is not standard on all LEAF. I would not buy one without it. Especially since the wear on the battery is only thought to make about a 1% battery life difference when repeatedly quick charging. ( 1 to 2 times daily)

    • TheFrequentPoster

      I doubt that expanding the charger network will matter. More than 90% of recharging happens at home, because of the slow recharging speeds. Even Tesla’s so-called “superchargers” are far slower than filling a gas car’s tank.nnAnd then there is the inverse relationship between charging speed and battery life, at least when you start into high wattages. The problem, as I understand it, is heat. I’ll admit that there’s a bunch I don’t know about battery chemistry, so I don’t know how firm the relationship is, i.e., whether or not it could be altered with different charging schemes.

      • jeffsongster

        Well… The quick chargers don’t really have the effect you refer to… The qc’s only cause about a 1% difference in batt life… So just use them to extend range and don’t worry about it . I have 2 leafs and this works fine for us. Driving over a 120 miles a day is no problem. We take a smart phone everywhere and check email or play a game while car charges for the 10 to 30 minutes it takes to get back to 85%.

        • TheFrequentPoster

          What are the details of the quick chargers you use for your LEAF? I did a look-up and didn’t find direct details other than a claim that DC charging will fill a LEAF from 0% to 80% in a half an hour. This implies 40 kWh per hour, but it’d be interesting to know the specifics, i.e., amps and volts.nnIn any case, I did find an article that said DC charging takes an extra 3% off of battery life at 30,000 miles. It also said that, at 40,000 miles, the penalty was the same 3%. More problematic was the level of degradation regardless of the charging method — 22% with Level 2, and 25% with DC.nnCould you imagine if your gas car’s tank lost a quarter of its capacity at 40,000 miles? That would be a real problem, and even more so if the tank only held 0.7 gallons to begin with. That’s how much a LEAF’s battery holds in equivalent gallons of gas. Even at equivalent mpg of about 115 on average, year-’round, in a place with mild winters, that’s still a problem once you get past the enthusiast/experimenter market and try to go mainstream.nnI own an EV and like it, but I really think EVs have a whole lot of work to do before they become mainstream.

  • TheFrequentPoster

    Whoever wrote that article does not own an electric car.

    • No. You’re right. She’s owned ten.

      • lol…. I don’t think they’ll catch on but, that was good.

      • TheFrequentPoster

        Then you either a) have unusual driving habits, or b) fully recharge your EV every day. If the latter, good luck with battery life, which might be why Nissan has been offering that special battery deal — the batteries have been wearing out sooner than expected. In real-world use, the driving range of an “entry level” EV, i.e., a LEAF, isn’t enough for 80% of people’s driving habits.

        • jeffsongster

          So… Nice trolling… Just keep spending on fuel… War… Misery… I’ve placed multiple bets on my Solar powered Nissan leafs. Frequent must be a paid troll to have the time to compose such masterpieces. Cheers!

          • TheFrequentPoster

            A song for Jeffy:nnhttps://www.youtube.com/watch?v=TuiNtC4kURk&noredirect=1

          • jeffsongster

            No magic… just basic science and efficiency. Some day when the oil companies stop sending people checks to troll on online services we will not need to unspin nonsense so often.

          • jeffsongster

            Shall we shorten your name to Freakie Postie… is that infantile enough for you to feel happy with your strange job.

          • TheFrequentPoster

            Speaking of infantile …

          • jeffsongster

            Yep. Whatever. you got me good… oh well guess I’ll just sulk away now… not. Bye useless poster poser.

          • TheFrequentPoster

            Jeffy, you seem angry.

          • TheFrequentPoster

            Ya got it a bit wrong. Okay, it’s true that Exxonmobil pays me $10,000 a month + $500 a post, but the Koch brothers kick in another $20,000 a month, $400 a post, and three round-trips a year anywhere in the world on their Gulfstream V jet. Then there’s the Republican National Committee. $20,000 a month and $750 a post.nnThis is really good work if ya can get it! The corporate jet trips are the best. Don’t ya just hate those grotty security checks at the airport? None for me, ha ha!

          • jeffsongster

            what ever. Keep wrecking useful discussions. If they’re not paying you to spout nonsense then there is no hope of convincing or educating you. Party on in your Gulfstream… or not I could care less.

          • TheFrequentPoster

            If you weren’t so badly behaved, I’d get your a ride. Wouldn’t you like to help me accelerate global warming?

          • I’m going to have to give @FrequentPoster:disqus a gentle warning. Some of your posts of late have been rather . Head into the realm of personal insults again, and we’ll be forced to ban you. nnnThanks.

          • PaulScott58

            Dump him. He’s clearly a troll on the payroll of some oil company. We have big problems to solve, and dealing with the prolific rantings of some shill for the oil companies is a huge waste of time.

          • TheFrequentPoster

            Hmm. Nice. Civil.

          • A warning to both of you. Personal insults aren’t tolerated on the site. Please keep it civil, and keep disagreements to facts, not conjecture.

          • PaulScott58

            You can dump me, too, Nikki. I refuse to be civil to trolls like this guy. People are dying by the millions because of oil and all he can do is criticize efforts to stop that. We’re at war with these people. Civility be damned!

          • TheFrequentPoster

            Will you apply the same standard to the obnoxious, nastiness that’s been hurled at me for no reason other than I am not an EVangelist? An example is directly below, in which I’ve been called a “troll on the payroll of some oil company,” etc.

          • Anyone who sends personal insults to another poster will be warned twice, then banned. The same goes for racist or homophobic comments and general douchebaggery 😉 nnWe welcome healthy, engaged discussion. Not personal insults. As moderator, I’m sending this to everyone.

          • Joseph Dubeau

            Looks like the frequent poster troll is gone!

  • For Tesla battery degradation not much of an issue really because the car comes with an eight year warranty unlimited miles. nnnOnce electric cars become more prevalent we should see more battery repair places popping up. Some battery problems are due to corroded terminals and they just need cleaning. nnnThink how many cell phone screen repair places there are now since smart phones incorporated touch screens. Could be the same for battery repair

    • Chris O

      You are right: for Tesla battery degradation is not an issue but not because of the warranty -because that only covers defects not wear- but because experience so far shows it loses only 6% capacity after 100,000 miles.nnnThat means 70% residual capacity is reached after 500K miles and even at 70% the range is still 180 miles…nnnMind you, there is such a thing as calendar life to consider.

      • Yes you’re right, I overlooked the actual degradation of the Tesla battery.

      • TheFrequentPoster

        Tesla batteries don’t perform any better than any others. They’re bigger and have a longer range, so they don’t get recharged as often. If you do the math, a Tesla battery ought to last for several hundred thousand miles.

  • Chris O

    Don’t think statistics like this will convince the mainstream car buyer. The next gen 200 mile EVs may though.

    • TheFrequentPoster

      Those range claims need to be taken with a big grain of salt.

      • Chris O

        You need to change your screenname to the negative poster. nn..and such long negative rants at that.

        • TheFrequentPoster

          Why bless your heart for your thoughtful, comprehensive, well-informed, intelligent reply to my comment!

          • Chris O

            Why bother…nnWhy would you spend so much time to become a “frequent poster” on a subject you clearly don’t believe in? nnSeems to me I’m dealing with either a shill or a troll. Neither are worth debating.

          • TheFrequentPoster

            Yes, why should you bother to be thoughtful, comprehensive, well-informed, or intelligent when you can be a fact-free EVangelist instead? Anyway, what do you imagine that I “clearly don’t believe in?” Would it be this, maybe?nnhttps://www.youtube.com/watch?v=TuiNtC4kURk&noredirect=1

  • Robert Wilson

    Two words ,transmition work!n

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