Op-Ed: Here’s What We Think the Tesla Roadster Battery Survey Says of the Longevity of the Nissan LEAF Battery

4 years ago by Mark Kane 26

Nissan Leaf battery pack

Nissan Leaf battery pack

Recently, Plug In America released an interesting report on the Tesla Roadster’s battery pack capacity loss. The main conclusion was that the average pack should, at 100,000 miles, still maintain 80-85% of capacity and that age and climate didn’t have much impact. This results are considered better than even Tesla Motors’ own estimations.

Blue Tesla Roadster

Blue Tesla Roadster

But to say that these results are either good or bad, we need to compare it with other vehicles.

Tesla Roadster’s have 53 kWh of lithium-ion cobalt cells, 18650 type that are used mainly for laptop computers. They are light (high-energy density) but considered as one of the less durable options out there. Tesla extended durability of the cells by managing temperatures, but still even in optimal conditions, these cells aren’t even close to LiFePO4. This is the drawback if you want a light battery pack.

Under these circumstances, the Tesla Roadster’s pack at 100,000 and 80% capacity isn’t bad. In fact, it’s even better than one could expect 5 years ago judging by the strength of laptop cells after just 1-2 years of use.

The Tesla Roadster 53 kWh pack needs to be discharged at rate of over 215 kW of power, which is about 4-4,5C. This is high. But a charging time of 3.5 hours means a rate of less then 0.5C.

Nissan Leaf li-ion cell

Nissan Leaf li-ion cell

For comparison we will use Nissan LEAF battery pack that, as you know, was criticized by Tesla CEO Elon Musk for its lack of an active thermal management system . This is big drawback and, in hot climates, LEAFs have problems with capacity fade. But the cells alone, in normal conditions or with thermal management, should be twice as durable those used by Tesla.

The LEAF’s lithium-ion cells are a different chemistry, which is more durable, but heavier and less energy density.

When you look at the spec sheet, you will see that the 24 kWh pack in the LEAF must provide over 80 kW (80 kW is maximum for motor and some additional power for other things). This is 3.5C rate. Not as high as in Tesla, but still high and without guarantee of optimal temperatures. Charge rate reaches 50 kW (some CHAdeMO DC chargers for a while put out 60 kW), but 0-80% in 30 minutes means 2C of charging, or 4 times higher than in the Roadster in the range of 0-80% and probably about 1C rate above.

US mileage record holder Steve Marsh’s from Washington state reported over 15% capacity loss in his LEAF after 78,600 miles. Let’s say it will be 20% at 100,000 like in the Tesla Roadster. Washington’s climate is probably helping in reducing capacity fade, but this result should be achievable everywhere if the LEAF had an active thermal management system.

2013 Nissan LEAF Euro-Spec in White

2013 Nissan LEAF Euro-Spec in White

So, we have two completely different cars with the same results of about 20% capacity loss after 100,000 miles. And now we can say that Nissan LEAF battery is actually more durable than Tesla’s because the Roadster’s pack is 53 kWh and LEAF is only 24 kWh. Equally durable cells should provide the Roadster with roughly twice the mileage of the LEAF at the same point of capacity degradation, but that’s unlikely to happen. Moreover, the LEAF battery is often subjected to fast charging and deeper charging/discharging cycles than the Roadster.

The point here is that you are either getting light weight or durability.  You can’t quite have both.

Mini E

Mini E

Anyways, there is something else to ponder. Tesla Motors can criticize the LEAF’s pack, but their Roadster technology isn’t fit for cheaper EVs with smaller batteries. Just imagine a Nissan LEAF with a 24 kWh Tesla pack.  The pack would be lighter, but to make it capable enough it would need to be 30-35 kWh.  Then, all the benefits from light cells vanish. The MINI E fleet had exactly this kind of pack from AC Propulsion. 28 kWh usable from 35 kWh and not bad durability, as reported by Tom Moloughney.

What we really see here is that Tesla is using the right type of cells for its high range vehicles and that Nissan made the right choice for the LEAF.  Different cells work in different applications, but they aren’t really interchangeable.

Source: Plug In America’s Tesla Roadster Battery Study

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26 responses to "Op-Ed: Here’s What We Think the Tesla Roadster Battery Survey Says of the Longevity of the Nissan LEAF Battery"

  1. Josh says:

    Excellent article Mark! You hit on several key points I try to inform others regarding battery life.

    I do think Musk’s comments about infearior battery technology was in regards to no active thermal management. The cell chemistry is not Tesla’s technology. Their technology is how those cells are arranged into a pack and the active management of the pack. You can also argue that their technology is figuring out how to get a larger pack into a vehicle.

  2. George B says:

    Good article, but I’m not following your logic here. How does the Tesla Roadster study have any implications on the LEAF? It’s a different chemistry, different pack size and Roadster has a temperature management system, and the LEAF does not. The study projects about 80 to 85% remaining capacity after approximately 600 cycles, which seems to include calendar life aging.

    There was a LEAF in Phoenix with about 30% loss after about 400 cycles and 17 months last summer. There are two LEAFs in the Seattle area, which has a near perfect climate for batteries, one of them was down about 15% after approximately 1,000 cycles and the other a similar amount after about 600 cycles. If anything, I believe the performance observed in the field suggests comparable cycling losses in climates that don’t require a temperature management system.

    The MINI-E is not a good example, I believe, it had a larger capacity battery pack to provide more range. The motor had 50% larger power draw than the LEAF as well. A better example would be the first and second generation smart EV, which had Tesla drive trains and batteries. Also the new RAV4 EV. The existence of these two vehicles seems to counter your claim that “Roadster technology isn’t fit for cheaper EVs with smaller batteries”.

    To be clear, I too believe that Nissan is doing an admirable job with their in-sourced battery manufacturing. They just need to make the chemistry more heat-resistant. While your article does a good job of provoking some thought, you seem to jump to conclusions, which are not supported by observation.

  3. Eric Loveday says:

    The RAV4 EV does have a 42 kWh battery pack though and only 103 miles of range. Yes, it lack aerodynamics and is surely a heavy vehicle, but doesn’t that seem like a lot of battery for not much range?

  4. bloggin says:

    It’s rather odd that Plug-In America is doing a study about the durability of what Tesla Roadster batteries ‘should’ do at 100K miles, and offering their ‘predictions’, when there are real world 100k mile roadsters available to review true battery capacity.

    Then it becomes even more of a stretch to take one single Leaf owner in the mild/optimal climate(30s – 70s) of Washington State(outside of the hot temps 80s – 100s and cold temps 0 – 20s that negatively impact the Leaf battery pack without thermal protection) that only has 78k miles and conclude the outcome at 100k miles, ‘should’ be the same as the more powerful thermal protected Tesla battery pack.

    Then come to a grand false conclusion:

    “So, we have two completely different cars with the same results of about 20% capacity loss after 100,000 miles. ”

    I bring this up to point out that it will not help Nissan to offer better heating/cooling management for the Leaf, if the EV community ‘pretends’ that their unprotected battery pack is not a problem long term. Nissan knows it’s a problem, and is why Nissan is the ONLY EV manufacturer that was ‘forced’ to offer an additional ‘capacity’ warranty, along with more heaters, as just more ‘patches’ the for the problem that’s not going away.

    Which is why the Tesla Roadster, Model S, Volt, ELR, Spark EV, Focus Electric, and the BMW i3 and i8 all offer a Liquid Thermal Management System to protect the battery, allow for faster charging, and increase it’s cell/capacity life.

  5. George B says:

    Eric, have you seen the range table Tony compiled for the RAV4? An easy and simple way to compare two vehicles is to drive steady 65 mph (approx. 100 km/h) on the freeway. The new RAV4 seems to deliver about 70% more range than the LEAF using this protocol. That said, it certainly is much less efficient than the LEAF, due to the tire selection, its weight and size.

    http://www.myrav4ev.com/forum/viewtopic.php?f=2&t=67&sid=a5c1398f0e2cdfc01598a9bc2f108e7b

    The MINI-E was a fantastic vehicle, which could have worked with a smaller pack and a less powerful motor. Tom Moloughney reportedly observed about 5% capacity loss after about 700 full battery cycles. This was without any active cooling, aside from a simple fan, and in a climate that’s not as easy on batteries as Seattle, but significantly milder than Phoenix. The drivetrain was from AC Propulsion, which in many ways inspired Tesla. The cells themselves were from Molicel. Although their chemistry was undisclosed, I’ve heard NMC and LiFePO from two separate sources.

    I think this article helps the reader understand that any information we receive about batteries should be interpreted carefully. Personally, I’m not buying the notion that the Roadster study somehow implies anything for the LEAF. There are too many differences between the two vehicles, and each approach has its strengths and weaknesses.

    The salient point of the Roadster study is this IMHO: “our study also found no discernable effect of climate on battery-pack longevity”. There were four Roadsters from Arizona, two from Texas and five from Florida. This is a tiny sample, but then thr Roadster population is not very large to begin with.

  6. kdawg says:

    So WHAT IS the correct chemistry for a 200 mile range compact car? (and why)

    Weight/price/size/power requirements & c-rates are all variables. Who’s got the best solution?

    1. Josh says:

      Currently only Tesla could build a “compact car” with a 200 mile range. They could reduce their battery size from the 85 kWh by 1/3 and build a smaller car around that. Still not sure it would be a compact car, more like a mid-size car (at least by rental car standards).

      There is no way Nissan could add three times as many battery modules into a LEAF and make it a usable package. Ford is already compromising interior space with their pack. Tripling the pack size in a Spark EV, Fit EV, or 500e would surely make them two seaters.

      So in my mind, the highest energy density cells (Panasonic) are the way to go right now. You just have to manage their negative aspects with thermal management.

  7. George B says:

    There have been several interesting announcements, including the one from Envia, but none of these improvements are publicly available. Personally, I’m intrigued by Toshiba’s SCiB lithium titanate batteries, which could work well without a temperature management system. The Honda Fit EV is using those, but the car has not been out in the field long enough to provide enough data to the interested public. The energy density of these batteries would require a larger vehicle, perhaps a mid-size sedan, for 200 miles of range. The Panasonic cells Tesla is using in the Model S reportedly have one of the highest energy densities on the market today. Although it should be easier to build a 200-mile EV with these, a TMS will be needed.

  8. Tony says:

    I don’t see the point of this article…
    It’s like comparing apples to bell peppers – it’s not even fruit vs fruit!

    You’re comparing a Tesla Roadster released in 2010, with 240v charging @ 70a, against a Leaf using public CHAdeMO public charging? Leaf home charging results in 3.3kWh @ 240V = ~14a. 2013’s have the 6.6kWh option, but 2011/2012 MY cars had 3.3kWh onboard chargers only; 6.6kWh was NOT an option, which actually results in a 7hr charge time.

    Unless you have a source for (relatively) affordable home CHAdeMO chargers, compare apples-to-apples.

    So in short, Roadster has MORE than twice the energy capacity, and charges in half the time (using the 70ax240V “Home Charger” ;6h using 40a x240V charger) than the Leaf.

    Factor in that it’s even mentioned in the Leaf manual to minimize DC QC to extend battery lifetime (Nissan says frequent QC can impact battery degradation up to 10% more over 10Y period over std L2 charging. but, we ALREADY know how accurate “Nissan Percentage” is in real life…), I’d say the roadster looks pretty good, especially considering they’ve been on the road since 2008 (non-prototype), and the Leaf was on the road in the US late 2010/early 2011, they can be considered a generation apart. Why don’t you compare the Model S, started delivery in early 2012 instead? Leaf doesn’t look so good then, does it? Especially with twincharging, supercharging, etc..

    So… the question is… How much did Nissan throw your way?

  9. I am left scratching my head over both the title and the conclusions. The Roadster has done quite well with Panasonic 2200ma 18650 cells that are ACTIVELY cooled and heated. I suspect the 2900ma and 3100ma cells will do equally as well. So would the Nissan LEAF prismatic lithium manganese cells if they were treated the same way; they are not. The GM Volt / Ampera using the same basic chemistry as LEAF use a much lower percentage of cell’s energy and are well insulated and cooled.

    For the Rav4 EV with Tesla drivetrain (that I have driven over 18,000 miles, and 3500 miles in just the past few weeks), the EPA range is misleading for comparisons for both the 2013 LEAF and 2012 – 2014 Toyota Rav4 EV. The EPA averages the range of 80% and 100% charge levels.

    The 80% – 100% charge levels and (average) EPA data is:

    66 – 84 (75) miles – 2013 / 2014 LEAF
    92 – 113 (103) miles- 2012 / 2014 Rav4 EV

    Other electric cars like Tesla Model S do not have this limitation of averaged EPA ranges with 265 EPA miles (85kWh) and 208 miles (60kWh).

    In practical, real world steady speed driving of 65mph, level terrain, dry hard surfaced roadway, no wind, sea level, 70F degrees ambient and battery temperatures and no cabin heating or cooling, then the following is true with ZERO battery degradation:

    84 miles range – 2011 / 2014 LEAF
    142 miles range – 2012 / 2014 Rav4 EV
    245 miles range – 2012 / 2013 Tesla Model S w/85kWh

  10. shrink says:

    Indeed, this is a great site, but this article is very poor and IMHO below standards for stories here.

    A Tesla Roadster study, which contains no LEAF data or references, proves nothing about a LEAF. The author draws far too many conclusions from an N of 1 and glosses over the severity of LEAF battery degradation in hot climates. At least 8 LEAF battery replacements are already in progress due to loss capacity after 2 years. That’s hardly “long-lasting” as the headline indicates. The author then glosses over the complexity of adding a TMS.

    This story should be retracted or at least re-labeled as opinion.

    1. Eric Loveday says:

      Noted…title has been changed to reflect the opinionated nature of this article…Thanks to everyone for the additional insight

  11. Say what??

    “And now we can say that Nissan LEAF battery is actually more durable than Tesla’s because the Roadster’s pack is 53 kWh and LEAF is only 24 kWh.” So how is battery capacity related to battery durability? This would seem to imply that a Model S’s larger 60 kWh & 85 kWh batteries are less durable than a Roadsters! (scarcasm: as IMO no scientific correlation) Proper battery thermo management and operation within a batteries engineer C-rating are the primary factors to a batteries lifecycle longevity.

    Why not include data from ~360 Leaf owners that have responded to Plug-In America LEAF Survey.
    http://www.pluginamerica.org/surveys/batteries/leaf/Leaf-Battery-Survey.pdf This is a small sampling og the 30,000 Leaf’s in U.S., but is a good first set of data. Perhaps if more Leaf owners reading this would submit milage & GID values so we can continue to learn more?

    Many THANKS to EV owners collecting and sharing real-world data. We all owe a hat-tip to you early adopters.

  12. These results are pretty much in line with what I’ve experienced with my ActiveE. I now have over 51,000 miles, have charged it 1,181 times and I’m measuring ~9% capacity loss.

    We ran a story here on my results about 3 months ago: http://insideevs.com/understanding-battery-capacity-loss-from-a-four-year-bmw-electric-trial-veteran/

  13. My capacity losses for my EV’s based in temperate San Diego:

    15% – 13 months, 25,000 miles w/ 2011 Nissan LEAF, serial number 2244

    10% – 5 months, 11,000 miles w/ 2012 Nissan LEAF, serial number 20782

    4% – 8 months, 18,000 miles w/ 2012 Toyota Rav4 EV, serial number 134

  14. Results from the Nissan LEAF test published on this website (and still the second highest commented article on this site):

    http://insideevs.com/all-the-results-from-the-largest-independent-test-of-nissan-leafs-with-lost-capacity-not-instrument-failure/

  15. Mark Kane says:

    I do not understand all the controversy and I’m a little sad.

    The article was about cells. If we consider 100,000 miles / 80% capacity result as good for the Roadster, then the same results can’t be considered as bad for the Leaf. Because its pack is smaller and cycles deeper.

    Lack of TMS maybe will not provide good results in the south, but Roadster without TMS also will not be so great.

    Just open your minds. Leaf with 24 kWh Tesla pack would be better then current one or would be 80% after 50,000 miles (half of the Roadster predictions)?

    “My capacity losses for my EV’s based in temperate San Diego:
    15% – 13 months, 25,000 miles w/ 2011 Nissan LEAF, serial number 2244
    10% – 5 months, 11,000 miles w/ 2012 Nissan LEAF, serial number 20782
    4% – 8 months, 18,000 miles w/ 2012 Toyota Rav4 EV, serial number 134”
    So 4% for RAV4 EV after 18,000 miles, times 5 and we get 20% at almost 100,000 miles. With 42 kWh pack, TMS, and new 18650 cells.

    At 25,000 will be lets say 5,5%. Considering pack size difference (42 kWh vs 24 kWh), with 24 kWh same type pack you should be at almost 10%. But maybe higher because deeper cycles and even more higher without TMS. For me close enough to Leaf to say that Nissan cells aren’t bad.

    “These results are pretty much in line with what I’ve experienced with my ActiveE. I now have over 51,000 miles, have charged it 1,181 times and I’m measuring ~9% capacity loss.”
    So at 100,000 miles it could be about 18%, with TMS, in New Jersey climate and about 32 kWh pack (about 28 kWh usable).
    Just considering pack size – Leaf cells will be equally durable at about 25% and still without TMS.

  16. George B says:

    Mark, understood, but I’m still at a loss why you wrote the article in the first place.

    I mentioned in my comment above that “the performance observed in the field suggests comparable cycling losses in climates that don’t require a temperature management system”.

    If that was the point you were trying to make, why did you including a number of other statements. Such as “Tesla Motors can criticize the LEAF’s pack, but their Roadster technology isn’t fit for cheaper EVs with smaller batteries”. Did you really mean to say that? Given your background, I’m sure that you are aware of the first and second gen smart EV.

    http://engt.co/15GjECf

    Please note that you were basing the cycling performance of the LEAF on one singular vehicle. Presumably, it’s the one that belongs to Steve Marsh. Do you realize how unscientific and potentially inaccurate this is?

    To illustrate this point, there was a second recorded case of a bar loss (15% capacity reduction) in Seattle recently. This one occurred at 44,700 miles, and it suggests a different cycling performance than the one data point you used for your article.

    http://on.fb.me/12Vhahl

    There was a recent case of a bar loss in the Bay Area at 21,700 miles. Note that this was not in Phoenix, but on the San Francisco peninsula, known for its mild climate.

    http://on.fb.me/16J92Sm

    Based on your comment, I realize that you mean well, but with all due respect, you cannot take a singular vehicle, compare it against a study based on 126 vehicles, write an op-ed article about, and then wonder why some readers are scratching their head.

    There is a lot of misunderstanding and misinformation about batteries. If your intention was to make readers think critically, then I’m all for it, but the way the article was written and given the data you used, it’s unfortunately also perpetuating some of the myths and misunderstandings instead of clarifying them.

    1. Jay Cole says:

      Hey George,

      Sorry this got held up in moderation 45 mins or so, the site really dislikes ‘3 links’ and auto holds them for approval..we aren’t “mod-ing” you or anything, (=

      1. George B says:

        Thanks, Jay! I was wondering why it wouldn’t show up. I will try to be more brief and use fewer links next time.

    2. Mark Kane says:

      Maybe you are right. For sure article isn’t perfect and more data is needed for fair comparision. I need to improve next time. I just wanted to look on the LEAF battery in the context of new data about Roadsters.

      I don’t have data about smart capacity fade, but for some reasons smart not using it any more. BMW also after test didn’t choose this solution despite the emphasis on low weight of i3.

      1. George B says:

        Mark, understood, and I could think of several reasons why a major automaker wouldn’t use a 18650 format factor cells to build automotive battery packs. Degradation is just one part of that, but as the Roadster study shows, likely not the most important reason to go with custom batteries.

        There was a lot of handwriting about the Roadster, and the longevity of the cells Tesla used early on. After all, they used only slightly improved laptop cells, which are not known for their durability. We appear to have a positive surprise here, which is good.

        What is often misunderstood – lithium oxide chemistries are temperature sensitive. Any range loss, especially early in the life of the vehicle, is typically driven by chemical processes that can be effectively mitigated by managing the temperature of the pack.

        We saw a LEAF last year, which lost about 7% of battery capacity by just baking on dealer parking lots. It had 160 miles on the odometer at the time of purchase. With larger packs, like the 85 kWh one the top Model S trim uses, the effects of mileage are even less pronounced. It takes only about 50 full cycles to achieve annual mileage of 12K.

        1. Mark Kane says:

          I also think that Roadster battery results are good. This is very good aplication for 18650 with TMS. In my opinion Model S is perfect.

          1. George Betak says:

            Yes, Tesla did quite well, all things considered.

  17. Dave K. says:

    I liked the article, and of course all this is speculative! Bottom line modern EVs with lithium batteries are new technology and unexpected results are almost certain! I own a Leaf with 24K on it and I live in the south and have seen only slight capacity fade, YMMV! All in all I expect all these batteries will be obsolete in 3-5 years and so the point is probably not relevant long term anyway.

  18. Tony says:

    Mark, seems you’re on an island by yourself. There’s reports of Leaf battery capacity loss all over the place. I met an owner with a 1yo 13k mi Leaf at my Chevy dealer about 2mos back, leasing a Volt because his Leaf could no longer do 68mi R/T from home-work-home. In 1 year. 13K miles. I think it’s insulting to the Roadster, Tesla, and it’s technology to even insinuate the leaf battery is anywhere near it’s category. I’d estimate the Roadster battery probably costs more than the entire Leaf itself, even the mfg price…

    And in closing, here’s even Leaf owners questioning just what in the world you’re talking about:

    http://www.mynissanleaf.com/viewtopic.php?f=10&t=13610