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Accelerating uptake of Electric Vehicles in New Zealand

Accelerated reported battery health loss in 30 kWh Leafs

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Update July 2018: Following the firmware release from Nissan (see http://www.cleanfleetreport.com/exclusive-nissan-leaf-battery-fix/) we are working on a revision to this report which will include updated results. We will update this page when this revised report is available. A wide variety of views and some of the main questions about the firmware upgrade are discussed in the Autofile July issue available at https://autofile.co.nz/magazine/download?magazine=56.

 

Unfortunately, we have some troubling news: it appears that some of the 30 kWh Nissan Leaf battery packs are reportedly degrading at around three times the rate of the 24 kWh variant at 2 years of age.

Owners of over 640 electric and plug-in hybrid vehicles have signed up to our Flip The Fleet project to share data from their cars each month – it’s a “by EV owners, for future EV owners” effort to provide science-based evidence for the benefits and constraints of electric vehicles in New Zealand. So far, we have found mostly good news that will encourage other people to switch to electric, but the latest discovery of accelerated reported degradation of the 30 kWh Leaf batteries is potentially a serious problem for their owners, and one we must face and try to manage as soon as possible.

One of the statistics reported each month by many of the Nissan Leaf and e-NV200 van owners is “Battery State of Health” (SoH) – it’s a measure of the battery’s current capacity to store charge compared to its ideal, factory state. Another measure of the battery’s health is the number of “bars” which is displayed on the dashboard.  Over the past three months, we have fielded an increasing number of queries by concerned 30 kWh Leaf owners who have noted a fall in SoH or bars.  By January 2018, we were so concerned that we enlisted the help of several volunteers to shoulder tap owners to get more battery scans into the Flip the Fleet’s communal database.  We were also gifted some battery scans collected by a concerned EV importer, who gathered these from various Leafs on auction floors in Japan.  Dr. Daniel Myall, Flip the Fleet’s statistician, led the analysis of the data and, along with co-authors Dima Ivanov, Mark Nixon, Walter Larason and Henrik Moller, has just published the findings. We were also ably guided by the knowledge, experience and courage of a wider reference group of around 10 EV owners from throughout New Zealand, amongst whom we would particularly like to thank Donald Love and Joe Barnett.  Joe and Donald guided the writing of the FAQs section below and did a lot of research to evaluate our results and their implications.

A picture paints a 1000 words: here’s one of the diagrams from the science report just published:

 

Figure 1 from the science report: All individual battery SoH measurements as a function of age with average 2nd-degree polynomial fits for both 24 kWh and 30 kWh Leaf models.  Nissan’s estimate for expected average decline is 80% SoH after 5 years (Nissan, 2012; Nissan, 2017) and is shown by a red dot. There was large variability between cars, but both battery models showed increasing decline with age.

The full science report can be downloaded from https://www.preprints.org/manuscript/201803.0122/v1 or by clicking the button below:

 

Download science report

 

 

We alerted Nissan to our preliminary findings in January 2018, and then sent them the final draft of the science report for review on 23 February 2018.  We have not heard back from them, and we are hopeful that Nissan will now choose to comment on the science report as part of the creative commons and open source peer review process.

In case you don’t want to wade through all the detail of the science paper itself, we have extracted the main points in the next section below.  After that you’ll find a Frequently Asked Questions (FAQ) section where you can explore what all this might mean for you:

 

Key findings by Flip the Fleet about the observed 30 kWh Leaf battery degradation:

  1. There are over 3,250 Nissan Leafs registered in New Zealand. While most are 24 kWh, there are approximately 600 30 kWh Leafs already on the road. Based on Trade Me listings, we estimate that at least another 180 30 kWh Leafs are either in transit or awaiting sale on dealer yards. For context, there were 5,022 new and used light electric vehicles registered in NZ as at the end of February 2018 (including a few hundred smaller Paxters used by NZ Post, which we don’t count towards this calculation), meaning the 30kWh Leafs make up an estimated 14% of this fleet.
  2. Reported battery health (capacity to hold charge) at two years of age was estimated to be declining approximately 3 times faster on average in 30 kWh Leaf battery packs than for 24 kWh Leafs.
  3. The reported rate of decline in 30 kWh batteries observed so far is accelerating as the cars get older.
  4. We have not yet tested sufficient vehicles to check that the reduction in reported battery health accurately measures reduction in maximum range of the vehicle on a single charge. Nevertheless, we believe that there is no reason to expect that the reported battery health does not broadly indicate an upper limit for the range of the vehicle.
  5. We cannot see any reason to believe that the accelerated rate of degradation observed in reported battery capacity so far will not continue in the near future at least.
  6. The oldest of these 30 kWh Leafs are now approximately 2.3 years old. There is no scientific way of predicting accurately how well they will last in the long term.
  7. The observed decline in reported battery health for 24 kWh Leaf batteries at 5 years is close to what Nissan estimated it to be. The observed decline so far in many 30 kWh Leaf batteries, at an age of less than 2.3 years, is already close to where Nissan estimated them to reach at 5 years of age.
  8. We do not know for certain what the underlying causes of the observed rapid decline are, but our working hypothesis is that it relates to greater degradation at elevated temperatures and higher states of charge of the batteries.
  9. Nissan guidelines advise against repeated rapid charges on long trips – it may be that some owners do not realise this and thus do not use their car within these guidelines. There is evidence in our data that reported battery health had degraded very slightly more in Leafs that used more rapid charging per distance travelled, but this effect does not appear to be isolated to 30 kWh models. Therefore, successive rapid charging on long trips by itself does not appear to be a sufficient explanation for the rapid decline that we observed in 30 KWh vehicles, when compared against their 24 kWh counterparts.
  10. If the high rate of decline in battery capacity that we observed in the first 2.3 years of a 30 kWh Leaf’s lifetime was to continue, the financial and environmental benefits of this model are likely to be significantly eroded.
  11. None of the findings negate that the Nissan Leafs, even the 30 kWh model, may be an excellent choice for specific owner’s needs, especially for local travel. However, the additional prices currently paid for the 30 kWh model may adversely distort its value proposition depending on future battery health and its potential need for multiple replacements.
  12. We advise all buyers of any EV model to always get a battery scan check before purchase, where possible. Caution is required with Nissan Leafs, however, as the battery health metric can sometimes have a sharp drop following purchase depending on how the car was treated prior to sale and during transport to NZ, assuming this car is a second hand import. As reported to us, the battery health metric can also fluctuate by up to 8% once on the road in New Zealand following rapid charging on long road trips and has some variation with season, sometimes reducing sharply during cooler weather.
  13. Tracking what happens in the future is an important priority for EV owners and businesses. Flip the Fleet will continue to monitor and report rates of change of battery health, and to research why the observed changes are happening. To do this more effectively, we invite all of NZ’s EV owners to sign-up to Flip the Fleet to report their monthly statistics. It’s free, takes 10 minutes a month max. Visit www.flipthefleet.org and signup if you wish to help.

The accelerated decline observed so far by Flip the Fleet is isolated to one variant of one EV model. It does not signal general concern for the practicality, financial and environmental benefits of all EVs.

 

 

Frequently Asked Questions:

What does my battery State of Health mean?
A battery’s capacity can be measured by a ‘State of Health’ (SoH) metric, the condition of a battery compared to its ideal condition. It is related to the fraction of electrical energy that the battery can hold as a percentage of the energy that the battery could store at time of manufacture. Battery capacity is important for electric vehicle owners because it is a primary factor in the maximum range that the car can travel once the battery is fully charged.

How can I measure my Leaf’s battery State of Health?
The car Battery Management System continuously measures the flow of energy into and out of the battery. Calculations are made of the percentage of observed capacity compared to when new. This metric is updated at regular intervals and stored in the car systems. Nissan can read the SoH metric with their scan tools and the same value is available via an OBDII adapter and the LeafSpy application. More details at https://flipthefleet.org/resources/nissan-owners-how-to-scan-your-battery/

Are there any other ways to see the State of Health?
The dashboard display has an outer thin scale representing SoH in “bars” where a new car has 12 bars. In this example, a Leaf in the US has lost 3 bars and the estimated range on a 98% charge is down to 72 miles (EPA rating 107 miles when new). The capacity bars are not linear with loss of the first bar at about 80% SoH. In countries where there is a Nissan warranty, a battery replacement is triggered for the 30 kWh Leaf when there is loss of 4 bars (about 60-65% SoH) within 8 years or 160,000 km.

Is the reported State of Health an accurate measure of battery capacity?
Initial readings at auction can be misleading as there are known instances of the Battery Management System being reset, just like odometer tampering. If the car has been recently used, with multiple slow charge and discharge cycles, it is more likely that the reported SoH will be more accurate as the car learns the current battery capacity. For the 24 kWh Leafs the reported SoH appears to provide a good indication of available range. Significant variations in the reported SoH for the 30 kWh cars have been observed and there is not yet enough data to determine the difference between reported SoH and actual capacity. It would be expected that Nissan has calibrated the SoH, capacity bars and range estimation but it is possible there are measurement errors.

Does this issue apply to all 30 kWh Leafs?
The science report presents an average line across all cars in the sample but there are variations between cars. The 30 kWh Leafs sourced from United Kingdom showed slower initial decline than those from Japan, but the rate of decline was similar at two years of age. It is possible that there were battery changes made by Nissan at some stage of the manufacturing cycle and further research over time is needed, with details of battery manufacture date, to confirm whether there are different trends developing.

I have lost a lot of reported capacity. Will it continue to drop at this rate?
As these cars are usually not imported soon after manufacture, the initial climatic conditions and battery treatment are probably unknown. It is possible that the rate of capacity loss will reduce if conditions are more favourable but there are currently no clear indications from the supplied data that there will a change in the rate of loss. Over the coming months with more data collected further insights should be available.

Can I improve my battery State of Health?
Nissan state in the manual: “The capacity of the Li-ion battery in your vehicle to hold a charge will, like all such batteries, decrease with time and usage. As the battery ages and capacity decreases, this will result in a decrease from the vehicle’s initial mileage range. This is normal, expected, and not indicative of any defect in your Li-ion battery.” The available capacity does vary with temperature and improvements may be seen in warmer months and more decline in cold months. While it is possible to gain short term improvements in reported SoH with rapid charging, the overall trend per year is a slow decline in capacity.

Can I slow the rate of capacity loss?
Battery capacity loss is primarily due to calendar ageing although very high mileage can add additional loss. The factors that cause the most capacity loss are high temperature with high state of charge over an extended period of time, which may have occurred in country of origin. Sustained high temperatures over 30℃ with high charge for extended periods are best avoided. Maximum battery life, while still providing usable range, is achieved when kept at a state of charge around 40% to 60% but this limits the distance that can be traveled. It is currently unclear exactly how much effect different storage and charging regimes might have. High state of charge for limited time is not especially damaging and one potentially beneficial strategy is to set the car to charge on a timer, with the charge finishing in the morning just prior to use. In addition to minimising the time at high charge, it allows the battery to cool down before charging, gives power cost savings if night rates are available and avoids loading the power grid at peak times.

How long should my battery last?
Nissan state in the manuals: “NISSAN estimates that battery capacity will be approximately 80% of original capacity after five years, although this is only an estimate, and this percentage may vary (and could be significantly lower) depending on individual vehicle and Li-ion battery usage.” The battery still has a useful life well below 80% but it depends on the range required by each owner for how long the car suits their needs or whether it would be better transferred to another owner with less range requirement. It is not yet known where more accelerated end-of-life effects might start (oldest Leafs here only 7 years old). The currently observed loss of capacity with the 30 kWh Leaf is more rapid than Nissan expectations and hence the range may continue to reduce faster than expected.

Does Nissan New Zealand give a warranty on the batteries?
It is our understanding that the 30 kWh Nissan Leafs were never sold new in New Zealand and Nissan New Zealand only offered a warranty on vehicles bought new in New Zealand from a Nissan dealer.

Is there a graph available showing what can be expected of my battery life/available range?
There are tables of estimated range in the MyNissanLeaf forum under Leaf Ownership > Range / Efficiency / Carwings > Range Chart. The first post is maintained with latest tables. http://www.mynissanleaf.com/viewtopic.php?f=31&t=4295

Am I covered by the Consumer Guarantees Act or Fair Trading Act?
Consumer NZ have put together an article covering your rights: https://www.consumer.org.nz/articles/nissan-leafs-not-going-the-distance

Is this problem on all Electric Vehicles?
No, however there is likely to be an amount of battery capacity loss over time with all electric vehicles that use lithium-ion batteries. Our data show that on average the 24 kWh Leaf has a slower rate of reported battery decline than the 30 kWh Leaf. It is also our understanding that other cars such as Tesla with active battery cooling are showing low loss of battery capacity.

How can I help?
If you haven’t done so already, sign-up to Flip the Fleet at www.flipthefleet.org to start sharing the data from your vehicle each month. The communal data will help us all by tracking how the batteries last from here on, and how well replaced or refurbished batteries last. Many of the EV owners that have already signed up to Flip the Fleet do not scan their batteries each month – you could help this current concern by following the instructions at https://flipthefleet.org/resources/nissan-owners-how-to-scan-your-battery/. If you are stuck, contact us at wecan@flipthefleet.org and we’ll try to get an EV owner in your neighbourhood to show you how. You can get a 20% discount on purchasing an OBD2 “dongle” to perform the scan from NZ Electric Vehicles Ltd. at http://www.nzev.co.nz/mini-elm327-bluetooth-kw902-obd-ii-car-auto-diagnostic-scan-tool/

Does this new information have an effect on my cars environmental impact?
EECA commissioned a Life Cycle Analysis (https://www.eeca.govt.nz/news-and-events/media-releases/research-confirms-environmental-benefits-of-electric-vehicles/) which concluded that as we keep cars longer than overseas, one battery replacement is assumed in the models which would still show a net environmental benefit compared to petrol cars. If your vehicle requires more replacement batteries than initially indicated, then yes your car’s negative environmental footprint will be greater than expected.

 

Daniel Myall, Walter Larason, Mark Nixon, Dima Ivanov, Joe Barnett, Donald Love and Henrik Moller.

 

 

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Comments

  1. Keith Chapman says

    “It is our understanding that the 30 kWh Nissan Leafs were never sold new in New Zealand and Nissan New Zealand only offered a warranty on vehicles bought new in New Zealand from a Nissan dealer.”

    You are totally correct in this FAQ answer.Here is an email I sent to “derrick.vandenberg@citynissan.co.nz” on January 23 under the header “Advice Sought”:

    Hi Derrick,

    Three months ago, in October, we reluctantly parted with our immaculate 1999 Nissan Pulsar, bought from you when we were living in Glenfield all those years ago.

    We replaced it with a zero-emission Leaf. As Nissan NZ are unable at present to market EVs satisfactorily, we worked through a registered dealer in Northcote who imported a JDM car and handled the compliance checks etc. for us.

    The car was a 2016, 30kWh, X model in fine visual condition throughout. It had 14,500 km on the odo, as verified by the AA. We have now travelled 2,200 km in it around town, bringing the odo up to 16,700 km, and until this week were getting estimated distances of around 165 to 175 km per 100% charge.

    We are planning a first “road trip” to our Taupo timeshare apartment in early February, and on Sunday I tested that a ChargeNet key fob would allow us to recharge while holidaying away from our Whangaparaoa retirement village home. I charged to 80% of capacity at the station situated outside The Warehouse, Albany, which gave me 130 km of estimated travel distance.

    In the evening I recharged at home as usual to bring the car up to 100%, but in the morning I noticed this had given me only 159 km of potential distance. I then counted the storage capacity bars and found that there are now only 11 of the original 12.

    This is worrying me somewhat. Various online forums, discussion groups and websites tell me that the loss of the bar indicates my distance to travel on a full charge will now be reduced by 15%.

    The car is less than two years old and has only 16,700 km on the odo. All the tables and comments I can find indicate that our car is undergoing exceptional battery capacity loss. For example, https://insideevs.com/battery-capacity-loss-chart-2016-30-kwh-nissan-leaf/ shows a Nissan warranty table which points to Bar 1 loss occurring at 27 months and 28,125 miles (45,263 km). This means our car should have been able to travel another 28,563 km (or at least another three months if you base it on time/aging alone) before losing 15% of its battery capacity.

    Are you able to offer me any advice on what I should do, please? The car is our only car, and we very deliberately chose a 30kWh model over a 24kWh for the sake of the improved range. I hate to think that it will let us down on holiday or, longer term and worse, that in retirement I have spent $25,750 on a lemon.

    Our car is Type: ZAA-AZEO, Chassis AZEO-202789, Model FSDARD9ZEO3DB–ABA, Engine Motor EM57, Plant T

    Regards,

    Keith Chapman

    Mr Derrick van den Berg of City Nissan (Takapuna, Auckland) replied:

    Good Morning Keith,

    Thank you for your email and congratulations on the purchase of your new Leaf.

    I will forward your email to our service/technical department as I do not have the specific knowledge to address your concerns appropriately.

    They will come back to you regarding your concerns.

    Best Regards,
    Derrick

    The service/technical department have failed to “come back” to me in any way whatsoever. Total silence!!

    I am assuming Nissan, having given EVs in New Zealand the raspberry some time ago, have NO INTEREST in safeguarding their reputation, let alone helping anyone who has had the “audacity” to import a JDM product against what was so clearly their policy on the NZ market.

  2. Dave Burkitt says

    We have a 2016 30kWh Leaf that we bought at 3 months old, when we got it I was charging it each night, since you can’t set the 80% limit in a 30kWh it was always at 100% each morning. After 3 datapoints on FliptheFleet I saw the steep decline and changed the way I charge it. I now leave it to go below 40% before recharging, and I only put enough in to get to around 65 – 70%. I now have 3 datapoints like this and the decline is much flatter.

  3. Fraser Burling says

    With a (2016 listed: 2015 according to MOT registration)30KWh leaf purchased in August last year and a SOH of 95% at purchase, and dropping one battery bar in the last 6 months, I bought a LeafSpy and found it read a charge of 23kWh at 82%. However it appears that the car still takes 30kWh on a charge according to my solar program and the charging device). Accounting for some loss in the transfer process I suspect I still have about 27kWh, and I still get over 220km on a single charge (It started at 240km on a single charge) . Yes I have noticed a drop but not as much as the LeafSpy says, and I wonder how much is the battery and how much might be mis-interpretation of the LeafSpy. I fill up once or twice a week only and have done only 1 rapid charge since buying the car, although it read around 120 in its lifetime. I did a day by day analysis of what LeafSpy said, compared to the dash board, and the distances travelled and found a discrepancy in the LeafSpy reports compared to distance travelled, and a major set of inconsistencies in just the one set of readings from full charge down to 8% (which I have posted on Facebook). In my honest opinion I think the now 11 bars on my leaf mean that I have less than 27.5 kWh but not 23kWh that the Spy would make me think. The distances I get, on up and down hill travel over 220km, would just not happen if I had only 23 kWh to work with.
    So in summary, the Leaf has lost battery percentage of possibly 8-10% but the Spy is not a reliable way to work with the 30KWh model (It was after all made for the 24kWh model). Yes this is accelerated but is it as accelerated as the Spy makes out or is the Spy not a suitable means for determining the rate of decline for a 30KWh model? I think this very important question must be answered, and a different means of calculating battery percentage loss other than the Spy needs to be utilised to help answer this question.

    • Donald Love says

      Fraser, the charging method of assessing capacity is interesting. What current is your EVSE set to ? If down at 6-8A the losses in the charging process are quite high (other loads in the car) and could be down to 80% efficiency so the 30kWh could be 24kWh into the battery. If higher rates the percentage losses are less. This is certainly confusing everyone and there is the possibility of some instrumentation errors in the car although others have noticed range drop as well.

    • Terry says

      Hi David,

      Questions:
      Q1. When (if at all) did you have the firmware fix installed to your Leaf, to resolve the 30kWh level reporting issues?
      Q2. When you wrote the above post, did you have your Leaf Spy settings set to the right battery size (30kWh) and model year?

      Terry

  4. Rusty says

    The life of a LiIon battery depends on three things: chemistry choice, temperature and charge level.
    The temperature is limited in well designed systems by an active cooling system. In the Leaf this has to be manually managed by not rapid charging in high temperature (>40degrees C) environments or after high discharge driving.
    The charge level is controlled by a well designed battery management system (BMS) or by manual charge limiting.
    For maximum cycle life and minimum degradation charge levels should be kept to less than 80% capacity. However the BMS will also have a buffer built in which declines with aging.
    The only way to measure degradation accurately is by eliminating the BMS readings.
    On first purchase benchmark by charging to 100% then drive immediately at a consistent moderate speed continuously on a levelish road until the battery shows as close to 0 as possible.
    Record the kWhrs used.
    This is the comparison method that must be used in your statistical analysis if you are to extract meaningful data. Unfortunately it is not one that your memebers are going to willing do!
    https://www.youtube.com/watch?v=kMh8Ie–X8E

  5. David says

    Hi, I own a 2016 #30 LEAF in the UK. My battery SoH is 99.51% after 22,443 miles as reported by LEAF Spy.

    I’ve seen reports of very fast battery degradation on #30’s and all of the ones that I’ve seen reported are from hot states in the USA. In the temperate UK. The #30 battery seems to be holding up well. It is noted that they get very hot after multiple Rapid charges, but in the UK, it’s not very often that you’ll need to do that.

    I’m not excusing Nissan for failing to have a proper battery TMS, but your data does look skewed based on the UK and N Europe experience of operating #30 LEAF’s

  6. Andy says

    How common is rapid charging in NZ? In the UK we find that if the Hx (internal resistance) and SOH (state of health) figures drop then a few rapids in a row, over a few days, improves both.

  7. ross webster says

    I have not seen anymore comments in the media from Nissan NZ since they said on the 22nd March they were investigating the problem? If Nissan NZ says they will offer the same 8 year 8 bar warranty the 30 kWh Leaf has overseas on our parallel imports, then we can have confidence in this model. Until then best to avoid it because of the uncertainty.

  9. Peter Olorenshaw says

    I think we should all read about the person who has a standout almost zero degradation in his (24kWh) battery through keeping the battery at a low charge (20-40%) whenever possible. And instead of “filling the tank” or even 80% filling the tank , only does this when needed. (The article is tilted “early Adopters as teachers” here on Flip the Fleet).

  10. Andrew says

    My Leaf is six year old and has only lost 2 bars from new. I only use the 6a trickle charge, at home, and rarely use fast charging, unless I absolutely have to. Very happy with the range and left expectance. The article was very helpful. I will no longer keep the car fully charged.

  11. XP says

    In fact, my nissan leaf 2016 30 kWh, has a grat degradation, but since new (march2016) to nov 2017, the car operation and capacity was perfect and the range that the display show was practically unvariable (or very slightly) during these 1,5 years, but in Nov 2017 I tak ethe car for the first inspection, and after that official dealer revision and immediately when I take the car from the dealer workshop, the behauvior isn’t the same and I feel some strange and different informations about SOC% and range, and in fact, after some seconds after startup, instead the battery inspection show a almost perfect state, the first bar gone…
    After some communnications with the customer care, they said to me thatthey will revise deeply the car in few days, but after one months I received a call of Nissan customer care saying that they will not make any revision and there is no rasons for do that.
    Since Nov 2017 15th to Apr 2018 15th, two bars was loosed, and I suppose that today 2018 July 14th, the third bar is near to be loosed (SOH 73,43) and I’m loossing almost 1% of SOH every month…but I still thinking about which could be the problem in the dealer workshop to make that the car seems another one after the revision, but nobody would like to investigate, and I have no access to the car detailed data.

  12. Jon Chamberlain says

    Hi

    I read that this had been resolved now, but there had been no further updates on your story.

    What is happening with this?

  13. Munrog says

    Hi, has the issue been resolved? Would it be ok to consider 30kw leafs now?

    • Daniel Myall says

      There are still some firmware versions which potentially have issues. We are working on an update that goes into the details around this and will post it when ready. Unfortunately, gathering enough longitudinal data to fully understand what is going on takes time.

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