Version 1
: Received: 15 March 2018 / Approved: 15 March 2018 / Online: 15 March 2018 (07:19:52 CET)
How to cite:
Myall, D.; Ivanov, D.; Larason, W.; Nixon, M.; Moller, H. Accelerated Reported Battery Capacity Loss in 30 kWh Variants of the Nissan Leaf. Preprints2018, 2018030122. https://doi.org/10.20944/preprints201803.0122.v1
Myall, D.; Ivanov, D.; Larason, W.; Nixon, M.; Moller, H. Accelerated Reported Battery Capacity Loss in 30 kWh Variants of the Nissan Leaf. Preprints 2018, 2018030122. https://doi.org/10.20944/preprints201803.0122.v1
Myall, D.; Ivanov, D.; Larason, W.; Nixon, M.; Moller, H. Accelerated Reported Battery Capacity Loss in 30 kWh Variants of the Nissan Leaf. Preprints2018, 2018030122. https://doi.org/10.20944/preprints201803.0122.v1
APA Style
Myall, D., Ivanov, D., Larason, W., Nixon, M., & Moller, H. (2018). Accelerated Reported Battery Capacity Loss in 30 kWh Variants of the Nissan Leaf. Preprints. https://doi.org/10.20944/preprints201803.0122.v1
Chicago/Turabian Style
Myall, D., Mark Nixon and Henrik Moller. 2018 "Accelerated Reported Battery Capacity Loss in 30 kWh Variants of the Nissan Leaf" Preprints. https://doi.org/10.20944/preprints201803.0122.v1
Abstract
Analysis of 1382 measures of battery State of Health (SoH) from 283 Nissan Leafs (“Leaf/s”), manufactured between 2011 and 2017, has detected a faster rate of decline in this measure of energy-holding capacity for 30 kWh variants. At two years of age, the mean rate of decline of SoH of 30 kWh Leafs was 9.9% per annum (95% uncertainty interval of 8.7% to 11.1%; n = 82). This was around three times the rate of decline of 24 kWh Leafs which at two years averaged 3.1% per annum (95% uncertainty interval of 2.9% to 3.3%; n = 201). For both variants there was evidence for an increasing rate of decline as they aged, although this was much more pronounced in the 30 kWh Leafs. Higher use of rapid DC charging was associated with a small decrease in SoH. Additionally, while 24 kWh cars with greater distances travelled showed a higher SoH, in 30 kWh cars there was a reduction in SoH observed in cars that had travelled further. 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. Improvements in the battery health diagnostics, continuous monitoring of battery temperatures and state of charge, and verification of a fundamental model of battery health are needed before causes and remedies for the observed decline can be pinpointed. 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 were to continue, the financial and environmental benefits of this model may be significantly eroded. Despite 30 kWh Leafs accounting for only 14% of all light battery electric vehicles registered for use on New Zealand roads at the end of February 2018, there is also the potential for the relatively poor performance of this specific model to undermine electric vehicle uptake more generally unless remedies can be found.
Keywords
electric vehicle; Nissan Leaf; lithium-ion battery; capacity loss; battery degradation
Subject
Engineering, Energy and Fuel Technology
Copyright:
This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Received:
16 March 2018
Commenter:
Peter Hallinan
The commenter has declared there is no conflict of interests.
Comment:
Hi Daniel and team, thanks for this interesting article and congratulations on making it available to the global community. Just out of curiosity,
a/ any data (or even hunches) about other variants of the Nissan Leaf ? or other electric cars such as the Zoe?
b/ I own a BMW i3 which has now travelled >61000km in the just over 3 years since I bought it new. As far as I can judge, the electric battery still manages to notch up about 150km before depletion, at which point the range extender kicks in to about double that to 300km before I have to consider recharging. I have noticed some variability in the range the battery will take me when fully charged - anything up to about 40km difference in range, but can't put my finger on why this variability happens.
cheers
Received:
16 March 2018
Commenter:
Keith Chapman
The commenter has declared there is no conflict of interests.
Comment:
Your article is deeply concerning to me as the owner of a 2016 30kWh Leaf since October. Even more concerning is the total disinterest of Nissan NZ. 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.
Received:
16 March 2018
Commenter:
Ken Morison
Commenter's Conflict of Interests:
I own a 24 kWh Leaf.
Comment:
The data speak for themselves. The affiliations of these authors shows they will be all keen to promote EVs. They will given a great deal of thought into the impact of publishing this data. Their discussion raises a number of uncertainties in the data and its interpretation, but there would have to be significant systematic errors for the trends to be incorrect. It is not clear that the 2nd order polynomial are correct, but at no point do they extrapolate them, and the indicated trends are consistent with past results (as found with a Google search).
Received:
19 March 2018
Commenter:
Brian Worboys
The commenter has declared there is no conflict of interests.
Comment:
I am very impressed with what you have achieved in a short time.
My concern is that there may be a bit of self-fulfilling-prophesy in the data for the 30kwh cars. The project is relying on interested volunteer Leaf owners providing their data. Once the word gets around that the 30kwh cars may have a problem, the owners of these cars, who suspect they may have a battery with accelerated decline will be keener to find out more about this, and join FtF, than other owners who have not noticed any untoward loss in predicted range. If this happens, then the data will be skewed towards cars with the more rapid decline. It won't be representing the whole fleet.
However, there will be 30kwh cars that began providing data from a time before the 30kwh battery came under suspicion. The data from this subgroup could be used to validate the trend of the whole group.
Received:
20 March 2018
Commenter:
Kirk Summerwill
The commenter has declared there is no conflict of interests.
Comment:
A few points for the author editor to consider:
The reference to a facebook group for information (NAZ EV Owners Group (2018) doesn't allow readers to find that evidence, nor is any critical evaluation or description of that evidence given - without better referencing I would mention that it is anecdotal rather than an online poll or other activity (if true). Caution is clearly required as cultural narratives may exist in USA audiences that may not be present elsewhere.
The study notes that the sample are self selecting and convenience sample, but no critical appraisal of the issues this may bring or the actual method and process of selection/recruitment is given so readers cannot determine the extent to which this is a methodological influence.
Overall though a compelling study. Greater control for user behavioural factors would be an advantage also.
The commenter has declared there is no conflict of interests.
Comment:
Thank you very much for your feedback. We agree that the reference to the NZ EV Owners Group on Facebook in the introduction has limitations and that mentioning anecdotal evidence instead would be a better approach. We'll make this revision in the next version of the report.
In the discussion (lines 294 to 302) we cover some potential issues around the convenience sample and why we don't believe sampling bias could explain the results. In a nutshell (i) the difference between the Leaf variants is huge, so any representativeness bias would have to be huge to explain the result; (ii) many people joined long before any suggestion of an issue with the battery was being aired (indeed most signup soon after buying their vehicle), (iii) many didn’t scan at the start but did so when we asked them to check. But more fundamentally, (iv) any bias would presumably be operating in both 24 and 30 kWh subsamples, so bias itself is most unlikely to be a sufficient explanation for the group difference. Now that the news of the 30 kWh battery capacity loss is being openly discussed, there is much more risk that those with unusually degraded batteries are more likely to sign-up – so we will work hard to test for such bias in the data received from now on.
We agree that it would be beneficial to provide more details on how users were recruited and we'll include this in the next version.
Many thanks for your critique.
Comment 6
Received:
21 March 2018
Commenter's Conflict of Interests:
I own a 2 year old Leaf 30 kWh with 45.000 km.
Comment:
To my understanding are the numbers publish based on the SOH value reported by LeafSpy.
I believe this value is an undocumented value and it is not clear what it stands for.
It must be a different value than Nissan is using, otherwise my Leaf shall not show a full health scale, bur0t LeafSpy shows SOH 81% at my 30 kWh Leaf.
Either SOH or the value shown by Nissan are wrong.
The commenter has declared there is no conflict of interests.
Comment:
Thank you for your critique.
Yes, we have based our main analysis on the State of Health (SoH) metric that is reported by LeafSpy. We are not sure what you mean by Nissan’s ‘health scale’ but expect that it might mean the number of ‘bars’ displayed on the dashboard to the extreme right of the state of charge bars. So, when you refer to your 81% SoH battery pack showing “full health scale”, do you mean that you are showing 12 out of 12 bars? Please confirm so that we can fully evaluate your concern.
In the meantime, we see no reason to discount the use of SoH as a broad scale metric, provided it is used within safe limits of inference. i.e.
As we say at lines 60-63 of our paper, “SoH is a value officially referred to by Nissan as 'LBSOH' and is generated by the car's battery management system and outputted by the Nissan Consult 3 tool (My Nissan Leaf, 2012)”. We agree that the exact details of how that metric is measured is not declared by Nissan, but the SoH metric is in common use and interpreted as the energy holding capacity of the battery as of now compared to when the car was first manufactured.
Our data show a broad scale association between SoH and the number of bars on the dashboard (see new figure at end) which Nissan use for warranty triggers and which is in common use in the market place. There is considerable variation between individual vehicles and overlap between models, but overall a strong correlation between the two measures.
Assuming that we have interpreted your comment correctly, you having 81% SoH is entirely as expected for your ‘12 bar’ 30 kWh Leaf. The data show that on average a 30 kWh Leaf loses its first bar at the latest by 76% SoH, and on average at a later stage of battery degradation than a 24 kWh Leaf. If the rates of decline reported in Figs 1 and 3 of our paper continue at their current rate, we expect many New Zealand 30 kWh owners to lose their first bar in the next six months (the average for the oldest 30 kWh Leafs in New Zealand is around 83% and our statistical model shows that it is falling at around 10% per year)
We observe temporal fluctuation (up and down) in SoH related to recent driving and charging behaviour (See Fig 2, and discussion at Lines 276-278 of the paper), but this ‘nuisance’ or ‘disruptive’ variation is insufficient to obscure the large difference observed between 30 kWh and 24 kWh Leaf variants.
Unless the instrumentation was changed in some drastic way between manufacture of the 24 kWh and 30 kWh variants (we hope that Nissan can confirm either way), the very large difference observed between the models cannot possibly be explained by measurement bias. Any such difference would have had to affect both bars and SoH, judging from the correlation in the figure above, so we do not expect SoH alone to be misleading our broader interpretation.
Social media reports from owners of 30 kWh Leafs in the hot climate of southern USA have reported strong and proportionate declines in actual range of their vehicle that are commensurate with loss of bars. The correlation between SoH and maximum range will become all the more evident once bars are lost, but the influence of short term fluctuations in range because of terrain, driving conditions and temperature will make this hard to detect in the early stages of battery degradation.
We have already completed preliminary testing on a range of 30kWh Leaf to compare SoH and energy stored in the battery as measured under controlled conditions. We are still refining our test procedure before conducting testing on a much larger number of vehicles. Details on our exact methodology will be made publicly available to allow others to conduct their own testing and compare to our results. Until this next stage of testing has been completed, we will continue to refer to ‘reported battery capacity’ rather than just 'battery capacity’ to make it formally clear that we have not yet directly measured energy-holding capacity.
In conclusion, we are confident that SoH is a reliable and scientifically-based metric of battery energy holding capacity that has sufficient repeatability to signal evidence of accelerated degradation of 30 kWh batteries in their first 2.3 years of life. Your concerns, and similar scepticism expressed by contributors to the EV owners social networks in recent days, suggests that we should now include the new Figure below in version 2 of the paper.
Your comments have helped us clarify the messages even if though we don’t agree with your critique. Thanks!
Comment 7
Received:
22 March 2018
Commenter:
Matt W
The commenter has declared there is no conflict of interests.
Comment:
Are you certain that Leafs are shipped at 0 years of age with the internal system reporting 100% SOH?
Also, even if Leafs do report 100% SOH at 0 years, are you sure that that the systems doesn't for example calculate some parameter SOH' and then simply apply a cut-off of 100% to SOH' to get SOH. The battery firmware could presumably do any kind of non-linear tricks it likes.
If either of those situations is correct then the curvature of the model may be less useful as a predictor of a future trend.
The commenter has declared there is no conflict of interests.
Comment:
Thank you for your feedback. It is our understanding that a new or reset Leaf battery management system (BMS) reports a SoH of 100% and the BMS then updates this value as the battery is cycled. We have seen cases of SoH at 101% or 102% so the BMS doesn't appear to clamp SoH to 100%. We will make this clearer in version 2 of the paper.
We agree that extreme caution should be applied when predicting future decline. As discussed in the paragraph starting on line 341, there is a need to test and refine an underlying model of battery SoH decline, and it is uncertain at this stage whether decline will progress in the fashion detected so far.
As we gain further longitudinal data in the 30 kWh cars over the next months the uncertainty around SoH's trajectory in the first year will have less influence on the model's shape. In the meantime we have refrained from forward extrapolation, partly because if the paucity of data in the first year and partly because the underlying model of battery degradation and its drivers are not certain. We need for more of the batteries' life cycle to elapse before we could make plausible projections of what to expect next.
Thanks again for your critique.
Comment 8
Received:
23 March 2018
Commenter:
Roberto San José Mendiluce
The commenter has declared there is no conflict of interests.
Comment:
Hola, me complace enviarle mis datos de contacto para que pueda compartir esta información con las personas que estén interesadas o Ud. crea necesarias.
También le envio el link del video de Nissan Tv. Espero que le guste.
Historia del primer taxi #Nissan #LEAF de Esp @TaxiNissanLeaf imposible contarlo mejor #EVhttp://bit.ly/1hK76Tz pic.twitter.com/nYjxkg5ASl
EMB15079_NISSAN_ELECTRICOS_V1.mp4
270.000 kilómetros recorridos ahorrando 21.060 litros de combustible, 18 cambios de aceite, de filtros, de pastillas de freno, juego distribución, etc, etc, de visitas al taller. No emitir gases contaminantes de efecto invernadero y contribuir a mejorar la calidad del aire... no tiene precio. https://www.facebook.com/brubaker.nissan/posts/1001629483300729
280.000 kilómetros recorridos con un Taxi 100 % ELÉCTRICO. Cada día se confirma la fiabilidad, rendimiento y necesidad de cambiar a sistemas de movilidad 100 % eléctrica. https://www.facebook.com/brubaker.nissan/posts/1061933267270350
300.000 kilómetros en seis años: la historia del primer taxi eléctrico en España. Roberto San José Mendiluce se convirtió, sin saberlo, en el primer taxista que conducía un coche eléctrico en España. Ahora hay unos 60 como él. https://www.linkedin.com/feed/update/urn:li:activity:6324564205504724992
Los coches eléctricos ya son una alternativa viable, y así nos lo han asegurado sus mejores probadores: los Taxistas. https://www.motorpasion.com/coches-hibridos-alternativos/los-coches-electricos-ya-son-una-alternativa-viable-y-asi-nos-lo-han-asegurado-sus-mejores-probadores-los-taxistas
Atte. Roberto San José Mendiluce.
Reciba un cordial saludo.
Carta de Presentación
Hola me llamo Roberto San José Mendiluce y soy el Primer Taxi 100 % Eléctrico en España.
Conduzco un Nissan LEAF desde Octubre del 2011 . Pertenece a la primera generación que se fabricó en Oppama (Japón) y está equipado con una batería de litio de 24 kWh. He recorrido más de 321.000 kilómetros con Zero Emission y Zero averias.
Mi objetivo es claro, transmitir las ventajas medioambientales y económicas que ofrece una Movilidad 100 % Eléctrica. Quiero demostrar la fiabilidad y el mínimo gasto en mantenimiento de este tipo de Vehículos. Para ello me he propuesto alcanzar las 200.000 millas recorridas con un Taxi 100 % Eléctrico, conservando la batería "original de fábrica" y sin haber efectuado ningún cambio de pastillas de freno.Publico toda la información que puedo sobre los Vehículo s Eléctrico s y las Energías Renovables y en especial lo relacionado con el Nissan LEAF.
Todas m is cuentas Sociales son "públicas" para que aquellas personas que tengan interés en la Movilidad 100 % Eléctrica puedan consultar dicha información.
Received:
23 March 2018
Commenter:
Roberto San José Mendiluce ( Brubaker.Nissan )
The commenter has declared there is no conflict of interests.
Comment:
Hola me llamo Roberto San José Mendiluce y soy el Primer Taxi 100 % Eléctrico en España.
Conduzco un Nissan LEAF desde Octubre del 2011 . Pertenece a la primera generación que se fabricó en Oppama (Japón) y está equipado con una batería de litio de 24 kWh. He recorrido más de 321.400 kilómetros con Zero Emission y Zero averias.
Mi objetivo es claro, transmitir las ventajas medioambientales y económicas que ofrece una Movilidad 100 % Eléctrica. Quiero demostrar la fiabilidad y el mínimo gasto en mantenimiento de este tipo de Vehículos. Para ello me he propuesto alcanzar las 200.000 millas recorridas con un Taxi 100 % Eléctrico, conservando la batería "original de fábrica" y sin haber efectuado ningún cambio de pastillas de freno.Publico toda la información que puedo sobre los Vehículo s Eléctrico s y las Energías Renovables y en especial lo relacionado con el Nissan LEAF.
The commenter has declared there is no conflict of interests.
Comment: English translations of the original comment and our reply are included below
Gracias por su comentario. Qué fantástico oír sobre tan largas distancias recorridas sin fallos mecánicos en el Leaf de 24kWh. También estamos muy interesados en publicar sobre los beneficios medioambientales y económicos asociados con el uso de vehículos 100% eléctricos. En éste momento, nuestro artículo ilustra la única amenaza seria a los beneficios económicos y medioambientales de los vehículos eléctricos. Coincidimos con usted, como tan bien ha relatado, en que las baterías de 24 kWh tienen una longevidad excelente. Esperamos que a nuestras observaciones sobre las baterías de 30 kWh les siga un mayor entendimiento científico de la causa y su solución.
Original comment: Hello my name is Roberto San José Mendiluce and I am the 1st 100% electric taxi in Spain.
I have driven a Nissan LEAF since October 2011. It belongs to the 1st generation built in Oppama (Japan), equipped with a 24 kWh lithium battery. I have logged more than 321,400 km with zero emissions and zero mechanical issues.
My goal is clear, to transmit the environmental and economic advantages from a 100% electric transport medium. I want to demonstrate the reliability and minimal maintenance in these types of vehicles. For this, I plan to drive 200,000 miles with a 100% electric taxi, with the original factory battery and without having had to change the brake pads. I publish all the information that I can about electric vehicles and renewable energies. In particular, all related to Nissan LEAF.
Our reply: Thank your for your comment and it is great to see such large distances traveled in a 24 kWh Leaf with no maintenance issues. We are also very keen to publish about the environmental and economic benefits of electric vehicles. This is the only serious threat that we have seen so far to the environmental and economic benefits of electric vehicles, and illustrated so dramatically by your experience. We agree that the 24 kWh batteries are lasting extremely well. We hope that our observations of 30 kWh batteries will be followed by greater scientific understanding of the underlying cause so that solutions to be developed.
The commenter has declared there is no conflict of interests.
Comment:
It would be really great to see a separate diagram for the 24 kWh "Lizzard" batteries (2014+) because I suspect, they would show much better values than the older ones.
Received:
6 April 2018
Commenter:
Henrik Moller
The commenter has declared there is no conflict of interests.
Comment:
Thanks for the suggestion Andras. A preliminary analysis could find no evidence of a difference in battery degradation in the two groups. However we have been sent many more records in the past three weeks and will be analysing these shortly. A formal test for differences in the two types of battery will be included in the next revision of the manuscript.
Comment 11
Received:
27 March 2018
Commenter:
Clive Appleton
The commenter has declared there is no conflict of interests.
Comment:
This is a very interesting and valuable piece of work you have undertaken and I hope to see the final scientific peer reviewed article.
As an aside.
I was alerted by a friend about the Listener article, unfortunately a day after I had signed up to buying a 2016 imported leaf from a Nissan agent. Conflicting advice from the agent has seen me having to write to Nissan NZ to get clarification on availability of batteries and parts. I have also asked them about your findings and had they any comment; I'm awaiting a response. As it stands, I'm unlikely to proceed with the leaf purchase.
Received:
29 March 2018
Commenter:
Kenneth Kar
Commenter's Conflict of Interests:
I am an owner of Nissan Leaf
Comment:
This paper uses age as the independent variable for battery degradation. Another important factor to consider is mileage. For a given age, some EVs have been driven over longer distance, and so their batteries may have gone through more cycles of charging and discharging. Battery capacity decreases with the number of cycling. The finding that 30kWh battery degrades at a higher rate may be partially explained by the fact that people drive further with a 30kWh Leaf, therefore the battery is subjected to more charging cycles . It would be interesting to see the analysis of SoH vs. mileage.
Received:
6 April 2018
Commenter:
Henrik Moller
The commenter has declared there is no conflict of interests.
Comment:
Thanks for your comment Kenneth. See lines 170 to 174 of the paper. There are indeed associations of State of Health with distance travelled in the data, but these were quantitatively weak effects. The dominant associations are 'calendar age' of the Leaf and whether it is a 30 kWh or 24 kWh variant. It is interesting that the association with distance went in opposite directions for the two variants, which we take as another clue that the batteries are responding quite differently from each other.
Comment 13
Received:
31 March 2018
Commenter's Conflict of Interests:
I lease a Nissan Leaf
Comment:
Just wanted to give you some feedback from a 2017 Leaf driver in Hawaii’s warm climate. At 12 months and about 13,000 miles the 1st bar disappeared (11 bars showing). Nissan dealer “said” this is normal. Our salesman said his 2016 Leaf 30 kWh battery is loosing bars faster than his 2013 Leaf 24 kWh battery. He also said he is getting similar feedback from other Leaf owners he has sold Leafs too.
Our typical commute is about 35 miles round trip plus town errands under 5 miles round trip (air conditioner always on). At home it’s in a garage so it’s only in the sun when out and about. 90+% of driving is flat land and under 45 mph due to the low speed limits and all the traffic lights. It’s usually plugged in to charge (level one charging) daily as soon as we get home with the battery typically around 60% or more in charge and by morning it’s 100% or close to 100%. So maybe keeping the battery at a higher state of charge is not good. Also I watched a video somewhere of someone reading from the 2018 Leaf manual which recommended waiting an hour after driving to allow the battery to cool down a little before plunging it in to charge. So maybe it’s similar for a 2017 Leaf. We ha e never done any level 3 charging and only occasionally use level 2 charging for a short time while at a store.
Received:
6 April 2018
Commenter:
Henrik Moller
The commenter has declared there is no conflict of interests.
Comment:
Thanks for your observations. Loss of the first bar indicates that your 30 kWh Leaf probably has a State of Health between 72% and 83% (see our graph at Comment #3 above). This is a very high rate of loss in 12 months. Social media networks have reported many similar examples, but of course we most need a large and representative sample before we can quantify the fleet averages in different regions and climates, and the effects of travel distance and charging patterns.
Your saleperson's comparison of their own 30 kWh and 24 kWh Leafs is allows a more tightly "paired comparison" because presumably both are operating in the same terrain and climate and being charged in similar ways. Another family that owns both a 30 kWh and 24 kWh Leaf has also reported (on social media) that the 30 kWh Leaf is losing battery capacity faster.
We hope that our paper will spur collation of data in systematic and robust ways using a 'citizen science' approach that learns from the experience of early adopters of electric vehicles of all makes and models.
Comment 14
Received:
5 April 2018
Commenter:
AE Cutten
The commenter has declared there is no conflict of interests.
Comment: Statistically you are comparing two sets of data. 30kW n=82 with 24kW n=201. The null hypothesis should be that there is no difference between each data set, ie. both batteries "belong" to the same "population". You are looking for evidence that thisw is not so and they are different. I think the appropriate statistical test is the Students t-test but there may be other more sophisticated tests available. I recommend you consult a qualified statistician on this. The putative results may be quite disturbing to recent 30kW purchasers. Its perhaps early days before the real result is known. It would be nice to know what Nissan have down to get the greater storage performance in the 30kW battery, but this is probably tightly held IP.
Tony (24kW owner.)
1 D BY ERIC LOVEDAY 107
It’s not quite as detailed as we hoped for, but at least Nissan is fully aware of the concern and is investigating the potential issue.
Earlier this week, we presented the highly detailed findings of an in-depth Nissan LEAF battery degradation study.
Battery Issues – Nissan LEAF 30-kWh Battery Degrades More Rapidly Than 24-kWh Pack
The takeaway from the published results were:
“At two years of age, the mean rate of decline of SoH of 30 kWh Leafs was 9.9% per annum (95% uncertainty interval of 8.7% to 11.1%; n = 82). This was around three times the rate of decline of 24 kWh Leafs which at two years averaged 3.1% per annum (95% uncertainty interval of 2.9% to 3.3%; n = 201).”
Or, in very simplified terms, the 30-kWh LEAF seemed to have much higher battery degradation rates than the 24-kWh LEAFs.
The study concluded by suggesting that the rate of decline in the 24-kWh version of the LEAF is acceptable, but suggests that the 30-kWh pack declines too rapidly to be considered within normal parameters.
Replacement Batteries – Nissan Introduces $2,850 Refabricated Batteries For LEAF
Following the release of the results of this study and our coverage of the potential issue, Green Car Reports reached out to Nissan for comment. EV communication manager, Jeff Wandell, offered this response:
“Nissan is aware that a limited number of customers have expressed concerns with the previous generation of the Nissan LEAF 30-kWh battery.”
“LEAF owners are some of our most devoted customers.”
“We take their concerns seriously, and have technical experts currently investigating the issues raised.”
We’re glad to know that Nissan is looking into this potential issue. We’ll report back if Nissan presents any additional information.
The abstract from the work titled “Accelerated Reported Battery Capacity Loss in 30 kWh Variants of the Nissan Leaf” contains more details on the issue. It states:
Analysis of 1382 measures of battery State of Health (SoH) from 283 Nissan Leafs (“Leaf/s”), manufactured between 2011 and 2017, has detected a faster rate of decline in this measure of energy-holding capacity for 30 kWh variants.
At two years of age, the mean rate of decline of SoH of 30 kWh Leafs was 9.9% per annum (95% uncertainty interval of 8.7% to 11.1%; n = 82). This was around three times the rate of decline of 24 kWh Leafs which at two years averaged 3.1% per annum (95% uncertainty interval of 2.9% to 3.3%; n = 201).
For both variants there was evidence for an increasing rate of decline as they aged, although this was much more pronounced in the 30 kWh Leafs. Higher use of rapid DC charging was associated with a small decrease in SoH. Additionally, while 24 kWh cars with greater distances travelled showed a higher SoH, in 30 kWh cars there was a reduction in SoH observed in cars that had travelled further.
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.
Improvements in the battery health diagnostics, continuous monitoring of battery temperatures and state of charge, and verification of a fundamental model of battery health are needed before causes and remedies for the observed decline can be pinpointed.
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 were to continue, the financial and environmental benefits of this model may be significantly eroded. Despite 30 kWh Leafs accounting for only 14% of all light battery electric vehicles registered for use on New Zealand roads at the end of February 2018, there is also the potential for the relatively poor performance of this specific model to undermine electric vehicle uptake more generally unless remedies can be found.
Myall, D.; Ivanov, D.; Larason, W.; Nixon, M.; Moller, H. Accelerated Reported Battery Capacity Loss in 30 kWh Variants of the Nissan Leaf. Preprints 2018, 2018030122 (doi: 10.20944/preprints201803.0122.v1)
Myall, D.; Ivanov, D.; Larason, W.; Nixon, M.; Moller, H. Accelerated Reported Battery Capacity Loss in 30 kWh Variants of the Nissan Leaf. Preprints 2018, 2018030122 (doi: 10.20944/preprints201803.0122.v1)
Par mon expérience personnelle : je viens de perdre une barre d'autonomie sur ma Leaf 30Kwh a 18000Kms ; a 6000Kms j'avais encore 230 Kms d'autonomie alors que maintenant je n'ai plus que 170Kms.(documents joints basés sur Leaf Spy Pro).
Je tiens a votre disposition mes relevés Leaf Spy Pro.Merci de me contacter pour envoi des images.
Received:
7 June 2018
Commenter:
Igor Divjak
The commenter has declared there is no conflict of interests.
Comment:
Thanks for making this excellent study public.
I have a 30kwh model Leaf which has experienced rapid battery decline. I also have an EV policy with Autosure which supposedly covers battery failure. I will be challenging their stance that this degradation is normal, in small claims court. I notice that in your study you mention that Nissan expected 80% capacity at 5 years of age, as represented by the red dot in your 24/30kwh comparison graph.
Unfortunately I can't find the reference for this in your study, or online. Could you please show me where I could find it? It would be helpful to show by way of comparison.
Received:
12 June 2018
Commenter:
Matt W
The commenter has declared there is no conflict of interests.
Comment:
Following up on my observation that the curves in Figure 1. appear to have been constrained to be 100% state of health at 0 years of life, even though there are no actual data at or very near 0 years.
As I said, curves fitted without this constraint would be a better predictor of the actual trends in the data and perhaps avoid implying a curvature not supported by the data.
As a further improvement, I would also remove from the curve fit all the data points throughout the time series that are at or very near 100%. I think we can agree that the state of health measure plotted appears cut off at 100% and a possibly significant number of data points appear to be sitting just at or below 100%.
The basic conclusion of the paper is clear directly from the data (accelerated decline in the 30 kWh model compared with the 24 kWh one(s)) and doesn’t rely on any curve fitting. I think we agree that curve fitting can be useful in predicting future performance but that such predictions are characterised by uncertainty and need to be viewed with caution. The inference that "both battery models showed increasing decline with age" is clear from the data but any conclusion (as the fitted models imply) of increasing rate of decline with age might not be so clear at all if the year 0 constraint and the 100% state of health data were not considered in the fit.
Received:
8 August 2018
Commenter:
Humberto Barreto
Commenter's Conflict of Interests:
I'm the original owner of a 2013 Leaf with 46,500 miles, displaying 12 bars, in Indiana, USA.
Comment:
In terms of the research question, differences between 24kWh and 30kWh batteries, the evidence seems pretty strong. It's an interesting and important question. I enjoyed reading the paper.
I was wondering if there is any theory that you could use to guide the functional form? Is there anything in chemistry that says "SoH = b0 + b1Km^-1 + b2Cycles^-2 + . . . ?
Also, can you make the data set available? I would enjoy poking around with it. I teach econometrics and it might make a good example for class.
Commenter: Peter Hallinan
The commenter has declared there is no conflict of interests.
a/ any data (or even hunches) about other variants of the Nissan Leaf ? or other electric cars such as the Zoe?
b/ I own a BMW i3 which has now travelled >61000km in the just over 3 years since I bought it new. As far as I can judge, the electric battery still manages to notch up about 150km before depletion, at which point the range extender kicks in to about double that to 300km before I have to consider recharging. I have noticed some variability in the range the battery will take me when fully charged - anything up to about 40km difference in range, but can't put my finger on why this variability happens.
cheers
Peter
Commenter: Keith Chapman
The commenter has declared there is no conflict of interests.
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.
Kind regards,
Keith
Commenter: Ken Morison
Commenter's Conflict of Interests: I own a 24 kWh Leaf.
Commenter: Brian Worboys
The commenter has declared there is no conflict of interests.
My concern is that there may be a bit of self-fulfilling-prophesy in the data for the 30kwh cars. The project is relying on interested volunteer Leaf owners providing their data. Once the word gets around that the 30kwh cars may have a problem, the owners of these cars, who suspect they may have a battery with accelerated decline will be keener to find out more about this, and join FtF, than other owners who have not noticed any untoward loss in predicted range. If this happens, then the data will be skewed towards cars with the more rapid decline. It won't be representing the whole fleet.
However, there will be 30kwh cars that began providing data from a time before the 30kwh battery came under suspicion. The data from this subgroup could be used to validate the trend of the whole group.
Commenter: Kirk Summerwill
The commenter has declared there is no conflict of interests.
The reference to a facebook group for information (NAZ EV Owners Group (2018) doesn't allow readers to find that evidence, nor is any critical evaluation or description of that evidence given - without better referencing I would mention that it is anecdotal rather than an online poll or other activity (if true). Caution is clearly required as cultural narratives may exist in USA audiences that may not be present elsewhere.
The study notes that the sample are self selecting and convenience sample, but no critical appraisal of the issues this may bring or the actual method and process of selection/recruitment is given so readers cannot determine the extent to which this is a methodological influence.
Overall though a compelling study. Greater control for user behavioural factors would be an advantage also.
Commenter:
The commenter has declared there is no conflict of interests.
In the discussion (lines 294 to 302) we cover some potential issues around the convenience sample and why we don't believe sampling bias could explain the results. In a nutshell (i) the difference between the Leaf variants is huge, so any representativeness bias would have to be huge to explain the result; (ii) many people joined long before any suggestion of an issue with the battery was being aired (indeed most signup soon after buying their vehicle), (iii) many didn’t scan at the start but did so when we asked them to check. But more fundamentally, (iv) any bias would presumably be operating in both 24 and 30 kWh subsamples, so bias itself is most unlikely to be a sufficient explanation for the group difference. Now that the news of the 30 kWh battery capacity loss is being openly discussed, there is much more risk that those with unusually degraded batteries are more likely to sign-up – so we will work hard to test for such bias in the data received from now on.
We agree that it would be beneficial to provide more details on how users were recruited and we'll include this in the next version.
Many thanks for your critique.
Commenter's Conflict of Interests: I own a 2 year old Leaf 30 kWh with 45.000 km.
I believe this value is an undocumented value and it is not clear what it stands for.
It must be a different value than Nissan is using, otherwise my Leaf shall not show a full health scale, bur0t LeafSpy shows SOH 81% at my 30 kWh Leaf.
Either SOH or the value shown by Nissan are wrong.
Commenter:
The commenter has declared there is no conflict of interests.
Yes, we have based our main analysis on the State of Health (SoH) metric that is reported by LeafSpy. We are not sure what you mean by Nissan’s ‘health scale’ but expect that it might mean the number of ‘bars’ displayed on the dashboard to the extreme right of the state of charge bars. So, when you refer to your 81% SoH battery pack showing “full health scale”, do you mean that you are showing 12 out of 12 bars? Please confirm so that we can fully evaluate your concern.
In the meantime, we see no reason to discount the use of SoH as a broad scale metric, provided it is used within safe limits of inference. i.e.
In conclusion, we are confident that SoH is a reliable and scientifically-based metric of battery energy holding capacity that has sufficient repeatability to signal evidence of accelerated degradation of 30 kWh batteries in their first 2.3 years of life. Your concerns, and similar scepticism expressed by contributors to the EV owners social networks in recent days, suggests that we should now include the new Figure below in version 2 of the paper.
Your comments have helped us clarify the messages even if though we don’t agree with your critique. Thanks!
Commenter: Matt W
The commenter has declared there is no conflict of interests.
Also, even if Leafs do report 100% SOH at 0 years, are you sure that that the systems doesn't for example calculate some parameter SOH' and then simply apply a cut-off of 100% to SOH' to get SOH. The battery firmware could presumably do any kind of non-linear tricks it likes.
If either of those situations is correct then the curvature of the model may be less useful as a predictor of a future trend.
Commenter:
The commenter has declared there is no conflict of interests.
We agree that extreme caution should be applied when predicting future decline. As discussed in the paragraph starting on line 341, there is a need to test and refine an underlying model of battery SoH decline, and it is uncertain at this stage whether decline will progress in the fashion detected so far.
As we gain further longitudinal data in the 30 kWh cars over the next months the uncertainty around SoH's trajectory in the first year will have less influence on the model's shape. In the meantime we have refrained from forward extrapolation, partly because if the paucity of data in the first year and partly because the underlying model of battery degradation and its drivers are not certain. We need for more of the batteries' life cycle to elapse before we could make plausible projections of what to expect next.
Thanks again for your critique.
Commenter: Roberto San José Mendiluce
The commenter has declared there is no conflict of interests.
También le envio el link del video de Nissan Tv. Espero que le guste.
Historia del primer taxi #Nissan #LEAF de Esp @TaxiNissanLeaf imposible contarlo mejor #EVhttp://bit.ly/1hK76Tz pic.twitter.com/nYjxkg5ASl
EMB15079_NISSAN_ELECTRICOS_V1.mp4
270.000 kilómetros recorridos ahorrando 21.060 litros de combustible, 18 cambios de aceite, de filtros, de pastillas de freno, juego distribución, etc, etc, de visitas al taller. No emitir gases contaminantes de efecto invernadero y contribuir a mejorar la calidad del aire... no tiene precio. https://www.facebook.com/brubaker.nissan/posts/1001629483300729
280.000 kilómetros recorridos con un Taxi 100 % ELÉCTRICO. Cada día se confirma la fiabilidad, rendimiento y necesidad de cambiar a sistemas de movilidad 100 % eléctrica. https://www.facebook.com/brubaker.nissan/posts/1061933267270350
288.000 kilómetros recorridos. Solo 4 barras de autonomía perdidas y las pastillas de freno con un 50 % de desgaste https://web.facebook.com/brubaker.nissan/posts/1104110163052660 …
El coste de recorrer +288.000 kilómetros sin consumir una sola gota de combustible es: https://www.facebook.com/brubaker.nissan/posts/1104417249688618 …
300.000 kilómetros en seis años: la historia del primer taxi eléctrico en España. Roberto San José Mendiluce se convirtió, sin saberlo, en el primer taxista que conducía un coche eléctrico en España. Ahora hay unos 60 como él. https://www.linkedin.com/feed/update/urn:li:activity:6324564205504724992
Los coches eléctricos ya son una alternativa viable, y así nos lo han asegurado sus mejores probadores: los Taxistas. https://www.motorpasion.com/coches-hibridos-alternativos/los-coches-electricos-ya-son-una-alternativa-viable-y-asi-nos-lo-han-asegurado-sus-mejores-probadores-los-taxistas
Atte. Roberto San José Mendiluce.
Reciba un cordial saludo.
Carta de Presentación
Hola me llamo Roberto San José Mendiluce y soy el Primer Taxi 100 % Eléctrico en España.
Conduzco un Nissan LEAF desde Octubre del 2011 . Pertenece a la primera generación que se fabricó en Oppama (Japón) y está equipado con una batería de litio de 24 kWh. He recorrido más de 321.000 kilómetros con Zero Emission y Zero averias.
Mi objetivo es claro, transmitir las ventajas medioambientales y económicas que ofrece una Movilidad 100 % Eléctrica. Quiero demostrar la fiabilidad y el mínimo gasto en mantenimiento de este tipo de Vehículos. Para ello me he propuesto alcanzar las 200.000 millas recorridas con un Taxi 100 % Eléctrico, conservando la batería "original de fábrica" y sin haber efectuado ningún cambio de pastillas de freno.Publico toda la información que puedo sobre los Vehículo s Eléctrico s y las Energías Renovables y en especial lo relacionado con el Nissan LEAF.
Todas m is cuentas Sociales son "públicas" para que aquellas personas que tengan interés en la Movilidad 100 % Eléctrica puedan consultar dicha información.
Facebook:https://www.facebook.com/brubaker.nissan
Twitter: https://twitter.com/TaxiNissanLeaf
LinkedIn: es.linkedin.com/pub/roberto-san-josé-mendiluce/5a/691/51
Google+: https://plus.google.com/+RobertoSanJoséMendiluce
Mail: taxi038@gmail.com
Teléfono de contacto: +34 699 96 64 61
Atte. Roberto San José Mendiluce
Reciba un cordial saludo.
Commenter: Roberto San José Mendiluce ( Brubaker.Nissan )
The commenter has declared there is no conflict of interests.
Conduzco un Nissan LEAF desde Octubre del 2011 . Pertenece a la primera generación que se fabricó en Oppama (Japón) y está equipado con una batería de litio de 24 kWh. He recorrido más de 321.400 kilómetros con Zero Emission y Zero averias.
Mi objetivo es claro, transmitir las ventajas medioambientales y económicas que ofrece una Movilidad 100 % Eléctrica. Quiero demostrar la fiabilidad y el mínimo gasto en mantenimiento de este tipo de Vehículos. Para ello me he propuesto alcanzar las 200.000 millas recorridas con un Taxi 100 % Eléctrico, conservando la batería "original de fábrica" y sin haber efectuado ningún cambio de pastillas de freno.Publico toda la información que puedo sobre los Vehículo s Eléctrico s y las Energías Renovables y en especial lo relacionado con el Nissan LEAF.
Commenter:
The commenter has declared there is no conflict of interests.
Gracias por su comentario. Qué fantástico oír sobre tan largas distancias recorridas sin fallos mecánicos en el Leaf de 24kWh. También estamos muy interesados en publicar sobre los beneficios medioambientales y económicos asociados con el uso de vehículos 100% eléctricos. En éste momento, nuestro artículo ilustra la única amenaza seria a los beneficios económicos y medioambientales de los vehículos eléctricos. Coincidimos con usted, como tan bien ha relatado, en que las baterías de 24 kWh tienen una longevidad excelente. Esperamos que a nuestras observaciones sobre las baterías de 30 kWh les siga un mayor entendimiento científico de la causa y su solución.
Original comment: Hello my name is Roberto San José Mendiluce and I am the 1st 100% electric taxi in Spain.
I have driven a Nissan LEAF since October 2011. It belongs to the 1st generation built in Oppama (Japan), equipped with a 24 kWh lithium battery. I have logged more than 321,400 km with zero emissions and zero mechanical issues.
My goal is clear, to transmit the environmental and economic advantages from a 100% electric transport medium. I want to demonstrate the reliability and minimal maintenance in these types of vehicles. For this, I plan to drive 200,000 miles with a 100% electric taxi, with the original factory battery and without having had to change the brake pads. I publish all the information that I can about electric vehicles and renewable energies. In particular, all related to Nissan LEAF.
Our reply: Thank your for your comment and it is great to see such large distances traveled in a 24 kWh Leaf with no maintenance issues. We are also very keen to publish about the environmental and economic benefits of electric vehicles. This is the only serious threat that we have seen so far to the environmental and economic benefits of electric vehicles, and illustrated so dramatically by your experience. We agree that the 24 kWh batteries are lasting extremely well. We hope that our observations of 30 kWh batteries will be followed by greater scientific understanding of the underlying cause so that solutions to be developed.
Commenter:
The commenter has declared there is no conflict of interests.
Commenter: Henrik Moller
The commenter has declared there is no conflict of interests.
Commenter: Clive Appleton
The commenter has declared there is no conflict of interests.
As an aside.
I was alerted by a friend about the Listener article, unfortunately a day after I had signed up to buying a 2016 imported leaf from a Nissan agent. Conflicting advice from the agent has seen me having to write to Nissan NZ to get clarification on availability of batteries and parts. I have also asked them about your findings and had they any comment; I'm awaiting a response. As it stands, I'm unlikely to proceed with the leaf purchase.
Commenter: Kenneth Kar
Commenter's Conflict of Interests: I am an owner of Nissan Leaf
Commenter: Henrik Moller
The commenter has declared there is no conflict of interests.
Commenter's Conflict of Interests: I lease a Nissan Leaf
Our typical commute is about 35 miles round trip plus town errands under 5 miles round trip (air conditioner always on). At home it’s in a garage so it’s only in the sun when out and about. 90+% of driving is flat land and under 45 mph due to the low speed limits and all the traffic lights. It’s usually plugged in to charge (level one charging) daily as soon as we get home with the battery typically around 60% or more in charge and by morning it’s 100% or close to 100%. So maybe keeping the battery at a higher state of charge is not good. Also I watched a video somewhere of someone reading from the 2018 Leaf manual which recommended waiting an hour after driving to allow the battery to cool down a little before plunging it in to charge. So maybe it’s similar for a 2017 Leaf. We ha e never done any level 3 charging and only occasionally use level 2 charging for a short time while at a store.
Commenter: Henrik Moller
The commenter has declared there is no conflict of interests.
Your saleperson's comparison of their own 30 kWh and 24 kWh Leafs is allows a more tightly "paired comparison" because presumably both are operating in the same terrain and climate and being charged in similar ways. Another family that owns both a 30 kWh and 24 kWh Leaf has also reported (on social media) that the 30 kWh Leaf is losing battery capacity faster.
We hope that our paper will spur collation of data in systematic and robust ways using a 'citizen science' approach that learns from the experience of early adopters of electric vehicles of all makes and models.
Commenter: AE Cutten
The commenter has declared there is no conflict of interests.
Tony (24kW owner.)
Commenter: Duretete Guy
The commenter has declared there is no conflict of interests.
Je confirme cet article de https://insideevs.com/nissan-issues-statement-on-leaf-30-kwh-battery-degradation/
Nissan Issues Statement On LEAF 30-kWh Battery Degradation
1 D BY ERIC LOVEDAY 107
It’s not quite as detailed as we hoped for, but at least Nissan is fully aware of the concern and is investigating the potential issue.
Earlier this week, we presented the highly detailed findings of an in-depth Nissan LEAF battery degradation study.
Battery Issues – Nissan LEAF 30-kWh Battery Degrades More Rapidly Than 24-kWh Pack
The takeaway from the published results were:
“At two years of age, the mean rate of decline of SoH of 30 kWh Leafs was 9.9% per annum (95% uncertainty interval of 8.7% to 11.1%; n = 82). This was around three times the rate of decline of 24 kWh Leafs which at two years averaged 3.1% per annum (95% uncertainty interval of 2.9% to 3.3%; n = 201).”
Or, in very simplified terms, the 30-kWh LEAF seemed to have much higher battery degradation rates than the 24-kWh LEAFs.
The study concluded by suggesting that the rate of decline in the 24-kWh version of the LEAF is acceptable, but suggests that the 30-kWh pack declines too rapidly to be considered within normal parameters.
Replacement Batteries – Nissan Introduces $2,850 Refabricated Batteries For LEAF
Following the release of the results of this study and our coverage of the potential issue, Green Car Reports reached out to Nissan for comment. EV communication manager, Jeff Wandell, offered this response:
“Nissan is aware that a limited number of customers have expressed concerns with the previous generation of the Nissan LEAF 30-kWh battery.”
“LEAF owners are some of our most devoted customers.”
“We take their concerns seriously, and have technical experts currently investigating the issues raised.”
We’re glad to know that Nissan is looking into this potential issue. We’ll report back if Nissan presents any additional information.
The abstract from the work titled “Accelerated Reported Battery Capacity Loss in 30 kWh Variants of the Nissan Leaf” contains more details on the issue. It states:
Analysis of 1382 measures of battery State of Health (SoH) from 283 Nissan Leafs (“Leaf/s”), manufactured between 2011 and 2017, has detected a faster rate of decline in this measure of energy-holding capacity for 30 kWh variants.
At two years of age, the mean rate of decline of SoH of 30 kWh Leafs was 9.9% per annum (95% uncertainty interval of 8.7% to 11.1%; n = 82). This was around three times the rate of decline of 24 kWh Leafs which at two years averaged 3.1% per annum (95% uncertainty interval of 2.9% to 3.3%; n = 201).
For both variants there was evidence for an increasing rate of decline as they aged, although this was much more pronounced in the 30 kWh Leafs. Higher use of rapid DC charging was associated with a small decrease in SoH. Additionally, while 24 kWh cars with greater distances travelled showed a higher SoH, in 30 kWh cars there was a reduction in SoH observed in cars that had travelled further.
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.
Improvements in the battery health diagnostics, continuous monitoring of battery temperatures and state of charge, and verification of a fundamental model of battery health are needed before causes and remedies for the observed decline can be pinpointed.
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 were to continue, the financial and environmental benefits of this model may be significantly eroded. Despite 30 kWh Leafs accounting for only 14% of all light battery electric vehicles registered for use on New Zealand roads at the end of February 2018, there is also the potential for the relatively poor performance of this specific model to undermine electric vehicle uptake more generally unless remedies can be found.
Myall, D.; Ivanov, D.; Larason, W.; Nixon, M.; Moller, H. Accelerated Reported Battery Capacity Loss in 30 kWh Variants of the Nissan Leaf. Preprints 2018, 2018030122 (doi: 10.20944/preprints201803.0122.v1)
Myall, D.; Ivanov, D.; Larason, W.; Nixon, M.; Moller, H. Accelerated Reported Battery Capacity Loss in 30 kWh Variants of the Nissan Leaf. Preprints 2018, 2018030122 (doi: 10.20944/preprints201803.0122.v1)
Source: Preprints
Nissan statement via Green Car Reports
Category: Nissan
Tags: featured, leaf battery, leaf battery degradation, Nissan LEAF, Nissan LEAF 30 kWh
Par mon expérience personnelle : je viens de perdre une barre d'autonomie sur ma Leaf 30Kwh a 18000Kms ; a 6000Kms j'avais encore 230 Kms d'autonomie alors que maintenant je n'ai plus que 170Kms.(documents joints basés sur Leaf Spy Pro).
Je tiens a votre disposition mes relevés Leaf Spy Pro.Merci de me contacter pour envoi des images.
Bien cordialement.
MEMO0002rd.jpg
P1160423rd.jpg
Commenter: Igor Divjak
The commenter has declared there is no conflict of interests.
I have a 30kwh model Leaf which has experienced rapid battery decline. I also have an EV policy with Autosure which supposedly covers battery failure. I will be challenging their stance that this degradation is normal, in small claims court. I notice that in your study you mention that Nissan expected 80% capacity at 5 years of age, as represented by the red dot in your 24/30kwh comparison graph.
Unfortunately I can't find the reference for this in your study, or online. Could you please show me where I could find it? It would be helpful to show by way of comparison.
Thank you.
- Igor
Commenter: Matt W
The commenter has declared there is no conflict of interests.
As I said, curves fitted without this constraint would be a better predictor of the actual trends in the data and perhaps avoid implying a curvature not supported by the data.
As a further improvement, I would also remove from the curve fit all the data points throughout the time series that are at or very near 100%. I think we can agree that the state of health measure plotted appears cut off at 100% and a possibly significant number of data points appear to be sitting just at or below 100%.
The basic conclusion of the paper is clear directly from the data (accelerated decline in the 30 kWh model compared with the 24 kWh one(s)) and doesn’t rely on any curve fitting. I think we agree that curve fitting can be useful in predicting future performance but that such predictions are characterised by uncertainty and need to be viewed with caution. The inference that "both battery models showed increasing decline with age" is clear from the data but any conclusion (as the fitted models imply) of increasing rate of decline with age might not be so clear at all if the year 0 constraint and the 100% state of health data were not considered in the fit.
Commenter: Humberto Barreto
Commenter's Conflict of Interests: I'm the original owner of a 2013 Leaf with 46,500 miles, displaying 12 bars, in Indiana, USA.
I was wondering if there is any theory that you could use to guide the functional form? Is there anything in chemistry that says "SoH = b0 + b1Km^-1 + b2Cycles^-2 + . . . ?
Also, can you make the data set available? I would enjoy poking around with it. I teach econometrics and it might make a good example for class.
Thank you for sharing your work,
Humberto
Commenter:
The commenter has declared there is no conflict of interests.
We have released a preliminary report around this update at https://flipthefleet.org/2018/30-kwh-nissan-leaf-firmware-update-to-correct-capacity-reporting/.
Once further data has been collected and analysed an update to the preprint will be posted.