Is the battery of the popular Nissan Leaf degrading too early?by Peter Griffin
A group of New Zealand citizen scientists claims to have discovered a problem with the battery powering the world’s best selling electric vehicle - the Nissan Leaf.
UPDATE 19 March: Nissan has responded to this story. You can skip to it here .
Researchers and electric vehicle enthusiasts from around the country claim to have found that the battery capacity, which offers range of up to 172km on a single charge, degrades three times faster than the lower capacity 24kWh battery model at two years of age.
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Nissan Leafs fitted with a 30kWh battery and aged up to 2.3 years, were already experiencing loss of battery capacity that Nissan estimated could be expected at the five-year mark.
Replacement of a Leaf battery can cost around $9,000, though the majority of replacements are for the 24kWh battery, which has been on the market for longer.
That may see Leaf owners facing reduced driving range and expensive battery replacements years earlier than expected. There are 3,250 Nissan Leafs registered in New Zealand, 600 of which have the 30kWh battery in them. A further 180 Leafs with the same capacity battery are on their way to New Zealand or sitting on dealers’ car yards. Overall, Leafs with the higher capacity battery make up around 14 per cent of New Zealand’s entire electric vehicle fleet.
The higher capacity battery option is proving popular with those shifting to electric vehicles and wanting to avoid the “range anxiety” that comes with purchasing lower capacity battery models. The 30kWh Leaf model has been on sale since early 2016.
Henrik Moller, University of Otago emeritus professor and co-founder of community electric vehicle project, Flip The Fleet co-authored the study into the Leaf battery performance, and claimed that the rate of decline in battery capacity seemed to be accelerating as the cars get older.
“We do not know for certain what the underlying causes of 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,” he said.
Repeated rapid charging of the batteries, which can see the battery fully charged in as little as 30 minutes and which is essential for long trips, could be part of the problem. But the researchers say that doesn’t explain the majority of the degraded capacity they are seeing.
The researchers crowdsourced the data for the study from Leaf owners around the country who have registered their cars with Flip the Fleet and shared data taken from their Leaf’s battery management system.
The key measure the researchers looked at is what is known as ‘State of Health’ which compares the energy the battery currently holds compared to what it would have been able to hold under ideal conditions at the time it was manufactured.
Of the 283 Leafs featured in the study, 82 had the 30kWh battery. The study claims that at around two years old, the Leaf’s battery capacity was dropping at nearly 10 per cent per year, compared to around 3 per cent for the lower capacity 24kWh battery, which allows maximum range of 135km.
The researchers assembled a panel of 12 reviewers to assess their methodology and have published their paper online ahead of submitting it to an international peer-reviewed journal.
Moller said the Flip the Fleet group were making the results public ahead of journal publication because of the fast-growing demand for electric vehicles and the potential for the poor performance of the high capacity Leaf battery to “undermine electric vehicle uptake” in New Zealand.
Nissan was sent the Flip The Fleet research results in late February.
Nissan's New Zealand managing director, John Manley, did not respond to requests for comment by deadline, but sent a statement after the story was published:
“Nissan is proud to be an innovator in electric vehicles - with more than 300,000 LEAF vehicles on the road - the most EVs of any manufacturer, completing more than four billion zero-emission kilometres worldwide.
"We are aware of the alleged findings and are conducting a thorough internal investigation.”
The results have also been shared with various consumer and motor industry bodies, including, Consumer NZ, the Automobile Association and the Vehicle Importers Association.
The Ministry of Transport is also aware of the research. The Government has the goal of reaching approximately 64,000 electric vehicles on our roads by the end of 2021 and a road user charge exemption for light electric vehicles was extended until then to encourage electric vehicle uptake.
Nissan has never sold 30kWh Nissan Leafs in New Zealand and only honours factory warranties on new cars bought in New Zealand, a policy common to most car makers. Aftermarket warranties offered by secondhand car dealers selling Leafs may provide cover, but policies often exclude battery replacement.
Consumer New Zealand’s head of testing, Paul Smith, said he believes owners of cars exhibiting this problem have a recourse under the Consumer Guarantees Act, which states goods must be of "acceptable quality".
"For buyers who made it clear the extra range of the 30kWh was a key factor at the time of purchase, the CGA case is even stronger. The act states goods must be fit for a particular purpose that you asked about.
"If your vehicle’s affected, you can go back to the dealer who sold the car (also likely to be the importer) and ask for a remedy."
Smith says if the problem can't be fixed, owners could claim compensation for any drop in value, or even reject the car for a refund.
Sales of the Leaf currently far outstrip those of other models of electric vehicles including the Mitsubishi Outlander, Hyundai Ioniq and BMW i3.
Moller said Leaf owners with the 30kWh battery model should get their battery scanned to determine its State of Health and contact consumer organisations such as the Automobile Association for advice.
He stressed that the Leaf had paved the way for electric vehicle take-up in New Zealand and that the 24kWh version was performing as expected.
“The accelerated decline observed by Flip The Fleet is isolated to one variant of the EV model. It does not signal general concern for the practicality, financial and environmental benefits of all EVs,” he said.
Visit www.flipthefleet.org for more information and advice for Leaf owners.
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