At this point most readers are aware that many Nissan LEAFs in very hot southern climates, like that of Phoenix, Arizona, have experienced some battery capacity loss, which has been translate by Nissan's on board instrumention as "bars lost."  The debate has been how much loss has there been, is Nissan's instrumentation over exaggerating that loss, and what is an acceptable amount to lose?

Understandably, Nissan has been more than a little guarded on the subject, and several theories have been floated (instrument failure, heat, mileage, driving style of those with loss) by the company ahead of results from actual testing of consumers cars done by Nissan at their testing facility in Casa Grande, Arizona.

Just recently Mark Perry, Nissan's Director of Product Planning and Advanced Tech, said that LEAFs, on the average, are still on a "glide path" to 76% capacity after 5 years/60,000 miles, very close to the expected national average of 80% (story here).

Nissan has also decided to convene an independent global advisory board, which is to headed up by Chelsea Sexton, noted EV advocate.  This board will also examine the issues and recommend a course of action for the company to follow, as well as aid Nissan in communicating better with their customers.

Nissan Exec Carla Bailo has issued an official letter to the LEAF community via Facebook and announcing the test results and the formation of this advisory committee:


Happy eve of National Plug In Day. We’re excited that Nissan LEAF owners are gathering nationally tomorrow to celebrate zero-emission motoring, and appreciate that so many of you are sharing your enthusiasm with others. You are truly our best ambassadors to the next generation of passionate EV drivers.

We also want to update you, the LEAF community, on our findings regarding battery capacity loss concerns expressed by a number of owners in the Phoenix market. Nissan takes customer concerns seriously, and we know many of you have been interested to hear what we’ve learned in our thorough investigation, and what it all means.

We identified seven LEAF owners in the Phoenix area who had reported concerns with their vehicles.  With their agreement we brought the cars to Nissan’s Arizona test facility, where we removed the batteries for evaluation, measured capacity, and conducted voltage testing on individual battery cells. These tests were diagnostic only; no modifications were performed to the battery packs themselves.

After returning cars to their owners, we analyzed the results of our tests, with specific emphasis on the rate of actual capacity loss for each vehicle. Our goals were simple: to determine 1) if there were any defects in materials or workmanship in the individual batteries or vehicle systems; 2) if the batteries were performing to specification; and  3)their performance relative to the global LEAF population.

This week, we will meet with these LEAF owners to share our findings on their individual vehicles. In the mean time, we can report the following overall findings:

  • The Nissan LEAFs inspected in Arizona are operating to specification and their battery capacity loss over time is consistent with their usage and operating environment.  No battery defects were found.
  • A small number of Nissan LEAF owners in Arizona are experiencing a greater than average battery capacity loss due to their unique usage cycle, which includes operating mileages that are higher than average in a high-temperature environment over a short period of time.
While we understand that some LEAF owners are concerned about battery capacity loss, we want all owners to remember that all battery-electric vehicles – and all lithium-ion batteries – demonstrate capacity loss over time. So while your LEAF may have been able to travel a certain distance or more on a charge when new, its range will decrease as the battery ages, miles accumulate and gradual capacity loss occurs. This loss in capacity will occur most rapidly in the early part of your battery’s life, but the rate should decrease over time. Information on gradual battery capacity loss is available in the paperwork that was delivered with your vehicle, in the owner’s manual and on the many vehicle resources available at

It is also important to put the scope of these concerns in perspective. Globally, there are more than 38,000 Nissan LEAFs on the road that have travelled more than 100 million zero-emission miles, and we expect these vehicles, in normal operating conditions, to retain 80 percent of battery capacity after five years. As each user’s operating characteristics are unique and many factors impact battery capacity, we can expect some vehicles to have greater than 80 percent capacity at five years, and some vehicles to have less.  In Arizona, we have approximately 450 LEAFs on the road.  Based on actual vehicle data, we project the average vehicle in that market to have battery capacity of 76 percent after five years – or a few percentage points lower than the global estimate.   Some vehicles in Arizona will be above this average, and some below.  Factors that may account for this differential include extreme heat, high speed, high annual mileage and charging method and frequency of the Nissan LEAFs in the Phoenix market.

We at Nissan stand by our product, and we also stand by our customers. Recently, we’ve asked Chelsea Sexton, a passionate advanced technology advocate, to convene an independent global advisory board. Members would be selected by Chelsea, not Nissan, and they would recommend their own mandate, but our hope is that they would hold up a mirror to us and help us to be more open and approachable in our communication and to advise us on our strategy. We should have more information on the advisory board in a few weeks.

As we work with individual owners to ensure their satisfaction, we are appreciative of your continued support of both the Nissan LEAF and the electric vehicle movement, overall. We look forward to continuing our dialogue here in the MyNissanLEAF forum and within the Nissan LEAF community.

Best Regards, Carla Bailo

Senior Vice President, Research & Development – Nissan Americas

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