Nissan has purchased Leafs from two owners in Phoenix who complained of losing battery capacity due to high temperatures.
The company says that the batteries are not defective, but plans to buy back the cars as a “good-will gesture” using the state’s buyback formula as a guide, said David Reuter, the vice president of corporate communications for Nissan Americas.
“In Phoenix, a small handful of Nissan LEAF customers have complained of gradual battery capacity loss, which is a normal occurrence in battery electric vehicles, is expressly excluded under the vehicle’s warranty and can be impacted by extreme heat, high speed, high mileage and charging method and frequency,” Reuter said in a statement.
Over the past several months, a number of Leaf owners in Arizona said they are experiencing falling driving range due to battery capacity loss. In response, Nissan performed tests on a number of cars and found the capacity loss occurred with drivers who have higher-than-average mileages in a hot environment over a short period, according to a letter posted to Leaf owners on Saturday.
Some range loss is normal for all electric vehicles that use lithium ion batteries. Nissan estimates that the average Leaf’s batteries will have about 80 percent of the original capacity after five years. The conditions in Arizona are more like 76 percent of capacity after five years, according to Carla Bailo, the senior vice president of research & development at Nissan Americas.
“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,” she wrote.
A group of Nissan Leaf owners did a controlled test earlier this month and found that the driving range of a 2011 model, estimated at 73 miles by the EPA, had slipped to 59 miles. (See Don’t Drive Your Nissan Leaf Too Much.)
Nissan has also hired EV advocate Chelsea Sexton, who worked in marketing for General Motors’ EV1, to create a global advisory board. The goal is to aid communication between Nissan Leaf owners and the company.
This capacity issue has affected a very small number of the roughly 15,000 people who have purchased the Nissan Leaf over the past two years. But the Arizona episode does shine a light on how electric vehicle driving range can be affected from factors such as climate, mileage, and charging patterns.
Batteries perform best and will last longer if they are shielded from temperatures extremes. Nissan’s Leaf battery relies on air cooling. By contrast, General Motors, Ford, and Tesla Motors have active thermal management systems where a liquid is circulated around the battery pack. (See, Are Air-Cooled Batteries Hurting Nissan Leaf Range?)