Nissan Leaf battery troubles give owners a negative shock

The hottest summer on record in the United States has raised the anger on a group of Nissan Leaf electric vehicle owners in the southwest to a full boil, after their cars began losing recharging capacity, leaving them low or out of juice in the extreme heat. A dozen even conducted an independent test of their cars to give Nissan data to back up their worries. Nissan replied this weekend with results from its own tests, saying everything's OK, mostly -- an answer that's only raised the owners' temperatures.

Like any device powered by lithium batteries that are frequently charged and discharged, the $35,000 Nissan Leaf will lose some of its charging capacity over time. Nissan says the average driver will see the energy available from the 24-kWh battery pack decline by 20 percent over five years. The battery can also temporarily lose some capacity in extreme hot or cold weather -- problems that other EV builders such as General Motors and Tesla combat by building heating and cooling systems into their battery packs, a step Nissan avoided with the Leaf.

No city poses a tougher test for an EV like the Leaf than Phoenix, where the average 24-hour temperature for July was 93 degrees, and several days posted highs above 110. Dozens of owners had complained to Nissan about their Leafs losing capacity far faster than expected -- with one saying his dash never showed more than two-thirds charged no matter how long it was plugged in. While Nissan swapped out the battery of one owner, it has said the worries were a bit overblown and denying any issue with the car's batteries.

That led a group of 12 owners to conduct their own tests earlier this month, driving their cars along a pre-planned route in well-documented conditions to measure just how much their range had fallen. By their estimates, a brand-new Leaf should have been able to travel 84 miles on the course before shutting into a safe mode known as "turtling," for the yellow turtle icon that pops up on the dashboard. Of the 12 test Leafs, two were able to travel nearly 80 miles -- but the average was 71, and one couldn't make 60 miles.

On Friday, Nissan executive Carla Bailo sent an open letter to Leaf owners, saying that Nissan's testing showed the Leaf performing as expected with no battery defects, although "a small number of Nissan Leaf owners in Arizona are experiencing a greater than average battery capacity loss" due to what she called high-mileage driving in hot weather over a short period of time. (The 12 Leafs in the customer test had between 2,500 and 30,000 miles.)

Bailo also said Nissan expects the roughly 450 Leafs its sold in Arizona to have an average battery capacity of 76 percent after five years -- a slightly worse rate of shrinkage than elsewhere -- with some owners suffering more. That did little to assuage worried owners about their newfound range anxiety; as one posted on the MyNissanLeaf forum after Bailo's letter: "If they truly believe this they would have a better battery warranty. I LOVE my Leaf, but I can't recommend them anymore because of this issue."

While Nissan has vowed to offer an improved battery in the next-generation Leaf, it will miss its 20,000-vehicle sales target for the United States this year. And although Nissan chief executive Carlos Ghosn says the company remains committed to expanding its EV models, other automakers see things differently; on Monday, Toyota's chief electric vehicle engineer said modern EVs "do not meet society's needs," and that Toyota will focus on hybrids while sharply curbing plans for an electric version of the Scion iQ. Either Toyota or Nissan is right about whether the world is ready for electric vehicles -- but it can't be both.