“
...the mean line says that after five years of normal usage, you’d be at 80 percent state of health… and at 10 years you’d be at 70. That’s the norm, so that’s Mr. Average somewhere in the world. There are going to be people doing better than that, and people doing worse than that.
Photo courtesy of Nissan, © Nissan
”
Andy Palmer Nissan Executive Vice President
ment, which was posted to the MyNissanLeaf forum, the company’s tests found that: • 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. Nissan also asked EV advocate Chelsea Sexton to convene an independent advisory board to “help us to be more open and approachable in our communication and to advise us on our strategy.” In October, Ms. Sexton, one of the producers of the film Revenge of the Electric Car, and a co-founder of Plug In America, sat down with Nissan Executive Vice President Andy Palmer to hash
things out. Palmer succinctly laid out Nissan’s case. “There is a degradation of a battery over life. It’s straightforward physics and chemistry. It’s non-linear. We did the original mean - the norm - based on…an assumption of 12,500 miles per year, and…the mean line says that after five years of normal usage, you’d be at 80 percent state of health…and at 10 years you’d be at 70. That’s the norm, so that’s Mr. Average somewhere in the world. There are going to be people doing better than that, and people doing worse than that.” Palmer then listed four major variables that can affect how quickly the battery degrades: 1. The speed and gradient on which you drive - a lot of high-speed highway driving means greater degradation. 2. Frequent fast charging - “We recommend one fast charge a day. The battery will take more, but if you do so, then you’ll have an effect on its state of health.” 3. Mileage of the vehicle - how many miles it’s done and how many it does per year 4. Temperature - cold and hot The LEAF is capable of continuously sending diagnostic information to Nissan through its telematics system, so the company’s geeks can monitor the state of health at the level of the cell or of the whole battery pack. According to Palmer, the data that Nissan has doesn’t show any evidence that the batteries are actually malfunctioning. “We’ve sold 450 LEAFs in Arizona, and we’ve got data for
OCT/NOV 2012 85