EV Expert Says Nissan LEAF’s Dashboard Lacks Most Important Number

By · December 20, 2010

LEAF dashboard indicator

The hashmarks on the right give some indication of the battery's state of charge. But it would be much more useful to have a numerical indication of the percentage of the battery's charge still remaining.

Earlier today, Marc Geller returned a loaner Nissan LEAF after one week of driving. It was a very good thing that Nissan gave Marc a free chance behind the wheel. As the co-founder of Plug In America, and an EV driver since 2001, he knows a lot about the life electric. After all, he’s been living with an electric car as his daily driver for a nearly a decade.

Marc believes that long-time electric car drivers have a tremendous amount to offer automakers that are producing new EVs. “Giving us a car for a week, the automakers would learn a lot that would otherwise come to them slowly but inevitably,” Marc told me.

While Marc thoroughly enjoyed his time with the LEAF, he does have one major gripe: the lack of a simple numerical percentage state-of-charge number on the dashboard. Instead, the LEAF provides 12 bars in a graphical display that indicates how much juice is left in the battery—plus it provides the car’s best guess at how many miles of range are left.

Marc believes the 12 bars are counter-intuitive. “We do not operate in a Base 12 world, yet Nissan decided that somehow 12 was a significant division point for expressing the capacity of the battery,” Marc said.

And the dashboard's expected range—expressed in number of miles rather than a percentage—is even worse. According to Marc, Nissan had the right instinct to provide what they thought drivers wanted: the number of miles of driving left in the battery, but the car’s computer is always trying to guess at the number depending on a number of factors. “It’s computing that range on the fly, which means when you go up a hill, and use more energy, to the car that just says you have decreased range,” Marc explained. “The car doesn’t know that you’re going down on the other side. When you go down on the other side, the flip happens.”

The number, therefore, is “irritatingly erratic,” according to Marc. For example, before taking off this week on one of his drives, the range number was 93 miles after a full night of charging. “When I switched to eco mode, the number was 102,” he said. “Within 15 miles, I had seen ranges of 102, 84, 66, 82 and 78.”

Keep It Simple

Instead, Marc would like to see Nissan and all other EV-makers simply display a percentage number of state of charge. (Are you guys listening?) Given the fact that the Nissan LEAF promises 100 miles of range, that percentage would be the starting point for a driver to fairly easily determine his or her remaining range, based on past experience and conditions the driver knows lie ahead. This should be calculated by the driver—without being thrown off by what the car tries but could never know.

“The best approximation of the number is never as nimble as the human mind,” Marc said.

Marc uses a special aftermarket device to see the actual percentage state of charge on his Rav4 EV. Unfortunately, the Nissan LEAF iPhone app makes the same mistake as the dashboard by providing a graph rather than a percentage number for the battery’s state of charge. But the mobile app offers some hope. Nissan could make an upgrade to the iPhone app to provide the SOC percentage, and LEAF owners could download the new version.

The need for the SOC percentage seems self-evident to Marc, after driving a Think City and then a Toyota RAV4 EV for so many years. “The reality is very simple, but [the carmakers] don’t get it, because they haven’t spent time driving an electric car.”

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