US heat browns Nissan's green LEAF

Nissan Australia says it has received no reports of reduced battery capacity in its all-electric LEAF hatchback, but some North American owners have claimed their cars are offering severely reduced driving range due to that nation’s sweltering summer heat.

Just 51 LEAFs have been sold since Nissan’s ground-breaking new zero-emissions model was launched Down Under in June – the first month of winter – but more than 400 have been sold in US states like Arizona, where temperatures this summer have peaked above 48 degrees C.

“There have been no issues reported here,” said Nissan Australia Media Enquiries General Manager, Jeff Fisher. “Arizona and neighbouring states have had protracted heat waves. Temperatures quoted are excessive even for Australia.”

Nissan claims the LEAF EV’s lithium-ion battery pack may lose as much as 20 per cent of its total capacity within five years, but extreme temperatures appear to have affected battery performance beyond Nissan’s expectations.

Drivers of the LEAF in Phoenix have noticed a significant loss of battery pack performance and a drop in driving range, with some reporting a worrying loss of range to around 100km from Nissan’s estimated range of 160km.

The issue so far, says Nissan America, is limited to a handful of customers. In fact, Nissan claims that data collected from the LEAF’s on-board software – Carwings – shows that less than 0.3 per cent of LEAFs in the US have experienced loss of battery capacity.

Unlike other electric vehicles sold in the US such as the Ford Focus EV, the Tesla Model S and the Toyota RAV4, the LEAF is unique in that the battery pack is not temperature controlled — either cooled or warmed — to protect it during operation in extreme conditions.

It’s worth remembering that any vehicle parked on black tarmac on a hot day can easily experience ambient temperatures above 48 degrees C, and some experts believe the lack of a battery cooling system may explain the reported loss of battery performance LEAF drivers are experiencing in the hot US states.

The problem came to the attention of Nissan in the US via social media after owners posted comments on the company’s Facebook page. Some claimed that when their car was left in the sun for extended periods at least one of the 12 segments that make up the battery charge indicator would disappear.

One website tracking the situation has speculated that up to 44 cases of reduced battery capacity have been identified, although only two owners have claimed to have lost a quarter of the bars after 40,000km of travel, and others claim they have lost two bars of charge after as little as 11,000km.

An open letter sent to US LEAF owners last month said the issue “may be considered normal depending on the method and frequency of charging, the operating environment, the amount of electricity consumed during daily usage and a vehicle's mileage and age”.

Senior Vice-President of Research and Development for Nissan Americas, Carla Bailo, said the LEAF’s integrated battery pack, which is warranted for eight years or 160,000km in Australia, will lose its capacity with age, but added that it is too early to tell “whether their performance is within the range of expectations or not”.

“This is normal and expected,”' she said. “'In general, lithium-ion batteries exhibit a higher loss of capacity early in life, with the rate of loss decreasing over time.

“Nissan has projected that LEAF batteries will generally have 80 per cent of their capacity under normal use after five years, and 70 per cent after 10 years.”

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