Over in the US, Nissan is set to enhance the warranty of the battery modules in its Leaf EV to stem the concern from certain owners about the battery’s durability. It seems that battery life wasn’t previously spelled out in the vehicle’s overall warranty.

The limited warranty coverage in the US, which applies to all existing Leafs as well as those entering the market in 2013, will see Nissan offering to repair or replace the lithium-ion battery if it loses more than 30% of its ability to hold a charge (in this case, below nine bars of the available 12 bars displayed on the battery capacity gauge) for the first five years or 90,000 km.

Automotive News reports that the move comes after months of communication between Nissan and seven US Leaf owners in Phoenix, Arizona, who claim that their vehicle’s battery is aging faster than Nissan told them to expect.

Leaf battery

In 2010, the automaker stated that the Leaf’s batteries would behave much like handphone batteries, slowly losing its ability to hold a full recharge after years of driving. The company told Leaf buyers that they could expect a 20% loss in charging capacity after five years of use, based on normal driving patterns.

The Phoenix owners, however, claimed the capacity loss was happening much faster than that. Nissan dispatched engineers to investigate, and found that the seven owners had been putting twice as much mileage on their cars as a normal driver would.

Nissan says that the new battery warranty coverage is to reassure consumers, adding that save for vehicles in areas of extreme summer heat and subject to heavier-than-normal driving, a typical Leaf owner isn’t expected to see that kind of capacity loss. In line with developments, the company is planning to unveil an improved battery gauge that will display remaining capacity with better precision.