DETROIT – Nissan’s late U.S. production start of the Leaf electric vehicle this year means the auto maker once again will battle other markets for units built in Japan, a top executive says.

“For the calendar year, we really won’t have a lot of localized supply yet to really unleash that full potential” of the Leaf, Bill Krueger, vice chairman-Nissan Americas tells WardsAuto at the 2012 North American International Auto Show here.

Leaf production begins in late 2012 at Smyrna, TN, in what Krueger calls more of a winter startup than fall.

And with more markets, including Canada and Mexico, launching retail sales of the EV this year, Leaf units from Japan – currently the only source of the car – become even more precious.

Nissan CEO Carlos Ghosn said at the show yesterday the auto maker intends this year to double the 9,674 Leaf deliveries it recorded in 2011.

However, Krueger considers a doubling of Leaf sales more of a global target than a U.S. goal, as different regions jockey for position in allocation of the EV. “Globally, there’s more markets that will be launching with the Leaf. It’s going to be more competitive,” he says.

Ghosn also said Leaf production was constrained last year due more to a battery bottleneck than a car-manufacturing issue.

Krueger says production of the car’s lithium-ion battery in Japan largely was slowed by

Electricity supply interruptions in the wake of the March 11 earthquake. The country strove to conserve energy in the summer months, as it shut down nuclear plants following a scare after the Fukushima reactor crisis.

“One of the unique things about the battery process is (that) they go into a curing process, which is kind of a long-term process,” Krueger says.

And unlike other auto-manufacturing processes such as stamping, which can stop and resume within minutes, battery production must continue once it has begun.

“It’s like baking a cake,” he says. “If you keep pulling it out and putting it back in, it really messes with the chemistry.”

Production of Leaf batteries in Smryna will start before car builds, so that a supply of batteries will be in the pipeline.

Nissan now is hiring and training battery-plant employees in Smryna, and Krueger says the auto maker is finding local workers in sufficient numbers and quality. Many are undergoing extensive training, as many steps of the battery-assembly process are unique in auto production, including a clean-room step.

Training to manufacture the Leaf batteries also has taken place in Japan and the U.K., where Li-ion production already is under way.