Battery maker A123 Systems hiring 400 workers in Michigan

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The battery maker A123 Systems Inc. says it plans to hire up to 400 workers over the next few months for its plants in the Detroit suburbs of Livonia and Romulus.

The Waltham, Mass.-based lithium-ion battery manufacturer said Tuesday that it needs the workers to "ramp up production and satisfy demand" for its power-grid and commercial transportation businesses.

The Detroit News says the company now employs about 780 employees in Michigan and says the new hiring would bring its work force in the state back to the level it had before layoffs in late 2011.

In March, A123 said it would spend about $55 million to replace defective battery packs in five battery packages that were assembled at its Livonia plant.

The company employs about 700 people at its battery plants in Romulus and Livonia and about 40 at its research and government solutions division in Ann Arbor.