The U.S. operations of electric car battery maker A123 Systems filed for bankruptcy protection and its automotive assets are being acquired by Johnson Controls for $125 million.

The announcement Tuesday comes one day after A123 warned in a regulatory filing that it likely would miss some debt payments and could be headed for bankruptcy court.

A123, based in Waltham, Mass., manufactures lithium ion batteries in Asia, Europe and North America, including batteries for plug-in hybrid and electric cars.

The company's SEC filing comes just two months after Chinese auto parts maker Wanxiang Group Corporation announced plans to invest up to $465 million in A123, including an initial credit extension of $25 million.

In 2009, A123 received $249 million in federal funding for advanced battery technology manufacturing in two sites in Michigan -- Romulus and Brownstown -- as part of a $2.4 billion stimulus package.