General Motors Brownstown Battery Assembly Plant’s LaTanya Clanton works on the Spark EV battery line Tuesday, May 13, 2014 in Brownstown, Michigan. GM is bringing all of its electric vehicle battery building capabilities in-house with production of battery systems for the 2015 Chevrolet Spark EV at Brownstown. The plant already manufactures complete packs for the Chevrolet Volt, Opel Ampera and Cadillac ELR. (Photo by John F. Martin for General Motors)