Director of global battery systems engineering for General Motors Denise Gray has announced at the conference call this afternoon that she is leaving the company to join a California-based battery start-up.

Gray was made director of battery engineering in 2006 with 25 people working with her. In her position, she had overseen all of the testing and development of batteries going into plug and non-plug versions of GM hybrids and extended-range electric vehicles. Gray also worked with battery suppliers to evaluate new cell technologies that may be used in production vehicles in the future. She was also one of the key people working to bring the Chevrolet Volt to fruition. Now, as she prepares to leave, the department has grown over 200 not including support staff in other departments like purchasing.

Gray stressed that her decision to leave GM at this time was a difficult one, especially with the nearing production launch of the Volt. However, with most of the serious development work on the pack now being complete, this new opportunity couldn’t come at a better time as has one son already attending the University of Michigan and a second two years away from college. Her husband retired from GM two years ago.

Gray’s nearly thirty years of service at GM will end Friday, March 5, 2010.