A newly patented technology from Oak Ridge National Laboratory can help extend the lifetime of batteries in plug-in hybrid vehicles by optimizing the battery's state of charge while driving. Developed by ORNL's Robert DeVault, the computerized control uses data about recharging locations to improve the coordination of the battery and engine operation for trips beyond the vehicle's electric range. Knowing where charging stations are located can improve how the vehicle rations its battery power for longer battery life. By maintaining a higher state-of-charge during most of a trip, the patented control ensures that the battery enters a final discharge mode at the end of a trip "just in time" to obtain maximum recharging from the electric grid. "If you don't know where the trip is going to end, the engine's generator will make more electricity then you need to get to where you plug in. That lowers efficiency, reduces capacity for getting electricity from the grid, and wastes fuel because you're operating the engine more than needed," DeVault said. Patent variations include the ability to implement the "just in time" control method without a navigation system or driver input.
