Acronyms List xxi UAV Unmanned Aerial Vehicles UL Underwriter's Laboratory UN United Nations UPS Uninterruptible Power Supply USABC U.S. Advanced Battery Consortium USCAR United States Center for Automotive Research UUV Unmanned Underwater Vehicles VDA Verband der Automobilindustrie VRLA Valve Regulated Lead Acid VOC Voice of the Customer VTB Voltage, Temperature monitoring Board VTM Voltage, Temperature Monitoring W Watt W/kg Watt per kilogram W/L Watt per liter Wh Watt-hour Wh/kg Watt-hour per kilogram Wh/L Watt-hour per liter ZEV Zero Emissions Vehicle