IntPtr status = Marshal.AllocCoTaskMem(Marshal.SizeOf(typeof(SYSTEM_BATTERY_STATE)));

    (UInt32)Marshal.SizeOf(typeof(SYSTEM_BATTERY_STATE))

  SYSTEM_BATTERY_STATE batt_status = (SYSTEM_BATTERY_STATE)Marshal.PtrToStructure(status, typeof(SYSTEM_BATTERY_STATE));

struct SYSTEM_BATTERY_STATE {

Structure SYSTEM_BATTERY_STATE