Ford Mondeo wont start sometimes especially when cold. battery still has full power

Car won't start sometimes. Put ignition on and after the glow plug light disappears ,turn the key and the speedo and rev counter go right round to max and sounds like a click as if battery has died or no kick to start it. The car start with a booster pack.
When the car does start normally or with booster ,it will start but will take a good few seconds before it gets any power to move.