I have a 2017 Q60 2.0T Premium. After four years I figured I'd better start thinking changing the battery. Popped the hood and found the battery in the regular place. I went to the trunk and grabbed some stuff and noticed a compartment in the trunk on the drivers side. Had a couple clips on it so I removed them, opened the compartment and there's another battery. Is this just a 2.0 addition? And does anyone know why there are 2?