You’re certainly not the first person to have a hard time finding the 2011 Audi Q5’s battery, and you probably won’t be the last. Rather than being located underneath the hood, the 2011 Audi Q5’s battery is located in the trunk.
Getting to the battery can be a bit of a hassle, but it is doable—you’ll just need to open up the trunk and then lift up the floorboard lining. Depending on your exact model, you may be able to see and access the battery immediately after removing the lining, or you might have to remove the spare tire and plastic lining that supports it first.