The 2010 Mercedes C300’s battery location is actually under the hood—it’s just a little hard to find. To reach it, you’ll need to remove the battery cover, which is a larger mesh plastic panel in the back left corner of the engine bay. Underneath, you’ll see the cabin air filter, which is a black rectangular object.
Lift out the cabin air filter and, underneath, you’ll see the battery. You’ll need a socket wrench and a Phillips screwdriver in order to remove it—but after that, installing a new battery will be easy!
I hope that’s helpful! The 2010 Mercedes C300’s battery can be a little elusive at first—-but once you know where to look, it’s easy to find!