Do Nikon batteries overcharge?

Just wondering, will the batteries for my D7100 overcharge if I leave them in the charger after they are fully charged?

Don't take this as gospel, but I'm pretty sure they will not, nor will any modern camera battery. The only thing you will be doing is wasting some electricity. Someone else may chime in with more factual data, but I say don't worry about it.

All lithium ion battery chargers are smart and will not overcharge your batteries. Li ion batteries are dangerous due to their high energy density and the ability to output a lot of current. Manufacturers take care that the battery isn't abused.