The factory does a poor job of grounding the battery to the chasis. By fixing this you can increase the performance of your electrical system. You can fix this issue by performing the following steps:
1) Remove the ground wire from the battery to the chasis using a 10mm socket.
2) Use a Dremel or similar tool to sand the paint off of the surface below the ground ring.
3) Sand the contact side of the copper ground ring.
4) Reinstall and coat the area with RTV, Paint or something else to prevent rusting and oxidation.