OER Parts offers a wide selection of Battery Accessories for your 1977 Mercury Comet. OER Parts offers 1977 Mercury Comet Battery Tender, 1977 Mercury Comet Battery Managment System, 1977 Mercury Comet Dual Battery System Controller Set, and 1977 Mercury Comet Battery Relocation Set. Battery Mat Battery Topper Battery Terminal Protectors Battery Post Cleaning Brush Battery Terminal Puller