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