The Viking Access Battery 12V 35AH is the battery that viking access uses as a backup power supply. If your home or business looses power, your viking gate opener can still work. This allows constant operation and control of your gate opener even when the power is out. These batteries do need to be replaced every couple of years. The Viking Access Battery 12V 35AH is your replacement battery. You can order yours online or Gate Openers Direct a call.