How long will a Deep Cycle battery last on a single charge?

Discharging batteries — like charging — depends on a number of factors. These include, but are not limited to, the initial state-of-charge, the depth-of-discharge, the age and original capacity of the battery, the load and the temperature at the time of discharge. To estimate the cycle life — at 70˚ F (21.1˚ C) — divide the ampere hour rating by the load in amps. For example; a new 72-ampere-hour battery with a 10-amp load should last approximately 7.2 hours. As the battery ages, this capacity will be reduced.