Deep discharge/ Deep Cycle Batteries are used as solar batteries or in backup power. They are designed to be discharged down as much as 80% time after time, and have much thicker plates.  Deep cycle batteries are capable of surviving prolonged, repeated and deep discharges which are typical in renewable energy systems. Deep cycle batteries are designed with thicker lead plates, which have less overall surface area than their thinner counterparts.  Because of the reduced availability of surface area for chemical reactions, deep cycle batteries produce less current than other types battery, yet they produce that current for longer periods of time.  Deep cycle batteries can be discharged up to 80 percent DOD(depth of discharge) without damage depending on the model.