Reviewers of deep-cycle batteries often find the additional reserve capacity of such batteries over standard lead-acid batteries useful but note that deep-cycle batteries can be very expensive. In addition, some reviewers claim that it may require a larger deep-cycle battery to start an engine compared to a standard battery.
Deep-cycle batteries are intended to be repeatedly charged and exhausted more often than standard batteries. Deep-cycle batteries have both larger capacities and longer overall lifetimes than standard batteries, according to most reviewers. However, deep-cycle batteries cannot discharge electricity as quickly as standard batteries of the same capacity, making deep-cycle batteries less reliable for starting engines.