The Optima blue top is designed for marine usage where there is no alternator or charging system. Optima blue deep cycle batteries are very popular for marine trolling motors, winches, special lighting, portable power, and emergency backup systems of all types. Optima deep cycle/starter batteries serve dual purposes: They function very well as starter batteries, but they also are designed to withstand repeated deep discharging. This ability makes the OPTIMA D34M and D31M especially useful when electrical loads exceed recharge rate (including times when the battery cannot be recharged at all, such as for marine trolling motors).
Optima Marine, D34M, D31M, Blue Top Starting / Deep Cycle Battery / Boat / Marine In the off-season, sometimes marine batteries sit for months at a time and lose their charge. But the OPTIMA Blue Top marine battery has such a low rate of self-discharge, that it can go unused for up to one year without recharging, if kept at or below room temperature. And because of its low internal resistance, OPTIMA marine recharges faster, getting you back on the water quickly. Our inventory cycles quickly on the D34M and D31M, this gives you the freshest of OPTIMA Marine batteries from our inventory.