What Are the Differences Between Car, Marine/RV “Dual Purpose”, and Deep Cycle Batteries?
Car and marine/RV starting batteries are specially designed with thinner (.04 inch or 1.02 mm) and more porous plates for a greater surface area to order produce the high current required to start an engine. They are engineered for up to 5,000 shallow (to 3% Depth-of-Discharge) discharges, which is over four engine starts per day. Starting batteries should NOT be discharged below 10% Depth-of-Discharge (DoD). They use sponge lead and expanded metal grid paste plates rather than solid lead plates. Marine/RV “dual purpose” batteries are a compromise between a car and deep cycle battery and are designed for starting and prolonged discharges at lower amperage that typically consumes between 20% and 50% of the battery’s capacity. The plates are thicker that in starting batteries, but thinner than in deep cycle batteries. Motive and stationary deep cycle batteries have much thicker (up to .25 inch or 6.35 mm) plates, thicker grids, more lead, and weight more than car batteries of the same si
