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We tested 700 pounds of deep-cycle AGM and gel batteries. The Trojan captures the Best Buy. Both Mastervolts are expensive but well worth it.

We used a carbon pile tester from Snap-on Tools (far left) for the reserve capacity test. A row of incandescent light bulbs (foreground) served as the discharge source.

The term “lead acid battery” usually conjures up the image of a standard flooded cell battery commonly found in cars and in 80 percent of all production boats. Actually, there are three basic types of storage batteries used in the marine industry that are constructed of lead and acid: flooded or wet-cell batteries, AGM (absorbed glass mat) batteries, and gel (gelled electrolyte) batteries. Lead acid batteries are further sub-grouped into three application-based categories: starting, deep-cycle, and dual-purpose. We’ll focus here on deep-cycle AGM and gel batteries. …