Behold the flooded lead acid battery, unfortunately a perennial favorite of all too many boaters. Why? They cost less than better battery types such as sealed or AGM's. When I say they cost less I mean they are the cheapest battery you can buy. They do work well, if you can, and do check them on a regular basis, and the hotter the ambient temperatures become, the more often you have to check them. The words of the day are "evaporation, and accessibility."
I look at Bob shuddering, and wringing his pasty white smooth hands as he stares down into the crammed full engine room. Battery problems again Bob? You had these changed just last year didn't you? Where did you get them from, Wallymart? You did? Hum-mm ahhh, who installed them Bob? Your skinny nephew did? When was the last time you checked the water levels in these Wallymart batteries?