The bowrider I just bought has what looks like a sealed rebuilt car battery. It has charged up and load tested fine, but I was wondering if I need a regular marine or deep cycle type. The boat is powered by a 3.0 Merc inboard, with no addional drains on the battery such as a trolling motor or juiced up stereo. The former owner told me he had replaced it once before with the same type but it only lasted a couple of weeks. The battery shop replaced it under warranty but with the next biggest size. Could this cause any problems? Thanks in advance.