Most WM stores have Midtronics testers supplied by East Penn, their battery supplier.. All Wal*Mart stores also have Midtronics testers. These are the industry gold standard for testing. The real test is after you charge it and it weakly starts or does not start your engine, well there's the answer. A group 27 should have your engine jumping to life like a cheer leader...

Sam's Club's in about 25 states & NAPA both sell the SAME EXACT marine batteries sold by West Marine. The only difference is the sticker, and the PRICE...