First of all, I am by no means a marine mechanic, nor a expert on this subject, however….. I have a 2007 Opti and I just ran into this same problem. I had a group 24 Pro Guide battery that had 810 Cold Cranking Amps, and I believe 146 minutes of reserve. It turned the motor over fine, and seemed to work OK for the most part, but if I ran the aerator all night and blacklight and 3 graphs, and didnt move much, the battery would go dead and I would have to jump off of the trolling batteries. Heres the deal…. I just put one of the new Lowrance X38 graphs on and it and all the sudden the battery seemed like it wasnt lasting as long. (I never associated this graph with using more power until I read above, but I would believe it because this was about the same time I noticed the battery not holding up like it should) Anyways…… I figured since the battery was 20 months old now it would be time to replace it before too long anyways, so I won some money in a tourney and decided to splurge. My Uncle is a recently retired Marine Mechanic, so I called and asked him what I could get. He said that Mercury says that for the Opti you need a 600 CCA battery or higher and it will be fine. However, I figure if you are going to spend thousands of $$$ on poles, $30 jerkbaits, $3.00 gas, etc… you probably shouldnt try to save $20 for something that ultimately decides if you can make it to weigh in or not, especially when you are going to have it 2 years or longer. I was in Mountain Home at night and the only place to buy a battery was Wal-Mart so I got the best they had. The Everstart Marine Maxx (the big yellow one) I dont remember the exact ratings on it, but I can tell you it is a group 29 battery, it doesnt fit the battery tray in a 2005 Pantera Classic, it weighs a ton, and it didnt have near the CCA the group 24 pro-guide had. So….. to try and shorten this up for you…. I know a guy in Fayetteville that is a fellow fisherman and owns a battery shop, (Vaughn Battery), so I made the effort to drive and ask him directly what I should buy. I told him I dont care what it costs, I want the best I can get. I told him about all the electronics, pumps, lights, etc… He said without a doubt the absolute best battery he had was the XXHD-M-27 Exide Batteries. It had more CCA, reserve, etc… and he said that he thinks it was built better than any battery he can sell me. I was prepared to buy a Trojan or an Optima, but he said this would outlast and perform as well or better. The best part is it costs $75. So for what its worth, this is what he siad he runs in his own personal boat because he believes it is the best one money can buy. Oh yeah, all this guy sells is batteries, so I gotta think he knows what he is talking about…
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