I have a Center Console Gheenoe Classic with an electric start, 25 HP 4 stroke Yamaha. I am installing a Riptide RT50. I could use some input on the battery slection. Should I go with a a single Dual Purpose AGM battery (been looking at the Odyssey 31M PC1500 and 34M PC2150) or should I install a separate battery for the trolling motor and keep my cranking battery? I like the single battery since it saves wieght over 2 batteries. Any input would be appreciated.