I know those optima batteries are high priced. But on one trip to lake conway my buddy forgot to secure it down and when we got to the ramp it had flipped over on the post and arched against the aluminm boat and melted down the battery post to almost nothing. We hooked it up and troilled around conway for about 2 hours. Is there a big difference in the time you can troll with a 27 series vs 31 series?