Bought a used boat last year and only got to use it twice due to health issues but getting ready for this year. Took the batteries up to Autozone and they say thy checked good but due to the age I feel like I should replace them to be safe. The starting battery is a generic brand AGM and the 2 trolling batteries are SRM-27 Interstates. Quality batteries but the date of service looks to be 2006. Would appreciate input on whether to swap them out or not and if so, what would be a good replacement that would not cost me an arm and a leg? Pathans in advance.