I have a late 90's Mecury Black Max 135hp with the same CAR batteries on it from when I bought the boat 2 years ago. I'm in the market to replace the cranking and both trolling batteries. I tried finding what Mercury reccomends online, but came up empty. I know it's gonna cost me, butI'm not looking to spend $1,000 on 3 batteries. So with that in mind, what do you guys recommend?