My two Interstate trolling motor batteries for my 24V Minn Kota Terrova are over 6 years old now. I can tell that they don't have the pep they used to but they are still holding up. Curious to know how long others have had theirs last. I replaced the started battery for peace of mind at the 6 year mark.
I had a set of Delco Voyagers that had over 6 years on them when I sold the boat. They still tested good.
I've got one with a '12 sticker on it, and another with '13 sticker on it. Just lost one that had '08 on it.
I have two group 31 deep cycles ...Interstates for my 24 volt TM...they are 6 years old now and still doing just fine
Invest in a load tester. It's the best way to determine the condition of lead acid batteries.
I've only made it 3 years, and they really needed to be replaced before that. My boat/batteries get a lot of use.
I can not tell how long they should last but I worked in the trucking field years ago. One of my jobs was delco battery warranty. Not a whole lot you can do with longevity on sealed batteries. Keep the terminals clean and battery charged. When very cold make sure they have a good charge in them. Also slow charging will keep a battery from what they called sulfating and the plates deteriorating. As stated a inexpensive load tester is a good tool to own and will tell you your batteries state with no guessing. It has been 15 years since my wrenching days but I do not think it has changed much.
My 2 Sears platinum series 31 deep cycle batteries just died last week. 1 was in its 8th year, other was in its 7th year so they got changed out last week. Best longest batteries I ever owned. Always kept them charged up and in winter, kept them in a heated garage charged up.
Running a MG 75# trolling motor with 2 Walmart Everstart 27 series. The batteries are 5 years old and I can work them for 9 hours without draining them. They stay on the charger at all times when not in use. Hopefully the next set will be just as good.
I have 4 Walmart Everstart 27 batteries, the oldest being a 2009. I now use the 2009 for my trailer winch and it still tests very good. 2 of the other batteries, which were tested last week on a 4 mile return trip to the ramp after the outboard failed to start due to an ignition problem, are for my Terrova. They made the trip at full speed and the test indicators on the Terrova were all showing except one.
Charge your batteries after every use and keep on maintain setting after that, keep them clean, keep the water checked (only use distilled water).