Seems like I'm replacing my boat batteries every time I turn around. What's the deal with that? I've had the same battery in my truck for the past 5 years as happy as you please. During the same time period, I've replaced two generator batteries, my windlass battery at least twice and the main bats one time. Anyone know why boats are so hard on them?

Let's face it, batteries degrade over time. And a marine environment is not usually the best conditions for a battery.

Most of us take our boat batteries for granted, in fact a battery can lose – depending on how and where it is stored – up to 25-35% of its charge per month – just sitting around. And of course there are a lot of factors that affect a batteries charge - temperature, humidity, etc. Remember those marine conditions?

Be sure you are getting the right battery for the intended task as well as keeping that battery healthy with the proper charging and maintenance.

When is the last time you checked the water level on your batteries?

Finally, batteries degrade over time, no matter how well treated. For regular lead-acid batteries at 3 years they will have lost approximately 25% in power, at 5 years that is closer to 40%, and then it is just down hill from there.

In reality after 5 years you are on borrowed time. Boat batteries have a 3 year warranty because that's about what they are expected to last.

Are you using marine specific batteries, or car batteries in a boat?
Also, where abouts do you live, as your local temps play a lot in battery life. For example, I am originally from Massachusettes, but now live in SW Florida. Batteries last twice as long up north because its not so hot every day.

I'm in Texas and am using marine specific batteries (what's the difference anyhow) that were installed by the dealer I purchased the boat from.

There are good brands of batteries and cheaper one. What I install in customers boats are Interstate marine batteries, and they are considered to be one of the best brands out there. Interstate batteries, as long as they are taken care of and have their water level checked once every 6 or 8 months (and topped off as needed) will last 3 or 4 years in the marine enviorment. (that's in Florida they last 3 or 4 years).

Now that's if you actually take care of them. If you make sure the water level is higher, if you make sure your keeping corrosion off of the terminals, 3 to 4 years is what you get.

If you use cheap brands of batteries. Batteries you get at Walmart, or the auto parts store brand name battery. Those will typically last 2 years at best, and that's if you take care of them. If you don't take care of them, I have seen batteries only go a season and they are done, they just will not take a charge.

They key difference between a marine battery and a car battery is the lead plates inside of the battery are structurally stronger, and the battery is designed to take a beating. Cars have suspensions to dampen the roads, boats do not, and those batteries feel every bump and smash of a wake in a boat, which would not happen in a car.

That's really about it. If you want a good battery, Interstate is what I use and recommend. Maintenance free batteries do not last as long as the batteries you do and can add water to. Adding water to batteries has an inherent danger to it if you are not used to working with batteries, as there is high strength sulfuric acid in the battery. But they do last longer in the long run.