Battery longevity

We bought our new 2012 fw in August of last year (2013). A couple of months ago, the battery would not hold a charge. Since it had a 12 month free replacement warranty, I called a local dealer for the battery and the guy says to bring it in. I take the battery to him and he takes one look at it and says that it was made in December of 2010 and couldn't do anything for me, it was just too old. Since I had to get a battery I went to another dealer and bought a different make of battery. I also contacted the original battery company (Deka) and explained the situation. I provided proof of when I bought the trailer and yesterday I get a check from them for the replacement cost of the competitors battery. Kudos to them

If you have a good charger (like the charge wizard) then leaving it plugged up all the time would be best.
I'd guess 5 years if left plugged up on a wet cell and more on an AGM style.

A.quality deep cycle RV / Marine battery should last 4 years or more. Even though deep cycle batteries are designed to be discharged never completely discharge the battery. Also check the electrolyte level frequently. There is no need to remove the battery during winter storageas long as you disconnect the cable or Turn off the battery switch. Cold is not the enemy of your battery heat Is. Be sure your battery has a full charge when it is put away for the winter. A battery minder is always a good idea if you have electric near where you store.

There should be some kind of date sticker and it may be several years old. Inexpensive 12v marine deep cycle batteries may only last a few years, but better ones one or two more (at least that's all I get out of them).

I'm pretty sure its a deep cycle rv/marine battery.

Is it simply a 12V "car" battery or something more substantial?