My side side is sealed. Not sure if AGM. I rode a motor cycle with AGM to arctic circle. Lasted for few more years.

 

I just bought a YUASA AGM battery for my Kawasaki BF.

 

I like the AGM batteries. Usually spend almost $100 for an AGM battery. Used to also use them when I rode motorcycles. They lasted about 4 years in my experience. I do trickle charge them for a couple days once a month if I'm not riding them.

 

I do no trickle charge my bike batteries, and get 7 years, and usually still going. But the, in the mower. I charge 1-2 during winter, and before I start for year. I used to take them out and put under kitchen sink. Now just leave them. Insualted but unheated, below freezing at times.

You don't need trickle charges, if you just charge them. But it takes the hassle of you. My sled and side by side, atv, Same. I just put a charge on them if they have not been run enough or for awhile.

Trickle chargers are nice, but laugh at folks that think they have to use them.. Ride it, helps alot too

 

"Ride it, helps alot too" <-- True. I don't ride in winter anymore and my battery will die if I don't crank 'er up once in awhile. The the last few winters either I haven't plowed snow at all, or just a couple of times at most. I don't have a garage and to hook up a charger I would have to leave a window or door partway open. That's not happening. If I don't start it up and let it idle to charge up the battery once a month I'll have to pull start it. The rest of the year isn't bad but I'll have to run it before winter gets here.