I just bought a 2009 Polaris Sportsman from a local guy. It has 1800 miles on it with the ORIGINAL battery.
When should I change the battery?

Battery life is more a function of time rather than use. 5 years is getting old. It's more likely to fail in low temps so using it for hunting in cold weather will increase your chances of a problem. A new battery for an ATV is cheap. If a new one makes you feel better, do it.

When you do...tell 'em its for a lawn mower.....

It will only be 1/2 as much $$

............. ...................

Replace the battery and consider purchasing a battery tender/trickle charger. I have had longer battery life since going this route.

my polaris 500x2 2007 still has the original battery. still starting great.

Maybe so but when they go you can be down hard. A battery is an inexpensive and critical component with minimal care needed to maintain them in reliable condition. I try to replace mine before they fail.

On my last three ATV's my average battery life is probably right at 4 years. I use mine almost daily throughout the year and I think that keeps it going longer than it would otherwise.

If you do buy a battery, buy the best. Yuasa. They seem to last forever. Check Amazon and your local ATV dealer. They are simply fantastic batteries. They may cost 2x what a "mower" battery costs, but will last 4x as long.

Thanks guys! I'll probably just replace it.

Odyssey Battery!

I have a 5 year old Odyssey battery in my wheeler that is in storage for 5 months during the winter. No trickle charger, just pull it out in the spring and start it up. Plenty of cranking power even after sitting all winter. My Odyssey battery should last 10 to 12 years and costs about the same as a regular ATV battery. Ebay and Amazon have them.

Walt,
Good point about the cranking power of the deep cycle batteries. I went that way for my Dodge.