dale937 has some good advice thomas.
I average about 7 years on a battery in my vehicles and I live in a colder climate than you during winter. It depends on how you use your vehicle and how well you keep the battery charged. I have a 10 year old battery in an old truck at the lake. It, and the battery in my boat get a full charge prior to close up in the fall. They are just fine come spring. The ATV is ten years old now and I don't expect that little battery will have survived this winter---we'll see.
If you leave the lights on, and the car not running for long periods, then only drive short distances, the battery won't last as long as one that gets a good charge up all the time.
That's my experience going back many years. Others will tell you differently, maybe, according to what they experience.
Cheers, George
