To speak to this, I don’t use tenders either. I bought a new zero turn mower in 2012 and it’s still on the stock battery, I start it once per month during the winter and off season and let it run for 10 minutes or so and that has yielded better results than using a tender. The farm I take care of had tenders for everything and we were constantly replacing batteries. After switching to my program, we haven’t replaced one. I don’t know why or how, just my experience so far.Mine is 3 1/2 years old and still going strong. It's a warm climate here but it's never had a battery tender on it.
My battery is 3 1/2 years old. I keep a tender on it during the winter months.My battery is more than 4 years old I use a battery tender in the winter and if my battery gets low. I have over 4000 miles just was wanting to know how long the stock battery is lasting for other people.