I finally got around to replacing the battery in my 2518. The original lasted 6 years. I am not sure if the new one will come close to lasting that long.
I never took the battery out over the winter months. I did start it up once or twice a month in the winter.
We'll see how long this new battery will last. It's a $30 one from Advance Auto.
Michael
I have had 2 lawn and garden batteries from Advanced, last less than a year in my mower. And that was with a trickle charger on it all winter. They were the cheaper $20 sale ones. I suspect a $30 one will last longer.
Previously, I have also had the $45 Interstate last for 5 years, in the same mower. I am buying Interstate from now on.