I purchased a lawn mower battery back in 2018 and only used until late 2021. During that time I only put about 20 hours on the lawn mower. Then I had problems with the mower and didn't get running again until in late August this year. When trying to start the mower for 2nd time using this year the mower would not turn over but the lights came on. So I checked the battery which was putting out 12 volts. I put a trickle charger on overnight and the next morning the battery was putting out 14 volts. So with the hood up on the mower, I started the mower and the battery exploded with the cap flying along with battery cracking and acid flying. Has anyone had this experience? What could be the cause?