As I recall, the life of a battery is mostly determined by the discharge/charge cycles it goes through, along with how well you maintain it.
"Age and Usage Patterns
The age and usage patterns of a lead-acid battery can also impact its lifespan. The lifespan of a lead-acid battery is typically measured in cycles, which refers to
one complete charge and discharge cycle.
The number of cycles a battery can endure depends on its quality, usage patterns, and maintenance. According to the search results, the average guaranteed lifespan of a basic lead-acid battery is around 1,500 cycles.
However, poor management, no monitoring, and a lack of both proactive and reactive maintenance can kill a battery in less than 18 months. With proper maintenance, a lead-acid battery can last between 5 to 15 years."
Disclosure This website is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites. Sealed lead acid batteries should hold a charge for at least 6-9 months if they...
www.batteryskills.com
I recently acquired an old battery, never really used, but it sat discharged for a few years, the build date was in 2018! I put it on a battery recondition cycle a few times( says it gets rid of sulfation) and it now is holding a charge. One of these days, I will put it in my van to see if it will perform well or it is just a surface charge.