How long do batteries last?

[Underwaterwelder]

I realized my two batteries are from 2010. How long do batteries usually last?

245 seaRay Weekender 2001, two identical batteries on a switch (1, both, 2, off)

 

[Golfman25]

You're on borrowed time. I usually get 5-6 years, left in boat over winter.

 

[b_arrington]

Battery life total depends on the usage pattern and care. For example, deep discharging shortens life. Regular trickle charging extends it.

Being on a mooring without access to charging, mine would drain and I would get 2-3 years. I also typically just hang out on the boat, not running the engine a lot. I agree that 9 year old batteries are on borrowed time.