My Deep Cycle batteries are 5.5 years old now.. At last check, they were still okay.
http://ecorenovator.org/forum/solar-...r-project.html
I check the water and add some if needed, at least once a year..
This system was built to run 120VAC pumps. In case of grid fail during a storm.
It works! It has stopped all grid fails during storms for 5.5 years!
I assumed the bank would last about 6 years.. So far, that goal seems possible.