[uwish]

deep cycle batteries have a 3-5 year life span. Both of mine lasted 3.5 years and only found out after a power outage, the LED's were still on but my pumps were not running. When I did a load test on the battery itself after taking it out of the housing, they were both dead. There is a great youtube video on how to drill out the rivets etc and replace the battery inside for ~ $50 in total. You don't have to go and buy a brand new EM battery backup with housing again.