Originally Posted by alanmalk
This is a worthwhile concern. Lead/Acid batteries do have a finite life even if kept on the proper charge/maintenance schedule. Ask anyone with a UPS (Uninterruptible Power Supply) for their computer. They stay on a well-regulated float supply and still fail at 3 to 4 years. Your battery may of course last longer if higher quality or larger, but it will fail.
Yes, all batteries eventually fail. But I can say from experience I took a deep cycle battery that an acquaintance was disposing because it was "no good" and using a desulphating charger, brought it back to "life" in about a months time, then used it for approximately 5 years. While desulphation chargers are more expensive, my deep cycle batteries tend to last between 7 and 10 years in Florida, and heat causes batteries to fail prematurely, not cold. So when I previously stated "properly maintained," I meant by a smart charger that has desulphation capabilities. Most batteries die before their time due to improper maintenance caused by sulphur build up on the plates which shorts out the battery's cells.