According to an article by Family Motor Coach Association (FMCA) the life span of your RV battery is greatly affected by how you use and maintain it! "The two most common causes for RV battery failure are undercharging and overcharging. Undercharging is a result of batteries being repeatedly discharged and not fully recharged between cycles. If a battery is not recharged the sulfate material that attaches to the discharged portions of the plates begins to harden into crystals. Over time, this sulfate cannot be converted back into active plate material and the battery is ruined. This also occurs when a battery remains discharged for an extended period of time. Sulfation is the number one cause of battery failure." states Mark Polk in his article titled Saving your RV Batteries.