Sounds like you are taking good care of your batteries. 3 years probably too long for it to be a drain, too short to make you happy. Make sure your charger is a good one, also "few weeks"? needs to be maintained the whole 4 months per... From the web:
"Once fully charged through saturation, the battery should not dwell at the topping voltage for more than 48 hours and must be reduced to the float voltage level. Charging beyond what the battery can take turns the redundant energy into heat and the battery begins to gas. The recommended float voltage of most low-pressure lead acid batteries is 2.25 to 2.27V per cell." (you have 3 cells= 6.75-6.81V float charge)
Miss: Your charger should fast charge to about 75% then float/trickle at the rates above. If not, you may be contributing to your own failure. Also; maybe change brand of battery or get one with better proration. Been here many years, never heard of anyone getting 8 years out here. My trucks: 3 years, cars: 3 years, my boat: 3 years. It's not just me and you getting 3 years, there are plenty, just not posting. Batteries are about $25-$30 a year no matter what you buy. AAA Arizona web site says 22 mo is average battery life span in AZ no matter the warrantee, so we get a long proration or 60 mo free replacement. Had a lifetime from sears years ago, boy did they lose money in AZ.
