I don't know if it is the heat and humidity or the fact that we sail year around but batteries here in Florida do not seem to last more than 4 years. I'm sure someone out there can boast getting 7-8 years out of his but I'm talking about average usage with minimum maintenance. I have never sat down to keep data on the number of cycles I get from my batteries but sailing all year round I'm sure that I do go through that finite number of cycles perhaps twice as fast as someone who only uses their boat 6 months out of the year.
And because we live aboard and use the boat every single day of the year, in the heat and humidity of the Caribbean, we should expect, what, a half a year, by your logic?
Mainesail is a professional at this stuff, you might be better served listening to what he's trying to tell you, rather than justifying your poor battery life with a bunch of silly excuses.
Now if you are using a 30 year old Constavolt charger, you're doing very well to get 3 years out of any battery.
