Having done a fair amount of research on solar electric with FLA batteries and there life expectancy and maintenance needs, I have learned a few things that I bring to my tractor batteries.
#1 is state of discharge. Some have mentioned a well tuned engine that starts quickly, this minimises the depth of discharge
Also mentioned big CCA batteries, while you will draw the same amount of amps the % of discharge will be much lower
My Simplicities will take a bit bigger battery, I have been able to find 625 CCA batteries for them and have get 10 and 11 years out of them 
#2 FLA's have a natural tendency to self discharge. This can be reduced by keeping the battery clean. If you have a dirty/wet battery top place a multimeter lead on one post and the other lead on top of the battery next to the post and slide it towards the other post and watch the voltage climb. People have told me I was full of it, till I pulled out my meter and showed them why their battery died after sitting for a while but a charger would bring it back
Any state of discharge will speed up the formation of a white substance called lead sulfate, the more of this that forms on the plates the less capacity the battery has because the LS acts as a insulator to the flow of electricity. That is why i keep the "Battery Tenders" on. The current snow mover battery has a date of 4/16, and is plenty strong yet 
I also use the felt washers and protective sprays to seal and keep the clamps and posts clean.
Cheers,
Gordy
Edit; 🤔 Had to change Lead oxide to lead sulfate
#1 is state of discharge. Some have mentioned a well tuned engine that starts quickly, this minimises the depth of discharge
#2 FLA's have a natural tendency to self discharge. This can be reduced by keeping the battery clean. If you have a dirty/wet battery top place a multimeter lead on one post and the other lead on top of the battery next to the post and slide it towards the other post and watch the voltage climb. People have told me I was full of it, till I pulled out my meter and showed them why their battery died after sitting for a while but a charger would bring it back
I also use the felt washers and protective sprays to seal and keep the clamps and posts clean.
Cheers,
Gordy
Edit; 🤔 Had to change Lead oxide to lead sulfate