My dad has always been meticulous with the maintenance and care of everything he owns, which has carried over into me, not quite as detailed as my dad, but detailed none the less. I can say from my memories of rigs my dad has owned as well as mine, deep cycle batteries have a long service life if maintained. Maintenance includes more than charging; regularly checking the water levels (if using wet cell batteries), and not overfilling them is critical. I think 3 years of trouble free service should be expected out of any deep cycle battery. I wouldnt mind paying to replace after 3 years, just for piece of mind, but 1 year is definitely premature aging. My dad and I always plug ours up to the charger as soon as the boat is backed in the garage, and left plugged up until it leaves the garage. Another factor to consider is the care for your charger. I dont know the physical differences between the different types of on-board chargers, but I believe it is the pulse chargers that are sensitive to the current coming from their power source. We make our own extension cords that reach from the charger to the outlet. They are less than 10 long and are made up of either 12 or 14 gauge wire, which is supposed to help keep the operating temperature of the charger lower. A faulty charger can be just as detrimental to the life of your batteries as anything else.Just my $0.02, probably all its worth.