marine batteries are the same as auto batteries just a deep cyckle .that means heavier plates . you can burn a battery up by leaving a charger on it that doesen`t cut off when it is cahrged . a car charge at a 30 amp or more some as much a 100 amps in police cars and any vehickle that require a lot of power .have saw car batteries last 5 years and some last 3 . thing it was just the time for it to start loosing its life . tha battery will probabley last a few more years if you don`t use it 12 hours dayes