Iv been running up to a dozen 6TL's , the ones that wore out lasted almost 6 years, the others are going strong, i always take em out and clean em 2 times,,sometimes 3 times a year,along with the bat box's ,Re Paint the metal ones>and always rotate a 5 amp 24 volt charger on them , so the most important thing with any bat is no dirt, clean terminals, and a full charge, all the time, when they sit they drain, low bats sulphate, fast charging is brutal to any bat, 1.5 amps is the ultimate charge for a bat. when i take em out i run the 1.5 ampers on em individually, bats are a big maintanence thing, hot or cold drains them at the same rate. at perfect temp they are draining, and yes i even take em out for the coldest winter months and bring them inside.to much money not to, and when i want to use the truck , and i do.. i cart the bats to the truck, the 5 tonners may keep em in this winter with the chargers on em, they are a bitch.Randy