IVE GOT TROJAN BATTERIES IN MY 2004 PIV THAT HAVE NEVER BEEN REPLACED. I ALWAYS CHECK THE WATER AND RECHARGE AFTER COMING OFF THE WATER. THEY HAVE PLENTY OF POWER LEFT AFTER A FULL DAY OF FISHING. I KEEP THINKING I WILL NEED TO REPLACE THEM DURING THE YEAR, BUT MY DEALER CHECKS MY BOAT EVERY SPRING AND SAID THEY ARE STILL GOOD. THATS SIX YEARS. THIS MIGHT BE THE YEAR THEY GO DOWN. I FISH LAKE BARKLEY ALL THE TIME AND DONT WANT TO BE WITHOUT POWER ON THAT LAKE. I THINK I WILL CHANGE THEM OUT THIS SPRING.