I've been moving for the past few weeks so the boat hasn't ran for awhile. It's a 470 mercruiser. Went to clean her up to take her out this morning and the battery was dead. I tried using one of those portable jump starters and that didn't work. Jumped it with my diesel and it took about 15 minutes for it to turn over. I ran the boat for about 20 minutes, turned the key off, then tried starting it again and nothing. As far as I know, I left nothing on for those 3 weeks. I bought a charger today and it's been charging for a couple of hours and it says it's at 12.8. Now, it this battery worth trusting anymore? I did buy a new battery today as well but haven't hooked it up until I know what the situation on the old one is. The battery has a purchase date of 8/06 so it's fairly new. It's a Les Schwab rv battery deep cycle. The new one I bought is a EverStart marine dual cycle for starting/trolling. The cranking amps are a little higher on the newer one than old. I guess the question is should try to use the old one still or pop the new one in. I guess if anything I can use the new one for the main and the older one for my fish finder. I've kind of been scared since I installed my fish finder to keep it on at all times when I'm fishing, I usually turn it off when I shut the boat off. Should I be worried about the battery being drained with the fish finder on without the boat running? Thanks
