OK, so I went down to my boat about 6:45AM today. I had all the cabin lights on until about 8:00-8:30. My wife and daughter arrived about 10:30 and th radio promptly went on. We turned if off when we ran for lunch. After lunch we ran the blower and attempted to fire up the engines but there was bot enough juice to get the engines to crank over. I know the battery selector switch was set to BOTH but I had the boat plugged in to shore power the entire time with the Battery Charger breaker ON. So after that I turned the Battery Selector Switch to OFF and resumed the shore power. After about 1-1/2 to 2 hours the boat fired right up. Is it possible I drained both batteries in the morning and the Charger could not keep up with my usage?? Yes, I realize that when I use house items I should only have the Selector on one battery and not both but that is not my question.
Cabin lights and radio should not run down two good batteries, so I must ask what size are the batteries and how old are they?
I know you get got the boat so you may not know the age of them. Sounds like they took enough charge to recover I guess in a week or so you will find out if they hold a charge or you could have them load tested.
Don't know the age but they are CCA at 0 is 650. They also said 23 amp avg 175 mins. Boat is getting hauled for winter in a week or so and I plan on pulling the batteries anyway. I will have them load tested and then I will know for sure. Next question ... should you unplug from shore power before starting the engines or does it not really matter?
Doesn't really matter......once the boat is on the hard for winter and you get them tested you will know if you need new batteries or not. Also somewhere on your batteries are stamped the date of manufactured. Anything over 4 years I would by new ones even if they test ok.
I would look into group 29 or 31 deep cycle batteries. These are big enough to handle the starting of your engines and also your 12v needs. If you do need new batteries wait and buy them this spring plus save the old ones for your cores.
rip131313, You don't mention the size of you boat. The AH capacity of the batteries sounds like they are group 24. The battery isolator is there for a reason and BOTH should only be used for emergencies. Pick one battery for STARTING and one battery for HOUSE. Only start the engine on the starting battery. Add more Deep cycle to the house side if necessary.
Drained Batteries?
Linear Mode
