Batteries

[Dj8312 2]

Hey y’all what’s the best batteries to get for starting my boat and running stereo I’ve read about size/class 29,31 and I know I need to start charging after each outing. But I’ve been having problems with batteries. I tried blue top optima and looking back it probably wasn’t the batteries fault it didn’t seem to last as long as I thought it should but my lack of maintenance such as charging. 

I can get more details but all I know at the moment is I have two batteries, 2 amps, a sub , and Roswell tower speakers that spin 

Do I need deep cycling or starting or dual purpose and does both batteries need to be the same? 

help me out please 

Edited July 20, 2018 by Dj8312

[Wylie_Tunes 146]

Engine size? For a typical small block, a group 24 cranking will do just fine and a 27 or 29/31 group size for a larger engine like an 8.1. 

Does the boat have a dual bank setup with battery switch? if so, then you'd likely want a dedicated deep-cycle. Now, this is where it gets tough to provide a simple answer. The size and/or amp/hour you will need, really depends on how long you want to drop anchor and play the system. This can get a little deep as you need to know the amps, what speaker loads their driving in order to get an idea of their potential current draw. Then you have to calculate that into amp hours based on how long you want to play with engine off. Even then, its a guess as music is not constant. 

[Dj8312 2]

It is a pcm Excalibur 330 possibly the boat actually belongs to my brother so I can’t reme for sure.  I know it currently has two batteries and has had for the last approximately 8 years he has owned it but as far as the switch and stuff I’m really not sure as I’ve never personally messed with the switch. I took batteries out and put batteries in but kept everything the way it was and didn’t trace any wires or look for switches.  I can try to get more info on the setup but may be a few days. 

Thanks wylie_tunes fore the reply I appreciate the help so far.