So I am planning on swapping out my batteries this spring. I have a twin set up and 3 batteries currently. On the port side I have a starting and house battery. On the other I have a starting batt. All group 31. I also have 3 switches under the back seat to allow me to turn them on and off and on the port side connect both together. I do sometimes run the stereo for a few hours at a loud volume and this would be the main use for my house batt.

Few questions. Should I buy 2 Cranking batts and a deep cel? Should I buy 3 dual purpose batts? What is the best way to set this up?

Two cranking, one deep cycle (house). I would even add another house battery, if you have the room.

What I was told is deep cells are not made for cranking the same way cranking batteries are not made for slow long draws.

I have had better luck using deep cycles for everything. They seem to last longer.

I have twins and 3 big amps. I run 3 deep cycles. And have a battery jumper pack incase I run batteries down while floating and enjoying a beer! It was a crapy feeling when engines would not start floating down a river.

I run 2 cranking and one deep cycle.

2 deep cell AGM batteries here. One for house, one for engine. Only AGM batteries for me.

Ths guys. I have decided Im going to get 2 gp 29 cranking and a 31 deep cycle. Looking into VSRs as well

Whenever charging batteries hooked up in parallel, is there a right and wrong way to connect the leads? I've been told a few different things, just want to see what you guys have to say.

It shouldn't matter IMO. Positive to positive and negative to negative. Any batteries in parallel should be the same battery.