1 or both batteries when floating
 

Curious if you guys run both batteries if you anchor and plan on sitting for a couple of hours or only one? I always run both but recently someone said I should run one only. Last time I did this the battery died and I wasn't able to start the boat.

Are your batteries isolated from each other? If so you shouldn't of had one die if you used just it for the stereo. You should just use the one for the radio while hanging out then flip to the starter/boat battery when it is time to go.

With a traditional dual-battery switch, you have the ability to isolate one battery from the house loads and hold it in reserve to refire the engine. This is the ideal method. If you anchor with the switch on "BOTH", you run the risk of depleting both battery banks. If you had your switch on only one battery and both ran down while at anchor, you have something thats not wired ideally.

I agree with Bruizza. I installed a Switch (Perko) to isolate my boat battery from my stereo battery. If one of them dies I have the ability to use the working battery to charge the dead battery. Ever since installing this switch, I have never had a battery problem. I can take a pic and post for you my set up to check it out. LMK

guessing its wired wrong. Pics would be great

always run on 1 and keep the 2nd for back up and alternate between them every few trips and when home they are both on trickle charger

I am always set on 1+2, except when motor is off and just listening to radio. Then I use just battery 1. Therefore battery 2 is always fully charged to start the boat.

Agreed, they should be isolated from each other. You can either run a dedicated perko switch to go between 1 or the other and have everything wired there and manually switch which one or both you want to use.
OR
You could also run a regular isolator which only links the batteries up to charge them both when the engine is running (normally through alternator output wire or oil pressure switch). You wire all your stereo stuff to run off of your secondary deep cycle battery and your primary cranking battery runs all the rest of the boat. While floating you are only discharging the secondary battery and when you start it back up, the other other battery is untouched (except for maybe the auto bilge) and they both get charged while running.
With a high enough output alternator this should also eliminate having to float charging the batteries.

Same here

Am I correct is thinking that both batteries have to be the same to run this two battery set up? I run my stereo off of a secondary battery that i just charge when i've got the boat at home but it would be awful nice if it was charging it while out on the lake as well when the boat is running.

Thanks for the info!

Negative. Both batteries can be different. In fact, it is recommended to have a standard cranking battery for starting the boat and normal running and a deep cycle battery to run off while you are floating because they are made to be discharged and charged like that on a regular basis.

Garon,

When battery banks are isolated by a dual-battery switch, it is ok to have batteries of different size, type, age, etc. If 2 or more batteries are to be wired together to make a larger battery bank, then yes, they need to be the same type, size, age, brand, etc.