Adding another battery for my stereo...

I have seen a lot of different methods of adding another battery, but what is the best for my situation. I am fine with one battery now but I added a big stereo. I would like the stereo to run on one battery and the boat on the other. However once the boat is running I want it to charge the stereo battery as well. What is the easiest way for me to do that and what will it cost?

Re: Adding another battery for my stereo...

Grab a dual battery setup like they use in 4WD's, using an isolator. RedArc do a kit.

Re: Adding another battery for my stereo...

Dual battery setups are very easy to install and have many advantages. You can use one at a time, use both at the same time, totally cut off power and charge both at same time. See the schematic. The isolator will prevent a component, such as your radio, which might accidentally drain one battery from draining both. You could always just power your radio from the main power supply and then when you've stopped and are just running the radio, switch the battery selector to 2 for example. 2 can be for only components while 1 is always cranking.

The other thing you could install is a Priority Start automatic battery disconnect. This device automatically cuts power when voltage drops below 11.4 volts.

Cost is about $50 for the switch, another $50 or so for the extra cables, and then the cost of a new battery. Consider one battery as your deep cycle and then the other as your cranking if you want.

Re: Adding another battery for my stereo...

Not sure what you mean by easiest, installing, using. The easiest to install is the Off, 1, 2, Both switch pictured above, but YOU have to constantly remember to change the switch from batter 1 to 2 or to both, or maybe you want off.

The Blue Sea Systems Add A Battery - iboats system you turn the switch on at the beginning of the day, and turn it off when you are done. You can play your stereo till the battery dies, but the engine battery has not been touched. Start the engine and both batteries will charge. You have to do nothing, it does it all.
An isolator will work, but it costs you about a volt to use.