Which one should I use... Dual battery isolator or VSR?

[95Bayliner]

I have an 120HP Force outboard motor that uses a stator/alternator with an output of 14 amps. I'm looking to add a second battery for my electronics, primarily a stereo system w/ amp. Amp specs state the current consumption is 38A (seems a bit high for a 50W x 4 RMS amp). Please don't blaze me for my sound system. I would like to an a cigarette auxiliary power port as well. Will I need another terminal box for this or how can this be achieved?

I've been reading and figured that battery 1 (starting) will be used for the motor and battery 2 (deep cycle) for house/accessories.

I could use some help determining if I should go with a battery isolator that uses diodes or a VSR for my particular application. I would also like to know if there's a way to integrate a battery switch with each application (isolator or VSR) to combine the two batteries in case I ever have problems starting the motor with battery 1.

I also have a question regarding deep cycle batteries... The specs I've been reading are a little confusing. IE... (X) amount of reserve capacity at (Y) amps. For simplicity's sake, let's say X = 120 minutes and Y = 38A. Does this mean I'll only get 2hrs of playtime before the battery is drained and needs recharging? Seem kinda like a rip off but I guess you gotta pay to play. Any recommendations on which deep cycle battery would be best to use in my application??

Let me know if additional information is needed and thanks in advance for everyone's input.

 

[nikon]

Re: Which one should I use... Dual battery isolator or VSR?

As I understand it, with an isolator you get voltage drop. So I installed a VSR. I already had two batteries on a switch, to hook up the vsr just connect it to the #1 and #2 posts on the battery switch. This way wires stay short and everything stays neat. If you need a wiring diagram they are usually on the back of the package.

 

[TSL812]

Re: Which one should I use... Dual battery isolator or VSR?

Keep in mind that if the amp draws 38a peak it probably won't draw anywhere near that under most conditions.