Newbie with Battery Isolater/Alternator Question

Hey Guys,

Well I am getting ready to get my boat back from the shop but have an interesting question for you, I have been doing alot of research over the last couple of weeks and I just have not been able to find the exact answer that I am looking for. I am looking at installing a stereo into my boat it is not going to be anything massivie just a Sony XM-604 600 watt marine amplifier (60watt RMS at 4 Ohms) and 4 Polk db 6501 6.5 inch non component speakers. I will be adding a 2nd deep cycle battery to run the stereo equipment as that seems to be the best way to go from what i have been reading so it does not interfere and draing the starting battery. I was debating between the battery swtich or isolater and i have decided on the isolater as it seems to be a pretty easy, automatic and straight forward set up. However my question is how do i figure out how big of and isolater i need as it seems they make them in differnt amp sizes. The boat is a 85 Rinker V170 w/3.0 mercruiser inboard and the stock alternator, will I also think about needing to upgrade that as well? if so what is the recommended size for this type of set up?

Thanks guys for all the help and if I simply missed a thread with this information in it just point me the way and I will take it from there!

Steve

Re: Newbie with Battery Isolater/Alternator Question

You don't need a second battery to run just one amp nor do you need to upgrade your alternator. Modern stereo amps are very efficient and will do just fine. You may not even notice the extra drain.

Not sure if you've already purchased the equipment, but I would use an MB Quart NAU460 and Infinity 612M speakers. That Sony amp is over priced and not as durable as the MB Quart and those Polks while sounding good at low volumes will sound like junk when you crank them up with that amp. I use my Polk 4"s as swim platform speakers only. Everything internal is Infinity. Now.. the Polk tweeters.. those sound like heaven.. it's the woofers that I'm not a fan of.

Just my $0.02.

Re: Newbie with Battery Isolater/Alternator Question

Mark,

Thanks for the tidbit, I actually have not purchased anything yet.. and good thing being it looks like that MB Quart Amp might be a better choice and its actually cheaper. I guess as far as the dual batteries go i was just worried about being on the water all day floating around with just the radio on and having the main battery go dead. So then I am assuming i should go with a dual purpose battery?

Re: Newbie with Battery Isolater/Alternator Question

Just put the largest size marine deep cycle battery that you can fit. Walmart has series 29s for around $70.. and it's the same Johnson Controls unit as Diehard, Interstate, etc.

If anything, just make sure that all of your battery cables are new-ish and in good condition as well as your orange alternator charge wire and ring terminal connection. I also can't stress enough to only use marine grade power wire for that amp.

Good luck!