Alternator/multiple battery question

My boat has a 65 amp alternator and a single battery, I plan on putting a single 4 channel amp (4 x 90) in the boat, and I am wondering at what point I would have to upgrade, I should be fine with my current setup right?

Anybody?

Correct you will be fine unless you sit around with the boat off and the stereo cranked for long periods of time.

The amp will draw around 20 amps peak, and that is only when you have maximum volume going out all four speakers, which unless you are playing a test tone is not much of the time.

The basic boat functions will require around 10 amps, so your alternator has 30 amps or so of reserve. Shouldn't be a problem as long as you are running at 2000 RPM or above most of the time.

If you spent most of your time at idle then a higher output alternator might come in handy. But if you spend most of your time riding then your current setup is fine.

As for the battery that essentially is a factor of how long you want to be able to run the stereo with the motor off. You should be good for two or three hours with your current setup and still have enough to start the boat. Of course, as the battery gets older this time will shrink...

Rod

Thanks guys, that is consistent with my thoughts.

I am also intersted in running this 4 channel at 2 ohms with subs on two of the channels and tower speakers on the other two. Any drawbacks to running a 2 ohm load? The amp is stable, but I have been told they run hotter when the load is at 2 ohm.

The first thing I always do when I get a boat is put in a Perko switch and a second battery. It's a pain to be out in a perfectly good boat that won't start because you have a dead battery. Too easy and too cheap not to do IMO.

Or........install a battery isolator between your two (or three) batteries and eliminate the need to remember to flip the Perko switch to protect your starting battery. In my mind, automatic (isolator) is better than manual (Perko switch) any day of the week. Just my $.02.

When I get my new boat (waiting is extremely painful) I was going to look into an isolator. I've never used one. How do they work? Where do you get them?

Chris:

Look at stingerelectronics.com under battery accessories. I just installed the 200 AMP version. Works awesome! The relay has four inputs: one for each battery, ignition, and ground. When the ignition is on, the relay completes the circuit between both batteries allowing the alternator to charge both. When the ignition is off, the relay breaks the circuit and seperates the batteries. No switchees to remember.

Tim

Battery Isolator wiring diagram.
http://www.malibuboatowners.com/forums/index.php?act=Attach&type=post&id=98415