Alternator Soze for Stereo System

I am installing a new system in a new boat and was wondering what amp alternator I should get and where? My system will include three amps and three batteries. What size are you guys running with your systems? Any help would be much appreciated!

This guy will help you out. http://thefloridakeys.com/batteryshack/ There are many people with very high end stereos on this website that have his alternators, including myself. He starts at 100 amps and goes up from there. He has been building alternators for something like 20 years, and uses brand new cases and parts with quality components.

Your stock alt should be able to handle the load not problem.

Bad assumption Phaeton. If he has a 70amp (or so) alternator, which is the norm on most new boats today, he may not have enough juice to run everthing he wants to run. If he runs say 1500 watts of power from those three amps, a couple ballast pumps, a light bar, and some other stuff, a 100amp or better alternator would probably be a good purchase.

-Mike-

Not such a bad assumption...Phaeton has as big of system as anyone on this site. I have a stock alternator and have over 2500 watts of power from 3 amps, a 5 bag ballast system with 10 pumps, and a light bar with 7 lights. I use 3 batteries and with everything wired up properly, there are no problems. It all comes down to the wiring.

Mike if it was a car then you have lights, heater, air, power windows, computer, etc. A boat draws much less power. He said nothing about a light bar but stated that he has three battery's so I assume they will hold up while he is running the accessories.

Just so you know I am running four amps.
JL Audio
300/4
450/4
500/1
1000/1

with a stock alt, three battery's and have never had an issue.

I'm running about 2000 watts between three amps off of stock alt.

Only time it gets a bit low is with the tunes up and the heater on while at low RPMs. Get up past idle speed, not a problem, the voltage comes right back up. With the heater off not a problem at all.

I will kind of have to agree with Mike, I have over 600 amp hours or equal to around 12 Optima Blue Tops in my boat, running over 4000 watts, 3000 are pushing full tilt wattages to the subs which consumes the majority of power. I purchased a 185 amp alternator from 'Bill' @ the Battery Shack, I would highly suggest any aftermarket stereo / Amp setup would really benefit from an aftermarket Alternator purchase.

Keep in mind that on OEM 70 Amp Alternator, their alternators at idle are only deliverying around 15 amps, and only support a two-stage regulator. Thats practically nothing when you factor in amps and other accessories. The aftermarket alternators are designed for maximun amps at low and mid idle situations.. I cant see how 3 batteries between 50-60 amp hours per battery is sifficient power for a big 3000 watts system without a large aftermarket Alternator.

60Amp hours X 3 Batteries = 180 amp hours
180 Amp Hours X 12 Volts = 2160 watts per hour

At full charge, even if you are listening at 75% volume, your dead before 1 hour of play..

Would you not agree?

I can play my system all day on ONE battery with NO problems. Then again I could do that on my last system also. We don't sit for hours with the system at high volumes with the boat off though.

I was going to add a couple of battery's to my boat for stero use was thinking of getting deep cycle one's.Since I don't need cranking amps figured that would be the way to go,but I have heard charging them off the alternator is not good and ruins the life of the battery what do you people think.

All three of my Optima batteries are deep cycle with no problem.