Alternator Questions Re: System Hookup

dajuice

Will a 70 Amp alternator be ok pushing 3 amps? 1-480 watt max and 2-400 watt max. They will be pushing 4 tower speakers and 2 12" subs. Any help would be appreciated, installing soon.

Wayne DuCharme · Newbie Joined: 16 Feb 2003 Posts: 26 City: Tacoma Wa.

we have had problems last year running the battery down, two amps and a 55 amp alt I am checking into a 100 amp alt, but we were also told to increase the size of the main cables to starter and ground to a 2 instead of an 8 wich came on the boat and ours is an old mc and known for these types of problems. I am going to post some results later on after we try this out ( cables first) then alt if we have to.....hope this helps.

Texas · Criminal Joined: 13 Mar 2003 Posts: 81 City: Houston

70 Amp aint enough.... you will burn it up too...
been down that road, make sure you are also running 3-4 batteries, it will cushing the power you need to drive those amps

SupremeWake · Soul Rider Joined: 14 Feb 2003 Posts: 322

Run HEAVY guage cable and see if you have a problem before going out and buying 4 batteries and a huge alternator. I'd bet that you'll be fine. Go to any quality high-end audio store, tell them what you have and see if they think you should run 4 batteries. Thats crazy. The only way you'd need more than 1 battery is if you are running at high volume for several minutes with the engine off. If you engine is running, your 1 batt. and 70 amp alt. should be able to handle what you have. Try it with heavy cable before wasting your money.

tabiggs, sweet boat though. I don't mean to crap on your audio knowledge, you have a sweet set-up. But does this guy really need to go out and buy 4 car batteries to run his 1300 watts? How does that 30 footer handle? I bet its fun to dock huh?

George · Addict Joined: 12 Jan 2003 Posts: 552 City: Chattanooga

There is no way you could possible need more than 2 batteries at most.i have ran my 2000 watt system for 30 minutes at a decent level and still cranked the first time.

SupremeWake · Soul Rider Joined: 14 Feb 2003 Posts: 322

I agree. I run (6) 6" coax's on 45 watts each and 400 watts to (2) 12" subs and it doesn't even phase the battery or charging system at all. I play it at a descent listening volume for several hours with the engine off at times, when I'm working on the boat or cleaning or something like that. Don't go out and buy any more batteries man. Set up your system with some phat cables and try it out first. You'll be happy with it.

MossSavage · Newbie Joined: 08 May 2003 Posts: 10

It all depends on the amount of bass you are pushing and the volume. Oh and if you get nervous about running too low and needing a jump to start your boat.

Heavy Bass music like Rap will drain the batteries quickly.

Fr3ak · Newbie Joined: 22 May 2003 Posts: 3 City: Austin, TX

This might be a little late for a reply, but an easy solution would be a farad capacitor. A good rule of thumb is 1 farad for every 1000watts in your system.

The idea behind a capacitor is much like a reserve that is kept charged when your amp is not drawing the full RMS or Peak watts.

Just an idea if its not too late.

Edit: Here's a link http://www.crutchfield.com/cgi-bin/S-CMjgQXoHu35/ProdGroup.asp?c=11&s=0&cc=01&g=725

boehnkew · Outlaw Joined: 26 Mar 2003 Posts: 112 City: Kennewick, WA

A capacitor will help prevent the amp from starving for power intermittantly, but won't help if the alternator, cables and connections can't keep up with the total demand of the system.

dajuice, Your amps add up to 1280 watts max. A better value would be the RMS watts (best is to know exactly how much watts at the given volume). If you can find this, divide the watts by the volts to determine the amps. Lets say it is 700 watts rms (pure guess) and you are actually drawing 500 watts (pure guess). Then (500 watts)/(13 volts) equals 38.5 amps, call it 40 amps. Most 12 volt systems operate at approx. 13.8v. So using 13 volts is a little conservative, but hopefully you get the idea.

If you are really drawing 40 amps through the stereo, then 30 amps is left to power everything else and recharge the battery. I'd probably bring some jumper cables (good idea anyway). It's always a good idea to make sure all the wire/connectors are clean, tight and appropriately sized.

Good luck,