1981 ski nautique

[kneuppc]

1981 ski nautique 351 windsor. 1 12 sub 4 tower speakers and 4 inboard speakers 2 amps. alternator went out. purchased and installed new alternator still no voltage being produced. thinking stereo system is overloading alternator looking for recommendations on alternator upgrades or other ideas.

[WakeSlayer]

How is your battery? How are your cables? Is the new alternator identical to your old one? Or does it require wiring changes that possibly did not get made?

Unrelated, but I hope you bought a marine alternator at the very least so you don't explode.

[surroundsound64]

Wakeslayer brings up a good point. The old alternator had an external voltage regulator on it. I'm guessing you probably got the same upgraded model that I did a few years ago (from white lake) which has an internal voltage regulator. You have to do some wiring adjustments. Pm me if you need help.

[kneuppc]

Battery is new and charged. tested good. cables and connections in good shape. Identical replacement alternator with external regulator. Contacted dealer I bought alternator from they are going to have it rebuilt for me but I am still concerned that it will not support my radio. wondering if I should upgrade alternator to 100 amp or go smaller with extra batteries.

[WakeSlayer]

I think you need to figure out your problem first. If the stereo isn't on, there is no draw. Get out the multimeter. Check your main breaker, all connections off it, and head forward. You have a different problem.

[kneuppc]

Ok I agree with you wakeslayer. But I guess my question then would be what could cause the alternator to keep going out. Performed all tests points to alternator failure. Could the voltage regulator cause alternator fail. I will be replacing it when I install rebuilt alternator. I appreciate all the help this is my first boat.

[surroundsound64]

I'd probably replace the regulator before sending alt off, unless they are footing the bill. But I would still change the regulator. You haven't by any chance been disconnecting the battery while it's running, have you? You can screw stuff up then too. A lot of people think its a good way to see if you're alternator is putting out, but the best way is the multi-meter, if you don't want to tear stuff up!

[kneuppc]

The place I bought the alternator from is paying to have it rebuilt. I have not been disconnecting the battery with it running. I know quite a bit about cars I work for Toyota for a living but I have never dealt with externally regulated alternators. I figure go ahead and get alternator rebuilt and install with new regulator. How can I check the regulator?

[surroundsound64]

Use a multimeter to see what the alternator output is. Easiest way, and sorry if you already know this, is to take your meter, but it on dc volts on at least 14v, using the appropriate leads for polarity, touch the battery terminals while it's running. If you get 14+/- about half a volt, it's doing what it's supposed to be doing.

[kneuppc]

That is what I did and got only 11.9 volts which was battery voltage. I think I am on the right track with the replacement alternator being bad when I bought it. I was just concerned that maybe the voltage regulator somehow took out the new alternator. Do you know what the aux lead is for on the alternator. Larry please keep the info coming it is all helpful. I appreciate anything you have to say.

[surroundsound64]

Yea, sounds like you're on the right track. I doubt the regulator toasted the alt, but I suppose it's a possibility. I think the aux is a reference line for the regulator to monitor system voltage. I'm not for sure about that though. I do remember figuring it out several years ago when mine was giving me problems, but the newer internally regulated ones do away with it.

[Texan1554]

If you're still worried about the power to the stereo do a search on here for adding an extra battery. Lots info on that install. Pretty easy ways to keep your stereo completely seperate from your starter battery.

[kneuppc]

Ok so I am a dummy. Voltage regulator was the problem. Go figure 2 new parts and I figure the alternator to be bad instead of the voltage regulator. Installed another new regulator and alternator is now charging. Ok so now I think I am going to install a secondary battery and either a surepower or a perco switch to help with the stereo system needs. Just gotta find room. Older boats are short on that.

[surroundsound64]

Ok so I am a dummy. Voltage regulator was the problem. Go figure 2 new parts and I figure the alternator to be bad instead of the voltage regulator. Installed another new regulator and alternator is now charging. Ok so now I think I am going to install a secondary battery and either a surepower or a perco switch to help with the stereo system needs. Just gotta find room. Older boats are short on that.

Heard that.

That's why I'm on the prowl for a newer 2000-2004ish boat. Married with 1 kid and #2 will be here in about 2 weeks and we're just flat out of room. Still going to keep the 81 since it's been with us since 85, but I gotta get something bigger now.