Need advice on alternator not charging

Dinows

Seaman
Joined
May 31, 2003
Messages
52
My son bought a 1990 Sea Ray last week with Mercruiser IO 350. The lights went dead as did the engine after sitting with the radio on for about an hour yesterday. So I went down today, gave the engine a jump, put my gauge on and it was putting out 7 volts. Now the issue, The alternator looks fairly new so I am having doubts. Is there a sure fire way of testing it beside hooking my voltmeter to the battery. Would hate to change the alternator if that wasn't the problem
Thanks Deano
 

NYBo

Admiral
Joined
Oct 23, 2008
Messages
7,107
Re: Need advice on alternator not charging

Pull the battery and have it load tested.
 

UncleWillie

Captain
Joined
Oct 18, 2011
Messages
3,995
Re: Need advice on alternator not charging

Many auto parts stores can also test Alternators.
Take it in and have them test it.

In reality, unless you have messed up the wiring badly,
If the battery does not go well above ~13.5 volts with the alternator spinning, it is bad!
 

Silvertip

Supreme Mariner
Joined
Sep 22, 2003
Messages
28,758
Re: Need advice on alternator not charging

Current cannot reach the battery if the terminals are corroded or loose. Check and clean them. Most auto stores will also check the alternator for free.
 

Dinows

Seaman
Joined
May 31, 2003
Messages
52
Re: Need advice on alternator not charging

Current cannot reach the battery if the terminals are corroded or loose. Check and clean them. Most auto stores will also check the alternator for free.

Thanks for all your help, I guess tonight I pull the alternator out.
 

Thalasso

Commander
Joined
Jan 18, 2011
Messages
2,876
Re: Need advice on alternator not charging

With the engine running take a multimeter and go across the terminals on the back of the alternator and see what it's putting out. Should be in the neighborhood of 13.5-14.5. If so you know something else is array.You might have a battery charger problem or like someone said earlier. Have them checked. ( batteries).
 

Dinows

Seaman
Joined
May 31, 2003
Messages
52
Re: Need advice on alternator not charging

Pulled it out tonight and it is obvious that it is fairly new. there were 4 wires on it, but the large orange wire was melted and burnt on the alternator terminal, any ideas ?????
Thanks Deano
 
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