Upgrade to 130A alternator....now tripping breaker

ferrall

Petty Officer 3rd Class
Joined
Jun 21, 2010
Messages
96
1994 Volvo Penta 5.8Fi PMDA

I upgraded to a 130A alternator. I upgraded all the wiring to it with 4 awg just as suggested on this forum. It charges great now but I have an issue of it tripping my 60A breaker in the engine compartment. This only happens when I'm cruising over 3000 rpm and not when I'm putting around the 2000 rpm mark or under. Any ideas? I did just order a new breaker just in case it's bad.
 

bruceb58

Supreme Mariner
Joined
Mar 5, 2006
Messages
30,454
There is a 60A breaker inline with your alternator. Obviously, if you are putting out more than 60A, that will pop.

You need to make sure the wire going from the breaker to the battery is also 4GA. Did you replace that too?
 

ferrall

Petty Officer 3rd Class
Joined
Jun 21, 2010
Messages
96
That wire was already 4 ga. I understand it'll pop but what puts out more than 60A? I have a stereo system and am running 2 amps but popping the breaker happens whether I have the stereo on or not.
 

bruceb58

Supreme Mariner
Joined
Mar 5, 2006
Messages
30,454
Your alternator can now output more than 60A and it charges the battery through that breaker. Have you looked at a wiring diagram?
 

ferrall

Petty Officer 3rd Class
Joined
Jun 21, 2010
Messages
96
Yes. I have the wiring diagram. Are you saying I should up my breaker?
 

bruceb58

Supreme Mariner
Joined
Mar 5, 2006
Messages
30,454
I would run the output of the alternator to either the battery, the common output of your battery switch or to the side of the breaker that feed the battery. Leave everything else alone.

Non Ford engines connected to Volvo drives do not run the output of the alternator through a breaker.
 
Last edited:

ferrall

Petty Officer 3rd Class
Joined
Jun 21, 2010
Messages
96
Shouldn't there be some type of protection though? What's to stop a battery from melting down or blowing up if your alternator goes crazy? That breaker is there for a reason, right?
 

bruceb58

Supreme Mariner
Joined
Mar 5, 2006
Messages
30,454
Most Volvos and others have the alternator go straight to the battery without going through a breaker. If it makes you feel safer, put in it's own 130A breaker inline between the alternator and the battery. On my Volvo, alternator feeds the battery directly without a breaker...from the factory.
 

bruceb58

Supreme Mariner
Joined
Mar 5, 2006
Messages
30,454
Just so you know, if you blow the breaker, your alternator is then unloaded and you run the risk of blowing it out form an over-voltage condition.
 

ferrall

Petty Officer 3rd Class
Joined
Jun 21, 2010
Messages
96
I replaced the breaker with the same 60A type and that took care of the problem. No more popping the breaker
 

bruceb58

Supreme Mariner
Joined
Mar 5, 2006
Messages
30,454
Its going to pop it again if your alternator ever puts out more than 60A. Kinda defeats the purpose of putting in the 130A alternator, don't you think?
 

ferrall

Petty Officer 3rd Class
Joined
Jun 21, 2010
Messages
96
If my alternator has to put out more than 60A then there's a huge problem elsewhere. But ya, you're right 130 was a little big. I just got sick of my 65A alt failing. Wish I'd gone smaller but now I have to deal with it
 
Last edited:

Scott Danforth

Grumpy Vintage Moderator still playing with boats
Staff member
Joined
Jul 23, 2011
Messages
47,296
If my alternator has to put out more than 60A then there's a huge problem elsewhere. But ya, you're right 130 was a little big. I just got sick of my 65A alt failing. Wish I'd gone smaller but now I have to deal with it

you have not dealt with it, you simply replaced a worn-out undersized breaker with a new undersized breaker. dealing with it will be either putting a 65 amp alternator back in, or upgrading the wiring and breaker for the new higher output.
 

ferrall

Petty Officer 3rd Class
Joined
Jun 21, 2010
Messages
96
The wiring is upgraded to 4 ga. What size breaker should I go with, 100A?
 
Last edited:

bruceb58

Supreme Mariner
Joined
Mar 5, 2006
Messages
30,454
Is the breaker only feeding 4 ga wire? In other words this breaker is going in between the alternator and the battery only. You aren't just replacing that other breaker right?

You have a 130A alternator. It can put out 130A. You need a 130A breaker.
 
Top