Mercruiser 5.0 alternator 55AMP vs. High 120-130AMP

dlogvine

Master Chief Petty Officer
Joined
May 4, 2015
Messages
832
Alternator on my 1998 Ebtide boat went bad, could be from getting submerged under water for a short period of time, when the drain plug was not tightened up completely, letting the water into the engine compartment. I'm planning on taking out the old alternator and first checking it out and if possible repairing it. However if the cost of repair will be too high or if it is not repairable, I will buy a new one. And here I found two types of alternators by the Amp outputs, standard with 55 Amps and High output of 120-130 Amps. The price difference is only about $30, so I wonder if I should get a high output amp or could it cause any damage to the batteries or the system? Thank you.
 

Bt Doctur

Supreme Mariner
Joined
Aug 29, 2004
Messages
19,092
you only have 10Ga wire from the alt to the starter unless you plan on updating the wire to 1/0 or 2/0 55-65 amp is all you need.
I guess if you tried dumping 100 amps into a relatively dead battery it could explode.
 

Scott Danforth

Grumpy Vintage Moderator still playing with boats
Staff member
Joined
Jul 23, 2011
Messages
47,296
agreed with Maclin. if your alternator got wet...... your starter did too and will soon die.
 

dlogvine

Master Chief Petty Officer
Joined
May 4, 2015
Messages
832
will see, looks like the problem is not in alternator but the connector on the wire. It broke and was barely touching the terminal. Im surprised it was feeding any juice back to the battery. Will test the alternator in the boat while running with ear muffs. Will see if the alternator feeds enough juice
 
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