115 Merc - battery charging problems

wipeout

Recruit
Joined
May 14, 2005
Messages
1
My late 70's 115 isn't charging the battery. I tested the voltage with and without the engine running and there is almost no difference. I am not too familiar with boat mechanics. But, from what I've been reading on the forum, it looks like the most probable cause is either the the stator, the rectifier, or both. I haven't tested the stator voltage yet. But, it seems that if that is 14 volts or so (running), then it sounds like the rectifier is bad? Is this right? Is there anything else that could cause this? I checked the wires for conninuity and they seem fine, except for the insulation on a few, which I am going to replace. What do you think?
 

WillyBWright

Fleet Admiral
Joined
Dec 29, 2003
Messages
8,200
Re: 115 Merc - battery charging problems

Welcome to iboats. :) <br /><br />The rotton insulation is a problem. But the more likely problem is a blown rectifier. They fail over time due to loose and/or corroded battery connections. Connecting the battery backwards will blow it in an instant.
 

mark35a

Recruit
Joined
May 15, 2005
Messages
1
Re: 115 Merc - battery charging problems

I'm having the same problem, have 12 volts with motor running. I have changed the rectifier it didn't help. How do I check the stator (this is the coils under the flywheel?) My motor is 1976 115 merc.
 

Barnacle_Bill

Admiral
Joined
Feb 8, 2004
Messages
6,469
Re: 115 Merc - battery charging problems

Yes, the stator is under the flywheel. Your manual will give you instructions for testing it.
 
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