1988 Mercury 90hp 3 cylinder charging

Schnidly

Petty Officer 2nd Class
Joined
Aug 12, 2001
Messages
143
Can someone tell me what kind of voltage I should get coming out of the rectifier to the battery? I just bought a new battery and installed a radio shack rectifier because I suspected mine was bad after testing it. I replaced the stator a year ago along with the switchbox. I am getting up to 16 volts on my multimeter on the positive post(battery post) on my new rectifier and 16 volts on my volts meter in the dash. When I initially test the charge it is around 12.75 and then will go up to 16 volts and it will vary in between as I throttle the engine speed. My concern is I just installed a new battery and new rectifier and can this high charging voltage burn out my newer stator or switchbox? Not even sure if I should be concerned?
 

enginepower

Petty Officer 1st Class
Joined
Jul 5, 2014
Messages
260
Maybe your old one had a regulator built in? But sounds like your regulator isn't doing it's job.
 

Schnidly

Petty Officer 2nd Class
Joined
Aug 12, 2001
Messages
143
There is only a full wave bridge rectifier that operates off of a 9 amp stator. From the stator the two yellow wires feed directly to the rectifier and from there it feeds the positive battery post on the starter solenoid.
 

Barnacle_Bill

Admiral
Joined
Feb 8, 2004
Messages
6,469
That is pretty common for a rectifier only system. Make sure all connections are clean and tight and use only marine batteries. There is a difference.
 

Schnidly

Petty Officer 2nd Class
Joined
Aug 12, 2001
Messages
143
Thanks Bill, is there anything I can do to lessen the 16 volts I see while the system is in a charging state which I believe to be all the time when the motor is running and the stator and rotor are running putting the ac voltage to the rectifier? My gauges and lights burned out, would the 16 volt charge output from the rectifier to the battery have burned them out? The voltmeter did not get affected and still works, but my tachometer, trim gauge and fuel gauge do not work. Replaced one 5 amp fuse.
 
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