# outboard motor rectifier test



## NottelyBILL (Nov 3, 2006)

does anyone know how to test a retifier on my Mercury outboard? An on board test and/or a bench test. Is there any other component that may cause engine not to charge battery? Like maybe a stator what ever that is?


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## huntnnut (Nov 3, 2006)

I'm no marine mechanic by any means, though it sounds like an alternator problem to me.


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## Watcher (Nov 3, 2006)

NB, I'm not sure if we are supposed to mention another site or not. If it's OK try Bass Boat  Central, they have a mercury motor thread I've used for help a time or two. I had to get help on a Johnson charging system once also.


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## darrelllu613 (Nov 3, 2006)

if u have a voltmeter you can check the output voltage leaving the rectifier....if u have your motor manual you can check what the output voltage is supposed to be and then compare. there shouldn't be much fluxuation in the two. If the output voltage isn't correct...it will not charge. Therefore,,,bad rectifier.


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## frankwright (Nov 3, 2006)

I gave away my mercury manual to the guy that bought my boat. There was a simple test in it for checking the rectifier. Mine went bad and would not charge the battery when the boat was running.
Rectifier is your most likely culprit though.


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## lake hartwell (Nov 4, 2006)

You probably already know this but EFI motors draw a small amount of current even when everything is off. If the boat sits for over 30 days at a time disconnect battery leads. Easy way to tell is with EVERYTHING turned off . Leave the neg cable connected and touch positive cable to positive battery post. In low light there will be a very small arc when cable touches post. Easy test and free!


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## little rascal (Nov 4, 2006)

*also....*

...look at the tach if you have one, if the tach quits working or is acting crazy and the batteries seem to not be charging(which you already know), that is a very good sign it is the rectifier gone bad.


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## coptercop (Nov 7, 2006)

*Try the Marine Doctor*

Here's the link:

http://www.themarinedoctor.com/cgi-bin/YaBB.pl

You can search for different brand motors, etc.  Ask his advice and he responds.  A lot of help available there.

TK


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## Cypress94 (Nov 13, 2006)

Best way to test it is with a voltmeter, with the engine cranked, hook it up to the battery and see if it is charging.  A full charged battery is 12.6 V.  (2.1V. per cell).  With the engine running, the rectifier should be sending approx. 13 to 13.5 v.  If voltage isn't coming up, it probably is bad.  Tach check is also correct, if the tach is erratic, then the rectifier is probably going bad.  The rectifier has 3 main purposes, to change A.C. voltage to D.C. voltage, sends tack signal and charges battery.


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## Unicoidawg (Nov 14, 2006)

pm Luter 
If it floats he knows how to fix it......
Unicoidawg


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