Alternator not charging on 9.9

[ryan.taylor93]

I have a 1992 yacthwin 9.9. I recently purchased the motor and its been sitting for 8 years. It took 5 pulls and it started up and runs perfect now. The only problem is the alternator isnt charging. There's 5 terminals on the bus bar, the first one on the left is a power supply, the 3 next to it have 5.8V and the last one is for the starter.


Should i be getting more then 5.8V on those 3 wires? is that round thing below the bus bar a voltage regulator and could it be bad? also is there a way to test it to see if its bad before I buy a new one?

 

[metriccrescentwrench]

Re: Alternator not charging on 9.9

is that round thing below the bus bar a voltage regulator and could it be bad? also is there a way to test it to see if its bad before I buy a new one?

That's the rectifier, and if it were bad it would cause your problem.

I believe there are going to be 3 wires on your rectifier, one red and two yellow or gray/yellow. If you can get your hands on a multimeter with a diode test function you can check the rectifier. Disconnect the wires, put the multimeter in the diode test position and take a reading between one of the yellow wires and the red wire, then reverse the test leads and take a reading on the same wires. The reading should be real high in one direction and low in the other. Repeat between the other yellow wire and the red wire, again the reading should be high in one direction and low in the other. Now repeat between each of the yellow wires and ground, again in each case you should see a high reading in one direction and low in the other.

 

[F_R]

Re: Alternator not charging on 9.9

Basically correct, but it is the 3 phase alternator and should have 3 yellow wires + the red one. There are 4 tests on each yellow as just described. 4 tests x 3 wires = 12 tests. It must pass all 12.

EDIT: Did we mention, you have to disconnect all of the rectifier leads from the terminal strip before doing the tests.

 

[ryan.taylor93]

Re: Alternator not charging on 9.9

okay so I did the Diode test, I don't know what the results mean but here's what I got

Putting the red lead from the multimeter on the red wires and the black on either of the 3 yellow wires got me nothing at all

Red lead on Yellow blue and black lead on red got 503
Red lead on Yellow and black lead on red got me 503
Red lead on yellow grey and black lead on red got 480

Yellow to yellow in any order got me nothing

Did I do this right?

 

[ryan.taylor93]

Re: Alternator not charging on 9.9

well from the research ive been doing on the internet i believe the rectifier is good. What do each of the 3 yellow wires do? and what sort of current should they have on them?

 

[Haffiman]

Re: Alternator not charging on 9.9

First check out your stator.
Disconnect the yellow leads from the strip, attach an OHM meter between any of the leads (red pin) and ground (black pin), it should be no reading/contact, open!
Attach red and black between the yellow leads, it should be resistance/contact, but will vary with combination of the leads.
Attach red pin to red lead from rectifier, and black to any of the yellow leads going into the rectifier. (leads disconnected from strip). It should be no contact.
Reverse and put the black on red lead from rectifier and red pin on any of the yellow leads, it should be contact.

If these tests are passed, connect all leads back and a batter B+ to the red lead from rectifier and black to engine ground.
Hook up a fully charged battery to the engine, (resting volt around 12,5 Volts).
Start the engine and keep the voltmeter hooked up on the battery. After about 5 min at 3000rpm, the voltage should climb above 13Volts.

 

[F_R]

Re: Alternator not charging on 9.9

Both of you guys are ignoring six of the twelve tests. In addition to the ones you have already done, you must connect your meter to the rectifier case (ground) and each of the yellow wires in turn, then reverse the connections for each wire. You should get a high/low reading on each wire.

There are six diodes in that rectifier, and each requires a forward test and a reverse test. It must pass all twelve tests, or it is no good.

It should be noted that many digital multimeters won't work for testing these things, however some will. The ones with a diode test setting will work. Analog meters (with a clock hand) will work. So will a simple circuit test light.

EDIT: To answer your question, each yellow wire is connected to a pair of diodes. Without getting into a long explaination, a diode allows electricity to pass through in one direction only. Your stator produces AC (electricity alternates back and forth), and the rectifier converts it to DC (electricity goes in only one direction). Batteries are DC and require DC to charge them.

 

[metriccrescentwrench]

Re: Alternator not charging on 9.9

Both of you guys are ignoring six of the twelve tests. In addition to the ones you have already done, you must connect your meter to the rectifier case (ground) and each of the yellow wires in turn, then reverse the connections for each wire.

You should get a high/low reading on each wire.There are six diodes in that rectifier, and each requires a forward test and a reverse test. It must pass all twelve tests, or it is no good.

YES, absolutely. If any one of those diodes is bad (and so far you've only tested 3 of them) your charging system is screwed.

And as a side note not entirely related, a 3 phase rectifier such as this one produces extremely clean DC, whereas the single phase rectifier (which I was thinking was in there) produces a pretty choppy DC voltage (but is of course perfectly acceptable for the intended use).

 

[einarjoergensen]

Re: Alternator not charging on 9.9

Hello

I have a quite similar problem on my Evinrude 50 1981. The charging voltage is low and the tachometer send wire voltage is low. Can a rectifier problem cause a lower charging voltage and tachometer voltage?

Regards,

Einar J?rgensen
Norway

 

[ryan.taylor93]

Re: Alternator not charging on 9.9

okay so i did do the other tests I forgot to do and it passed. the rectifier is good.......I'm used to checking alternators on cars and it shows 14.5 volts when the negine first coems on. Like haffiman said thought after 5 minutes itll get up to 13V......i'm getting 13V so I guess everything's good, I was expecting more than that so that's why I thought something was wrongg