hmmm.....alternator not charging???

[itsaboattime]

Hey fellas..........I have a 1983 Johnson 50 horse. While running I have 12 volts at the battery. I believe I should have about 13 or 14 volts right?? I have tested the rectifier and it checks out good following the procedures I found in the FAQ section. I haven't found any procedures in FAQ to test my alternator. Do they exist?? My dealer is temporarily out of manuals for this motor. Any help would be greatly appreciated.

Thanks!!

 

[F_R]

Re: hmmm.....alternator not charging???

Are you sure you did all the steps in the rectifier test? Two directions for each yellow to red and two directions for each yellow to ground? That's 8 or 12 steps, depending on whether it has two or three yellow wires.

Stators can go bad, but it is much more likely the trouble is with the rectifier.

 

[itsaboattime]

Re: hmmm.....alternator not charging???

Yeah.......... Pretty sure I did them all. I will go do them again. I will post my readings when done.

 

[itsaboattime]

Re: hmmm.....alternator not charging???

O.k. I went back and redid the rectifier tests. all 3 yellow wires tested out fine but the red one has a infinate resistance both ways. soooooo I guess I pick up a new one tomorrow on my way home from work. I dont know why I got a good test on all the wires the first time I did them.

The wife says my brain is goin soft as I get older

Who knows

 

[Vic.S]

Re: hmmm.....alternator not charging???

Firstly a word of caution about the rectifier test.

If you are using a digital multimeter then use it on the diode test range. Some meters will not test diodes on the ohms ranges, some will work OK on some of the ranges but not others, so unless you know how your meter behaves with diodes on the ohms ranges use the diode test range. You may not get zero or infinity readings but you will see a big difference between the forward and reverse readings.

Secondly to check the coils. With the meter on its lowest ohms range you should get a very low resistance reading between any two of the yellow wires (disconnected from the rectifier of course) and you may be able to detect that the resistance between yellow and yellow/blue is double that between either of those and yellow/gray

Finally to check the output from the coils use the meter on an AC volts range and you should get readings in excess of 12V between yellow/gray and both yellow and yellow/blue if the motor is revved a bit. (sorry I don't know what you will get between yellow and yellow/blue)

 

[itsaboattime]

Re: hmmm.....alternator not charging???

Thanks Vic. I have taken the old rectifier off and am taking it with me to my dealer tomorrow. hopefully I can get him to test it.

 

[F_R]

Re: hmmm.....alternator not charging???

Make sure that whatever caused the rectifier to blow doesn't cause the new one to blow also. That could get expensive.