alternator problem, no charge

[luckystreak]

Hi guys, newbie here.

Just recently got my 1973 johnson 50hp outboard motor going that I bought from a dealer, who has not long gone bust, along with a boat and trailer. I was told it was a runner but I didn't get them to show me (live and learn) :redface:

Hasn't taken an awful lot to get it running though which was impressive for a 1973 engine that I think has been sat around for a few years! Worst problem would be that the carburetors were blocked, so didn't take much, just a lot of persevering to get it going. Was imprest with it when we got it running! Had no idea it would be such an animal! I'm new to outboard motors.

Anyway..... I do have a problem that has left me stumped. The motor won't charge my battery. I've tested all wiring again, tested my rectifier, and the stator and they are all fine, so it leads me to believe that the magnets aren't working. This is the outcome that I really didn't want. Is the only way of solving this to buy a new flywheel or second hand one with working magnets? Or is there a way of re-magnetising the magnets?? ambitious I know but really don't want to take my flywheel off! I have my reasons, but don't want to bore you with that too.

Thanx, Jo

 

[tashasdaddy]

Re: alternator problem, no charge

the magnets are working if the motor is running. 99% it is the rectifier, it's only job is to convert the AC voltage made my the motor to DC voltage to charge the battery.

 

[Vic.S]

Re: alternator problem, no charge

I think its only a three wire rectifier so disconnect the wires (yellow) coming from the stator and measure the AC volts between them.** Should be well in excess of 12 once the revs are increased a little. Also try with a load on them, a couple of bulbs say.

If that seems Ok reconnect yellows to the rectifier, but not the red wire. Check the DC volts beteen the case and the red wire. Also try it with a load on.

If thats OK start looking for a problem between there and the battery. Don't overlook the negative/ ground connection.

** If I'm wrong and its a four wire type check between yellow/gray and yellow and between yellow/gray and yellow/blue

 

[F_R]

Re: alternator problem, no charge

Magnets never go bad. At least not the ones made since WWII.

 

[luckystreak]

Re: alternator problem, no charge

Thanks guys, you've been really helpful.

When I checked the rectifier I took it off the engine and tested it that way. Says in the manual the reading should be 1.0-2.0 when testing it with an amp reader off the yellow wire. That test showed the rectifier was working but I shall try it your way and leave it connected to the boat this time. Fingers crossed it is just the rectifier!

I feel a lot better now you have told me that the magnets don't go wrong as easily as I had thought!

Thanks again. Jo

 

[R.Johnson]

Re: alternator problem, no charge

With the rectifier off the engine, did you mean ohm's test? You are not going to get a reading with a amp meter. With the engine running, put a volt meter across the battery. You should see a rise in voltage above what the reading is with the engine at rest. Beside's the magnets, a stator failure is quite rare. If all the connections are sound, and in order, I would take another test on that rectifier.

 

[Vic.S]

Re: alternator problem, no charge

With the rectifier off the engine test it in the way described by Joe Reeves on the Engine FAQs board

http://forums.iboats.com/showthread.php?t=190638

BUT if you use a digital multimeter use the "Diode test" range because digital meters do not necesarily work for diode testing on the Ohms ranges.

 

[luckystreak]

Re: alternator problem, no charge

ok, had a friend of mine check the rectifier and it is the rectifier that is broken. All but one diodes are open circuit.

So that sorts that little problem. Thanks guys.

My next question though ... I've had a look in the parts section on this site and there is a replacement rectifier on there which I think will be right for my engine. It says it will replace omc 583408 and 0583408 is the part number of my rectifier. Just wanted to double check and see if anyone knows it is the right one as I don't understand what CD1 is.

 

[CharlieB]

Re: alternator problem, no charge

CDI is the Outboard Electronics Division of Rapair, Inc.

Their products are top of the line, often better AND cheaper then OEM.

 

[ezeke]

Re: alternator problem, no charge

CDI Electronics is a separate company; Their parts are excellent.

 

[luckystreak]

Re: alternator problem, no charge

oh ok i see :redface: I read it as CD 1 because in my manual it mentions CD1,CD2,CD3 etc and I wasn't sure what these represent, are they something to do with how many cylinders the engine has??

If it says it will replace my rectifier part number then it should be ok, shouldn't it??

It looks like at some point this rectifier may have been changed before, because if what I'm looking at on this rectifier is the part number, then it's different to the one that's on the parts catalogue for my engine.