No Charge

I started the old 50 horse Mercury on the muffs yesterday and did the voltage check at the battery. I didn't see any gain on my dial type meter when I accelerated a little bit, DC volts 50 range. What I got to wondering is- are there other things that can keep a motor from charging besides the rectifier and if so where do you start checking them? Is there a set pattern for checking, maybe fuse first then across the rectifier contacts etc? How do I know that changing the rectifier will start the motor charging? I would rather spend the money on a good digital meter than to start throwing parts on that I don't need. By the way have a happy fourth- we are waiting for a little cooler weather to get the boat out.

Re: No Charge

You can test the rectifier and the stator winding, and their may be a fuse on the charging circuit.

Re: No Charge

I tested the rectifiers as described in--MyOutboardEngine.com-- and the one on the 50 horse failed by the wrong reading on one post. The readings on the 25XD were consistently opposite of what they should have been according to the described tests. I ordered two new ones. I figure if I need one for one motor I would just go ahead and order for both motors. Does anybody know how many volts-amps the Sierra 62351A1 puts out?

Re: No Charge

The charging systems on older Mercs are maybe 9A. If you bought a rectifier for a Merc, there should be no issue. I doubt you tested the 25XD rectifier properly. The diodes in rectifiers can fail open or fail shorted. The do not fail inverted.....I will bet that rectifier is fine...

Re: No Charge

Thanks for the information--I have found out that the amount of charge depends on the condition of the stator too. I think I did test the rectifier right but I think the results listed in---MyOutboardEngine.com are backwards. I found another bench test for testing the diodes from CDI Electronics and it tested good so I reinstalled it. I will test the output at the battery after this heat wave breaks.