Battery won't charge. Is it my Stator or Rectifier?

[crawlerboy]

Hello.

I have a 2002 50HP 4-Stroke EFI Merc. This season it doesn't seem to be keeping a charge on my starting battery. I've done some searches on this forum and it sounds to me like my Rectifier is first suspect and possibly my Stator.

I'm handy with wrench and a volt meter. Would like to repair myself. Can somebody help me with a test that would tell me what my problem is.

The boat runs fine after startup with a fully charged battery. My in-dash volt meter is registering under 12 volts and eventually flat lines at 10 the more I run the boat. At the point that gets down to about 10v I get an alarm of two beeps, this alarm repeats every couple of minutes. Of course if I shut the boat off, the battery is too dead to start it back up.

I don't know if this tells anything but I tried switching the battery while it was running. I have a trolling motor battery on board, thought I'd switch to it. As soon as I disconnected the battery leads the motor died.

So wondering what readings to get off of Stator or Rectifier with my voltmeter. If I'm looking at my Stator correctly it only has 2 yellows wires coming off of it.

Thanks for any info you can offer.

 

[Chris1956]

Re: Battery won't charge. Is it my Stator or Rectifier?

Newer motors like yours normally have voltage regulators. You might give us a model number, and we can look it up. Disconnecting the battery while the motor is running is exactly what causes rectifiers to blow. However, since we do not know what you have, it is hard to be more specific. You have already done the battery charging test, and found it wasn't. Unless something is disconnected or a fuse is blown, it is likely your rectifier or VR.

 

[crawlerboy]

Re: Battery won't charge. Is it my Stator or Rectifier?

I did read in these forums when searching the subject, disconnecting while running is bad so won't do that again, but that was after the problem so not the original cause at least.

If I'm looking at the right part of the tag here the model # is 50ELPTEFI. Thanks.

 

[Chris1956]

Re: Battery won't charge. Is it my Stator or Rectifier?

You can test the output of the stator to the VR when running. It will be an AC signal. I would start the meter in the hundreds of volts scale, and then ramp it down to get the exact voltage. A service manual will tell you if that is correct, however, if you have voltage, it is another sign that the VR is bad.