2002 Mercury Optimax 225 Issues - Charging System? Need help

[thilltony]

My engine was throwing warning alarms at the end of a trip. I installed Vessel View, and it indicated a bad oil tank sensor, so I ordered a new tank, replaced it, and all was good for a while, then the alarms went off again. So I parked the boat for the season.

Over the fall/winter I replaced switches, the old gauges, and I replaced the batteries with huge HD ones, as the old ones kept needing to be charged, even though they weren't old and were 1000A batteries.

Today, I decided to run the boat. The brand new batteries read 13.1v. She started instantly and sounded good. I ran her for 10 -15 mins on the hose with no alarms. But then I noticed less than 12v on the gauge. The multimeter showed 12.6v at the solenoid and at the batteries, but when I started her, it dropped to 11.77v. She is not charging at all.

Now I'm wondering if all my issues aren't actually due to low voltage. I know that newer engines need good voltage. Unfortunately, my "2002" manual from Ebay is actually for a 1998/1999 Optimax, and it's a different charging system. There is no "Terminal B" to ground that I can see.

So, I need help. Does anyone know the procedure for testing the regulator and rectifier? I've got battery voltage but no output. Thanks.

[EuropeanAM]

If you would, please take a moment to review the Announcements at the top of the Forum, and be sure to provide the Required Info (serial number) when posting. Thanks!

Just a matter of note- we don't support the 'bay, or anything purchased there here in the forums. Shouldn't be a problem since it doesn't even pertain to your engine.

If you have a Voltmeter, supply water to the engine, START the engine, and read the voltage on the LARGE RED output terminal of the alternator (after idling for 2-5 minutes).

If that reading is LESS THAN 13.4 VDC, unplug the small connector and check the voltage on each of the terminals in that connector.

Report back with results (including voltage on the large output terminal).