Volt Meter or Alternator Issues:

Joined
Jun 5, 2009
Messages
6
Hello All,


Preface This Story :

2000, 2855 Ciera Sunbridge with 7.4L Mercruiser with Bravo III I/O.

Battery #1 and #2 are both brand new, strong batteries. Previuosly one battery was good and one was very weak and dragging the good one down. The Alternator was replaced 2-3 months ago. Don't know if it was a rebuilt or brand new. Voltmeter I believe is the original one.

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* When I first got the boat the Voltmeter read 13 to 14 volts after I started her up. The first run about 1 hour all was OK.

* I started to have some issues a few days later.

* Come down to the boat and both batteries are dead. Charged them up overnight and they were now fully charged.

* Went out for the day and when I returned to port, I tried to start the boat again to check the batteries and they were both bareley able to crank the engine.

* Then both batteries were then replaced.

* I was told that when the batteries were replaced the alternator was checked again and all was good now with the batteries and the alternator.

* We went out for the weekend. On route, battery #1 was "ON."

* When I started the engine at the dock the Voltmeter read 12 Volts.

* The volt meter started to slowly dropwhile we were underway, starting at 12, 11-1/2, 11, 10-1/2, 10. All in Approx. 30 minutes to get down to 10 volts.

* Then the alarm went off. I slowed down at the 5MPH and the alarm stopped.

* I switched the battery over to #2.

* The #2 battery was starting to drop after about 20 minutes of cruising.

* After I tied up, about 30 minutes later. We smelled an electrical burning odor. I opened the hatch and there was smoke.

* After about 10 minutes the smoke cleared, I could see what looked like a stream of smoke rising from the vent opening in the alternator. But it could have been from underneath.

* Not sure what caused the smoke, but there was quite a bit.

* I charged the batteries over night. Just since I was connected to shore power.

* On the ride home the voltmeter read a hair under 12 volts, with no issues to report for the entire ride home, approx 40 minutes. No voltage drop on the voltmeter and no smoke.

* When we docked I checked the engine hatch and all seemed OK and no smoke.

* A few days later I went to the boat.

* I turned "ON" the ignition and the voltmeter read 12 volts.

* I turned on the blower motor and after 3-4 minutes the voltmewter was reading 10 volts.

* Then I started up the engine. It cranked real well as a strong battery would. Not like one reading only 10 volts.

* I have never seen again the 13 -14 volts I first saw after starting it up when I got the boat a few weeks ago.

* For the last week the new batteries seem to be working ok and staying strong, just the reading of the voltmeter seems to be a bit radical.

* I don't know if this will happen again but before I take a chance that the possibility of the new batteries running down because there is an issue with the alternator

* I would like to solve this issue with the alternator, batteries or the voltmeter. Not sure where the issue lies.

* Does this sound like a faulty or intermittent alternator? Is the the voltmeter flaky? The batteries are good. Any advice or suggestions as to what to test for or look for would be appreciated. I don't want to end up with 2 more dead batteries.

* Also what about the smoke? Someone suggested, I believe they said, it was oil vent blowback or possibly something like that.

* The manual says the alarm goes off for 3 things. Low oil pressure which was fine. Overheating which it was not, and the drive oil level which from what I can tell was OK also. Please Help!!!

Thanks in advance :)

Ed
 

lowvlot

Petty Officer 1st Class
Joined
Jul 5, 2009
Messages
231
Re: Volt Meter or Alternator Issues:

Ed,
I am curious to if you ever found the problem. I would believe it to be the alternator. Have you put a volt meter on the charge leads of the alternator and read the voltage? I would start there.
 
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