Join Date: Apr 2000
Location: Chicago, IL
Thanked 0 Times in 0 Posts
Rep Power: 0
Batteries Won't Charge from Engine Alternator
Tried searching the forums here, various Internet sites, and researching through the Don Casey and Nigel Calder books... but I cannot figure out my issue.
I purchased a 1987 Catalina 34 (as a replacement for a 1983 Hunter 28.5) this past winter and delivered it from Whitehall, MI to Chicago the first weekend this month (May 2011). I made 3 stops along the way at Grand Haven, South Haven, and New Buffalo before heading across to Chicago. Everything went well, but on the 2nd leg from Grand Haven to South Haven (longer than the first leg) we noticed the voltmeter at the engine instruments had dropped below 12V even though the engine was running most of the day (6+ hours) due to head on winds. Next, we noticed the tachometer acting erratic and suspected a loose belt. The belt was tightened that evening, and we assumed the problem was solved. The next day, though, we had continued battery issues. After charging on shore power the 2 batteries (both West Marine Group 24 12V Starting Batteries 1000 MCA) seem to have around 13.5V. When heating the glow plugs on the Universal Diesel M-25XP on both batteries (or either using a battery isolation switch), the volts drop down below 11V until the engine is started. When the engine is started, the volts go back to the charged "battery" level of around 13.5V. Throughout the day (engine running or not), the volts slowly drop while using various medium load electronics on the boat. My understanding is that with the engine running, the alternator (Motorola 55AMP internally regulated) should be producing roughly a volt more than the batteries to charge the batteries under power with minimal load. I, however, get no such "jump" in volt readings from when I turn the key to on and then start the engine and the volts slowly drop. I ran some tests with a multimeter, and received some results which seemed to indicate that the alternator may not be operating correctly (diodes shot or faulty regulator). I removed the alternator and took it to a good auto electric shop in the area. They tested it and said there were no problems with it mechanically. I am at a loss.
As far as I know from the previous owner and yard mechanics, there were no issues last year. The previous owner, though, was at a slip with shore power which seems to charge the batteries fine. I am on a mooring in Chicago, though, without power access.
Is the problem likely with the alternator (already checked), batteries (will charge with shore power; no different starting and house load type), wiring (what I can trace seems good), etc.? Thoughts, questions, advice? Any assistance to avoid calling out a mechanic to service the boat in the water would be appreciated.