Batteries Won't Charge from Engine Alternator

[efiste]

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.

Eric

[jaybeegee]

Hi! Have you also checked that the batteries are ok? A car battery shop will tell you instantly using some testing device they have.

[Traveling Light]

If the batteries hold a charge from an AC charger and the alternator checks outs then it may be a very simple problem. For example, I once "messed up" because I did not run a wire from one battery to the other to complete the circuit. It may be a bad electrical connection, or the batteries are wired up incorrectly. Are your terminals clean? Are the cables OK?

[MarkSF]

The alternator won't produce much more than 13.5V so if the batteries are at 13.5V when they have just been charged by the shore charger, you can't see the effect of the alternator. What you need to do is test the alternator with slightly discharged batteries.

I suggest disconnecting the shore charger at least 24 hours before, then try it. Alternatively you could turn off the charger and turn on some items (lights are good) for 1/2 hour.

Either way the resting voltage of the batteries should have dropped to 12.5V or so, in which case you can now test the alternator. Start the engine. The voltage should go up to 13.7 or so and stay there while the engine is running. If not, the alternator, or the wiring to it, is faulty. If the alternator tests fine then you could have a wiring issue.

Please report back on what you find.

[shogan50]

A few thoughts. 1. Mine charges at 14.4-14.6 at anything above idle. 2. 11V at the battery after 10 seconds of glow plug use, sounds to me like batteries might be pretty tired. 3. I recently had flakey charging symptoms that turned out to be loose wing nuts on battery connections. 4. Is your exciter wire connected/corroded?

[efiste]

@Traveling Light - I believe the batteries are connected correctly. This is a task I completed on my own, but used the context of how the cables were tied together and laying in the battery compartment along with the owner's manual to confirm. Everything has been working fine regarding how the DC electronics operate on either position 1, 2, or ALL of the battery isolation switch. However, I did have a situation the other day that I could not quite figure out. I removed 1 battery from the boat to recharge from home. I did not plan to connect the disconnected batteries wires (here is where my lack of electrical expertise will start to shine), but I could not get any DC power to the cabin lights (for example) with either battery bank selected. In this case, I believed the battery still connected was battery 1. I thought since one of the large #4 reds and the single large #4 black were connected to that battery, I should be good to go. I have other smaller wires in the battery compartment, but they are for the sump float and shore power battery charger (both of which were not in play for my unexpected results). I did not have a lot of time to complete my testing, so I had to connect all of the wires to the single battery to get power. Now, I realize that there are many factors in play here, but I would say that in general this boat has had pretty good care. Therefore, I would assume my error (or lack of knowledge) over the boat having something wrong. It has been a few years since my last boat. I have attached the general wiring diagram for the Catalina 34 as reference. I did indeed connected the black #4 tie between the 2 batteries.

Eric

[efiste]

@MarkSF - After running the engine for many hours (6+ during 2 of the trip legs from MI to IL), the voltmeter at the engine instruments never "jumped" to ~13.5V (as expected when the batteries where not at top charge) and in fact slowly went down to <12V as we motored on. I think this is a symptom of the problem, but I am not sure of what since the alternator checked out.

Eric

[efiste]

@shogan50 - The <11V is when actually prepping (warming) the engine prior to starting. After the engine has started, the voltmeter at the engine instruments returns to the battery charge level (minus a little each time I start the engine). In other words, it is really like the alternator is not producing power (which it does), the batteries are not able to be charged (which they are), or something in between is a problem.

BTW, the cabling all looks good, but I will need to give it another once over since the alternator came back with no issues. Also, the batteries are newer (both starters no deep cycle as mentioned) but were not maintained over the winter. I have one connected to a house charger now. The charger is NOT indicating any deep discharge.

Everyone's help is greatly appreciated.

Eric

[Traveling Light]

If you are new to the Chicago Harbors I suggest you contact the Chicago area Catalina fleet. My boat (Pearson 28) is in Monroe Harbor and I'll bet that there are lots of people in the club and at Monroe that will coming to your assistance.
Catalina sailing in Chicago I used to belong when I had a Catalina and they are very nice people.

[kd3pc]

alternator has a fault or the regulator is toasted...