Hi All, I'm a rank amateur and a new owner of an 86 O'Day 272. So far with your help I've managed to get the engine (westerbeke 10two diesel) tuned up and running reliably. Now it's on to the Electrical. The boat is equipped with two NEW deep cycle batteries and a Shore Power Panel (AC?) It also has a 35amp mitsubishi alternator, a 15 amp charger that runs on shore power and a 1/2/all battery switch. The problem thus far is that one of the batteries usually the 2 alway seems to be depleted at starting time. It will barely crank the diesel over. A switch to 1 or all has always started the motor. Today my partner attempted to start the motor with bat 2 and smoke came off the terminal! He cleaned the bat two terminals and the problem appears to be solved????? Here are my questions. 1.) How do I test the Alternator 2.) How do I test the Charger 3.) Are there certain electrical connections I should clean and inspect? 4.) Should I have a starting battery or are the Deep Cycles up the the Starting Task Thanks for any input!
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Good questions
At the risk of being castigated by the community here, I suggest you buy a book or two. The questions you ask are complicated, and require LONG answers, which is why they write books. Plus, you can also find it on the Internet, from this website, Boastus.com, West Marine.com (and their catalogs) and others. Calder's Boatowner's Manual, 2nd edition probably now on sale since they've come out with a thrid edition, should do you well. BUY IT! Or anything Don Casey's written on electrical systems -- he's very good, too. Sorry for the rant, but we've all been there, and have probably typed most of these answers already, right here. Oh, BTW, there's an archive search you can do right here. Welcome to the club. By this time next year, you'll be writing these. All the best, you'll do just fine, and keep asking. Stu
At the risk of being castigated by the community here, I suggest you buy a book or two. The questions you ask are complicated, and require LONG answers, which is why they write books. Plus, you can also find it on the Internet, from this website, Boastus.com, West Marine.com (and their catalogs) and others. Calder's Boatowner's Manual, 2nd edition probably now on sale since they've come out with a thrid edition, should do you well. BUY IT! Or anything Don Casey's written on electrical systems -- he's very good, too. Sorry for the rant, but we've all been there, and have probably typed most of these answers already, right here. Oh, BTW, there's an archive search you can do right here. Welcome to the club. By this time next year, you'll be writing these. All the best, you'll do just fine, and keep asking. Stu
You found the problem
The smoke was from the connection heating up due to resistance to the current flow. The smoking terminal needed cleaned is all. 1. Alternator test. Without an ammeter there little you can do to test the alternator. You can verify that the voltage is changing and is at the proper level but that is no guarantee that it is putting out it's rated capacity. Since it is only a 35 amp alternator you could install and automotive ammeter between the alternator and the batteries and test it that way. The trick is to load the alternator down with everything you can turn on. If you can get 35 amps going elsewhere in the boat the alternator should eventually start putting out its rated capacity given the engine is running fast enough. 2. Charger test. See #1 but put the ammeter between the charger and the battery. A clever person could rig an ammeter to do both by using the ground side of the circuit. Put the ammeter between the battery negatives and the ground buss and connect the alternator and charger grounds to the buss also. 3. Clean connections. yes there are ones that tend get dirty more frequently. All the battery terminals and anything that is near the bilges. I have it on good authority that sea water and acid are good corrosives. 4. My wife has some power tools she uses regularly. One is a 1500 Watt hair dryer. The math goes like this 1500 W @ 120 Volts is 12.5 amps. 1500 W @ 12 volts is 125 amps. That is what my inverter has to supply when she is "doing maintenance" in the head. Factor in that it takes 3-5 minutes to do the maintenance. That is a lot of juice. Most 100+ HP car starters are a 1200ish Watt motor. You have a MUCH smaller starter than my wife's hair drier and you are not going to crank your starter for 3-5 minutes either. A deep cycle battery will do you fine.
The smoke was from the connection heating up due to resistance to the current flow. The smoking terminal needed cleaned is all. 1. Alternator test. Without an ammeter there little you can do to test the alternator. You can verify that the voltage is changing and is at the proper level but that is no guarantee that it is putting out it's rated capacity. Since it is only a 35 amp alternator you could install and automotive ammeter between the alternator and the batteries and test it that way. The trick is to load the alternator down with everything you can turn on. If you can get 35 amps going elsewhere in the boat the alternator should eventually start putting out its rated capacity given the engine is running fast enough. 2. Charger test. See #1 but put the ammeter between the charger and the battery. A clever person could rig an ammeter to do both by using the ground side of the circuit. Put the ammeter between the battery negatives and the ground buss and connect the alternator and charger grounds to the buss also. 3. Clean connections. yes there are ones that tend get dirty more frequently. All the battery terminals and anything that is near the bilges. I have it on good authority that sea water and acid are good corrosives. 4. My wife has some power tools she uses regularly. One is a 1500 Watt hair dryer. The math goes like this 1500 W @ 120 Volts is 12.5 amps. 1500 W @ 12 volts is 125 amps. That is what my inverter has to supply when she is "doing maintenance" in the head. Factor in that it takes 3-5 minutes to do the maintenance. That is a lot of juice. Most 100+ HP car starters are a 1200ish Watt motor. You have a MUCH smaller starter than my wife's hair drier and you are not going to crank your starter for 3-5 minutes either. A deep cycle battery will do you fine.
When in doubt...
...replace the bad battery. It won't heal and it will only aggravate matters. Every five years is typical.
...replace the bad battery. It won't heal and it will only aggravate matters. Every five years is typical.
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