I've been coping with a lot of dead batteries. So, I've been taking them ashore and charging them up. I finally got a voltmeter and measured the batteries with the motor running. I only got 11.9 and 12.0 respectively. Could I have the alternator miswired or is it not producing a charge? How do I tell the difference. I'm tired of calling TowBoatUS each time I go out for a sail.
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Bryce Grefe
alternator
You should have around 13.5 Volts at the battery with the motor running. You can check the voltage at the alternator on one of the two diodes on the alternator. If you have 13.5 Volts with the motor running at the diodes, then you have a wiring problem, else the likelihood is the diodes are gone. If you've switch the batteries either on or off while the motor is running you probably fried a diode. Good Luck Bryce S/V Spellbinder H410
You should have around 13.5 Volts at the battery with the motor running. You can check the voltage at the alternator on one of the two diodes on the alternator. If you have 13.5 Volts with the motor running at the diodes, then you have a wiring problem, else the likelihood is the diodes are gone. If you've switch the batteries either on or off while the motor is running you probably fried a diode. Good Luck Bryce S/V Spellbinder H410
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Paul Akers
Check tour panel
Let's assume that you have a voltage guage on your master panel. When the engine is running at charging rpm's, switch the volt meter to 1 and/or 2 to get the readings of the voltage going to your batteries from the alternator. A guide to follow: 12.6v = Full Charge (100%) 12.4v = 75% 12.2v = 50% 12.0v = 25% <12.0v = 0%
Let's assume that you have a voltage guage on your master panel. When the engine is running at charging rpm's, switch the volt meter to 1 and/or 2 to get the readings of the voltage going to your batteries from the alternator. A guide to follow: 12.6v = Full Charge (100%) 12.4v = 75% 12.2v = 50% 12.0v = 25% <12.0v = 0%
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Ricky Prevete
Sorry Paul
The voltages you gave are for a battery that has been under no load for some time, not for charging voltages. The voltage put out by an alternator will vary according to presets (and the battery condition, if there's a smart regulator). But the voltages given by Bryce are much closer to accurate.
The voltages you gave are for a battery that has been under no load for some time, not for charging voltages. The voltage put out by an alternator will vary according to presets (and the battery condition, if there's a smart regulator). But the voltages given by Bryce are much closer to accurate.
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Paul Akers
You're right, my mistake.
I should have clarified that the voltages are for a standing battery and NOT a battery under charge.
I should have clarified that the voltages are for a standing battery and NOT a battery under charge.
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Bryan C.
Not charging
Bryce is right, your batteries are not charging. You might consider getting a book on marine electrical systems as to how to perform tests and how the wiring should be. I have found Nigel Calder's book: "Boat Owners Mechanical and Electrical Manual" to be excellent in this area, but it may be more comprehensive than you need. Look at the bright side, if your alternator is shot its a good excuse to buy one of those high performance alternator.
Bryce is right, your batteries are not charging. You might consider getting a book on marine electrical systems as to how to perform tests and how the wiring should be. I have found Nigel Calder's book: "Boat Owners Mechanical and Electrical Manual" to be excellent in this area, but it may be more comprehensive than you need. Look at the bright side, if your alternator is shot its a good excuse to buy one of those high performance alternator.
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Paul Akers
Have it tested
Remove the alternator and take it to be tested. Draw a wiring diagram before you disconnect any wires. They will perform a bench test, diagnose any problems and put you right back in business in short time. To find a local shop, go to any local automotive parts store and ask them where they would recommend you bring it.
Remove the alternator and take it to be tested. Draw a wiring diagram before you disconnect any wires. They will perform a bench test, diagnose any problems and put you right back in business in short time. To find a local shop, go to any local automotive parts store and ask them where they would recommend you bring it.
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Gene Kinney
Thanks for the advice
Thanks again to all of you for your help. I'm going to take the alternator and have it tested. I like the idea of a more powerful alternator just to be sure I don't have the problem again. I'll let you know. Gene S/V Kin-Ship
Thanks again to all of you for your help. I'm going to take the alternator and have it tested. I like the idea of a more powerful alternator just to be sure I don't have the problem again. I'll let you know. Gene S/V Kin-Ship
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