#1
IP: 205.215.242.140
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New alternator mystery - high voltage
Can anyone explain why I'm reading 17+ V out of my new alternator (purchased from Moyer within the last two weeks)?
I'm getting this reading with a multimeter where I have the red lead on the output "B" terminal of the alternator, grounded on the engine block. When I check the voltage at the solenoid large terminal, I get around 12.5V. My built-in (Moyer/analog) voltmeter also reads 12.5V, so does a little additional voltmeter which plugs into the cigarette lighter adapter. (To be clear: all of these reading are with the engine running). The batteries are freshly charged, and I get the same reading with the battery switch set to battery 1 (start) or 2 (house) I double-checked the wiring today (which was redone recently), and the only departure from the Moyer wiring diagram, is that the alternator output "B" terminal goes directly to the large terminal on the solenoid, instead of through an amp meter and the "batt" terminal on the ignition switch. (And I'm pretty sure this is what the directions on the alternator said to do if you don't have an amp meter). The engine starts and runs great, but with this high reading I'm afraid to damage my batteries and electronics. Can anyone explain this so I can relax? Thanks in advance! Dennis P.S. I did not buy the high capacity alternator that Moyer sells, it's the $230 model, and this is an early model engine. |
#2
IP: 24.152.132.65
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Is there any chance in the past two weeks that the battery was switched off with the engine running, even for an instant?
__________________
Neil 1977 Catalina 30 San Pedro, California prior boats 1987 Westsail 32, 1970 Catalina 22 Had my hands in a few others |
#3
IP: 137.103.82.194
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Alternator - 17 volts
Battery - 12.5 volts These two things are not connected to each other |
#4
IP: 205.215.242.140
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Except as a way to double-check the reading coming off the meter.
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#5
IP: 205.215.242.140
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Almost sure not. Are you asking because that could damage the alternator/voltage regulator?
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#6
IP: 24.152.132.65
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Quote:
__________________
Neil 1977 Catalina 30 San Pedro, California prior boats 1987 Westsail 32, 1970 Catalina 22 Had my hands in a few others |
#7
IP: 12.172.250.194
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Quote:
Bad connection from the alternator? Broken wire? Badly corroded wire from alternator? |
#8
IP: 24.152.132.65
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Hey Naty, any resolution?
__________________
Neil 1977 Catalina 30 San Pedro, California prior boats 1987 Westsail 32, 1970 Catalina 22 Had my hands in a few others |
#9
IP: 137.200.32.6
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Quote:
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#10
IP: 32.211.28.40
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In all this voltage checking, don't forget to check the other side of the circuit - the ground between the engine/alternator and battery negative. I've had strange things happen because of a) bad ground between alternator and block, and b) bad ground cable to/from engine.
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The Following User Says Thank You to Al Schober For This Useful Post: | ||
Dave Neptune (09-22-2017) |
#11
IP: 165.89.84.89
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Voltage reads 16+ volts
I ran into this same problem this weekend while motoring back to the mooring. My new Balmar smart gauge that was throwing code 4 (Battery voltage above acceptable level for selected battery type). My chartplotter was also displaying 16V. I was charging my house battery. As I was in a rocky inlet, I had no choice but to continue on. When I could safely stop the engine but still not at the mooring. I switched the battery selector to both, restarted the engine and continued on. At that point, the voltage was 13.5 volts. After picking up the mooring, I stopped the engine and noted the voltage drop for both batteries at 12.7 volts after resting. All connections seemed secure and no changes has been made other than connecting the Balmar. Suggestions?
Thanks, Tom s/v Servus |
#12
IP: 137.200.0.112
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Describe your alternator and regulator setup. My regulator will do this if the sense or ground wires get loose.
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