Johnson 1980 50hp charging circuit

burnsie88

Seaman Apprentice
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Apr 26, 2014
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30
Hi guys,

I have a 1980 50hp and ive noticed its over charging the battery (getting upto 17V). can someone give a basic response to how how the charging circuit works? im guessing its probably goes altinator to rectifier to regulator?

thanks
 

bonz_d

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Apr 22, 2008
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Kinda. Flywheel, stator, timing base are the main ingrediants. These all form your charging circuit.
 

burnsie88

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Apr 26, 2014
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Hi Bonz_d

Is there some type of regulator to controll the charge the engine put backs into the battery? do you have any idea what my problem might be?
 

Barnacle_Bill

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Feb 8, 2004
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6,469
That is pretty common on a non-regulated motor. Make sure all connections are clean and tight and make sure you are using a marine battery.
 

undone

Petty Officer 2nd Class
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Jul 26, 2014
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Like he said, that's normal for a motor without a voltage regulator, and many J/E's came without them. As long as you don't run for long periods of time at 17V it's not a problem. You can also turn something on and the voltage will drop.
 

bonz_d

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Have never checked the voltages on mine but there is no mention of over-volts in either of the 2 OMC manuals I have.
 

burnsie88

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Apr 26, 2014
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thanks for the replies guys.

When it alarms i normally just turn on somestuff so ill just keep doing that.

thanks
Burnsie
 

burnsie88

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Apr 26, 2014
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Hi fellas
If I take an ohm reading over stator what kind of reading should I expect? Is there any test I can do on the rectifier to check it as well?
 

ondarvr

Supreme Mariner
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Apr 6, 2005
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11,527
If it's producing DC voltage the rectifier is working, and since what you are describing is normal for this motor, most likely everything is working correctly.
 

UncleWillie

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Oct 18, 2011
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Thanks for the replies guys.
When it alarms I normally just turn on some stuff so I'll just keep doing that.
Thanks, Burnsie

What is the "It" that alarms?
Is this a new symptom? Or did you just add something that added a high voltage alarm to the boat?
Did it used to be in the 14 volt range and it is now 17? Or did you just add the capability to measure the voltage and found it to be 17?
 
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burnsie88

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Apr 26, 2014
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UncleWillie
the "it" is the sounder. The sounder over voltage alarm is going off and reading 17v off the battery.


ondarvr
if this is normal for this motor how can i stop it from going over 14.4V which is the maximum charging voltage for the battery? even with turning things on i cant get it below this.

Thanks for your time guys!
 

UncleWillie

Captain
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Oct 18, 2011
Messages
3,995
Assuming the Sonar is a new item and the Battery has been running at 17 volts for the last 35 years....

The preferred solution would be to add a regulator to the alternator.
This may be prohibitive expensive, or not reasonably possible.

The cheapest solution would be to add a ~5amp regulator in the Power Line going to the Sonar.
There are many ways to do it, but something like THIS will point you in the right direction.
You would need to mount it in water resistant case. Radio Shack has many options.
 
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