115HP Johnson Alternator Charging Test

[74Baja]

Our battery looses charge after several days of use (between charges with an external charger). The battery terminal voltage is 12.07 volts with engine off, and 12.8 volts with engine running. Is this low? Exactly how do we check alternator condition? amp output? I hear alternator output should be about 8 amps.

 

[DJ]

Re: 115HP Johnson Alternator Charging Test

74Baja,<br /><br />You just tested it's output. It should show you 13 plus volts while running and the voltage will climb in an (don't know year of engine)unregulated system.

 

[74Baja]

Re: 115HP Johnson Alternator Charging Test

Originally posted by DJ:<br /> 74Baja,<br /><br />You just tested it's output. It should show you 13 plus volts while running and the voltage will climb in an (don't know year of engine)unregulated system.

 

[74Baja]

Re: 115HP Johnson Alternator Charging Test

The Johnson 115 is from 1974.

 

[DHPMARINE]

Re: 115HP Johnson Alternator Charging Test

Anything can happen,but you need more voltage when running,as said previously.Most likely you need to replace the rectifier/diode,but more important,tighten your battery connections first.Wing nuts are great,but never should have been put on boat batteries.<br />DHP

 

[Marc J.]

Re: 115HP Johnson Alternator Charging Test

Hey 74Baja, drop me a line at marc930@aol.com. I'd like to find out more about your boat.

 

[Marc J.]

Re: 115HP Johnson Alternator Charging Test

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