Johnson 25hp alternator

[DaveyHAZZ]

Hey there...Have a 1991 Johnson 25hp. Read up on it that it has a 4 amp alternator...So i have a question! If my battery is 11.5 volts, how long would my motor take to fully charge it to 12.5?

 

[Chris1956]

Re: Johnson 25hp alternator

That is not an easy question to answer, because voltage is not linearly related to the amount of charge of the battery. A battery that is 1/2 charged can still be 12VDC.

In theory, if your battery has a rating of 60A hours, it will take 15 hours for your motor to charge it from dead. However, batteries do not like to be completely discharged, and your motor puts out that 4 Amps at near WOT, and something less at cruise.

If you repost in the electrics forum, you may get a more informative answer, as I am not a chemist.

 

[tashasdaddy]

Re: Johnson 25hp alternator

charge you battery at home. the motor is only designed to maintain a fully charged battery, that is just used for starting the motor. if you have electronics, trolling motor, you need a separate deep cycle battery for those, and charge at home.

 

[14ftgrumman]

Re: Johnson 25hp alternator

If I had a 12 volt battery that read 11.5, I'd be having it load tested.