Charging voltage for 1989 70hp Johnson

[George Roper]

I have a 1989 70hp Johnson outboard. Everything works well but I am wondering what reading I should be getting on the volt meter and at the battery when the motor is charging? Can anyone help me.

 

[bassman284]

Re: Charging voltage for 1989 70hp Johnson

Should be 13.9 to 14 volts.

 

[George Roper]

Re: Charging voltage for 1989 70hp Johnson

Thanks Bassman284

I guess I have an issue somewhere because I am getting about 16 when the motor is running at high RPM. At idle I get about 13. I have been going through alot of nav light bulbs as well. I guess I need to have the system checked out. I do have a book but my electrical skills are very poor. LOL

Thanks anyways for the info.

 

[seahorse5]

Re: Charging voltage for 1989 70hp Johnson

Your motor has an unregulated charging system and the battery regulates the charging voltage. A larger battery such as a group 27 or group 31 keeps the voltage lower. In the old days, folks would turn on their running lights to help keep the voltage inline as most outboards had unregulated systems.

Never use a maintenance free or any type of gel or sealed battery with that system.

If you put two batteries in parallel, the voltage will be more managable.

 

[eavega]

Re: Charging voltage for 1989 70hp Johnson

My '76 70 HP Johnson can show voltage of up to 17 Volts. I've been told that is not unusual for the unregulated systems.

-E