battery charging?

[airshot]

How do I know if my 1991 40 hp Johnson has the capability of charging the battery? Would their be a generator/alternator or would it charge thru the magneto or does it not charge the battery? Thanks in advance for your help.

Airshot

 

[steelespike]

Re: battery charging?

With the motor running at about 1500 to 2,000 rpm measure the voltage across the battery terminals.Should be about 14 volts.The charge system will maintain thevbatterty for normall starting and other light applications.If it doesn't charge A good battery will start it and do running lights for a long time.Ours would sit all week and get heavy use on the weekeds lights and starting.It would go 3 or 4 weeks and usually give obvious signs before failing.
Ours was only an 18 so hand starting was easy.

 

[Vic.S]

Re: battery charging?

I think you will find that electric start models have a stator coil and rectifier for battery charging while hand start models do not.

The rectifier is a small cylindical object a bit more than an inch diameter and about the same height bolted to the side of the power head. It will have three yellow wires, two with blue and gray tracers (the AC input from the stator) and a red wire coming from it terminating on a nearby terminal strip.


If there is a rectifier then check that the battery volts rise when running as steelspike suggests.

If in doubt about the rectifier it can be tested as described on the "Engine FAQ" board

 

[airshot]

Re: battery charging?

My older evinrude did not have charging capabilities so I manually charged the battery once a month, I did not know if this Johnson had the ability or not, but thanks for the tip, I will check the voltage next time out..

Airshot