89 Johnson E40ELCEC 40hp not charging battery

[toonerpete]

with engine off I get 11.75 volts
with engine running it reads 12.2 volts
I was thinking it should be 14 or 17 volts
any ideas what the problem could be?

 

[Barnacle_Bill]

Re: 89 Johnson E40ELCEC 40hp not charging battery

Test your rectifier.

 

[toonerpete]

Re: 89 Johnson E40ELCEC 40hp not charging battery

Thanks, I have the Johnson manuel But I was wondering if voltaage should be highter than 12.2 volts?

 

[ezeke]

Re: 89 Johnson E40ELCEC 40hp not charging battery

Depends on the RPM, level of discharge, wiring and other factors. Put a voltmeter directly on the battery terminals and check the voltage with the engine off, then at varying speeds with the engine on. The battery should not read 11.75 volts so you might want to take it to a battery dealer and have it load tested.

 

[toonerpete]

Re: 89 Johnson E40ELCEC 40hp not charging battery

Thanks, I will do that althought the battery is new.
could the magnets be weak?

 

[toonerpete]

Re: 89 Johnson E40ELCEC 40hp not charging battery

Thanks, It is a new battery But I will have it load tested as you suggest.

 

[ezeke]

Re: 89 Johnson E40ELCEC 40hp not charging battery

Battery dealers will tell you that your new battery is fully charged, but they generally are not.

At any rate, something is not right or your static reading would be at least 12 volts.

At least one side of your rectifier is working or there would be no change with the engine running.

 

[Vic.S]

Re: 89 Johnson E40ELCEC 40hp not charging battery

To judge the state of charge of your battery measure the volts across it after it has stood for say 12 hours with no load or charging, 12.7 -12.8 is good and fully charged

12.5 and above is OK

12.2 is only about half charged

11.7 is effectively flat.

Don't leave it discharged or even partly discharged or it will be stuffed. Get it on charge asap.

If the state of charge is low it will take some while before a volts reading on the boat with the engine running rises to the 14 ish or higher that you expect for a fully charged battery

Charge the battery then put it back on the boat and see what you can get.

As said you can test the rectifier by following the instructions on "testing small rectifiers" on the engine FAQs board. BUT if you are using a digital multimeter use the diode test range, not a resistance range, as they do not necessarily work for diode testing on all the resistance ranges.