2009 merc. 250 pro alternator issues

[pvjiffy]

I have a 2009 merc. 250 on a ranger Z520 Owed it since new. I have had to replace the fusable link wire that run from the alt. to the battery ?????? any help? Just wonder dealer is not sure whats going on.Just wondering if anyone else has had this problem.Thanks

[EuropeanAM]

There are only a few possible causes:

-REVERSE polarity battery connections (even if only for a second)
-Reverse polarity JUMPER cable connections (even if only for a second)
-Reverse polarity CHARGER connections (even if only for a second)
-EXTREMELY high load condition on some electrical accessory (in excess of 100 amps)
-Lightening strike (very rare- I have seen one case where this occurred).


Reverse polarity "oops" would be my guess....

[pvjiffy]

Thanks for the repley,I have been a automotive tech.,Now a shop owner for over 35 years none of the above has happen i do have a lot of electronics on my boat but not 100 amps worth.This is the third link i have replaced ???? My dealer wants to take another look but I am not hopefully they will find issue Thanks

[EuropeanAM]

Two other items (rare) to consider:

-Onboard charger

Try isolating the cranking battery (disconnect onboard charger, isolate charging leads). Utilize a separate charger for the engine cranking battery (for the time being) and see if the problem ceases.

I have seen at least one case where there was an intermittent problem in the onboard charger that caused problems of this sort.... very difficult to catch.

-Alternator:

Remove and inspect alternator- look for obvious damage (such as lower cover loose, allowing contact with top of engine block, loose or damaged output terminal, obvious signs of water intrusion, etc).

[pvjiffy]

Will do Thanks for the reply