Bruce
2019 20 TRX Patriot
Mercury 250 ProXS Fourstroke
HDS 12 Live - Console
HDS 9 Live - Bow
Yes, it is possible in the case of a shunted diode (or diodes).
And yes, it could be caused by disconnecting the battery with the engine running, or a reverse-polarity connection (though the fusible link lead will most commonly burn out prior to damage).
Dual Mercury Master Technician- for Mercury Outboards, Mercruiser and Mercury Racing at European Marine in Greenville, SC.
Still consider myself a "Marine Apprentice" after 47 years (learn something new every day).
Mercury Parts, Mercury Outboards, Smartcraft & Accessories, Injector Service, TDR Reeds- BBC Sponsor
Bruce
2019 20 TRX Patriot
Mercury 250 ProXS Fourstroke
HDS 12 Live - Console
HDS 9 Live - Bow
I checked it today with the different meter and got somewhere between 25 and 30 V AC. So does this mean I need a new alternator or is there some other part I can replace it instead?
Bruce
2019 20 TRX Patriot
Mercury 250 ProXS Fourstroke
HDS 12 Live - Console
HDS 9 Live - Bow
If you got high voltage at the large RED output terminal with the engine running- you have a BLOWN FUSIBLE LINK LEAD.
Replace the fusible link lead (be SURE to disconnect battery power FIRST).
Dual Mercury Master Technician- for Mercury Outboards, Mercruiser and Mercury Racing at European Marine in Greenville, SC.
Still consider myself a "Marine Apprentice" after 47 years (learn something new every day).
Mercury Parts, Mercury Outboards, Smartcraft & Accessories, Injector Service, TDR Reeds- BBC Sponsor
Bruce
2019 20 TRX Patriot
Mercury 250 ProXS Fourstroke
HDS 12 Live - Console
HDS 9 Live - Bow
A reading above 0.25 VAC at the battery terminals is an indication that the alternator needs to be replaced.
Make sure your meter's AUTO-RANGE feature is turned OFF.
Dual Mercury Master Technician- for Mercury Outboards, Mercruiser and Mercury Racing at European Marine in Greenville, SC.
Still consider myself a "Marine Apprentice" after 47 years (learn something new every day).
Mercury Parts, Mercury Outboards, Smartcraft & Accessories, Injector Service, TDR Reeds- BBC Sponsor
Thanks Don. I checked it with two different meters. Neither had a auto range.
Bruce
2019 20 TRX Patriot
Mercury 250 ProXS Fourstroke
HDS 12 Live - Console
HDS 9 Live - Bow
Sounds like an your alternator is toast
Former USAF Gunner B-52H
Definitely does sound that way (diode failure more than likely).
Dual Mercury Master Technician- for Mercury Outboards, Mercruiser and Mercury Racing at European Marine in Greenville, SC.
Still consider myself a "Marine Apprentice" after 47 years (learn something new every day).
Mercury Parts, Mercury Outboards, Smartcraft & Accessories, Injector Service, TDR Reeds- BBC Sponsor