Battery not being charging by Alternator

onislandtime

I HATE CHASING ELECTRICAL PROBLEMS! Rinker 342 starboard start battery is not being charged by Alternator. Multimeter shows 14.9 output on alternator and check battery (while engine is running) battery shows 12.6. Obviously nothing coming from alternator. When I go out on boat I see that the battery is losing voltage and of course eventually gets below 10V and alarm sounds. I have to put jumper cables from port battery to starboard battery and It then shows both batteries charging 13v and plus.

reneechris14

Power goes from alternator to isolator. Check bottom lug on isolator to see if power is getting there. Isolators do go bad.

reneechris14

does battery except charge from shore power?

JoeStang

When mine did the same thing it was the battery isolator. I'm sure a 342 owner can help with location and diagnosis of it, its a simple and cheap part.

reneechris14

onislandtime

@reneechris14 yes the battery charger charges battery. I didn't check the isolator ugh!

Dream_Inn

Yep, I've replaced my isolator.  They do go bad and it seems like your symptoms are pointing to that.

Michael T

.....also I believe if the ignition is on and the battery polarity bis reversed it can blow them. 

Cableguy Greg

I replaced my isolator with the ProMarinar ProIsocharge and it works great.