When I attempted to start my in-board diesel recently, I cranked the engine a couple of times for 15 seconds or so, but it would not start. I went below to discover that the batteries -- 4 years old but still useable because I take good care of them -- were bubbling and emitting a foul odor. I then commenced to disconnect the battery cables, only to discover that both the positive and negative cables were very, very, VERY hot to the touch.
What gives? Bad alternator? Bad regulator? Or perhaps a bad starter? And is there any thing I can to check these out without taking them off and having them bench tested?
Once the batteries cooled, I removed them from the boat. Though they had been fully charged -- 12.6 volts or so -- one battery could not hold a load. So I''ll replace both and use the remaining good one as an emergency on-board spare.
But I''m also concerned that hooking up new batteries to a faulty charging/starting system will damage them.