So I thought something might be up when starting the engine or using the electric head was switching off the stereo/gps. Batteries, though the standard lead acid ones) are fairly new. I was thinking ground and sure enough, I found 2 issues. The ground wired to the keel bolts was corroded in one spot and the buss bar connection to the ground running from the engine was reduced to more easily connect to the buss bar. The corroded spot was cut out and a new bus bar was connected with correct gauge wire.
This is leading up to my question, with all my crawling around with my voltmeter made me realize that my battery bank would drop from 12.9 volts after running the engine for a long time to 12.5 volts 30 hours later... Not a precipitous drop and plenty to start the engine but what might account for this voltage drop?
