Yes the voltage gauge does indeed indicate that power is coming in and is then cut off just as the click is heard and then comes in and is then cut off. For some time now, I noticed that when the engine charges the battery the charge doesn't last nearly as long as when it is charged with shore power. Maybe this is a problem that has been going on for some time and is worse now. Is it normal for the battery to react so differently to the two types of charging? I think the charge from shore power last three times as long.
