optima battery how to tell when fully charged
I have optima batteries, and would like to know how to tell when they are fully charged. I have heard that voltage is not an accurate way to tell, and because it is an AGM battery it is not possible to use a hydrometer. My understanding of a battery monitor is it counts what goes in and what goes out, well enough if the battery is starting at a full state of charge, of course that gets me back to what is a full state of charge? So what am I missing here?