How do you know how full your batteries are? With AGM or flooded batteries, you can get a rough idea using a “state of charge” graph and your system’s current voltage.. but, sometimes you want more details. What if you want an exact percentage, want to know exactly how much current is flowing in/out of your batteries at any given time, or have Lithium batteries that don’t have enough voltage drop to determine state of charge by voltage alone?

I recently upgraded my batteries and saw that Victron has a full-featured battery monitor in the $160 range.... Read the rest