Originally Posted by Sailor Doug
Using voltage to gauge battery capacity requires that you have no load on them for 24 hours.
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Have to disagree.
Been using a built in digital voltmeter, wired direct to the batteries, for more than ten years. As an experiment
I disconnected the house bank from the boat one night and took readings every hour during the night until I finally had to reconnect the batteries in the morning (fridge). I wrote down the readings every hour and still have that list somewhere in my boat papers box.
After the first two readings, two hours, they hardly changed at all. On the order of hundreths of a volt. These were four fairly new golf cart batteries.
Those battery monitors may be wonderful but considering the expense and complexity I prefer my simple digital voltmeter; bought it new for ten bucks at an electronics
hobby store. Just two wires to hook up. No complex regulating routine either.
I have also found that, having become one with my boat, I know about what my draw is at any given time and pretty closely through a day.