Over the years I have come to learn that most boat owners drastically over discharge their battery banks when using voltage as a predictor.


In a recent survey on SailboatOwners.com there were in excess 1000 responses, 98.4% from sailboat owners. The survey was about battery use. Of those 1000+ responses, 1188 to be exact, 72.42% of responders regularly discharged the bank below 12.1V. D'oh!!!!!


The bottom line with lead acid batteries is that even at your average house loads the terminal voltage should not be dipping below 12.1V, if you expect any sort of decent life from them.


As we can see in this experiment, under a 5% load to capacity discharge, 49.3% SOC is achieved at 12.10V.