I use a three meter homemade DC BATTERY MONITOR panel This monitors the 12VDC level of the two battery banks wired in parallel and when I see them drop back to around 12.0VDC I know it is time to start re-charging. 12.0VDC is very close to the battery bank being at their 50% charge state.
In my setup my battery does just fine making it through the one day/night run off the batteries until 8AM the new morning and just get down to the 12.0VDC charge state. Then I run my generator to re0charge the battery banks back up to their 90% charge state using the on-board smart mode charger which will take about three hours of generator run time. Then i am good for the next one day/night run off the batteries...
Note this handy chart...
Keep in mind this is just a monitor point of knowing the batteries are close to the 50% charge state. The only real exact way to know that is to do a hydrometer check.
I have been doing this monitor check method since around 2009 doing my camping off the batteries and it seems to work out pretty good for me.
I was wanting to get one of these VOLTMINDER units that has a built-in alarm that you can preset to alarm for any low voltage setting 10.5 to 13.8VDC. Using this if you had it set for 12.0VDC then when the batteries dropped down below that point an ALARM WILL sound.
Roy Ken
