I second what
@jberger said! % will especially drift in the winter months with less sunshine. (Unless you are somewhere more sunny than me.... I'm in Ohio.... lol) Voltage based settings with a delay are always safer than % based settings! As batteries age, you have less capacity as well, so if you go % based and you have less capacity, you will end up starting at a lower and lower actual % until you end up with power outages!
I have 4 Victron Multiplus-2 120v stacked for 120/240, and I use my Cerbo GX's auto start for my gen. Generally speaking, with LifePo4 batteries, we always set our customers' start setpoints to 50.7V with a ~15 second delay. That delay allows for voltage sag under short surge loads, and you will normally be starting at ~15%. It will vary a little, but I generally like seeing a start of somewhere between 10-20%. I have played around a bit with stop setpoint at home, as I also don't want to run excessively. I discovered that in the winter months, I actually prefer stopping at maybe 70-80% rather than 40-50%, because my gen was starting too often. (Especially when the electric dryer was being used.... sometimes we would have 2 gen starts in one day...)
You could set the stop to somewhere between 54-55 volts. Mine is currently set to 54V during quiet time (less runtime when we are sleeping), and 55V during the day.
Here is a screenshot of what the settings should be looking like at 48V with LifePo4. Note especially the yellow highlighted settings! Also note that the green highlighted settings will depend on you batteries. Charged voltage should be 0.2 or 0.3V lower than your absorb voltage. AH will of course be your total battery amp-hours.
