I have a Raspberry Pi in a remote location. It is connected to two 12V car batteries with a 24V-5V 10A DC-DC converter. The 5V converter is connected to the DFR0494 (V1.3 firmware) and a 3.7V 6000mAh LiPo battery, which is mounted on a Pi 3B+.

It all works great. The DFR0494 powers the Raspberry Pi and discharges the battery (to a level around 5.4%) and then starts charging the battery (to a level around 80%) and the cycle repeats. Sometimes, the battery discharges below 5.4% and the DFR0494 cuts power to the Raspberry Pi. Sometimes it then recharges the battery and the power is restored. Sometimes the power is not restored (but the battery keeps charging). The 12V car batteries do not discharge completely.

I was expecting the DFR0494 to keep the battery charged all the time and only discharge the battery when the 5V supply stops.

When does the DFR0494 start charging the battery and when does it stop charging the battery? Here is a graph of the battery level over a period of days: