DFR0494 Raspberry Pi UPS HAT - charging algorithm
owl198 2024-04-30 18:59:00 180 Views2 Replies 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:
If you are using a standard 3.7V Lipo (full voltage is 4.2V). The logic of the battery output is as follows:
The 5V power output will be automatically disconnected when the battery level is less than 5%. Plug in the charger and when the battery level rises to 7%, the 5V power supply will be automatically switched back on.
And it will stop charging when the battery voltage is 4.2V.
This is to keep the battery from being over-discharged or over-charged.
Yeez_B 
