Hi there,
I designed tiny ESS for lighting, charging from PV panel to LifePO4 Battery pack.
The light turns on during the night and turns off when sun rises. it's a sort of security lighting system powered by PV panel.
the specification is follows,
1. PV Panel:
1-1.Pmax: 60W
1-2.Vmp:18.2V
1-3.Imp: 3.3A
1-4.Voc: 21.9V
1.5. Isc:3.43A
2. Battery Pack:
2-1.Type: LiFePO4
2-2.Voltage & Ampere: 12.8V, 40Ah (4S2P)
2-3. Max. charge voltage: 14.6V
2-4. Discharge Cut-off voltage: 10.32V around
2-5. Standard charge current: (0.2C)8A
3. Circuit diagram
When the SOC of battery is remained above 0%, there's no trouble charging the battery. and the battery supplies power to the controller.
But, when the battery is fully discharged during the night since the current is consumed by lighting, BMS cuts-off discharging, there's no power supplied to the controller.
In this condition, and sun rises, It fails to charge the battery. the voltage of battery being connected to controller is 2.6V around, while the real voltage of battery is 10.8V around.
If I disconnect and reconnect the PV panel or Battery pack, it starts charging.
How can i fix it?
Best Regards,
