Thank you for providing the details. We have thoroughly analyzed the issue you described, and we have identified the reason behind the inability of the batteries to charge—specifically, the activation of the low-temperature protection mechanism.
Your data told us that the temperature sensor detected a temperature below 0 degrees Celsius, the charging current for the B51100 was limited to 0A, and the discharging current was limited to 30A. You can find the relationship between current and temperature below.

Discharging---Temperature
Temperature ≤ 0℃, battery allowable discharge current is 30A (100*0.3=30)
0℃<temperature≤5℃, the allowable discharge current of the battery is 40A (100*0.4=40)
5℃<temperature≤50℃, the allowable discharge current of the battery is 50A (100*0.5=50)
50℃<temperature≤55℃, the allowable discharge current of the battery is 40A (100*0.4=40)
55℃<temperature≤65℃, the allowable discharge current of the battery is 20A (100*0.2=20)
Temperature>65℃, the battery allowable discharge current is 0A (100*0=0)
Charging---Temperature
Temperature ≤ 0℃, battery allowed charging current is 0A (100*0=0)
0℃<temperature≤5℃, the allowable charging current of the battery is 10A (100*0.1=10)
5℃<temperature≤55℃, the allowable charging current of the battery is 50A (100*0.5=50)
55℃<temperature≤65℃, the battery allowed charging current is 20A (100*0.2=20)
Temperature>65℃, the allowable charging current of the battery is 0A (100*0=0)
Each B51100 battery is equipped with two temperature sensors. The battery temperature you observed at the inverter is the higher temperature recorded by one of the sensors. Although the temperature detected at the inverter is above zero, the other sensor detected a temperature below zero Celsius, and it will trigger stop charging.
This discrepancy is a result of the battery's placement and the ambient conditions. Different areas of the battery experience varying temperatures, and since the two sensors are located in different positions within the battery, they register different temperatures—one below zero and the other above zero.
To address this issue, we recommend adding wind barriers or insulation layers externally to the battery, especially when it is placed near a vent or in contact with a cold surface. This will help raise the overall temperature of the battery, preventing the activation of the low-temperature protection mechanism.
Should you require further assistance or have additional questions, please feel free to reach out.
Thank you for your understanding and cooperation.
Best regards
Lu Wang