In low-temperature conditions, if the battery temperature is below 0°C, for battery packs without heating function, charge immediately after discharge if the battery temperature is above 0°C, or place the battery in a warm storage room and charge only after the battery temperature rises to above 5°C. For battery packs with heating function, please check if the charger is working while charging. After fully charging, disconnect the charger as soon as possible; do not leave the battery unattended for an extended period after it is fully charged.
1. Heat the battery pack
Without considering battery pack heating, it's virtually impossible to avoid capacity loss, especially given your environment is -25 degrees Celsius. Even simple room-temperature charging and discharging at such low temperatures will cause capacity loss, let alone charging at such a low temperature. Recommendation: Heat the battery pack.
For low-temperature charging of ternary lithium batteries, our company's single-cell batteries (30Ah) can currently only be guaranteed to charge and discharge at 0℃ without causing battery damage. If the module needs to be charged and discharged at -25℃, external heating is recommended. Furthermore, it's not significantly related to voltage; as long as lithium is inserted into the negative electrode during charging, lithium plating may occur.
2. Reduce charging speed
At -20℃, if a ternary lithium battery is charged at a rate of C/30, the final capacity will only be 77% of the nominal capacity. If the charging speed is reduced to C/100, the final capacity can reach 100%, but it will take four consecutive days to fully charge a single battery. Therefore, it is advisable to first charge slowly to raise the battery temperature, and then switch to fast charging. Some car manufacturers' BMS also have this function, for example, charging at a rate of C/5 to 20%, and then charging at full speed.
3. Increase battery temperature
Charge your electric vehicle indoors whenever possible, such as in an underground parking garage. Some car manufacturers with well-designed thermal management systems can significantly improve the range of electric vehicles in cold winters.
