In battery packs with many cells in series, the entire pack can be taken down if a single cell is weak or non-operational. It is already known that high temperature can lead to pack and cell degradation. This is the reason why a temperature sensor is added to the battery pack, in order to make sure that a user doesn’t charge or discharge the cells if the temperature is out of the safe range. However in large packs, the temperature may not be uniformly distributed. Battery management for large battery packs may need multiple temperature sensors. Cell and pack protection is very important in larger packs, as there is a larger potential safety hazard to the user if the system malfunctions. So redundant safety monitoring, as well as cell balancing, is typically required.