Battery temperature compensation with closed-loop fan control

A dual-loop control configuration employs battery temperature as a feedback metric in order to prevent overheating when recharging batteries. Temperature sensors are used to obtain the battery temperature. Depending on the battery temperature that is measured, a processing device such as a battery interface module determines whether that temperature exceeds a temperature threshold. The processing device also determines a charge rate of the batteries. The processing device is configured to vary the fan speed to increase or decrease airflow for cooling the batteries based on this information, and also regulates the charge rate of the batteries as a function of the fan speed. This arrangement may be used as part of a battery backup system, such as in an uninterruptible power supply used in a data center. Alternatively, it may be used in the power supply system of an electric vehicle. Fluids besides air may also be employed.