Battery pack for job-site electrical equipment, and method for diagnosing battery pack for job-site electrical equipment

A battery pack for job-site electrical equipment, the battery pack comprising:

• a first positive-electrode terminal and a first negative-electrode terminal configured to receive charge power from a charger;
• first through nth battery modules (i) coupled in series in order and (ii) configured to be charged by the charge power, wherein each of the first through nth battery modules includes two or more rechargeable battery cells coupled in parallel, the first battery module includes a second positive-electrode terminal coupled to the first positive-electrode terminal, and the nth battery module includes a second negative-electrode terminal coupled to the first negative-electrode terminal, and n is any natural number greater than or equal to two;
• and
• a control circuit configured (i) to derive respective full charge capacities of the first through nth battery modules based on measured values associated with respective states of charge of the first through nth battery modules, and (ii) to detect a malfunction in at least any one of the first through nth battery modules based on the respective full charge capacities derived.