When an SOC difference between battery pack blocks (1a, 1b, 1c, 1d) exceeds a threshold, or a temperature difference between the battery pack blocks exceeds a threshold, a control section (4) changes cooling modes and cooling control maps for cooling fans ...

A storage battery (1) includes a battery casing (3), a cover (2) closing an opening of said battery casing (3), and a thinner see-through window portion (4) provided on a sidewall of battery casing (3) for visual recognition, from the outside, of a level o...