Patent ID: 7998610

Claim:
An electric power source comprising: a plurality of batteries; a battery case in which the plurality of batteries are stacked in two or more tiers, the battery case comprising a holder case, the holder case comprising: an intermediary duct for conducting cooling air; a first sub holder case and a second sub holder case, wherein the intermediary duct is disposed between the first sub holder case and the second sub holder case in a direction of stacking the batteries; and an outer duct comprising a first outer duct provided outside the first sub holder case, and a second outer duct provided outside the second sub holder case; wherein the first sub holder case and the second sub holder case are disposed between the first outer duct and the second outer duct, wherein the intermediary duct is disposed between the first sub holder case and the second sub holder case so that cooling air can be blown to the intermediary duct, the holder case and the outer duct, which are so structured as to cool the batteries contained in the holder case, and wherein a partition is disposed inside the intermediary duct which is divided by the partition into a first intermediary sub duct disposed to the first sub holder case side and a second intermediary sub duct disposed to the second sub holder case side, so that the first intermediary sub duct is linked to the first sub holder case, while the second intermediary sub duct is linked to the second sub holder case, and wherein the first sub holder case contains the batteries in the greater number of tiers than does the second sub holder case, and wherein an inside width in the first intermediary sub duct is larger than an inside width in the second intermediary sub duct.