Battery cooler and battery unit

A battery cooler provided in a battery unit, the battery unit comprising:

• two or more battery cells arranged side by side in a predetermined direction with a predetermined space interposed therebetween;
• and a restraint member that restrains the battery cells from relatively moving in the predetermined direction, the battery cooler being disposed in the predetermined space between the two battery cells adjacent in the predetermined direction,
• the battery cooler including an outer wall that forms an internal space including a cooling passage through which a cooling fluid flows, and is deformable in a flexural manner in the predetermined direction, wherein
• the outer wall includes
• a first plate part that faces one of the battery cells in the predetermined direction, and
• a second plate part that faces the other battery cell in the predetermined direction, and faces the first plate part across the internal space in the predetermined direction,
• the first plate part includes
• a first contact portion that is in contact with an outer surface of the one of the battery cells, and
• a first non-contact portion that is continuous with the first contact portion, forms a first gap, with the one of the battery cells, allowing expansion deformation of the one of the battery cells, and is not in contact with an outer surface of the one of the battery cells, and
• the second plate part includes
• a second contact portion that is in contact with an outer surface of the other battery cell, and
• a second non-contact portion that is continuous with the second contact portion, forms a second gap, with the other battery cell, allowing expansion deformation of the other battery cell, is not in contact with the outer surface of the other battery cell, and is not in contact with an inner surface of the first non-contact portion.