Patent ID: 8785014

Claim:
A nickel-metal hydride secondary battery module comprising: a plurality of power generating elements each having a negative plate containing a hydrogen absorbing alloy; a battery case provided with partition walls and a plurality of compartments, each of the partition walls having at least two of the compartments arranged adjacently on each of two sides thereof, each of the compartments accommodating at least one of the power generating elements, a plurality of gas intercommunication holes, wherein each of the partition walls comprises one of the gas intercommunication holes, the gas intercommunication holes allowing for a gas to pass between the compartments; and at least one of safety valves placed on the battery case, the safety valves being less in number than the number of the compartments; wherein each of the gas intercommunication holes has a hole sectional area per battery module capacity in a range of 0.03 to 0.30 mm 2 /Ah, wherein the battery case is formed of a first case member and a second case member, both being made of resin and being welded to each other in a butting relation, the first case member including a plurality of plate-shaped first partition wall portions, each first partition wall portion forming part of one of the partition walls, the second case member including a plurality ofplate-shaped second partition wall portions, each second partition wall portion forming another part of one of the partition walls, each second partition wall portion being welded to a corresponding first partition wall portion in the butting direction of the first case member and the second case member, each intercommunication hole including a communication groove extending in a thickness direction of each of the first partition wall portions to provide communication between front and rear surfaces thereof, the communication groove having a shape opening in a side which will face one of the second partition wall portions when the corresponding first partition wall portion is to be welded to the second partition wall portion; and each intercommunication hole having a shape having a larger dimension in the butting direction than a dimension in a groove width direction perpendicular to the butting direction and the thickness direction.