A battery module includes a plurality of rechargeable batteries each having a gas exhaust member openable at a threshold pressure; a housing holding the rechargeable batteries and having a gas exhaust hole; and a valve member covering the gas exhaust hole, wherein a pressure for opening the valve member is lower than the threshold pressure.
1. A battery module comprising:
a plurality of rechargeable batteries each having a gas exhaust member openable at a threshold pressure, wherein the threshold pressure is substantially equal for each of the rechargeable batteries;
a housing holding the rechargeable batteries and having a gas exhaust hole; and
a valve member covering the gas exhaust hole, wherein a pressure for opening the valve member is lower than the threshold pressure.
2. The battery module of claim 1 , wherein the pressure for opening the valve member is between about 60% and about 90% of the threshold pressure for opening the gas exhaust member.
3. The battery module of claim 1 , wherein the housing comprises a body holding the rechargeable batteries and a cover coupled to the body.
4. The battery module of claim 3 , wherein the valve member is on the cover.
5. The battery module of claim 4 , wherein the cover has guide ribs to provide a passage through which a gas exhausted from the rechargeable batteries can flow.
6. The battery module of claim 5 , further comprising:
a protecting member having gas exhaust holes on the gas exhaust members of the rechargeable batteries, and
a gas exhaust protrusion extending around a circumference of each the gas exhaust holes between the body and the cover.
7. The battery module of claim 3 , wherein the valve member is on the body.
8. The battery module of claim 1 , wherein the valve member has a curved internal face protruding toward a center of the valve member, wherein the curved internal face contacts itself.
9. The battery module of claim 1 , wherein the valve member comprises an elastic material.
10. The battery module of claim 9 , further comprising a gas exhaust protrusion extending along a circumference of the gas exhaust hole, wherein the valve member is within the gas exhaust protrusion.
11. The battery module of claim 1 , wherein the valve member is rotatable.
12. The battery module of claim 11 , wherein the valve member comprises a rotating shaft having a center located higher than a side mass center of the valve member in a gravitational direction such that the valve member is biased into a closed position.
13. The battery module of claim 11 , wherein the valve member is tapered.
14. The battery module of claim 11 , wherein a support step is located adjacent the gas exhaust hole to contact a lower end of the valve member when the valve member is in a closed position.