Case for vehicle's battery pack

A case for a battery pack, which includes a battery module assembly in which four battery modules, each having a plurality of cylindrical secondary battery cells, are electrically connected in series, the case comprising:

• an upper pack case having a hole formed to expose an electrode post electrically connected to the battery module assembly;
• a lower pack case having a lower frame and a side frame;
• an electrode terminal configured to surround the exposed electrode post;
• a case sealing unit interposed between the lower pack case and the upper pack case to prevent external fluid from flowing in;
• and
• a terminal sealing unit interposed between the electrode terminal and the upper pack case to prevent fluid from flowing in from the outside,
• wherein at least one channel is formed at an interior surface of the lower frame in a region adjacent to the side frame,
• wherein a battery module assembly support having a step with a predetermined height from the lower frame is formed at the lower frame and extends from the channel,
• wherein the at least one channel comprises at least two channels, and
• wherein at least one drain is formed at the battery module assembly support to pass through a center of the battery module assembly support and connect the channels.