They are housed in a plastic box that has no open vent so if you find your battery is fading rather quickly, check to see if there is a vent or hole in the base that is covered with a label.
What could happen is that the tape that is used to connect the cells is open to any intrusive vapour and can form a short circuit if there is enough water condensed.
You aught to be able to open the case to view the cells. If you can, you may be able to remove them and dry and clean them if they need it.