A lead storage battery with a monobloc container receives plate groups in cell compartments which are adjustable in width using a series of side wall ribs. Each rib includes a cell connector formed on the container wall, which is in turn provided with support portions which extend into the container compartment to define a roughly T-shaped cross-section. Each rib is further joined to the bottom of the container along its cross-section. Since the support portions are aligned with, or substantially aligned with the container wall, a large-surface support is provided for receiving a plate group, preventing the potential for wearing into the outermost electrodes of the plate group during vibrational stress, and the failure of the mass which can then result.