Nickel-cadmium batteries stored for a long period of time will show a low liquid level because

• A. electrolyte evaporates through the vents.
• B. electrolyte becomes absorbed into the plates.
• C. the electrolyte's specific gravity decreases.
• D. the electrolyte leaks out.

Answer: (B)

When nickel-cadmium cells sit unused for a long time, the visible liquid level drops because the electrolyte is absorbed into the porous plate materials. The electrolyte (potassium hydroxide) wicks into and around the active constituents of the electrodes, so it seems the level has fallen even though the total amount of electrolyte inside the cell hasn’t significantly changed. This absorption is a normal behavior for NiCd cells during extended storage.

The other possibilities aren’t typical causes here: these cells are sealed, so evaporation through vents isn’t the normal mechanism; a change in the electrolyte’s specific gravity reflects charge state rather than a loss of liquid level during storage; and leaks would show actual loss and external fluid, not just a lower level inside the cell.