To provide a path for electrolyte

To hold the positive and negative plate firmly

To avoid short in between the positive and negative plates

To keep positive and negative plate in a sequence array

Barometer

Hydrometer

Anima meter

High rate discharge tester

Bending of the electrodes

Reducing the strength of electrolyte

Making short between the electrodes

Increasing the internal resistance

Zinc

Carbon

Copper

Lithium

Increases

Decreases

Falls to zero

Remains same