What measures specific gravity in batteries?

What measures specific gravity in batteries?

• A. Hydrometer
• B. Odometer
• C. Thermometer
• D. Barometer

Answer: (A)

Measuring the specific gravity of a battery’s electrolyte is about checking how dense the sulfuric acid solution inside the cells is, which reflects the battery’s state of charge. A hydrometer is the instrument used for this purpose. It works with a float inside a liquid-filled tube: you draw electrolyte into the test jar, place the hydrometer in, and the density of the liquid pushes the float up or down. Denser electrolyte (higher specific gravity) usually indicates a more fully charged battery, while a lower density (lower specific gravity) suggests discharge and dilution of the acid as the battery uses its stored energy. Read the scale at eye level, and keep in mind that temperature affects density readings, so temperature compensation is often considered during testing. The other devices measure different things—odometer records distance traveled, thermometer measures temperature, and barometer measures atmospheric pressure—so they do not assess a battery’s electrolyte density or state of charge.

Measuring the specific gravity of a battery’s electrolyte is about checking how dense the sulfuric acid solution inside the cells is, which reflects the battery’s state of charge. A hydrometer is the instrument used for this purpose. It works with a float inside a liquid-filled tube: you draw electrolyte into the test jar, place the hydrometer in, and the density of the liquid pushes the float up or down. Denser electrolyte (higher specific gravity) usually indicates a more fully charged battery, while a lower density (lower specific gravity) suggests discharge and dilution of the acid as the battery uses its stored energy. Read the scale at eye level, and keep in mind that temperature affects density readings, so temperature compensation is often considered during testing. The other devices measure different things—odometer records distance traveled, thermometer measures temperature, and barometer measures atmospheric pressure—so they do not assess a battery’s electrolyte density or state of charge.