Regarding hydrometer readings of lead-acid electrolyte, which statement is true?

Regarding hydrometer readings of lead-acid electrolyte, which statement is true?

• A. The hydrometer reading requires temperature correction at 80°F
• B. The hydrometer reading does not require temperature correction if the electrolyte temperature is 80°F
• C. Hydrometer readings are not used for lead-acid electrolyte
• D. Temperature correction is required only at temperatures above 100°F

Answer: (B)

Temperature affects the density of lead-acid electrolyte, so a hydrometer reading must be interpreted against a standard temperature. Hydrometers used for this purpose are calibrated to a reference temperature, commonly 80°F. When the electrolyte is at that temperature, the reading already corresponds to the standard, so no temperature correction is needed. That’s why the statement about not needing correction at 80°F is the best fit. If the electrolyte is not at 80°F, you would apply a temperature correction to convert the reading to the 80°F reference value, because warmer solutions are less dense (lower SG) and cooler solutions are more dense (higher SG). The other options are not correct because: readings are indeed used for lead-acid electrolyte, temperature correction isn’t only required above 100°F, and correction is not required at 80°F since that is the reference temperature.

Temperature affects the density of lead-acid electrolyte, so a hydrometer reading must be interpreted against a standard temperature. Hydrometers used for this purpose are calibrated to a reference temperature, commonly 80°F. When the electrolyte is at that temperature, the reading already corresponds to the standard, so no temperature correction is needed. That’s why the statement about not needing correction at 80°F is the best fit.

If the electrolyte is not at 80°F, you would apply a temperature correction to convert the reading to the 80°F reference value, because warmer solutions are less dense (lower SG) and cooler solutions are more dense (higher SG). The other options are not correct because: readings are indeed used for lead-acid electrolyte, temperature correction isn’t only required above 100°F, and correction is not required at 80°F since that is the reference temperature.