When must a correction be applied to the specific gravity reading of a lead-acid battery electrolyte?

The requirement to correct the specific gravity reading of a lead-acid battery electrolyte pertains to the impact of temperature on the density of the electrolyte. Specific gravity measurements are affected by temperature variations; thus, if the electrolyte temperature is either below 70 degrees Fahrenheit or above 90 degrees Fahrenheit, adjustments need to be made to ensure accurate readings.

At temperatures less than 70 degrees Fahrenheit, the electrolyte becomes denser, which can result in a higher specific gravity reading than the actual state of charge of the battery. Conversely, at temperatures exceeding 90 degrees Fahrenheit, the electrolyte becomes less dense, potentially leading to lower specific gravity readings. Therefore, making corrections in these temperature ranges is essential for reliable assessment of the battery’s state of charge.

By applying these corrections, technicians ensure that they have an accurate understanding of the battery's condition, which is crucial for maintenance and performance evaluations. This understanding helps in making informed decisions regarding charging, discharging, and overall battery health.