If the electrolyte specific gravity reads 1.200, what does this indicate about the battery's charge state?

• A. Fully charged
• B. Overcharged
• C. Not fully charged
• D. Undetermined

Answer: (C)

The main idea is that electrolyte specific gravity in a flooded lead-acid battery reflects how concentrated the sulfuric acid is, which changes with the state of charge. When a battery is fully charged, the electrolyte is more concentrated, and the SG is higher—typically around 1.265 to 1.300 at 25°C. As the battery discharges, the solution becomes more dilute and the SG drops. Seeing a reading of 1.200 means the electrolyte is less concentrated than it would be at full charge, so the battery is not fully charged. Remember to account for temperature, since SG readings shift with temperature; adjust the reading to the standard 25°C if needed. In short, 1.200 indicates a partial state of charge, not fully charged.