If a battery with a built-in hydrometer has a green indicator, it means that the charge is full.

If a battery with a built-in hydrometer has a green indicator, it means that the charge is full.

• A. Charge is full
• B. Charge is low
• C. Needs water
• D. Defective

Answer: (A)

A green reading on a built-in hydrometer means the battery is fully charged. The hydrometer checks the electrolyte’s specific gravity, which rises as the battery charges because the sulfuric acid concentration increases. When the charge reaches the proper full-charge range, the indicator shows green. If the battery were low on charge, you’d typically see a red or other color rather than green. The green signal isn’t about needing water or about a defect in the battery; it specifically signals that the charge state has reached full.

A green reading on a built-in hydrometer means the battery is fully charged. The hydrometer checks the electrolyte’s specific gravity, which rises as the battery charges because the sulfuric acid concentration increases. When the charge reaches the proper full-charge range, the indicator shows green. If the battery were low on charge, you’d typically see a red or other color rather than green. The green signal isn’t about needing water or about a defect in the battery; it specifically signals that the charge state has reached full.