A hydrometer is built into the maintenance-free battery. The hydrometer is temperature-compensated. The color on the hydrometer indicates the condition of the battery.

Under normal operation, one of two color conditions on the hydrometer is possible:

A green dot on the hydrometer means the battery is ready for testing.

If the hydrometer is dark with no green visible, and there is a cranking complaint, inspect for trouble in the charging or electrical systems.

Occasionally, a clear or light yellow color appears. This means the battery fluid level is below the bottom of the hydrometer. A low fluid level can be caused by any of the following conditions:

Replace the battery if its condition affects the cranking system.