Battery Hydrometer Displays Dark or Yellow Dot

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 or floating ball
^ A dark condition, with no green visible

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:
^ A prolonged charge
^ An excessive charge
^ A broken case
^ Excessive battery tipping
^ A faulty charging system

Replace the battery if its condition affects the cranking system.