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.