Battery Hydrometer Displays Dark or Yellow Dot

CAUTION: Batteries produce explosive gasses. Batteries contain corrosive acid. Batteries supply levels of electrical current high enough to cause burns. Therefore, to reduce the risk of personal injury while working near a battery:
^ Always shield your eyes. Avoid leaning over the battery whenever possible.
^ Do not expose the battery to open flames or sparks.
^ Do not allow battery acid to contact the eyes or the skin.
- Flush any contacted areas with water immediately and thoroughly.
- Get medical help.




Molded into the top of the maintenance-free battery is a built-in temperature compensated hydrometer (1). The built-in temperature compensated hydrometer is also known as test indicator, state of charge indicator, dot, or eye. Built-in hydrometers provide a go/no go indication of the battery state of charge, based on the specific gravity of the electrolyte. Use the hydrometer in the following diagnostic procedure:
^ Make sure the vehicle is relatively level.
^ Make sure the top of the hydrometer is clean.
^ Use a light in poorly-lit areas.
^ Tap the hydrometer on the top to dislodge any air bubbles. Air bubbles will give a false indication.

Under normal operation, one of the following three indications will be observed:




^ The green dot is visible (A).
- Any green appearance in the hydrometer is interpreted as a green dot.
- The green dot means the battery is at least 65 percent charged and is ready for testing. Refer to Battery Not Operating Properly. Battery Not Operating Properly
^ The dot is black or dark (B). This indicates the state of charge is below 65 percent.
- If there is a cranking complaint, Refer to Battery Charging. Service and Repair
- Charge the battery.
^ The dot appears clear or light yellow (C).
- A diagnosis cannot be made at this fluid level.
- A clear or light yellow dot means that the fluid level is below the bottom of the hydrometer.
- Do not charge or test the battery when a clear or light yellow dot is visible.
The following can cause a low fluid condition:
^ Overcharging
^ A cracked battery case
^ Tipping the battery
^ Normal usage
Replace the battery when there is a yellow or clear hydrometer along with a cranking complaint. Do not charge or test the battery when a clear or light yellow dot is visible.