Built-In Indicator Test

If equipped, an indicator (hydrometer) built into the top of the battery case (2) provides visual information for battery testing. Like a hydrometer, the built-in indicator measures the specific gravity of the battery electrolyte. The specific gravity of the electrolyte reveals the battery state-of-charge; however, it will not reveal the cranking capacity of the battery. A load test must be performed to determine the battery cranking capacity.

Before testing, visually inspect the battery for any damage (a cracked case or cover, loose posts, etc.) that would cause the battery to be inoperative. In order to obtain correct indications from the built-in indicator, it is important that the battery be level and have a clean sight glass (1). Additional light may be required to view the indicator. Do not use open flame as a source of additional light.




To read the built-in indicator, look into the sight glass and note the color of the indication. The battery condition that each color indicates is described in the following list:
- Green - Indicates 75% to 100% battery state-of-charge. The battery is adequately charged for further testing or return to service. If the starter will not crank for a minimum of fifteen seconds with a fully-charged battery, the battery must be load tested.
- Black or Dark - Indicates 0% to 75% battery state-of-charge. The battery is inadequately charged and must be charged until a green indication is visible in the sight glass (12.4 volts or more), before the battery is tested further or returned to service.
- Clear or Bright - Indicates a low battery electrolyte level. The electrolyte level in the battery is below the built-in indicator. A maintenance-free battery with non-removable cell caps must be replaced if the electrolyte level is low. A low electrolyte level may be caused by an overcharging condition.