To test the cell, first make sure the fluid level is to the proper full mark. If the fluid is not full, add distilled water to bring the level up, then charge the battery.
1. Plunge the tube of the hydrometer below the layer of oil until you hit the top of the battery plates.
2. Squeeze the bulb to force out any drops of oil that may have become trapped inside the hydrometer tube.
3. Release the bulb to extract the electrolyte below the oil layer.