Automotive Electronics Practice Test

What is the maximum allowable difference between the highest and lowest hydrometer reading when measuring the specific gravity of the electrolyte?

1. 0.010

2. 0.020

3. 0.050

4. 0.50

The correct answer is: 0.050

When measuring the specific gravity of the electrolyte in a battery using a hydrometer, it is critical to ensure that the readings are consistent across the cells. The maximum allowable difference between the highest and lowest hydrometer readings is typically set at 0.050. This standard helps ensure that the electrolyte levels are balanced and that each cell is functioning properly. A difference greater than 0.050 could indicate issues with individual cells, such as unequal charge levels or potential problems with the battery's overall health. Maintaining this small variance is essential for optimal performance and longevity of the battery. A narrower threshold, such as 0.010 or 0.020, would provide an overly stringent measure that may not be practical in typical battery assessments, taking into account minor variations that can occur naturally. Conversely, a threshold of 0.50 significantly exceeds acceptable limits and would not reflect the necessary attention to balance and health of the battery cells.