the battery is charged and dark if the battery is discharged
A charge indicator (eye) operates by showing green or red when
the battery is charged and dark if the battery is discharged. This
charge indicator detects __.
a. Battery voltage
b. Specific gravity
c. Electrolyte water pH
d. Internal resistance of the cells
The Correct Answer and Explanation is :
The correct answer is b. Specific gravity.
Explanation:
A charge indicator (often referred to as a “charge eye”) in a battery operates by detecting the specific gravity of the electrolyte inside the battery. Specific gravity is a measure of the density of the electrolyte relative to water, and it directly correlates with the charge state of the battery.
- Battery Charge State: When a battery is charged, the chemical reactions inside produce a higher concentration of ions in the electrolyte, which increases its specific gravity. Conversely, when the battery is discharged, the concentration of these ions decreases, leading to a lower specific gravity. The charge indicator detects this change in specific gravity to determine the battery’s charge level.
- Indicator Colors:
- Green: This indicates that the battery is fully or sufficiently charged. The specific gravity of the electrolyte is high, reflecting a good charge state.
- Red: This typically means the battery is not charged enough, or is in a discharged state, corresponding to a lower specific gravity.
- Dark/No Color: This means the battery is completely discharged, and the specific gravity of the electrolyte has dropped to a very low value.
- Specific Gravity vs. Other Measures:
- Battery voltage (a): Voltage can give a rough estimate of the charge level, but it doesn’t accurately reflect the battery’s condition under varying loads or temperatures. The specific gravity, however, provides a more consistent and reliable measure of the state of charge.
- Electrolyte water pH (c): The pH level of the electrolyte is not typically used to measure the charge state in most battery types. The pH could indicate acid concentration but is less useful for determining charge state compared to specific gravity.
- Internal resistance of the cells (d): Internal resistance is an important factor in battery performance, but it is not directly detected by a charge indicator. It may affect how a battery performs but doesn’t directly correlate with charge state in the way specific gravity does.
Thus, the charge indicator works primarily by detecting the specific gravity of the electrolyte to give an accurate visual representation of the battery’s charge level.