Specific Gravity Of Electrolyte
Check the specific gravity of the electrolyte using a hydrometer and a thermometer.
NOTE:
Specific gravity varies with temperature of electrolyte so that it must be corrected at 20°C (68°F) using the following calculation:
S20 = St + 0.0007 x (t - 20)
S20 : Specific gravity corrected at electrolyte temperature of 20°C
St: Measured specific gravity t: Measured temperature (°C)
S20 = St + 0.0007 x (t - 20)
S20 : Specific gravity corrected at electrolyte temperature of 20°C
St: Measured specific gravity t: Measured temperature (°C)
- When measuring in a simplified manner using the battery terminal voltage, calculate the specific gravity by the following formula.
Specific gravity = [0.187 x battery terminal voltage (V)] - 1.1
Perform the steps 1 and 2 before measuring the voltage in order to stabilize the voltage.
- Measuring the specific gravity of the electrolyte in the battery will disclose the state of charge of the battery. The relation between specific gravity and state of charge is as shown in the figure.
| (A) | Specific gravity [20°C (68°F)] |
| (B) | Amount of discharge (%) |
| (C) | Good |
| (D) | Need to charge or replace |
| (A) | Specific gravity [20°C (68°F)] |
| (B) | Electrolyte temperature |
| (C) | Good |
| (D) | Caution |
| (E) | Need charging |
Check
- Specific gravity: 1.250 - 1.290, and difference between cells is 0.04 or less → Battery is normal
- Specific gravity: Less than 1.250, or difference between cells is 0.04 or more → Battery needs to be charged or replaced