How do I temperature compensate my hydrometer readings?

How do I temperature compensate my hydrometer readings?

If you are using a non-temperature compensated hydrometer, make the adjustments in the table below. For example, at 30° F (-1.1° C), the specific gravity reading would be 1.245 for a 100% State-of-Charge. At 100° F (37.8° C), the specific gravity would be 1.273 for a 100% State-of-Charge. This is why a temperature-compensated hydrometer is highly recommended and more accurate than other means when testing flooded battery types. For non-sealed batteries, check the specific gravity in each cell with a hydrometer and average the readings.

Table 2 - Hydrometer Temperature Compensation

Temperature Add or Subtract to Hydrometer Reading Add or Subtract to Voltmeter Reading
0°F / -17.8°C -.032 -.192
10°F / -12.2°C -.028 -.168
20°F / -6.7°C -.024 -.144
30°F / -1.1°C -.020 -.120
40°F / 4.4°C -.016 -.096
50°F / 10°C -.012 -.072
60°F / 15.6°C -.008 -.048
70°F / 21.1°C -.004 -.024
80°F / 26.7°C 0 0
90°F / 32.2°C +.004 +.024
100°F / 37.8°C +.008 +.048
110°F / 43.3°C +.012 +.072
120°F / 48.9°C +.016 +.096
130°F / 54.4°C +.020 +.120
140°F / 60.0°C +.024 +.144
150°F / 65.6°C +.028 +.168
160°F / 71.1°C +.032 +.192