Lucent Technologies KS-20472 - Figure 7-1: Correcting Capacity for Temperature

Lucent Technologies Round Cell Batteries
Issue 3 December 1999 Operation and Maintenance 7 - 17
Perform Discharge Capacity Test, continued
Discharge Capacity Test, continued
Step Action
6
Measure the electrolyte temperature again near the end of the
discharge.
7
Determine the percent of rated capacity for the battery at 77°F
(25°C) using the following formula:
% Rated Capacity = ([discharge time (minutes) / rated
discharge time (minutes)] / 100) ± K
Note: K is the correction factor for electrolyte temperature at
the beginning of the discharge. Add 0.5% per degree
Fahrenheit for temperatures below 77°F/25°C or subtract 0.5%
per degree Fahrenheit for temperatures above 77°F/25°C. K
may be obtained from Figure 7-1.)
Example:
Assume electrolyte temperature of 60°F (15.55°C) at start of
discharge and 276 minutes to 1.75 volts. From Figure 7-1, K
(the correction factor) equals plus 9 at 60°F. Therefore, percent
of 5-hour rated capacity is (276/3) + 9 = 101 percent.
Figure 7-1: Correcting Capacity for Temperature
8
Recharge cells as soon as possible following a discharge.
+30
+20
+10
–10
40 50 60 70 80 90
Electrolyte Temperature - Degrees F
Correction Factor - K
100 110
–20
0