Exide Technologies Section 95.10 User Manual
Page 13
9.4 DETERMINING STATE OF CHARGE
If the normal connected load is constant (no emergency load connected), the following
method can be used to determine the approximate state of charge of the battery. This
state of charge can be identified to some degree by the amount of charging current
going to the battery. When charging, the current read at the charger ammeter will be a
combination of the load current plus the current necessary to charge the battery. A
condition where the current remains constant for a period of three consecutive hours
would reflect approximately 90 to 95% state of charge.
If the normal connected load is variable (e.g., telecommunications), the following
method can be used to check the state of charge of the battery. With the battery on
float and stabilized, measure the voltage across a pilot unit. If the voltage is stable for
three consecutive hours, the battery is considered 100% charged.
9.5 EFFECTS OF TEMPERATURE
Temperature has a direct effect on the life of a battery. The design life of the battery is
based on an average annual temperature of 25°C (77°F). As the temperature increases
above 25°C (77°F), the life of the battery decreases. The chart below shows the effects
of temperature.
For example: If a battery has a design life of 10 years at 25°C (77°F), but the actual
annual average battery temperature is 35°C (95°F), the projected life of the battery is
calculated to be only 5 years [10 years - (10 years X 0.50) = 5 years].
Temperature records shall be maintained by the user in accordance with the
maintenance schedule published in this manual. The battery temperature shall not be
allowed to exceed the maximum temperature shown above. It is important to maintain
the battery temperature as close to 25°C (77°F) to achieve the optimum service life
from your battery.
10
Maximum Annual
Average Battery
Temperature
25°C (77°F)
30°C (86°F)
35°C (95°F)
40°C (104°F)
45°C (113°F)
50°C (122°F)
Maximum
Battery
Temperature
50°C (122°F)
50°C (122°F)
50°C (122°F)
50°C (122°F)
50°C (122°F)
50°C (122°F)
Percent
Reduction
In Battery Life
0%
30%
50%
66%
75%
83%