Alpha Technologies AlphaCell SMU - Manual (Page 10)

745-680-B9-001 10
4.0 Temperature, Battery Capacity, and Battery Life
There are several factors that affect the capacity and the life-span of a battery. These include
charging method, discharge depth, end voltages, and ambient temperature. The most signifi cant
of these is temperature. In order to maximize capacity and life-span, ambient temperature should
be controlled and the battery’s fl oat voltage should be set to the appropriate value (for fl oat voltage
specifi cations see section 5.1).
4.1 Battery Capacity and Ambient Temperature
The capacity of the battery is directly linked to ambient temperature: The lower the
temperature the lower the capacity; the higher the temperature the higher the capacity. The
standard capacity data are based on an optimal 25°C ambient temperature. The effect of
temperature on capacity is as follows:
110
100
90
80
70
60
50
-20 -10 0 10 20 25 30 40 50
Percent of Rated Capacity
Ambient Temperature (°C)
Fig. 4-1, Capacity as a Function of Temperature
Excessive temperatures (over 50°C, 120°F) may cause the heat generated in the recombination
process to exceed the rate at which the heat can be transferred out of the battery and thermal
runaway may begin. Thermal runaway is a dangerous cycle that can severely damage equipment.
CAUTION!