6
Figure 1- Temperature effect
5.
SPECIFICATIONS
The figure 2 illustrates the relationship between battery capacity and temperature. A reduction in capacity and
performance will be experienced as the temperature falls from the nominal operating temperature. Conversely, as
the temperature increases the capacity and performance of the battery will also increase. These conditions are not
permanent; the capacity will be restored as the temperature returns to the nominal operating temperature range.
5.1 CAPACITY
The capacity of Hawker
®
VRLA aircraft battery is rated in ampere-hours at the 1-hour rate (AhC
1
). An 18 ampere-hours
battery will sustain an 18-ampere discharge for 1 hour down to a battery voltage of 20 volts. By conventional definition,
the battery is deemed airworthy if it delivers its rated capacity for 48 minutes down to a voltage of 20 volts at +20°C
i.e. 80% nominal C
1
capacity.
5.2
TEMPERATURE EFFECT
The ideal environmental temperature range for battery operation is 23°C to 25°C; temperatures outside this range have
an effect on the life and performance of the battery. These effects are detailed in figure 1:
-40°C to 22°C
23°C to 25°C
26°C to 50°C
Reduced Capacity
Undercharge
Reduced life
Optimum life &
Performance
Increased Capacity
Overcharge
Reduced life
Figure 2 - Battery capacity as a function of temperature
20
30
40
50
60
70
80
90
100
110
120
130
-50
-40
-30
-20
-10
0
10
20
30
40
50
60
Percentage Performance @ 20
o
C
Temperature (°C)
Battery Capacity (C
1
) as a Function of Temperature (
o
C)
Summary of Contents for HAWKER 9250-0083
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