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EN54-7A17
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7.7. Battery temperature measurement.
The PSU has a temperature sensor to monitor the temperature parameters of installed batteries. The sensor is
located near the batteries; hence, temperature readings should not be confused with the ambient temperature.
Temperature measurement and compensation of the battery charging voltage can extend the life of the
batteries.
7.8. Standby time.
Battery-assisted operating depends on battery capacity, charging level and load current. To maintain an
appropriate standby time, current drawn from the PSU in battery mode should be limited.
Required, minimum battery capacity to work with the PSU can be calculated with the following formula:
Q
AKU
= 1.25
﴾
﴾
I
d +
I
z
﴿ •Td + ﴾
I
a +
I
z
﴿ •Ta + 0.05
Ic
﴿
where:
Q
AKU
– The minimum battery capacity [Ah]
1.25
– the factor related to the decrease in battery capacity due to aging
I
d
– the current drawn by the load during inspection [A]
I
z
– PSU current consumption [A]
Td
– required inspection time [h]
I
a
– the current drawn by the load during an alarm [A]
Ta
– alarm duration [h]
Ic
– short-term output current
Rearranging the above equation, the approximate runtime of the system with two 17 Ah batteries can be
determined.
The following data can be assumed:
Id = 2,5 A
Iz = 0,078 A
Ia = 5 A
Ta = 0,5h
Ic = 7 A
The approximate runtime of the system with two 17 Ah batteries will amount to 4h 9min.
