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EN54-2A17LCD
RED POWER
39
The battery test will also be automatically locked when the PSU is in the operating mode, in which the
battery test is impossible. Such condition occurs, for example, during battery assisted operation or when the power
supply is overloaded.
In this case, the LCD will display the crossed out
„START” message in the PSU Settings -> PSU -> Battery test
menu.
Fig. 28. Battery test
– inactive.
8.6. Measurement of the resistance of the battery circuit.
The PSU is checking the resistance in the battery circuit. During the measurement, the PSU driver takes into
account the key parameters in the circuit,
and once the limit value of 300m ohms is exceeded, a failure is
indicated.
A failure may indicate considerable wear or loose cables connecting the batteries.
8.7. 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.
8.8. 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] (Table 15)
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 17Ah batteries can be
determined.
The following data can be assumed:
Id =0,5A
Iz = 0,065A
Ia = 1A
Ta = 0,5h
Ic = 2A
The approximate runtime of the system with two 17Ah batteries will amount to 22h 45min.
