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Batteries of smaller capacity, i.e. < 17 Ah, are not recommended since the charging current
in step 1 (see below) is 2.4 A, which normally is higher than the recommended maximum
charging current for these batteries. Too high charging current can cause abnormal internal
heating which may damage the batteries.
28.1.2
Battery charging functions:
Battery charging is performed in two steps:
1. Constant current. The charging current is constant (fixed) until the battery /
charging voltage reaches 29 V
2. Constant voltage. The charging voltage is reduced from 29 to a value between
26.6 and 28.2 V (depending on the temperature) and will be constant (fixed) at this
level until the batteries are fully charged.
When the battery is fully charged the stand-by "charging current" is 0-0.5 A (typical 0.1 A)
and the "charging voltage" will stay constant (fixed) at the "step 2" level, until the batteries
have been discharged and have to be charged again. A new charging cycle will then start.
The duration of "step 1" and "step 2" respectively is dependent on the battery shape when
the charging starts.
28.1.3
Battery protection functions
The battery charging will be turned off if the current from the power supply to the
Main board 5010 exceeds 6.3 A. The battery charging will remain turned off as
long as the FT1020G3 current consumption exceeds 3.3 A. The following fault
message will be shown:
In case of faulty charger, the following fault message will be shown:
In order to not damage the batteries, the voltage output will be switched off at
approx. 18 V. This only happens in case of no main power source (230 V AC), i.e.
when the backup batteries are used as power source.
If the battery voltage is below 10 V (5 V per battery), the battery charging will be
turned off. (The batteries are most certainly damaged and have to be changed.)
In case of mains failure and after a time delay of 1-300 minutes (programmable in
EBLWin but max. 30 minutes, the following fault message will be shown:
28.2
Current consumption calculations
The following calculations should be carried according to the application requirements of
the related current standards, such as AS7240.2, AS1670.1, and AS1670.4.
In order to avoid overloading the power supply, the battery capacity calculation must be
performed as per AS1670.1 clause 3.16.4. The total FT1020G3 current consumption
(excluding battery charging current) has to be calculated.
Note: The batteries will not charge when fire alarm is activated in FT1020G3.
Use the values in chapter "Current consumption", page 174, to calculate the total system
current i.e. alarm current I
.
DC
FAULT: Control Unit xx high current
consumption
FAULT: Charger Control Unit xx
FAULT: Mains, Control Unit xx
and quiescent current IQ.
A
178
Technical/Programming Manual
FT1020G3 Rev 2.2.1
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