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4466 EXTERNAL POWER SUPPLY - FIRE ALARM SOLUTIONS TECHNICAL DESCRIPTION
4.4.4.
BATTERY CHARGING FUNCTIONS
A battery discharged to its final voltage can be recharged to at least 80% of its rated capacity within 24 hours and to its rated capac-
ity within another 48 hours.
The battery charging cycle is performed in two steps:
1. Constant current: The charging current is constant (fixed) until the battery / charging voltage reaches approximately 14.5 V
per battery.
2. Constant voltage: The charging voltage is reduced (and temperature compensated) to approximately 13.6 V per battery at
25˚C, 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 0-0.25 A (typical 0.1 A) and the "charging voltage" will stay con-
stant (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 depending on the battery condition when the charging started.
4.4.5.
SECURITY FUNCTIONS
The unit has a number of security functions:
•
The battery charging will be turned off if the current from the rectifier to the charger board exceeds 4.5 A. The battery charging
will remain turned off as long as the continuous output current consumption exceeds 1.5 and 3.0 A respectively.
•
In order to prevent damage of the batteries, the voltage output will be turned off at approximately 19 V. This only happens when
the backup batteries are used as the power source. The output will be turned on at approximately 21 V.
•
If the battery voltage is below 15 V, the battery charging will be turned off. The batteries are probably damaged and have to be
changed.
When the battery charging is turned off, a fault will be generated in the c.i.e. The fault message is depending on the system that the
unit is connected to.
When the system is in alarm state, the charger fault will be suppressed.
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