Technical / Programming Manual
FT128 Rev 2.2
172
25.1.1 Battery Charging Functions:
Battery charging is performed in two steps:
1. Constant charging current. The charging current is constant (fixed)
until the
battery / charging voltage is 29 VDC.
2. Constant charging voltage. The charging voltage is reduced from 29V to a value
between 27 and 27.6 VDC (depending on the battery type, shape, temp. etc.) and
will be constant (fixed) at this level until the batteries are fully charged.
The stand-by "charging current" is 0-0.5 A.
The charging voltage will stay constant (fixed) at the "step 2" level until the batteries have
been discharged and have to be recharged. A new cycle will start with "step 1". The "step
1" and "step 2" times are depending on the battery shape when the charging started.
25.1.2 Battery Protection Functions
The battery charging will be turned off if the current from the power supply to the Main
board 4556 exceeds 1.8 A, i.e. the FT128 current consumption exceeds 0.8 A. The battery
charging will remain turned off as long as the FT128 current consumption exceeds 0.75 A.
It will generate a fault and the following fault message will be shown:
FAULT: High current consumption in CU
Date: DD-MM Time: HH:MM
Normally every 14
th
minute the battery voltage is checked. A battery voltage below 18.9
VDC will generate a fault
and the following fault message will be shown:
FAULT: Battery
Date: DD-MM Time: HH:MM
Note: Regarding this fault and the New Zealand convention, see chapter “FAULT:
Battery´, page 125.
When 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).
Every 4
th
hour the battery circuit (connection cables, fuses, etc.) resistance is checked. A
resistance over 1.4 Ω will generate a fault and the following fault message will be shown:
FAULT: Low battery capacity
Date: DD-MM Time: HH:MM
Note: Regarding this fault and the New Zealand convention, see Section FAULT: Low
Battery Capacity, page 125.
In case of mains failure (230 V
AC
), i.e. when the backup battery is used as the only power
source, the battery will be switched off at a battery voltage below 18 V
and the CIE will
shut down. When the mains power restores, the battery voltage will be checked and when
it is at least 22VDC, the battery will be switched on and the CIE will work again.
The charging current is 0.7 A (typical). (Very close to the end of the charging cycle it will lower.)
In the New Zealand convention every 60 seconds and 24.4 V respectively.
This is done in order to avoid damaging the batteries.
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