Deep Discharge - Siemens C25 Service Manual

Private Communication Systems
Mobile Phones
7.4

Deep Discharge

In case of a deeply discharged battery, the phone can not be turned on and the
normal charging process can not be started.
In this case, charging the battery is divided into two different steps, which have to be
run subsequently:
a) Trickle charge
Trickle charge mode is automatically started if the battery voltage is below a certain
value when the charger is connected to the mobile. This mode is not terminated
automatically but has to be terminated by disconnecting the charger.
Trickle charge mode has to last minimum until the battery voltage has exceeded a
certain level. During trickle charge the charging symbol will not be visible and the
telephone can not be turned on. This is because the battery voltage is too low to
operate the telephone
Action:
Insert battery into handset and connect travel charger to the telephone. Wait for
appr. 1 hour, then disconnect and reconnect charger. If the battery voltage is high
enough again, the charging symbol will come up.
If the battery is discharched very deeply, the symbol may not come up and the trickle
charge time possibly has to be extended up to 24 hours.
b) Normal charge
When the battery voltage is above the a.m. value (e.g. by trickle charge) the mobile
will start the normal charging mode and show a charging symbol in the display.
Action:
Connect charger to the telephone.
The charging symbol will come up as an indication that the normal charging process
has been started by the mobile.
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