Sharp VL-SW50U Service Manual page 135

VL-swsou
Timer ,
Initial -
charging N -
00
Charge
voltage
Charge
current
n
Timer
.
i
Quick charging
Trickle
:
. . i
charging
:
8
0
fW
a
m
m *
-AC
detection
I
tf+p 8
i
D
t .
t=o 30 mim
60 min
180&m
Charging time
Fig. 13-1-2 Charging characteristics of Ni-Cd 1500 mAh battery
3.Nickel hydrogen battery charging mode
When the nickel hydrogen battery is attached to the adapter which is not attached with the DC plug, it will be detected
that the T terminal is present, and the quick charge operation of nickel hydrogen will be started.
The charging operation of the nickel hydrogen battery is divided into the operating modes of five stages. The adapter goes
through these modes sequentially.
When the nickel hydrogen battery is attached, the precharge will be operated at first.
In this mode, it is charged at a constant current of about
0.5
A, and it will shift into the next mode in 2 minutes.
Since this period is provided to activate the battery, the end of charging is not detected. It functions the overvoltage
detection, abnormal-temperature detection and other battery-protective operations alone.
The next operation is the initial charging operation like the Ni-Cd battery.
Differing from the Ni-Cd battery, the limit voltage of the overvoltage detection is 5.1 V and the function to detect an
abnormal temperature is added.
The 3rd stage of the quick charging mode is equivalent to the quick charging of the Ni-Cd battery.
The function to detect the phenomenon in this mode and the mode shift .by detection are as follows:
-AV
detection
If -AV (22 to 62 mV) is detected, it will shift into the trickle charge mode.
Overvoltage detection
If the battery voltage exceeds 5.1 V, it will be judged as abnormal, and it will shift into the trickle charge mode.
AT
detection
If the gradient of the temperature rise of the charging battery exceeds lOC/min., it will be judged as the end of
charging, and it will shift into the auxiliary charging mode.
Abnormal-temperature detection
If the battery reaches a temperature of 60°C to 65OC during charge, the charging operation will stop to protect
the battery and it will shift into the auxiliary charging mode.
Timer operation
When
180
minutes have passed since start of quick charging, it will shift into the auxiliary charging mode.
In the auxiliary charging mode which it will shift into due to
AT
detection and timer activation of quick charging, it will be
charged at a constant current of about 0.5 A like the preparatory charging mode.
13-3