Datasheet

Trickle Charge
NiMH Button Cells are also suitable for trickle charging.
A large number of applications need the use of cells or
batteries which are kept at all times in a fully charged
state to guarantee an emergency power supply or a
standby operation.
To correctly specify a suitable constant charge current
regime the following criteria apply:
■
Maximum permissible trickle charge current
(see page 11)
■
Adjustment of the losses of capacity resulting from
self-discharge
■
Consideration of the charging efficiency as a function of
the temperature and charge current
■
Minimum recharge time from full discharge
To compensate the constant losses by self-discharge
and to be able to recharge a discharged battery, for
example due to a mains failure, a trickle charge current
of 0.03 CA is recommended.
At this charge rate a life of up to 6 years (at room
temperature) is to be expected. A reasonable reduction
in life expectancy must be considered, when the battery
will be overcharged at the maximum permitted over-
charge current.
The most suitable method to fully charge sealed
re charge able NiMH Button Cells is the constant current
charge for a timed period.
Standard Charge
Applicable for all NiMH Button Cell series. Charging is
with constant current: 14–16 hours at 0.1 CA. Occasional
overcharging at the nominal charge current (see page
11) is permissible. In special cases, a 24 hour charge
at the nominal current is recommended, to achieve or
re store the full performance of the cell or battery.
This is a normal measure for:
■
Initial charge to put into operation
■
First recharge after prolonged storage
■
Deep-discharged cells and batteries, particularly those
which have been discharged into reverse unintentionally
Accelerated charge
Accelerated charge means charging 7–8 hours at
0.2 CA. It is recommended that charging is controlled
by means of a timer.
Limited Fast Charge with Voltage Control
1)
NiMH Button Cells can be fast charged with the charge
rate, specified for each cell. Because of the specific
charge current values this is called a limited fast charge
(0.5 CA). It is possible to recharge more than 80% of
the nominal capacity within 3 hours. Charging must be
terminated after 3 hours. The cells must be fully dis-
charged before charged with this method. Limited fast
charge is recommended only at room temperature appli-
cation.
1)
Except V 200 H, V 350 H
2.8 CHARGING METHODS FOR NIMH BUTTON CELLS
ROBUST FAMILY
page 18 | 19