Page 483 - Battery Reference Book

47/16 Constant-current charging

transistorized and short-circuit proof. Cells and Another feature of this low-cost design is the choice
batteries on charge are protected against a.c. supply of 240V a.c. or 120V a.c. by means of internal tap.
failure. Nominal constant current is derived from a trans-
former, full-wave silicon bridge rectifier and output
0 AC supply input: 240V, 50Hz. limiting resistors.
Charging rates: Model 1, 1OmA.
Model 2, 22mA. AC supply input: 240 V a.c. 50 Hz/120 V a.c. 60 Hz;
Model 3, 30mA. a.c. input fuse.
AC supply cable: 2 m three-core.
47.5.2 Varta charger designs for Charging rate: up to 600 mA by means of internally
nickel-cadmium batteries selected resistors (present before dispatch).
Maximum cell capacity: 10 cells up to 6Ah.
Varta supply two types of universal constant-current Output: Belling Lee 4 mm sockethpade captive-type
charger for use with sealed nickel-cadmium batteries, terminals on front panel.
the specifications of which are given below. DC output fuse.

Vurtu type CC306C automatic The final charge voltage of a nickel-cadmium bat-
tery can vary from approximately 1.4 to 1.5 V, but the
The charger will handle from one to 30 nickel- effects of battery age, temperature and rate of charge
cadmium cells in series connection up to 6Ah will give variations outside this range. This voltage
capacity. variation, together with the flat nature of the charge
The rate of charge is adjustable over two ranges curve, makes it impossible to guarantee an overcharge
selected by the range switch 0-60 and 0-600mA. A rate by the constant-voltage method.
potentiometer in conjunction with a calibrated meter
provides fine adjustment. The meter is calibrated 0-60 47.5.3 Nife Jungner designs for
and 0-600 mA.
The circuitry of the charger is safe against short- nickel - cadmium batteries
circuit and reverse polarity connection. Nife Jungner recommend that their nickel-cadmium
The instrument incorporates a timer with the facility
to provide preselected charging periods from 1 to 14 h cells be charged with constant current and with the
with automatic cut-off, thus allowing the charger to cells connected in series. In those cases where paral-
lel batteries are used for capacity reasons, the char-
be left unattended once the charging cycle has been
started. ging equipment should be designed to give equal
current to each battery. In effect, the parallel con-
0 AC supply input: 240V ax. 50Hz/120V ax. 60Hz nection is eliminated during the charging sequence.
by means of voltage selector mounted on the rear Most applications require charging from a standard
panel. a.c. supply of 220 or ll0V. The charging equipment
AC supply cable: 2m of three-core PVC covered. can be very simple, but should give a reasonably con-
0 Charging rate: up to 600 mA over two ranges: 0-60 stant current. Figure 47.15 shows two examples of
and 0-6OOmA by means of panel-mounted range full-wave rectifiers recommended for charging sealed
switch. nickel - cadmium batteries.
0 Cell capacity: 1-30 cells in series.
Controls (all on the front panel): meter calibrated Ni$e Jungner type NUC-612
0-60 and 0-6OOmA; potentiometer for current Nife Jungner supply a constant-current charger type
selection; manually reset timer with automatic NUC-612 designed to charge from one to 12 of any of
cut-off.
the range of KR series nickel-cadmium rechargeable
Vurtu charger type CC106C OIK I1 cells, connected in series, at a constant current. The
combined rotary odoff and selector switch is set to
The output is preset up to ten nickel-cadmium cells the type of cell to be charged, and the output voltage
connected in series, and the rate of charge is internally is then automatically adjusted to maintain a constant
selected prior to dispatch. The circuit is designed such charging current according to the number of cells being
that the output terminals are ‘floating’, this gives the charged. The charger is provided with a safety fuse
unit added versatility in as much as more than one and LED indicator, but any other control or ammeter
can be added together, thus two units (with the same is rendered unnecessary by the automatic system. The
output) with output terminals in parallel (positive to specification of this charger is given below.
positive and negative to negative) can give a capability
of charging up to 12 Ah batteries at 1.2 A; conversely 0 Supply voltage: Standard 220 V f 10% single phase
two units connected in series (positive to negative, etc.) (other voltages can be provided for as an optional
give a capability of charging up to twenty cells up extra).
to 6Ah. 0 Frequency: 50Hz.