Note: Descriptions are shown in the official language in which they were submitted.
Rechar~eable ~attery System
This invention relates to a rechargeable
battery system.
There are a large number of applications today
in which dry cells are used. Such applications include
lanterns and torches, various transistorised apparatus
such as radios, cassette recorders, radio-controlled
models.
One of the major problems existing with dry
batteries is the fact that they have a short life and
are relatively expensive to replace, particularly at
short regular intervals. Another disadvantage of the
dry cell resides in its use in apparatus which are not
operated regularly but are merely used for standby
purposes. With these the problem resides in the fact
that when a dry cell gets old, there is a significant
tendency for it to leak, thus not only making a nasty
mess, but also causing signific~nt destruction to the
apparatus in which it is situated.
One proposal for getting round both these
problems is the replacement of dry batteries by nickel
cadmium cells of similar capacity. These cellq are
rechargeable and thus do not require to be replaced
when they become di~charged. As a result the cells
have a particularly long life, an~ are not sub~ect, due
to their different construction, to the leaking of
dangerous chemicals as they age. ~owever, s~ch
replacements are not entirely satisfactory since, if
they are to be used as straight dry battery
replacements, they require to be removed and
individually recharged in an exterior ch3rger provided
for this purpose. Particularly, where a nu~ber of ce]ls
are required, this increases substantially the time
necessary to recharge the batteries and the time in
which the particular piece of apparatus is non-
operational. The provision of individual batterycharges is expensive and, if travelling is involved by
the user of the apparatus, either the charger must be
carried around as well as the apparatus or the risk of
discharging the batteries rendering the apparatus un-
useable occurs. Furthermore, where the user of the
apparatus travels between countries, a different
charger is required on ~any occasions in the different
countries since the electricity supply provided varies
from country to country.
Another proposed solution has been to provide
apparatus in which the nickel c~dmium batteries are
built into the apparatus and a charging arrangement has
also been built in. This however has the disadvantage
tha~ if one wishes to change over from battery operated
apparatus to rechargeable apparatus, then it is
neces~ary to scrap the original apparatus an~ buy new
ones. Thus perfectly good apparatus has to be s~rapped
for an apparat~s which is considerably more expens;ve
and which is totally vulnerable to any failure on any
part of the cell and charging ~ystem. Furthermore,
~recharging can normally only be carried out with a
specific mains supply.
The present invention seeks to provided a
rechargeable battery in which some or all of the above
disadvantages are obviated or reduced.
According to the invention, there is provided
a rechargeable battery comprising ~ casing designed to
fit into a space occupied at present by one or more
batteries; one or more nickel cadmium cells in said
caqing, a ~harging unit in said casing connected to
said nickel cadmium cell or cells and connecting means
for connecting said charging unit to a supply of
electricity.
Preferably the casing is dlvided into two
compartments by a partition, one compartment housing
the nickel cadmium cells and the other comPartment
housing the charging unit. The connecting means ~or the
charging unit may comprise a connector socket opening
to the exterior of the casing.
Preferably the charging circuit is of the
constant current type and may be constructed to operate
either on a.c or d.c.
The construction may also be such that the
charger is able to work on virtually any known
electricity supply, for example ranging from 12volts
d.c. up to 250volts aDc.
Where the construction of the apparatus
permits, the rechargeable ba~teries may be charged in
situ without the necessity of removing them from the
apparatus.
The invention will now be desceibed ln greater
detail, by way of example, with re~erence to the
drawings in which -
Figuee 1 is a diagrammatic view showing thelayout of a rechargeable battery in accordance with the
invention which is intended to replace 2 U2 type dry
cells;
Figure 2 is a diagrammatic view showing a
suitable layout of a rechargeable battery in accordance
with the invention intended to replace a type 996
lantern battery:
Figure 3 is a circuit diagram showing a
suitable form of charging circuit for use with the
rechargeable batteries in accordance with the
invention, and
Figure 4 is a fragmentary view of one ~oem of
inductive coupling ~or connection of the charging
circult with the mains.
Referrin~ firstly to Figure 1, the
rechargeable battery comprises an exterior casing 1 of
insulating material, for example, havin~ the shape of
two series connected U2 dry cells. To this end the
casing has a positive bubble type terminal 2 a~ one end
and a negative flat terminal 3 at the other end. The
casing 1 is divided into two, by a partitioning wall 4.
To one side of this parti~ion wall ~the left side of
the drawing) two series connected nickel cadmium cells
6 are housedO Because of the increase in efficiency of
the nickel cadmium cells, the two cells 6 wlll provide
the effective equivalent of the dry batteries which
they are replacing. This capability enables the nickel
cadmium cells 6 to be located in only one half of the
casing. ~ne other half of the casing carries recharging
system 8 for the nickel cadmium cell 6. As can be seen,
the charger 8 is arranged on a circuit board lO which
lie~ longitudinally in the casing and has at one end a
mains socket 11 ex~ending to the exterior of the casing
1 in the middle area thereof. This socket is
connectable to the mains supply by a suitable ~lex. The
circuit board 10 also mounts all the components
necessary for providing the charging operation, the
circuit details of which will be described in
connection with Figure 3. In the charger illustrated
diagrammatically, in Figure 1, there can be seen a
transformer 14 a regulatlng transistor 15 and other
components.
Figure 2 shows the invention as applied to a
different type of battery, in this case a type 9~6
square section battery which is usually used as a
lantern battery. In this case, four nickel cadmium
cells 6 are used, only two of which are shown. The
arrangement is generally similar to the battery shown
in figure 1, comprising a casing 1 divided by a
partition 4, the upper part housing the nickel cadmium
cells 6 and the lower part housing the charging circuit
8.
In the present battery, both positive and
negative terminals are in the form ~f spring contacts
20 and 21 respectively extending from the top 22 of the
casing 1. As a result, the mains socket 11 is si~ua~ed
in the base 23 of the battery and is located in the
middle of the circuit board 10.
Figure 3 shows a suitable circuit for charging
the nickel cadmium cells 6 of the batteeies shown in
figures 1 and 2. In this respect~ however, it will be
noted that the circuit shown has an additional feature
of being also chargeable from a d.c. source.
In the circuit shown, a main~ input 30 is
connected to the primary of a step down transformer 32
(shown in figures 1 and 2 at 14). The secondary of this
transformer 32 is connected to opposite corners o~ a
bridge rectifier 33. The positive corner of ~he
rectifier is connected through a diode 34 to the
positive terminal of the nickel cadmium cells, one of
which is shown at 35, this positive terminal al~o being
connected to the positive terminal 36 of the battery.
The negative corner of the bridge rectifier 33 is
connected to t~e emitter of a control transistor 38
(shown in figures 1 and 2 at 15) via an emitter
resistor 39, the collector of the transistor 3~ being
connected to the nega~ive terminal of the nickel
cadmium cell~ 35 and thus on to the negative terminal
40 of the battery. The base of the transistor 3~ is
connected to the series connection of a pre-set
variable resist~r 41 and two diodes 42 and 43, which
series connection i5 connected directly across the d.c.
output corners of the bridge rectifier 33.
A d.c. input 46 is also provided for enablin~
charging from a d.c. source. This input i5 in the form
3Q of a coaxial jack socket with an associated switch 47
which isolates the secondary of the transformer from
the d.c. source when the jack plug is in position. The
input leads from the d.c. input are thu~ connected to
the a.c. corners of the bridge rectifier, thus ensuring
that, whichever way the d.c. input is poled, the nickel
~admium cells are still charged with the correct
polarity.
It will be seen that with suitable values of
the components, the circuit provides constant current
charging ~nd will enable the battery to be charged from
almost any available supply of electricity. Thus, for
e~ample, 240 and llOv a.c. mains can be used as well as
a 12volt d~cO source.
It is desirable if, dueing the condu~tion o~
the battery the cells and the charging apparatus are
potted in a suitable resin for both security and
stabil ity.
Figure 4 shows one example~ schematically of
the possibility of providing an inductive mains
connection for the charging circuit instead of the
necessity of providing a lead connection with this
arrangement, the mains transformer 32 (Fig.3) is 3plit
into two, only the secondary winding being present in
the battery, the prîmary winding being separated from
the secondary winding and being provided in a mains
connection unit.
Thus, as shown in Figure 4, a mains unit Sl is
provided with a seating 52 which i5 surrounded by the
primary winding 53 of the transformer. The seating 52
is shaped to receive the bottom end 54 of the battery
housing 55. As seen a secondary winding 56 is located
at this point of the battery housing together with the
transformer core 57.
As an alternative to the arrangement shown, it
is possible to provide an upstanding core of the ma~ns
unit which extends into a recess in the battery housing
so as to locate the ~wo halves of the transformer. In
another example, two partial cores are prov$ded, one
for each winding and the two cores are merely
juxtaposed for charging purposes.
As stated previously, the present rechargeable
battery may take the place of a single ba~tery where
the apparatus use~ a single battery or may take up the
area of two or more or~ginal dry batteries in an
- arrangement which occupies ~he same shape as the
original dry cells. Where the apparatus require a
number of dry cells in certain circumstances, these may
be replaced by an equal number of rechargeable nickel
cadmium cells, each with their built-in charger as
referred to above.
2Q It will be appreciated that various
modifications can be made to t~e above described
embodiments without departing from the scope of the
invention. For example, the invention may be u~ed in
any circumstances where one or more dry batteries are
used provided that the dry battery or the combination
of batteries provides sufficient room ~or housing the
nickel cadmium cells and the charging apparatus. While
it may be usual to remove the batteries for recharging,
where the apparatus in which they are used permits,
they may be charged in situ without harming the
appa r a tus .
~n auto~atic circui~ breaker would be provided
to guard 3gainst overloads~ This could operate on a
9 ~
thermal basis if required. So as to avoid the necessity
of manual resetting, the breaker could be constructed
to reset once the overload condition is removed.
The switch contact 47 of the charging unit can
be omitted, thus cutting out all mechanical moving
parts. In this case two bridge rectlfiers would be
provided, connected in parallel, ~he low voltage input
being connected, for example to the aOc. input of the
second bridge rectifier. In this way it can be ensured
that the load is automatically isolated.
The exact charging circuit can of course be
varied as circumstances dictate, there being a number
of possible variations in known charging circuits which
could be applied here. The location of the various
parts of the rechargeable battery can be varied in
respect to the casing and casing of any desired shape
may be used.
