ZENER-DIODE-CONTROLLED BATTERY CHARGER

• Document Type: CREST
• Collection: General CIA Records
• Document Number (FOIA) /ESDN (CREST): CIA-RDP81-00120R000100020051-9
• Release Decision: RIFPUB
• Original Classification: K
• Document Page Count: 3
• Document Creation Date: December 23, 2016
• Document Release Date: March 18, 2014
• Sequence Number: 51
• Content Type: CONT

Declassified and Approved For Release 2014/03/18: CIA-RDP81-00120R000100020051-9
Sept. 7, 1965
C. M. GOLD
EENER-DIODE-CONTROILED BATTERY CRAMSER
Filed Feb. 20. 2962
ELT' 2
BY
nirmrroR:
CHARLES IA. GOLD
ATTORNEY
Declassified and Approved For Release 2014/03/18: CIA-RDP81-00120R000100020051-9
Declassified and Approved For Release 2014/03/18: CIA-RDP81-00120R000100020051-9
United States Patent Office
3,205,422
Patented Sept. 7, 1965
1
3.205.422
ZE.NER-DIODE-CONTROLLED BATTERY
CHARGER
Clarks M. Gold, Franklin Square. N.Y., assignor to
'far ditty International Corp., New York, N.Y., a COr?
poration of New York
Filed Feb. 20, 1961. Ser. No. 90,360
1 Claim. (Cl. 320-39)
-This invention relates to a device for charging electric
storneee batteries or accumulators. More particularly it
? provides a novel means for automatically disconnecting
? the battery from the charging source, when said battery
is fully charged.
It is known that a storage battery is generally regarded
as fully charged when its voltage, sshile on charge, reaches
a point at which gases start generating at the electrodes.
Accordingly, the means provided for disconnecting it
automatically at the end of charge arc usually controlled
by battery voltage, although other means of control arc
sometimes used.
In eases where voltage control is utilized, the means
for disconnecting the battery front the charging source
usually comprise a line switch or contactor, operated front
a voltage relay whose coil is connected across the bat-
tery terminals. The line contactor is in series in the charg-
ing circuit. When the battery voltage reaches a predeter-
mined value, the voltage relay is energized causing the
contactor to break the charging circuit and thereby dis-
connecting the battery from the charging source.
The system described above sufferi from many draw-
-backs among which arc its lack of accuracy with respect
to voltage at which the break should occur. Further-
more, its bulkiness, excessive weight and high cost also
? are distinct disadvantages.
ft is an object of this invention to provide a more ac-
curate, a lighter, a more compact and a more economical
control system for automatically disconnecting a bat-
tery from a charging source.
It is a further object of this invention to provide a
more durable system of this type by eliminating, at least
in part, the moving components present in a conven-
tional circuit.
These and other objects of the invention will become
apparent upon consideration of the accompanying speci-
fications, claim and drawings of which:
FIG. 1 is a schematic diagram of one embodiment of
the invention;
FIG. 2 is a schematic diagram of another embodiment
of the invention.
Referring now to FIG. 1, there is shown a battery I
which is connected to a charging source 2 by means of
an electrical circuit arranged in accordance with the in-
vention. As can be seen from the diagram, the battery
1 is shunted by a Zcner diode 3 and is in series with a
variable resistor 4 and a relay coil 5. The contact blade
6 of the relay is connected to the negative terminal of
the charging source. When the contact blade 6 is in
-ON"-position the negative terminal of the charging
sotrce is connected directly to the negative terminal of
the batter/ 1 and the charging circuit is closed. When
the cc,-a:acc blade 6 is in "OFF"-position the battery is
disconnected and a pilot light 7 is connected instead to
indicate the end of charge.
The characteristics of the Zeiler diode 3 employed in
fats invention are such so as to make it conducting when
battery voltage reaches its "full-charge" point. The 'Lauer
diode 3 does not break down immediately upon connec-
tion across the charging source, since the current drain
hanarv being charged results in a lowered poten-
_
Declassified and Approved For Release 201
to
2
In the operation of the system, until the "lull-charge"
point is reached the &net diode 3 is not conducting and
the contact blade 6 remains in the "ON"-position. When
the "full-charge" point is reached, the Zener diode 3
breaks down and starts conductina* in the reverse direc-
tion. As a result, current starts flowing through relay
coil 5 and the contact blade 6 is attracted to -OFF--
position, disconnecting the battery from the charging
source. It will be readily understood that the function
of variable resistor 4 is to limit the current in the diode
branch of the circuit to a suitable value for the com-
ponents.
FIG. 2 illustrates a transistorized version of the in-
vention. One feature of this embodiment is that all MO*.
15 ins parts are eliminated from the system. As seen in this
figure, storage battery 1 is connected to charging source
2 through a series transistor 23.
The transistor 23 has its emitter 24 connected to the
positive source terminal and its collector 25 connected
20 to the positive battery terminal so that the emitter-to-
collector resiqance may be in series in the charging line.
The base 16 of the transistor 23 is connected to the
collector 19 of a second transistor 17. The collector 19
of the second transistor, in addition to being connected
25 to the base 16 of the transistor 23 is also connected to
one end of a resistor 13, the opposite end of which is
connected to the positive battery terminal. The emitter
IS of the transistor 17 is connected directly to the positive
source terminal. The base 10 of the transistor 17 is
30 connected to a point intermediate a Zener diode 11 and
a resistor 12. The Zeiler diode 11 and resistor 12 serially
connect the positive source terminal to the adjustable
tap of a potentiometer 14 which shunts battery 1.
From FIG. 2 can be seen that the Zener diode 11 is
aa biased in reverse direction. Its characteristics are selected
so that reverse breakdown will occur when the difference
of potential between the positive source terminal and
the tap potentiometer 14 reaches a given value_
The principle of operation is as :cllows:
40 When a storage battery is inserted in the circuit and a
charging source connected to said circuit as shown in
FIG. 2, a difference of potential will be established across
the Zener diode 11. The magnitude of this potential dif-
ference will depend on the poiition of the adjustable tap
45 of potentiometer 14. To insure proper operation, the
adjustable tap will be set so as to develop a potential dif-
? ference that would be somewhat below the reverse break-
down voltage of the diode 11, the exact setting being
selected as will be explained further.
50 With the battery and the charging source connected as
shown, a difference of potential will also appear between
the positive source terminal and the positive battery ter-
minal, thereby biasing the transistor 23 so as to render
?it conducting. As a result, current will start flowing
53 through same, charging the battery.
? By refcriing to FIG. 2, it further will become apparent
that transistor 17, by contrast to transistor 23, will not
become conductive as a result of the charging voltage
? being applied to the circuit, and will remain in a non-
conductive state as long as the Zener diode 11 does not
break down. Now, according to the invention, the cir-
cuit components and the setting of the adjustable tap of
potentiometer 14 will be such that the breakdown of
Zener diode is to occur only when the battery voltage
55 reaches its "full-charge" value. When the "full-charge"
is reached and the Zener diode is broken down, current
will start flowing through the resistor 12, rendering the
transistor 17 conductive. As a result, a voltage drop
7O N_Vp.?:. alelroisns s t Cut notry la3, nd drivetirnegb ythe bas disconnect r rtehnet
4/03/18: CIA-RDP81-00120R000100n9nnsi_q
Declassified and Approved For Release 2014/03/18: CIA-RDP81-00120R000100020051-9
3,205,422
The new devices wt forth above can be used without
any great modification of existing equipment or increase
of production cost. It will be understood, however, that
numerous variations and modifications of the invention
herein described can be made without departing from the
spirit and scope thereof, hence the same is not to be
limited to the specific embefAiments disclosed except as
defined in the appended chim.
What is claimed is:
A battery-char,46; system, comprising a source of di-
rect current connectable across the terminals of an elec-
tro-chemical battery; circuit means for connecting said
source with said battery and including a switch in series
with said battery and said source, said switch having a
first positiort wherein said source is comiected with said
battery and a second position wherein said source is dis-
connected therefrom; a relay coil for operating said
switch, and a Zener-type breakdown device conductive
4
upon attainment of a predetermined battery voltage con-
nected in series with said coil and said switch for dis-
connection of said delice from said battery upon break-
down thereof to energize said col and displace said switch
5 from said first position into said second position.
References Cied by the Examiner
UNITED STATES PATENTS
10
15
2,013,618
9/35
Woodbridge
320-40
2,499,663
3/50
Medlar
320-48 X
2,769,131
10/56
Immel
317-33 X
2,979,650
4/61
Godslialk et aL
320-35
LLOYD McCOLLUM, Primary Examiner.
MILTON 0. HIRSIIFIELD, ROBERT C. SIMS,
RALPH D. BLAKESLEE., Examiners.
?
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Declassified and Approved For Release 2014/03/18: CIA-RDP81-00120R000100020051-9