Note: Descriptions are shown in the official language in which they were submitted.
Method for Recharging a Rechargeable Battery
This invention relates to a method for recharging a
chargeable battery for a vehicle, a machine, a motor boat
or the like, whereby the output voltage from a ba-ttery
charging generator connected to the battery is used as a
charging voltage the magnitude of which can be varied by
controlling the field of the generator and whereby the
recharging is performed by means of repeated charging
cycles each of which consists of a charging period and a
test period during which the battery is loaded and the
charging from the generator to the battery is disconnected.
The magnitude of the charging voltage during a charging
period is determined with regard to the test result achieved
during the immediately preceding tes-t period. The invention
also relates to a charging regulator for recharging of a
rechargeable battery for a motor vehicle, a machine, a motor
boat or the like, said regulator being connected to a line
between the battery and a ba-ttery recharging generator of
a type in which the output voltage thereof can be varied by
varying the magnetizing current of the generator. During
repeated charging cycles each of which consists of a test
period and a charging period, -the regulator interrupts the
charging during each test period while the battery is loaded
in order to measure -the charging condition of the battery
and to control the output voltage of the generator during
the next following charging period, depending on the detected
charging condition.
In recent years battery run electrical equipment such as,
for example, refrigerators, heaters and radio equipment has
become more and more common in, for example, long distance
trucks and motor boats. ~s such equipment consumes a sub-
stantial current compared with the equipment that was
previously conventional, the new equipment produces a bigger
load on the battery, especially as the generator and its
regulator are designed to provide current only when the
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engine that drives the generator, as well as the vehicle
or boat, is running. If the engine has not been running
for a couple of hours while one or more of the above items
of eauipment has been connected, the battery is normally
more or less discharged.
In accordance with one aspect of the present invention
there is provided a method for recharging during operation
a chargeable battery connected to an electrical system of a
motor vehicle, a machine, a motor boat or the like wherein
the output voltage from a generator connected to the battery
is used as a charging voltage the amplitude of which can be
varied by controlling the field of the generator, and wherein
the recharging is performed by one or repeated charging
cycles during which the charging is performed at a raised
charging voltage which, by controlling the output voltage
of the generator, is just below the upper limit of the range
of operating voltage of the electrical system.
In accordance with a further aspect of the present invention
there is provided a voltage regulator for recharging during
operation a rechargeable battery which is connected to an
electrical system of a motor vehicle, a machine, a motor
boat or the like, said regulator being connected to a line
between the battery and a generator having an output which
can be varied by varying the magnetizing current of the
generator, wherein the regulator comprises a control device
arranged to define cyclic charging periods of equal time
during which, by controlling the magnetizing current of the
generator, there is applied to the battery an increased
voltage which is just below the upper limit voltage value
of the electrical system.
Other features and characteristics of the present invention
will be obvious from the following specification in conjun-
ction with the enclosed drawings in whicho
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Fig. 1 i5 a block diagram showing a conventional charging
regulator system;
Fig. 2 which corresponds to Fig. 1 illustrates a charging
regulator system according to the present invention;
Fig. 3 is a flow chart which shows how a charging regulator
according to the invention functions;
Figs. 4 - 6 show by a dotted and a con-tinuous line, respec-
tively, how charging current, charging voltage and charging
quantity varies with time when using a conventional charging
voltage regulator and a regulator according to the invention,
~espectively, and
Fig. 7 is a block diagram showing the principal design of a
charging regulator according to the invention.
Fig. 1 shows schema-tically in the form of a block diagram
how a battery 1, a generator 2 and a charging regulator 3
are internally electrically connected in a conventional
charqing regulator system having a negative earth to be
used, for example, in a motor vehicle. The positive pole
of the battery 1 is connected to the charging output 5 of
the generator 2 and is also connected, via an ignition key
switch 6, to one terminal of a charging light 7, the other
terminal of which is connected to the regulator voltage
output 8 of the generator 2. This other terminal of the
light 7 is also connected to the supply- and measuring
input 9 of the regulator 3. A line 10 connects the regulator
output 11 of the regulator 3 with the Eield winding input 12
of the generator 2.
When the ignition key switch 6 is closed as the engine is
started, the battery is connected to the regulator 3 and
hence to the field winding of the generator 2. Before the
charging commences, current flows from the battery 1 to the
regulator 3. This current passes through the charging
lamp 7, which is thus lit. When the generator 2 is
recharging the battery 1, the voltage of the output 8 is
equal to -the battery voltage. At this time there is no
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current flow through the charging light 7, which consequently
is not lit. The regulator 3 operates in such a manner that
by detecting the voltage at the output 8 it controls the
generator field so that the output voltage of the generator 2,
i.e. its charging voltage, has a pre-determined value. When
the input voltage oE the regulator is less than this voltage
value, the battery is completely recharged. The charging
ceases when the input voltage reaches said value.
It will be appreciated that recharging of the battery 1 with
the above--described conventional charging regulator system
is not achieved in the expected manner if the generator runs
at a low speed, if the connections between the generator 2
and the battery 1 are in poor condition, or if the charging
ability of the battery 1 is reduced. At low speed of the
generator 2 no more charging is achieved than that which is
needed for the charging light 7 to go off, and one is misled
into believing that the charging is working perfectly when in
reality perhaps only a few amperehours have been added to the
battery lalthough the engine has been working for a consider-
able time. It is very common for the conductors, theconnections between the conductors and the poles of the
battery 1 and battery master switch to be in poor condition
which causes a potential drop. Since the regulator 3
detects the voltage at the generator 2, and not at the battery,
the charging voltage may be as much as lV less than the pre-
determined charging voltage at low charging amperages. This
causes minimal or no charging of the battery 1. The conven-
tional regulator 3 also controls the output voltage of the
generator 2 so that this has a constant value which is
independent of the charging ability of the battery. This
also results in the effective charging being very poor with
an extremely discharged battery.
The object of the present invention is to provide a method
of, and a charging regulator for, recharging a rechargeable
battery in which the method and regulator do not have above
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disadvantages. This object is achieved by the invention
having the characteristics recited in the appended claims.
In Fig. ~ in which the same reference numbers as in Fig 1
are used where applicable, 13 denotes a charging regulator
according to the present invention. Apart from the output 11,
which is identical to that of the regulator 3, the regulator
13 has four inputs 14, 15, 16 and 17. The input 14 is
connected to the regulator voltage output 8 of the generator
and is arranged to receive a starting signal from the gener-
ator 2 showing that the generator is working and is generatinga charging voltage. The input 15 which is connected to the
charging output 5 of the generator and to the positive pole 4
of the battery 1 can be compared with the input 9 of the
regulator 3 which is a feed- and test signal input. The
input 16 is directly connected to the positive pole 4 of the
battery 1 and is therefore the test signal input for the
battery voltage, and the input 17 which is connected to the
positive pole 4 of the battery 1 via the ignition key switch 6
and the charging light 7 can also be considered as a starting
signal input the function of which can likewise be compared
to that of the input 9 of the regulator 3.
The regulator 13 according to the invention differs from
the conventional regulator 3 in the following respects: By
way of the charging liaht 7 or any other acoustic or optic
alarm means, a warning is provided when -the generator 2 does
not reach its working voltage as a result of operating at
too low a speed. It also provides a warning if the potential
drop between the generator 2 and the battery 1 is unaccept-
ably high. The charging voltage and therefore also the
charging current to the battery 1 is regulated with respect
to the condition of the battery~ The charging is carried out
by means of repeated charging cycles each of which consists
of a charging period, and a test period with the battery
loaded. The charging voltage is determined on the basis of
the test result. An extremely discharged battery cannot
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assimilate maximum charging for an unlimited time, which
is why there is also a time limit in order to protect the
battery against this type of overcharging.
It will now be explained in more detail how charging
according to the invention takes place with reference to
the flow chart in Fig. 3. A refers to the starting condition.
The regulator commences to be fed with current, via the
input 15 and the charging programme is set at ~ero. Stage
represents a charging period during which a charging voltage
which provides a compensating charge to the battery is
applied to the battery for a certain period of time (5 minutes).
If a 12V battery is used (which will be assumed to be the case
in the following description) typical value for a compensating
charge voltage is 14V and the period of time is 5 minutes. To
achieve this, the batterv voltage is compared to a reference
voltage and the regulator controls the field current of the
generator so that said voltages are equalised. To check the
condition of the lead between the generator and the battery,
the battery voltage is compared to another reference voltage
(9V), which is considerably smaller than the first said
reference voltage. If the battery voltage happens to be
lower than the second reference voltage the voltage detection
of the regulator 13 is changed from the battery pole 4 to the
charging output 5 of the generator 2. After the above
mentioned time (5 minutes) has lapsed the regulator programme
switches over to C.
Stage C is a measuring phase. The battery voltage is
measured for a certain period of time (1 minute) but is cut
off if the battery voltage drops below a certain voltage
(13.2V) before the time is ended. While measuring, all
alarms are blocked, and the charging of the battery is cut
off by cutting the field current of the generator 2. It is
presumed that the battery is loaded while measuring. This
is automatically the case with cars where the head lights or
other equipment of the type hereinbefore referred to is
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switched on. The measuring of the ba-ttery voltage takes
place by comparing it to the said reference voltage. If
the battery voltage is equal to or less than the reference
voltage, the programme continues to D. If the battery
voltage is higher than the reference voltage the programme
continues to F.
At D the battery is charged with a charging voltage (14.6V)
for a certain period of time (8 minutes) which is equal to
quick charging of the battery. The said tim~, however, is
counted from the moment the voltage exceeds a certain value
(14.4V), whereby a charging time which takes into considera-
tion the capacity of the battery is achieved. In other words
D comprises the charging phase which also applies to E.
During stage E charging takes place with a voltage (14V)
related to the compensating charge for a time (2 minutes)
which is shorter than the time of stage D. Thereafter the
charging programme switches to C.
If the battery voltage is higher than the first reference
voltage the charging programme of the regulator switches to F.
Stage F is a compensating charging phase which takes place
for a comparatively long time (1-3 hrs). After this the
programme switches to B.
It can be observed that the sequence consisting of C, D and E
provides quick charging of the battery, while the sequence
including C, F and s provides a compensating charging of the
battery.
Stage G represents the different test measurements or com-
parisons which are carried out according to the invention
and which have previously been partly explained. In this
stage the battery voltage and the generator voltage are
continuously compared to the reference voltages to determine
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overvoltage, undervoltage or unacceptable potential drops
in the lead between the generator and the battery.
In Flg. 4 the programme stages A, B, C, D and E are again
shown. In relation to charging current as well as charging
voltage and amount of charging, the graphs (continuous)
showing charging according to the invention are all above
those (dotted) which represent a conventional system of
charging.
Although it is obvious that a man skilled in the art, having
knowledge of how a charging regulator according to the
invention functions, can make this invention in a number of
ways, one example of the invention will be explained in the
following, referring to the block diagram shown in Fig. 7.
While for simplicity the invention is described with
reference to Fig. 7 in a rather general manner, in practice
the whole regulator is preferably constructed on one so-called
IC circuit with which further test and control functions
outside the scope of the present invention can be achieved,
if so desired.
In Fig. 7 the battery 1, the generator 2 and, within a dotted
outline, the regulator 3 are again ~hQwn Numeral 18
denotes a control unit the inputs of which are connected to
a comparator 19, a clock 20 consisting of an oscillator,
and a binary counter, arranged to generate control pulses
to control all time lapses in the control unit 18, and a
counter 21~ The outputs of the control unit 18 are connected
to a reference voltage source 22 arranged to generate the
previously described said reference voltages to the generator
2, to the clock 20, to the co~mter 21 and to the load 23.
The inputs of the comparator are connected to the reference
voltage source 22, the generator 2 and the battery 1. Apart
from said connection to one of the inputs of the control unit
the output of the comparator 19 is connected to an alarm
device 24 arranged to provide an optic and/or acoustic alarm.
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A temperature detector 25 thermally connect:ed to the battery
l is arranged to generate a signal related to the temperature
of the battery and to control the reference voltage source 22
with this signal, so that all reference voltages and thereby
also the battery charging voltage are increased with a
decreasing battery temperature. The opposite takes place
with an increasing battery temperature.
The comparator 19 includes a number of comparing circuits
arranged to compare the reference voltages from the reference
voltage source 22 with the generator- and battery voltages
as described previously. As a result of these comparisons
control signals are generated to the control unit 18 and
alarm signals are generated to the alarm device 24. This
is arranged to provide warnings with different characteris-
tics for different errors so that these can be easilyidentified.
The control unit 18 is arranged to control the generator
voltage, in the manner that is characteristic of the invention,
governed by inputs from the comparator l9, the clock 20 and
the counter 21. If the battery 1 is not sufficiently loaded
during the measuring phase, which is often the case with
diesel engine driven motor boats, the load 23 is automatically
switched on. The number of charging cycles when charging
takes place at a voltage related to quick charging is counted
by the counter 21, which is arranged to provide a switch off
signal to the control unit when a pre-decided number of ~uick
charging cycles (e.g. 8) has taken place.
