GB2065998A - Apparatus for recharging batteries by means of pulsating current - Google Patents

Abstract

An apparatus for recharging dry batteries or accumulator batteries by means of pulses of alternating current or any other type of intermittent pulses and for a slight discharging of the batteries or accumulators during the periods appearing between the recharging pulses and comprising a mains connection circuit (A) and a recharging circuit (B) connected thereto having terminals for one or more batteries to be charged and a rectifying means (8) supplying a direct current to a controllable guide means (19). The apparatus comprises a control unit (C) which is connected to the guide means (9) and which defines the moment (75) of the alternating current pulse or the other intermittent pulse when the recharging circuit (B) is activated and a recharging voltage is supplied to the battery (13). The guiding means (9) may be a tyristor which is made conducting by the control circuit (C) at a predetermined moment (75). The control circuit (C) comprises means for optional continuous or stepwise controlling of the trigging moment (75) for the recharging pulse during the extent of the recharging and thereby for controlling the length of the recharging periods and the intermediate discharging periods. The apparatus comprises means for changing the level and the duration of the recharging voltage during the recharging operation especially after a given recharging period by increasing the recharging voltage and concurrently therewith move the trigging point (75) for the recharging pulse so that the duration of the recharging period is reduced and the duration of the discharging period is increased.

Description

SPECIFICATION Apparatus for recharging of batteries by means of pulsating current The present invention generally relates to an apparatus for recharging of dry batteries and accumulators, and more particularly the invention relates to an apparatus for recharging the dry batteries or accumulators by means of intermittent pulses preferably alternating current pulses, whereas the batteries or accumulators are allowed to slightly discharge during the periods intermediate the recharging pulses.

An apparatus for recharging of dry batteries or accumulators by means of pulsating alternating current is previously known from the Swedish patent 7805501-9. For the purpose of adapting the average recharging current over the dry batteries or accumulators the said previously known apparatus comprises a Zener-diode which is connected parallelly over the batteries or accumulators and a PTC (Positive Temperature Coefficient) resistance connected in series current which is as constant as possible, and whereby recharging pulses are intermittently supplied to the batteries over a diode, whereas a counter directed discharging current appears during the periods between the recharging current pulses.

The PTC-resistance functions so that it is blocked at a low counter-electromotive force (EMF) from the batteries thereby forcing all current to pass through the batteries. At a high counter-EMF the PTC resistance successively opens to allow an increasing portion of the current to pass, so that thereby a successively reduced portion of the current passes through the batteries or accumulators.

The said previously known apparatus gives a very good result and is well suited for recharging of dry batteries and some smali types ot accumulators. On the contrary the known apparatus cannot be utilized for recharging of large batteries which need high recharging currents since the PTC-resistances at present available on the market can only stand such small current intensities as up to 1 amperes at the maximum.

Other previously known battery recharging apparatus have in turn a restricted possibility of recharging batteries to over 70% of the battery capacity and for making such recharging possible current intensities must be utilized which are substantially higher than the maximum current intensities than the said PTC-resistances can stand.

Many battery recharging apparatus also have a relatively low efficiency and are designed so that heat is developed in the battery cells what may damage the cell and causes a development of harmful vapors or detonating gas.

The object of the invention therefore is to solve the problem of providing an apparatus for recharging of dry batteries and especially accumulator batteries by means of intermittent pulses preferably alternating current pulses, in which the batteries are recharged by means of the said intermittent alternating current pulses whereas they are allowed to slightly discharge during the periods appearing inbetween the recharging pulses and in which high current intensities can be utilized without damaging the accumulator batteries or the components included in the recharging apparatus.

Another object of the invention is to solve the problem of providing a recharging apparatus having a high efficiency and operating substantially completely without the development of heat in the battery cells and in which the risk of the appearance of harmful vapors and detonating gas is eliminated or at least strongly reduced. The invention also intends to provide a battery recharging apparatus which is designed completely safe in that the output recharging terminals are current less before the battery to be charged is connected and which becomes current less as soon as the battery is fully recharged. A further object of the invention is to solve the problem of providing an alternating current apparatus in which the recharging current intensity can be controlled within wide ranges, for instance from 2 amperes and practically without any upper limit.

According to the invention the apparatus comprises a controllable current directing means and a controllable trigger circuit which is controlled by the current directing means so as to ignite and letting one of the alternating current pulses through for recharging of one or more batteries or accumulators. The trigger circuit comprises a rectifying means giving a substantially constant operating voltage to a time controlling means which controls the time of igniting the current directing means. The apparatus also comprises means for allowing some discharging during the periods appearing between the recharging pulses.

By utilizing a current directing means which is controlled by the trigger circuit it has been possible to foresee that only the intended periods of the alternating current is let through the recharging of the battery, and by utilizing a time controlling means which control the time when the current directing means is ignited it is possible to control the ignition moment between 0 and 1800 of the period thereby varying the recharging current intensity from maximum recharging current intensity down to practically no recharging current intensity at all.

Further characteristics of the invention will be evident from the following detailed specification in which reference will be made to the accompanying drawings.

In the drawings figure 1 shows a block diagram of an apparatus according to the invention and figure 2 shows a circuit diagram of an apparatus according to figure 1. Figure 1 diagrammatically shows the recharging function of the apparatus according to figure 2 and figure 4 diagrammatically shows a corresponding recharging function of a modified embodiment of the recharging apparatus. Figure 5 shows a modified circuit diagram of a recharging apparatus according to the invention and figure 6 shows more in detail a circuit diagram of a controlling means included in the apparatus according to figure 5. Figure 7 diagrammatically illustrates an alternative method of recharging batteries or accumulators by means of the apparatus according to figures 5 and 6.The apparatus diagrammatically illustrated in figure 1 comprises a mains connection circuit A to which is connected a recharging circuit B having terminals for the battery to be charged. The recharging circuit B is controlled by a controlling circuit C and it is adapted to be connected for recharging by the assistance of a switching to circuit D. For maintaining a stable and an exactly predetermined voltage the recharging circuit is connected to a voltage stabilizing circuit E and for disconnecting a fully recharged battery the recharging circuit is connected to a disconnection circuit F.

As conventional the mains connection circuit comprises a fuse 1, a main switch 2 and a transformer 3 for stepping down the alternating current voltage of the mains to a suitable recharging voltage. Parallelly over the transformer 3 are connected a capacitor and a transient protector in the form of a varistor 5. From one terminal 6 of the mains connection circuit a main conduit 7 leads to the recharging circuit which in series comprises a diode 8, a controllable current directing means in the form of a tyristor 9, a fuse 10 and a controllable resistance 11. From the resistance 11 one pole terminal 2 of the battery or accumulator 1 3 to be charged is connected. The second pole terminal 14 for the battery or accumulator is connected to a return conduit 1 5 leeding to a second terminal 1 6 of the mains connection circuit.Both the diode 8 and the tyristor 9 are connected with the anode directed to the terminal 6 of the mains connection conduit and with the cathode directed to the input pole terminal 12 of the battery. In the return conduit 1 5 from the output terminal 14 of the battery an amperemeter 17 is connected. From a point of the main conduit 7 between the fuse 10 and the controllable resistance 11 to a point succeeding the amperemeter 1 7 in the return conduit 1 5 a cooling fan 1 8 is connected. Parallelly over the tyristor 9 is connected a diode 1 9 in series with a resistance 20. The said circuit is intended to transmit a slight current past the tyristor 9 so that the cooling fan 18 is supplied with current even when the tyristor 9 is inactive.Between the controllable resistance 11 and the input battery pole terminal 12 a switch 25 for the switching in circuit is connected as will be explained closer in the following.

The controlling circuit C is connected to the recharging circuit D over a rectifier bridge 22 which is connected parallelly over the tyristor 9. At the positive terminal of the rectifier bridge a conduit 23 comprising a matching resistance 24 is connected. The conduit 23 branches into a first conduit branch 25 conprising a resistance 26 and the conduit branch 25 in turn branches into two conduit branches 27, 28, one of which is connected to the anode and the other to the gate of a PUT-transistor 29 (Programmable Unijectiontion Transistor). The conduit 27 to the PUT-transistor 29 comprises in series a resistance 30 and a controllable main resistance 31 by means of which the recharging current can be controlled.The purpose of the resistance 30 is to prevent a current surge or a short-circuiting of the PUT-transistor 29 when the majn resistance 31 is turned to fls zero-position. The second conduit branch 28 comprises a controllable balancing resistance 32 which is adjusted matching the PUT-transitor 29 so thah the said transistor gives a suitable recharging current intensity. Parallelly over the gate and the cathode of the PUTtransistor a second balancing resistance 33 is connected in series with a trimming resistance 34.

From a point between the balancing resistance 33 and the trimming'resistance 34 a conduit 35 leads to the negative terminal of the rectifier bridge 22.

Parailelly over the rimming resitance 34 and the anode of the PUT-transistor 29 a trigger capacitor 36 is connected which defines the point when the PUT-transistor ignites the tyristor 9, whereby the trigger capacitor 36 defines the length, width and height of the recharging pulse. From a point on the conduit 23 between the resistances 24 and 26 to a point on the conduit 35 subsequent to the trigger capacitor 36 a Zener diode 37 is connected. The controllable resistance 34 connected ta the cathode of the PUT-transistor 29 is with the output 38 thereof connected to the gate 39 of the tyristor 9 over a diode 40 having the anode thereof connected to the output of the trimmer resistance 34 and the cathode connected to the gate 39 of the tyristor. Between the diode 40 and the gate 39 a switch 41 of the disconnection circuit F is connected as will be explained closer in the following.

The switching in circuit D is connected directly over the terminals 12 and 14 of the battery and it comprises a conduit 42 including two current directing diodes 43 and 44 having the anodes turned to the pole terminal 1 2 of the battery and the cathode of the latter diode 44 connected to a switch in relay 45. The opposite terminal of the relay 45 is over a diode 46 and resistance 47 connected to the second pole terminal 14 of the battery. The relay 45 is formed with a switch 21 which is connected between the resistance 11 and the terminal 12 of the main conduit 7. In nonactivated state of the relay 45 the switch 21 is disconnected and the recharging current to the battery thereby is disconnected.

Parallelly over the relay 45 the voltage stabilizing circuit E is connected. The said circuit comprises a rectifier bridge 48 which with the alternating current terminals is connected to the transformer output over a first conduit 49 comprising a switch 50 and a resistance 51 and a second conduit 52 comprising a resistance 53.

The negative terminal 54 of the rectifier bridge 48 is connected to the output of the relay 45 over a conduit 55. A capacitor 56 is connected parallelly over the negative terminal 54 and the positive terminal 54 and the positive terminal 57 of the rectifier bridge 48. From a point between the capacitor 56 and the positive terminal 57 a conduit 58 is connected which includes a resistance 59 and a voltage stabilizer 6 which gives a stable smoothed direct voltage. The conduit 58 is connected parallelly over the negative and positive terminals 54, 57 of the rectifier bridge 48. From the voltage stabilizer 60 a conduit 68 leads back to the positive terminal of the relay 45 over a fuse 62 and diode 63. From a point between the voltage stabilizer 60 and fuse 62 a capacitor 64 is connected to the conduit 55.

Between the conduits 42 and 1 5 a transient protection in the form of a diode 65 is connected.

The disconnection circuit F is connected parallelly over the switching in circuit D between the conduits 42 and 1 5. In the conduit 42 a variable resistance 66 is connected, and from said resistance to the conduit 1 5 a double relay 67 is connected. The relay comprises a first switch 41 which normally is closed and which is connected between the relay 40 and the gate 39 of the tyristor and a second switch 68 which is connected in a conduit 69 across the main conduit 7 and the return conduit 15 and which includes a signal bulb 70. At the positive terminal of the relay 67 a conduit 71 is connected which includes a normally closed switch 72 and a diode 73 which with the anode is connected between the fuse 6Z and the diode 63 in the conduit 61 from the voltage stabilizer 60.

The above described apparatus operates as follows: For connecting the apparatus the switch 2 is closed whereby a current from the secondary side of the transformer 3 leads both through the conduit 69 with the signal bulb 70 and over a bridging conduit 79 having a resitance 80 which bridges the switch 68 of the relay 67 and also past the tyristor 9 through the bridging conduit including the diode 19 and the resistance 20 and further through the cooling fan 1 8. Consequently the signal bulb 70 and the cooling fan 18 are always actuated when the main switch 22 is connected. A current also leads from the cathode of the diode 8 to the rectifier bridge 22 and from there to the Zener-diode 37 and the time controlling circuit with the PUT-transistor 29. The Zener-diode 37 gives a constant operation voltage to the said circuit.The main resistance 31 in connection with the trigger capacitor 31 determines the time when the PUT-transistor 29 ignites the tyristor 9 over the gate 39 thereof.

Since the switch 41 is normally closed recharging pulses can move as far as to the said gate 39 as long as the switch 41 is disconnected what is made by means of the disconnection relay 67.

Since, however, the switch 21 is normally disconnected no charging of the battery 13 can be made until the relay 45 is activated. If the battery 1 3 is not completely discharged the remaining current of the battery is sufficient for activating the switching in relay 45 in that a current passes in a circuit from the terminal 12 of the battery through the diodes 43 and 44, the relay 45, the diode 46, the resistance 47 and back to the second terminal 14 of the battery. When the relay 45 is thus connected the switch 21 closes the recharging pulses can pass from one terminal 6 of the transformer through the main conduit 7, the diode 8, the tyristor 9, the fuse 10, the resistance 11 and through the battery 13 and back through the return conduit 1 5 to the second terminal 1 6 of the transformer.Recharging current pulses go to the battery during the moments when the tyristor 9 is ignited what is made by the controlling circuit over the gate 39. During those periods which appear between the recharging current pulses the battery is allowed to discharge slightly in that a current goes from one terminal 12 of the battery through the resistance 11 and through the conduit with the cooling fan 1 8 back to the second terminal 14 of the battery. Such recharging periods are of essential importance for the recharging of the battery.

If the battery should be very strongly discharged so that the remaining current thereof is not sufficient to activate the switching in relay 45 the recharging can be started in that the switch 50 of the conduit 49 is closed whereby a primary current goes through the resistance 51, the conduit 49, the rectifier bridge 48 and back through the resistance 53 of the conduit 52. A rectified secondary current thereby passes from the negative terminal of the switching in relay 45 through the conduit 55, over the terminals 54 and 57 of the rectifier bridge, through the resistance 59, the voltage stabilizer 60, the capacitor 64, the fuse 62 and the diode 63 back to the positive terminal of the relay 45, whereby the relay 45 is activated and the switch 21 is closed.When the battery 13 is fully recharged and the counter EMF thereof has reached a certain level a current through the conduit 42, the diode 43 and the resistance 66 will pass through the disconnection relay 67 and back to the return conduit 1 5 over the resistance 47. The disconnection relay is thereby activated and the switch 41 in the conduit from the time controlling means is opened whereas the contact 68 in the conduit having the signal bulb 70 is closed. Thereby the pulses to the gate 39 of the tyristor 9 are cut off and a recharging current can no longer pass through the battery 13, and the signal bulb 70 will light with a higher effect.

If the battery 1 3 is strongly discharged it may happen that also the disconnection relay 67 is activated to the effect that the switch 41 is opened. To avoid this the switch 72 is opened so that the current over the relay 67 from the voltage stabilizer circuit is cut off.

Figure 3 diagrammatically illustrates the recharging of the battery 1 3. It is presupposed that the recharging is made with the positive pulses 74a of a periodically alternating current and that some discharging is allowed during the negative pulses 74b of the same periodically alternating current. By controlling the main resistance 31 the point 75 at which the tyristor 9 is trigged can be moved to any chosen position between 0 and 1800 of the positive pulse and the recharging does not start until the tyristor 9 is ignited when being trigged. The portion 76 of the pulse 64a preceding the trigging point 75 allows a discharging and only the portion 77 of the pulse succeeding the trigging point 75 gives a recharging of the battery.Since the discharging in this case is made by the cooling fan 1 8 which has a relatively high resistance the discharging 78 is made only with a slight amount, for instance 12% of the recharging current. By moving the trigging point 75 by controlling the main resistance 31 the recharging can be made with any intended current intensity from maximum recharging with the trigging point located 0 to no recharging at all at 1 800.

By utilizing a transformer having a central terminal and using two diodes of substantially the same coupling type as in Figure 2 and by utilizing a so called triak coupling it is possible to reverse the negative pulse portion 74b as illustrated in Figure 4 to a positive recharging pulse 74a'. Still a discharging is allowed during the pulse portions 76, 76' preceding the trigging points 75, 75'.

Figure 5 diagrammatically shows an alternative apparatus according to the invention for recharging dry batteries or accumulator batteries.

The apparatus comprises a transformer 3' which on the secondary side is designed with double output terminals or enabling a switching over of the recharging voltage from one level to another as will be further explained in the following. From the secondary side of the transformer 3' two diodes 8a and 8b are connected which each let through one halfperiod of the periodical alternating current so that a continuous train of positive pulses are obtained. The diodes 8a and8b give a current to the tyristor 9 whereby the current in a main conduit is supplied to one battery terminal 12 over a resistance 82. From the other battery terminal 14 the current is returned through conduit 83 to the central point at the secondary side of the transformer.From the main conduit 81 current is directed to the controlling circuit C which will be explained more in detail in the following.

The apparatus comprises a circuit 84 applying a load which provides a reversing of the current during the periods when there is no recharging so that the apparatus gives a discharging during the said reversed current periods. From point 85 a control voltage is supplied to the said load circuit 84 over a resistance 86 to the base of a transistor 87 which connects a resistance 90 connected to the pole terminal 12 of the battery. In order to assure that the transistor 87 closes when the guide voltage at point 85 ceases a resistance 91 is connected between the base of the transistor 87 and the return conduit 83.

For giving a smoothed direct current a capacitor 92 is connected between the main conduit 81 over a diode 93 to the return conduit 83. This circuit gives a drive current to a relay 94a having two switches 94b enabling a switching over of the secondary side of the transformer 3' between two different voltages. It is obvious to the expert that the relay including the switches by conventional couplings alternatively can be designed for successively varying the voltage on the secondary side of the transformer.

In Figure 5 the different terminals of the controlling circuit C of the recharging apparatus are designated a-g which points have been marked in Figure 6 which shows the controlling circuit more in detail.

From point 95 between the diodes 8a, 8b and the tyristor 9 the drive voltage is delivered to the controlling circuit C over a fuse 96. The drive voltage is supplied to the main conduit 97 of the controlling circuit over a diode 98 and a resistance 99 and is further supplied to a stabilizing circuit 100 providing the voltage stabilizing circuit marked with E in Figure 1. A voltage capacitor 101 connected between the return conduit 83 and the input of the stabilizing circuit 100 smooths the rough rectified voltage. From a point 102 at the input of the diode 98 voltage is over a resistance 103 supplied to the base of a transistor 104 the emitter 105 of which is connected to the return conduit 83.

When the voltage is higher than 0 V current is supplied from point 106 of the main conduit 97 through a resistance 107 to the collector 108 of the transistor 104 and by the transistor to the return conduit 103. When the voltage at the point 102 of the main conduit is merely zero the transistor 104 is not conducting, and current is thereby supplied from point 106 of the main conduit 97 over the resistance 107 to the base of a transistor 109 which with the emitter is connected to the return conduit 83. The collector of the transistor 109 is connected to a synchronizing circuit 110 which is an IC-circuit, for instance a circuit of the type "Signetics NE 555". A resistance 111 forsees that no signal enters the IC;-circuit 110 when the transistor 109 is non-conducting.The IC-circuit 110 starts a delay time cycle which defines the time of the pulse when the recharging starts. The length of the delay time is controlled by means of a capacitor 112 from the input current at point 11 3. The capacitor 112 is connected to the IC-circuit 110 at terminal VI thereof. When the capacitor 112 is charged to the reference voltage of the IC-circuit the said circuit emits a signal at terminal VII, which signal over the resistance 114 makes a transistor 11 5 conducting. A resistance 11 6 forsees that the transistor is not made conducting when there is no signal from the IC-circuit 110. The transistor 11 5 amplifies the signal from the IC-circuit 110 and makes in turn transistor 11 7 conducting. The resistance 11 9 foresees that the transistor 11 7 is kept currentless in its non-conducting state. A voltage is supplied to the collector of the transistor 117 by charging a capacitor 121 over a resistance 11 8.

When the transistor 11 7 is made conducting the voltage of capacitor 121 goes through the transistor 117 into a transformer 122. On the secondary side the transformer thereby supplies a trigging pulse over the terminals d and e of the controlling circuit to the tyristor 9 which is thereby ignited and supplies the recharging current to the battery 13. In the inactive state of the transistor 11 7 a resistance 120 connected parallely over the primary side of the transformer 122 foresees that no voltage variations or sounds appear in the transformer depending on the transformer inductance. A variable resistance 123 connected between the main conduit 97 and the transistor 11 5 supplies a predetermined base charging current to capacitor 112.The transistor 11 5 gets its main current for making transistor 11 7 conducting from the capacitor 11 2 when charged.

The controlling circuit comprises an amplifier unit which is shown in the lower half of Figure 6.

To said amplifier unit the battery voltage enters from the outer terminal c of the control circuit.

Over a resistance 124 the voltage is supplied to the minus terminal of an operation amplifier 125 in the form of an IC-circuit. The said input signal is inverted by the operation amplifier 125 and is amplified by a value which is determined by a resistance 1 26. The plus terminal of the operation amplifier 125 is supplied with a fixed voltage the value of which is determined by the resistance dividing circuit 12 7,1 28. The output voltage from the operation amplifier 125 goes through a fixed resistance 1 29 and a variable resistance 130 and provides a charging of the capacitor 112 from point 113. The charging of the capacitor 112 follows at different speed depending on the input voltage at the operation amplifier 125.A high battery voltage and thereby a high input voltage of the operation amplifier 125 gives a slow charging or capacitor 112 and a low recharging current for the battery.

The variable resistance 130 is formed as a voltage dividing circuit together with a fixed resistance 132 and supplies a voltage to a second operation amplifier 133. The said input voltage is compared with a reference voltage provided by a resistance dividing circuit 1 39, 140 which is connected to the negative terminal of the second operation amplifier 133. When the voltage over the variable resistance 131 connected parallely over the fixed resistance 129 is less than the voltage between the resistances in the resistance divider 139, 140 the operation amplifier 130 is activated and a current is supplied through a resistance 134 to a transistor 135 which amplifies and transmits the current over the input terminal f of the controlling circuit C to the relay 94a which in turn switches over the switches 94b of the transformer to a higher voltage.At the same time the transistor 1 35 supplies a current over the diode 136 and the variable resistance 1 37 to a point 138 between the fixed resistance 129 and the variable resistance 130. Thereby the resulting charge current for the capacitor 112 becomes iower what means that the charging time for the capacitor 112 is made longer and that the recharging pulses to the battery are made shorter.

By the above described switching over the mains transformer 3' between two different voltage levels the effect is obtained that the recharging of the battery follows with different characteristics. This is diagrammatically illustrated in Figure 7 in which five recharging pulses are illustrated. In the two first pulses the recharging is made by a character which is similar to direct current recharging in that the trigging point 75 at which the recharging is started is located relatively close to 0 and thereby relatively long recharging periods 77 and corresponding short discharging periods 76 are obtained. Following the recharging of the accumulator battery the counter-EMF of the accumulator increases and at the same time also the tendency of the accumulator to develop hydrogene gas is increased.As previously mentioned this involves serious disadvantages and restricts the recharging capacaity of the accumulator. For eliminating such disadvantages the charging is switched over, as mentioned above, to a more accentuated alternating current recharging in that the voltage of the transformer is increased. The voltage curve consequently becomes higher, and at the same time the trigging point 75' when the recharging is started is moved by the influence of the current going through the diode 136 and the variable resistance 137 which actuates the charging of the capacitor 112. By moving the trigging point 75' a substantial distance and preferably to point adjacent the 180" point short recharging periods 770 and corresponding long discharging periods 76' are obtained.For time reasons no hydrogene gas can be developed at such recharging and the accumulator is charged practically completely without hydrogene gas development and to a substantially higher charge level than is possible by means of conventional direct current charging apparatus.

For making an external controlling possible of the control circuit the output terminal g of the control circuit is connected to a point 113 at the capacitor 112 and the corresponding second control conduit is connected to the return conduit 83.

It is to be understood that the above specification and the embodiments of the invention illustrated in the drawings are only illuminating examples within the scope of the inventional idea and that different kinds of modifications may be presented within the scope of the appended claims.

A mains connection circuit B recharging circuit C controlling circuit D switching in circuit E voltage stabilizing circuit F disconnection circuit 1 fuse 2 main switch 3 transformer 4 capacitor 5 varistor 6 terminal (of A) 7 main conduit 8 diode 9 tyristor 10 fuse 11 resistor 12 pole terminal 13 battery (accumulator) 14 pole terminal 1 5 return conduit 16 terminal (of A) 17 ampere meter 18 cooling fan 19 diode 20 resistance 21 switch 22 rectifier bridge 23 conduit 24 matching resistance 25 conduit branch 26 resistance 27 conduit branch 28 conduit branch 29 PUT transistor 30 resistance 31 main resistance 32 balancing resistance 33 balancing resistance 34 trimming resistance 35 conduit 36 trigger capacitor 37 Zener diode 38 output (of 34) 39 gate (of 9) 40 diode 41 switch 42 conduit 43 diode 44 diode 45 switching in relay 46 diode 47 resistance 48 rectifier bridge 49 conduit 50 switch 51 resistance 52 conduit 53 resistance 54 terminal (neg. of 48) 55 conduit 56 capacitor 57 terminal (pos. of 48) 58 conduit 59 resistance 60 voltage stabilizor 61 conduit 62 fuse 63 diode 64 capacitor 65 diode 66 resistance 67 double relay 68 switch 69 conduit 70 signal bulb 71 conduit S vv l tD l l 73 diode 74 pulse (a and b) 75 point (trigging -) 76 portion (of 74a) 77 portion (of 74a) 78 discharging portion 79 bridging conduit 80 resistance 81 main conduit 82 resistance 83 return conduit 84 load circuit 85 point 86 resistance 87 transistor 88 resistance 89 90 resistance 91 resistance 92 capacitor 93 diode 94 relay (a and b) 95 point 96 fuse 97 main conduit 98 diode 99 resistance 100 stabilizing circuit 101 voltage capacitor 102 point 103 resistance 104 transistor 105 emitter 106 point 107 resistance 108 collector 109 transistor 110 synchronizing circuit 111 resistance 112 capacitor 113 point 114 resistance 11 5 transistor 11 6 resistance 117 transistor 118 resistance 119 resistance 120 resistance 121 capacitor 1 22 transformer 123 resistance 124 resistance 125 operation amplifier 126 resistance 127 resistance divider 128 129 resistance 1 30 resistance (variable) 131 resistance (variable) 132 resistance 133 operation amplifier 134 resistance 135 transistor 136 diode 137 resistance (variable) 138 point 1 39 resistance divider 140 resistance divider

Claims (11)

1. Apparatus for recharging of dry batteries or accumulator batteries by means of pulsating current, preferably alternating current, comprising a mains connection circuit (A) and a recharging circuit connected to the mains circuit (A) and having terminals for one or more batteries (13) to be recharged, characterized in that the recharging circuit (B) comprises a rectifying means (8; 8a, 8b) which gives a direct current to a controllable current directing means (9) which amplifies and supplies a recharging current to the batteries during a predetermined portion of the alternating current pulse and which is controlled to become conducted at a predetermined moment by a control circuit (C), and in that the apparatus comprises means (18; 84) allowing a slight discharging during the periods (76, 78) appearing between the recharging pulse periods (77).

2. Apparatus according to claim 1, characterized in that the current directing means is a tyristor (9) which with the anode is connected to the mains circuit (A) and with the cathode to one pole terminal (12) of the battery or accumulator (13) to be recharged, and which with the gate (39) is connected to the control circuit (C) which defines the time of the pulse (74) when the tyristor is made conductive.

3. Apparatus according to claim 1 or 2.

characterized in that the control circuit (C) comprises means (30--34; 130-137) for successively or stepwise moving the trigging point (75) of the alternating current periode when the apparatus starts supplying a recharging current period when the apparatus starts supplying a recharging current to the battery (13).

4. Apparatus according to claim 1,2 or 3, characterized in that the time controlling means is a PUT-transistor (29), a trig condensator (36) connected over the anode and the cathode of the PUT-transistor (29), a trimming circuit (33, 34) connected over the gate and the cathode of the PUT-transistor (29) and a second trimming circuit (30--34) connected over the gate and the anode of the transistor (29) which trimming circuit (30--32) enables a controlling of the point (75) at which the PUT-transistor (29) ignites the tyristor (9).

5. Apparatus according to claim 4, characterized in that the second trimming circuit comprises a variable main resistance (31) which is the main control means by which the ignition point of the tyristor (9) can be controlled and which defines the length of the recharging period and thereby the intensity of the recharging current.

6. Apparatus according to any of claims 3, 4 or 5, characterized in that the control circuit (9) comprises a diode (40) for preventing the appearance of a reverse current at the gate (39) of the tyristor (9).

7. Apparatus according to any of the preceding claims, characterized in that it comprises a switching in relay (45) and a switch between the tyristor (9) and one pole terminal (12) of the battery (13) to be charged which switch (21) is open at non-actuated relay (45), and in that the switching in relay (45) for starting the recharging is adapted to be actuated either by a rest charge of the battery (13) or by a secondary circuit (F) from the mains circuit (A), and in that the apparatus comprises a disconnection relay (67) and a switch (41) connected in the conduit between the control circuit (C) and the tyristor (9) which switch (41) is closed in the non-actuated state of the disconnection relay (67), and in that the disconnection relay (67) is adapted to be actuated at fully recharged battery, whereby the said switch (41) opens and brakes the control pulses to the tyristor (9), whereby the recharging of the battery ceases.

8. Apparatus according to claim 1 or 2, characterized in that the mains connection circuit (A) comprises a transformer (3) the secondary side of which has two ouputs of different voltage level and in that the control circuit (C) comprises means (136, 137, 94a, 94b) for sensing the counter EMF of the battery and which when the battery has reached a predetermined counter EMF provides a continuous or stepwise increase of the voltage of the recharging current and concurrently therewith a delay of the ignition moment (75') of the tyristor so that the recharging is made by an increased voltage and a reduced recharging pulse period.

9. Apparatus according to claim 8, characterized in that the components of the apparatus are designed for starting the recharging with relatively long recharging pulse periods and intermediate short discharging periods, and in that the means four increasing the recharging voltage and reducing the recharging pulse period comprises a relay (94a) which is adapted to be actuated from the control circuit (C) when the counter EMF of the battery increases a predetermined value and which thereby actuates a switch on the secondary side of the transformer (3) which connects a higher secondary voltage.

10. Apparatus according to claims 8 and 9, characterized in that the means for reducing the length of the recharging pulse period is a circuit (133) intended to compare the counter EMF of the battery with the nominal recharging voltage and when a specific counter EMF is reached to reduce the charge voltage over a capacitor (112) the charge period of which defines the length of the discharging periods of the current pulses for the battery, whereby the said discharging periods (66') are made longer and the recharging pulse periods (77) are made correspondingly shorter.

11. Recharging apparatus substantially as herein described and shown in the accompanying drawings.