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ENCYCLOPEDIA OF RADIO ELECTRONICS AND ELECTRICAL ENGINEERING Recharging batteries. Encyclopedia of radio electronics and electrical engineering
Encyclopedia of radio electronics and electrical engineering / Power Supplies The recovery of galvanic batteries has long been of concern to electronics lovers. Various methods of "revitalizing" elements have been repeatedly published in the technical literature, but, as a rule, they helped only once, and they did not give the expected capacity. As a result of the experiments, it was possible to determine the optimal current regeneration modes and develop chargers suitable for most elements. At the same time, they acquired their original capacity, and sometimes even slightly exceeding it. It is necessary to restore the cells, not the batteries from them, since even one of the series-connected battery cells that has become unusable (discharged below the permissible level) makes it impossible to restore the battery. As for the charging process, it should be carried out with an asymmetric current with a voltage of 2,4 ... 2,45 V. At a lower voltage, regeneration is very delayed and the elements after 8 ... 10 hours do not gain even half the capacity. At a higher voltage, there are frequent cases of elements boiling up, and they become unusable. Before starting to charge the element, it is necessary to carry out its diagnostics, the meaning of which is to determine the ability of the element to withstand a certain load. To do this, a voltmeter is first connected to the element and the residual voltage is measured, which should not be lower than 1 V (an element with a lower voltage is unsuitable for regeneration). Then the element is loaded for 1 ... 2 seconds with a 10 Ohm resistor, and if the element voltage drops by no more than 0,2 V, it is suitable for regeneration. The electrical circuit of the charger, shown in fig. 1 (proposed by B. I. Bogomolov), designed to charge six cells simultaneously (G1 ... G6 types 373, 316, 332, 343 and others similar to them).
The most critical part of the circuit is the transformer T1, since the voltage in the secondary winding must be strictly within 2,4 ... 2,45 V, regardless of the number of regenerated elements connected to it as a load. If you cannot find a ready-made transformer with such an output voltage, then you can adapt an existing transformer with a power of at least 3 W by winding an additional secondary winding on it to the desired voltage with a PEL or PEV wire with a diameter of 0,8 ... 1,2 mm. The connecting wires between the transformer and the charging circuits should be as large as possible. The duration of regeneration is 4...5, and sometimes 8 hours. Periodically, one or another element must be removed from the block and checked according to the method given above for diagnosing the elements, or you can monitor the voltage on the charged elements with a voltmeter and, as soon as it reaches 1,8 ... 1,9 V, regeneration stop, otherwise the element may overcharge and fail. The same is done in case of heating of any element. The elements that work in children's toys are best restored if they are put on regeneration immediately after the discharge. Moreover, such elements, especially with zinc glasses, allow reusable regeneration. Modern elements in a metal case behave somewhat worse. In any case, the main thing for regeneration is to prevent a deep discharge of the cell and put it on charge in time, so do not rush to throw away the spent galvanic cells. The second scheme (Fig. 2) uses the same principle of recharging the elements with a pulsating asymmetric electric current. It was proposed by S. Glazov and is easier to manufacture, since it allows the use of any transformer with a winding having a voltage of 6,3 V. The HL1 incandescent lamp (6,3 V; 0,22 A) performs not only signal functions, but also limits the charging element current, and also protects the transformer in case of short circuits in the charging circuit.
Zener diode VD1 type KS119A limits the charge voltage of the element. It can be replaced by a set of series-connected diodes - two silicon and one germanium - with a permissible current of at least 100 mA. Diodes VD2 and VD3 - any silicon with the same allowable average current, for example KD102A, KD212A. The capacitance of the capacitor C1 is from 3 to 5 microfarads for an operating voltage of at least 16V. A chain of switch SA1 and control sockets X1, X2 for connecting a voltmeter. Resistor R1 - 10 Ohm and button SB1 are used to diagnose the G1 element and monitor its condition before and after regeneration. The normal state corresponds to a voltage of at least 1,4 V and its decrease when the load is connected by no more than 0,2 V. The degree of charge of the element can also be judged by the brightness of the HL1 lamp. Before the element is connected, it glows at about half the heat. When a discharged element is connected, the brightness of the glow increases noticeably, and at the end of the charging cycle, connecting and disconnecting the element causes almost no change in brightness. When recharging elements such as STs-30, STs-21 and others (for wristwatches), it is necessary to connect a 300 ... 500 Ohm resistor in series with the element. The cells of the type 336 and other batteries are charged in turn. To access each of them, you need to open the cardboard bottom of the battery. If it is required to restore the charge only for batteries of the STs series, the regeneration circuit can be simplified by eliminating the transformer (Fig. 3).
The circuit works in the same way as above. -charging current (1 charge) of the G1 element flows through the elements VD1, R1 at the moment of the positive half-wave of the mains voltage. The value of Izar depends on the value of R1. At the moment of the negative half-wave, the diode VD1 is closed and the discharge goes through the circuit VD2, R2. The ratio of Izar and Irazr is 10:1. Each type of element of the SC series has its own capacity, but it is known that the amount of charging current should be approximately a tenth of the electrical capacity of the battery. For example, for STs-21 - capacity 38 mAh (Icharge=3,8 mA, Idischarge=0,38 mA), for СЦ-59 - capacity 30 mAh (Icharge=3 mA, Idischarge=0,3 mA ). The diagram shows the values of the resistors for the regeneration of the STs-59 and STs-21 elements, and for other types they are easy to determine using the ratios: R1=220/2·lzap, R2=0,1·R1. The zener diode VD3 installed in the circuit does not take part in the operation of the charger, but acts as a protective device against electric shock - when the G1 element is disconnected at contacts X2, X-, the voltage cannot increase more than the stabilization level. The KS175 zener diode is suitable with any last letter in the designation, or it can be replaced by two zener diodes of the D814A type, connected in series towards each other ("plus" to "plus"). As diodes VD1, VD2, any with a working reverse voltage of at least 400 V is suitable. The regeneration time of the elements is 6...10 hours. Immediately after regeneration, the voltage on the element will slightly exceed the passport value, but after a few hours the nominal value will be set - 1,5 V. It is possible to restore the elements of the SC in this way three to four times, if they are put on time for recharging, preventing a full discharge (below 1V). A similar principle of operation has a circuit shown in Fig. 4. She does not need special explanations.
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