29.06.2020
Homemade charger for aa batteries. Do-it-yourself charger for a crown
Today, there are a lot of different devices that run on batteries. And all the more annoying when, at the most inopportune moment, our device stops working, because the batteries are simply dead, and their charge is not enough for the normal functioning of the device.
Buying new batteries every time is quite expensive, but trying to make it yourself homemade device for charging finger batteries is quite worth it.Many craftsmen note that it is preferable to charge such batteries (AA or AAA) using direct current, because this mode is most beneficial in terms of safety for the batteries themselves. In general, the transferred charge strength from the network is about 1.2-1.6 of the value of the capacity of the battery itself. For example, a nickel-cadmium battery with a capacity of 1A / h will be charged with a current of 1.6 A / h. At the same time, the lower the indicator of this power, the better for the charging process.
IN modern world there are quite a few household appliances equipped with a special timer that counts down a certain period, then signaling its end. When making a do-it-yourself device for charging finger-type batteries, You can also use this technology, which will notify you when the battery charging process is completed.
AA is a device that generates direct current, charging up to 3 Ah. In the manufacture, the most common, even the classic scheme, which you see below, was used. The basis, in this case, is the transistor VT1.
The voltage on this transistor is indicated by the red LED VD5, which acts as an indicator when the device is connected to the network. Resistor R1 sets a certain power of the currents passing through this LED, as a result of which the voltage in it fluctuates. Meaning collector current formed by resistance from R2 to R5, which are included in VT2 - the so-called "emitter circuit". At the same time, by changing the resistance values, you can control the degree of charging. R2 is permanently connected to VT1, setting the constant current with a minimum value of 70 mA. To increase the charge power, it is necessary to connect the remaining resistors, i.e. R3, R4 and R5.
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It is worth noting that Charger functions only when batteries are connected.After turning on the device in the network, a certain voltage appears on the resistor R2, which is transmitted to the transistor VT2. Then, the current flows further, as a result of which the VD7 LED begins to burn intensively.
A story about a homemade device
USB charging
You can make a charger for nickel-cadmium batteries based on regular USB port. At the same time, they will be charged with a current with a capacity of approximately 100 mA. The scheme, in this case, will be as follows:
To date, there are quite a few different chargers sold in stores, but their cost can be quite high. Considering that the main meaning of various homemade products is precisely saving Money, then self-assembly is even more appropriate in this case.
This circuit can be improved by adding an additional circuit to charge a pair of AA batteries. Here's what happened in the end:
To make it more clear, here are the components that were used in the assembly process:
It is clear that we cannot do without elementary tools, so before starting the assembly, you need to make sure that you have everything you need:
- soldering iron;
- solder;
- flux;
- tester;
- tweezers;
- various screwdrivers and a knife.
Read also: Overview of chargers for finger-type batteries
Interesting material about making your own hands, we recommend viewing
A tester is necessary in order to check the performance of our radio components. To do this, you need to compare their resistance, and then check with the nominal value.
For assembly, we also need a case and a battery compartment. The latter can be taken from the children's Tetris simulator, and the case can be made from a regular plastic case (6.5cm/4.5cm/2cm).
We fix the battery compartment on the case using screws. As a basis for the circuit, the board from the Dandy prefix, which needs to be cut out, is perfect. We remove all unnecessary components, leaving only the power socket. The next step is to solder all the parts based on our scheme.
The power cord for the device can be taken from a regular computer mouse cord with a USB input, as well as a part of the power cord with a plug. When soldering, polarity must be strictly observed, i.e. solder plus to plus, etc. We connect the cable to USB, checking the voltage that is supplied to the plug. The tester should show 5V.
It is worth saying that such a battery is called “Krona” only in countries former USSR. The name comes from a conventional battery of the same size, produced at that time.
It is recommended to charge these batteries with a current of no more than 20-30mA, otherwise we will significantly shorten their life.
The circuit is simple and is based on a Chinese charger for mobile phones. Cheap chargers come in 2 types, but both options are pulsed and are implemented according to a self-oscillating circuit with an output voltage of 5V.
The first variety is the most popular. There is no output voltage control here, but it can be changed by choosing a zener diode installed in the input circuit near the 1N4148 diode. Usually there is a nominal value of 4.7V or 5.1V, and charging 6F22 requires 10 -11V, so we will replace it with another one with the desired value. The output electrolytic capacitor should also be replaced, as it is rated for 10V. We put on 16-25V, with a capacity of 47 to 220 microfarads.
In the second variety, output voltage control is provided through an optocoupler and a zener diode. The zener diode can be conventional or adjustable, like the TL431. In my sample, the usual one is 4.7V.
Consider the principle of alteration of the 2nd variety. We first remove everything that is after the transformer, except for the output voltage control unit. Those. we leave the zener diode, optocoupler and a couple of resistors. I also replaced the rectifier diode, because. The Chinese declared an output current of 500mA, and put a diode with a maximum current of 200mA (according to the datasheet), soldered FR107. I replaced the output electrolyte with a higher voltage one and picked up a 10V zener diode. As a result, at the output we have the desired voltage of about 10.5V.
After checking the converted charger, we assemble the current stabilization unit based on the LM317. In principle, for such small currents, you can do without a microcircuit, but simply put a quenching resistor. But I preferred good stabilization, after all, this battery is not such a cheap product.
The stabilizer circuit is the same as for the converted screwdriver charger.
The stabilization current depends on R1. Calculation program for LM317 here. The HL1 LED will light up when the load is connected, because. there is a voltage drop across R2. As the charge progresses, the current drops and at some point the voltage drop across R2 will become insufficient for HL1 to glow. This will happen at the end of the charging process, when the voltage on the battery equals the voltage at the output of the charger. Those. practically have an automatic shutdown.
Due to the meager current, LM317 does not need to be placed on a radiator. To complete the design, it remains to attach a connector at the output, which can be taken by disassembling the unusable "Krona" and installing everything in a suitable case.
And another very simple option!
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Charging attachments for rechargeable batteries 6F22.
To power small-sized electronic equipment, Ni-Cd and Ni-MH batteries of AA and AAA sizes are widely used today. Less common are batteries used instead of galvanic voltages of 9 V (“Krona”, “Korund”): domestic Ni-Cd “Nika”, 7D-0.125 and foreign Ni-MH size 6F22 from different manufacturers (the same size includes batteries GP17R8H, GP17R9H and others from GP). The capacity of these batteries is 0.1 ... 0.25 Ah, the nominal voltage is 8.4 ... 9.6 V, and their charging requires specialized chargers, which are extremely rare on sale rather expensive universal devices). The article below describes two attachments that allow you to charge nine-volt batteries from an existing power source. The charging attachment to a stabilized power source with an output voltage of 12 V is assembled on three transistors (2 x KT315B, KT361B), an attachment to the charger for cell phone, which is an adjustable boost voltage converter, - on three KT342AM transistors and a K561LN2 microcircuit. Drawings of printed circuit boards of both attachments are given. .
In general, there are a lot of schemes for such chargers. This article presents a simple and affordable option that will help you make a Krona charger with cost and effort savings. The proposed scheme based on charging for a mobile phone allows you to make a device with your own hands. Video blogger Aka Kasyan.
By the way, a 9-volt battery is called Krona only in Russia and other countries that came from the USSR. In the world, it is known as standard 6 f 22. Krona owes its name to a simple battery of the same standard that was produced in the USSR.
Everything you need to assemble the device, you can find in this Chinese store. Look out for products with free shipping.
The battery crown is an assembly of series-connected batteries, a rather rare 4a standard. In general, there are 7 of them. As a rule, this is a nickel-metal hydride type.
Charging schemes for battery Krona
It is recommended to charge the battery crown with a current of no more than 20 - 30 milliamps. It is recommended that you never increase the current above 40 milliamps. The charger circuit is relatively simple and is based on a Chinese mobile phone charger. A cheap Chinese charger comes in two main types. Both, as a rule, are pulsed and implemented according to self-oscillating circuits. The output provides a voltage of about 5 volts. 
First type of charger
The first variety is the most popular. There is no output voltage control, but it can be changed by selecting a zener diode, which, as a rule, is in the input circuit in such circuits. The zener diode is most often at 4.7 - 5.1 volts. To charge the crown, we need to have a voltage of about 10 volts. Therefore, we replace the zener diode with another with the desired voltage. It is also advised to replace the electrolytic capacitor at the output of the charger. We replace with 16 - 25 volts. Capacitance from 47 to 220 microfarads.
Second type of charging
The second variety - the circuit for charging mobile phones is a self-oscillating circuit, but with output voltage control by means of an optocoupler and a zener diode. In such circuits, either a conventional zener diode or an adjustable one, like tl431, can be used as a control element. In this case, there is the most common 4.7 volt zener diode. 
The video shows a method of alteration based on 2 schemes. First, we remove everything that is after the transformer, except for the output voltage control unit. This is an optocoupler, a zener diode and two resistors. We also replace the diode rectifier. We replace the existing diode with fr107 (an excellent budget option).
We also replace the output electrolyte with a high voltage. We select a 10 volt zener diode. As a result, charging began to produce the output voltage necessary for our purposes.
After reworking the charger, we assemble a current stabilization unit based on the lm317 chip. 
In principle, for such negligible currents, you can do without a microcircuit. Instead, put one quenching resistor, but preferably good stabilization. Still, the battery crown is not at all a cheap type of battery. The stabilization current will depend on the resistance of the resistor r1, the calculation program for this microcircuit can be found on the Internet.
This scheme works very simply. The LED will be on when the output is connected to a load. In this case, Krona, since there is a voltage drop across the resistor r2. As the battery charges, the current in the circuit will drop and at one point the voltage drop across each resistor will be insufficient. The LED will just turn off. This will be at the end of the charge process, when the voltage at the Krona is equal to the voltage at the output of the charger. Consequently, the further charging process will become impossible. In other words, an almost automatic principle.
You don’t have to worry about Krona, since the current at the end of the charge process is almost zero. It makes no sense to install the lm317t chip on the radiator because of the meager charge current. It won't heat up at all.
At the end, it remains to attach the connector for the Crown to the exit, which can be made from the second non-working crown. And, of course, think about the case for the device.
Charging for Krona from dc-dc converter
If you take a small dc-dc converter board, then you can easily make USB charging for the crown. The converter module will increase the voltage of the USB port to the required 10-11 volts. And then, along the circuit, the current stabilizer on lm317 and that's it.
To power small-sized electronic equipment, Ni-Cd and Ni-MH batteries of AA and AAA sizes are widely used today. Less common are batteries used instead of galvanic voltages of 9 V ("Krona", "Korund"): domestic Ni-Cd "Nika", 7D-0.125 and foreign Ni-MH size 6F22 from different manufacturers (the same size includes batteries GP17R8H, GP17R9H and others from GP). The capacity of these batteries is 0.1 ... 0.25 Ah, the nominal voltage is 8.4 ... 9.6 V, and their charging requires specialized chargers, which are extremely rare on sale (usually the ability to charge such batteries available only in rather expensive universal devices). The article below describes two attachments that allow you to charge nine-volt batteries from an existing power source.
You can make your own charger (charger) for batteries of size 6F22 based on a rectifier with a quenching capacitor, but due to the galvanic connection with the network, it can be unsafe to operate. A charger with a step-down transformer is safe, but, firstly, there may not be a suitable transformer either at home or in a store, and you will have to wind it yourself, and secondly, the dimensions of such a device will be larger. Possible way out from the position - to make a charging attachment to an existing source, for example, to laboratory block power supply with an output voltage of 12 V or to a charger from a cell phone (5 V). The diagram of the charging attachment to a stabilized power supply with an output voltage of 12 V is shown in fig. 1.
The charging current of the battery battery connected to connector X1 is set with a trimming resistor R8. Transistors VT1, VT2 and resistors R4 - R7 form a charging current control unit. The VD1 diode prevents the battery from discharging through the set-top box and the power source if the latter is disconnected from the network or the voltage is lost in it. After connecting to the set-top box, a current I charge1 flows through the battery being charged, determined by its own voltage UB, the power supply voltage Upit by the resistance of the resistor R3 and the inserted part R8 (the effect of shunting resistors R6 and R7 can be ignored) and, finally, the voltage drop UVD1 on the diode VD1: I charge1 \u003d (U pet - U B - U VD1) / (R3 + R8). When the battery is discharged to 7 V, this current does not exceed 2.5 mA, so the voltage drop across the resistor R8 is not enough to open the transistors VT1, VT2, the HL1 LED does not light and the VT3 transistor is closed. When you press the SB1 ("Start") button, the transistor VT3 opens, and charging current increases to the value of I zar2 = (U pit - U B - U VD1 - U VT3) / R8, where U VT3 is the voltage drop in the emitter-collector section of the transistor VT3. In this case, the voltage on the engine of the tuning resistor R6 increases so much that the transistor VT1 opens, therefore, after the button is released, both of these transistors remain open and the battery starts charging with a current of 15 ... 50 mA (depending on the input resistance of the tuned resistor R8).
LED HL1 indicates the progress of the process. As the battery is charged, the voltage of the battery rises, and the charging current and the voltage drop across resistor R8 decrease. When the battery voltage reaches approximately 10.5 V, the transistor VT1, followed by VT3, closes, the HL1 LED goes out and the battery charging (stops. From that moment on, only a small current I charge3 (about 1 mA) flows through it, determined mainly resistance of resistor R3. If due to a battery malfunction or a short circuit of the output of the set-top box, the current in the charging circuit exceeds 50 ... 60 mA, transistor VT2 will open, transistors VT1, VT3 will start to close and as a result, the output current will be limited. shown in Fig. 2.
This device is an adjustable voltage boost converter. On inverters DD1.1-DD1.3, a master pulse generator with a repetition rate of about 30 kHz is assembled, and on DD1.4-DD1.6 and transistor VT1, a control pulse shaper for transistor VT2, which operates in the key mode. impulse voltage, formed on its collector, is rectified by the diode VD1, capacitors C6, C7 are smoothing. After connecting to the X1 connector, the battery starts charging through the HL2 LED (it lights up) and the R7 resistor. If the charging current turns out to be more than 20 ... .25 mA, the voltage drop across this resistor will open the transistor VT1, it will bypass the resistor R4 and the duration of the control pulses will decrease, therefore, the rectified voltage and charging current will decrease. This ensures its stabilization during the charging process. When the battery is discharged, the transistor VT3 is closed and the HL1 LED does not light. As it charges, the current through the serial circuit VD2R9 increases, the voltage drop across the trimmer resistor R9 increases and there comes a moment when the transistor VT3 starts to open. As a result, part of the rectifier output current begins to flow through this transistor and the HL1 LED, and the charging current decreases. In other words, the brightness of the HL1 LED gradually increases, and the HL2 LED decreases. The latter continues to glow faintly even after charging is completed, since the current of the VD2 zener diode and a small (about 1 mA) charging current flows through it, which is safe for the battery (it can remain connected to the set-top box for an unlimited time). Drawing printed circuit board the first prefix is shown on rice. 3, and the second one in Fig. 4.
All parts are mounted on them, except for the connectors for connecting the battery and power source. Fixed resistors - P1 -4, C2-23, tuning resistors - SPZ-19a, oxide capacitors - imported (for example, the Jamicon TK series), the rest - K10-17. transistors n-p-n structures can be series KT342, KT3102, and p-n-p - series KT3107. LEDs - any with a direct voltage of 1.8 ... 2.5 V and a maximum allowable current of up to 25 mA. Possible replacement of the diode 1N5819 (see Fig. 1) - D310, D311, diode KD522B (see Fig. 2) - KD521A, 1N5819, zener diode KS162A - KS175A, KS182A. Choke L1 (see Fig. 2) - DM-0.2, button SB1 (see Fig. 1) - PKN-159. If the output current limiting mode in the first attachment is not needed, the elements VT2, R5, R7 are not installed. To connect a rechargeable battery to attachments, two-pin connectors are used (similar to the pads used in batteries of this type), which exclude incorrect connection, and to connect to a power source and a cell phone charger, the corresponding connectors are used. The author used a charger with an output voltage of 5 V, which is equipped with a USB-A socket. To dock with it, the charger was equipped with a cable with a USB-A plug, which made it possible to charge the battery from a computer. Appearance mounted attachments is shown in fig. 5 and 6.
Set up the first prefix in this sequence. Having set the sliders of the trimming resistors R6 - R8 to the lower (according to the diagram) position, connect a discharged battery to the X1 connector and a milliammeter connected in series with it with a measurement limit of 100 mA. The power supply is turned on and, by pressing the SB1 button, the maximum (initial) charging current is set with the resistor R8 (no more than 50 ... 60 mA). Then the battery is replaced with a constant resistor with a resistance of 100 ohms and, by moving the slider of the resistor R7, the current is increased by 10 mA in relation to the previously set one. Next, a freshly charged battery is connected (without a milliammeter) and, slowly turning the trimmer resistor R6, the HL1 LED goes out. After that, several control charging cycles are carried out and, if necessary, adjustment is repeated.
The second prefix is adjusted as follows. By setting the slider of the resistor R9 to the lower (according to the diagram) position, the capacitor C5 is temporarily closed with a wire jumper. Then, as in setting up the first set-top box, a discharged battery and a milliammeter connected in series are connected to the output. Turning on the power supply, with a tuned resistor R2, a current is set in the charging circuit that exceeds the desired charging current by 10 ... 20%. After removing the jumper from the capacitor C5, it should decrease. The required value is set by selecting the resistor R7 (I charge ~ 0.6/R7). Then a fully charged battery is connected and the charging current is set to about 0.5 mA with resistor R9. If desired, the indication of the end of battery charging in this memory can be made more clear. To do this, instead of the transistor VT3 and the zener diode VD2, a parallel voltage regulator KP142EN19 is installed (Fig. 7). Now only the charging current will flow through the HL2 LED. It should be noted that the nominal voltage of some batteries of this size, in particular GP17R9H, is 9.6 V, and when charged, the voltage on it reaches 12 V, so a 13.5 V power supply is required to charge it using the first set-top box.
