After turning on the device to the network, a certain voltage transmitted to the VT2 transistor appears on the R2 resistor. Then, the current flows on, as a result of which the VD7 LED is started intensively.

Story about homemade device

Charging from a USB port

You can make a charger for nickel-cadmium batteries based on a regular USB port. At the same time, they will be charged with a current tank of about 100 mA. The scheme, in this case, will be as follows:

To date, there are quite a lot of different charging devices sold in stores, but their cost can be high enough. Considering that the main meaning of various homemade is the savings moneyT. independent assembly Even more appropriate in this case.

This scheme can be refined by adding an additional chain to charge AA batteries. That's what happened in the end:

To be more clearly, these components that were used in the assembly process:

It is clear that we cannot do without elementary toolkit, so before the start of the assembly it is necessary to make sure that you have everything you need in stock:

• soldering iron;
• solder;
• flux;
• tester;
• tweezers;
• different screwdrivers and knife.

Read the same: Learning which car compressor is better?

Interesting material about manufacturing with your own hands, we recommend for viewing

The tester is necessary in order to test our radio components. To do this, you need to compare their resistance, after which to verify with a nominal value.

For assembly, we will also need a hull and battery compartment. The latter can be taken from the children's simulator Tetris, and the housing can be made from a conventional plastic case (6.5 cm / 4.5 cm / 2cm).

Fresh battery compartment on the housing using screws. As the basis for the scheme, the fee is perfect for a dandy console, which you want to cut. We remove all unnecessary components, leaving only the power socket. The next step will have a soldering of all the details based on our scheme.

Power cord for device You can take a regular cord from computer mouseHolding uSB entrance, as well as a part of the supply wire with a plug. When soldering, it is necessary to strictly observe the polarity, i.e. Swim plus to the plus, etc. We connect the cord to USB, checking the voltage that is fed to the plug. The tester should show 5B.

At one of the radio amateurs websites saw a scheme for charging portable Ni-Mn and Ni-CD batteries with an operating voltage of 1.2-1.4 V from a USB port. With this device, you can charge portable rechargeable batteries The current is about 100 mA. The scheme is simple. It is not difficult to collect her even a novice radio amateur.

Of course, you can buy a ready-made memory. On sale they are now a great set and for every taste. But their price is hardly satisfied with a novice radio amateur or one who is able to make a charger with their own hands.
I decided to repeat this scheme, but make a charger to charge two batteries at once. Issued uSB current 2.0 is 500 MA. So you can safely connect two batteries. The final scheme looked like this.

I also wanted to have the ability to connect external source power supply 5 V.
The scheme contains only eight radio components.

From the tool, you will need a minimum set of radio amateur: soldering iron, solder, flux, tester, tweezers, screwdrivers, knife. Before soldering radio components, they must be checked for goodness. For this we need a tester. Resistors check very simple. We measure their resistance and compare with a par. About how to check the diode and the LED there are many articles on the Internet.
For the body used a plastic case of 65 * 45 * 20 mm. The battery compartment cut out from the children's toy "Tetris".

About the alteration of the battery compartment will tell more detail. The fact is that initially
pros and cons of power terminals batteries are mounted opposite. But I needed that in the upper part of the compartment there were two isolated plus terminals, and at the bottom one total minus. To do this, I was transferred to the bottom with a lower plus terminal, and the total minority cut out of the fasteners, surging the remaining springs.

As a flux when soldering the springs, a soldering acid was used in compliance with all safety regulations. Place soldering be sure to rinse in running water to complete removal Acid trace. The wires from the terminals swept and missed the inside of the housing through the drilled holes.

The battery compartment secured three small screws on the cover cover.
Fee drank from the old modulator gaming console "Dandy". Removed all unnecessary details and printed tracks. Left only the power socket. Thick copper wire used as new tracks. In the bottom cover drilled holes for ventilation.

The finished fee was tight in the housing, so I did not fix it.

After installing all radio components, we check the correctness of the installation and clean the fee from the flux.
Now we will deal with the disintegration of the power cord and the charging current setting for each battery.
As a power cord used USB cord from old computer Mouse and a piece of feeding wire with a plug from "Dandy".

The power cord needs to pay special attention. In no case cannot be confused "+" and "-". I have a power-to-central contact with a white strip on the plug "+" power. A "-" food goes on the black (without a strip) to the outer contact of the plug. On the USB cord "+" goes to the red wire A "-" on the black. Saw plus with a plus and minus with a minus. Playing places carefully insulating. Next, check the short circuit cord by connecting the tester in the resistance measurement mode to the plug terminals. The tester should show endless resistance. Everyone needs to be thoroughly reworked, no matter what to burn the USB port. If everything is fine, we connect our cord to the USB port and check the voltage on the plug. The tester should show 5 volts.

The last setting step is the installation of charging current. To do this, tear the chain of the VD1 and "+" battery diode. In the gap, we connect the tester in the current measurement mode on the limit of 200 mA. Plus the tester on the diode, and minus to the battery.

Insert the battery to the place, observing the polarity, and feed meals. The LED should light up. It signals that the battery is connected. Next, changing the resistance R1, set the required charge current. In our case, it is approximately 100 mA. With a decrease in resistance of the resistor R1, the charging current increases, and with an increase decreases.

The same makes the same for the second battery. After that, we twist our body and
charger is ready to use.
Since different finger batteries They have different
capacity, it will take different times to charge these batteries. Batteries
1400 mA / h with a voltage of 1.2 V will be charged with this
schemes about 14 hours, and 700 mA / h batteries will be required only 7 hours.
I have accumulators with a capacity of 2700 mA / h. But I did not want to charge them 27 hours from the USB port. Therefore, I made a power socket for an external power supply of 5 volts 1a, which I was lying without a case.

Here are some more photos of the finished device.

Stickers Drew the program FrontDesigner 3.0. Then printed on laser printer. I cut out with scissors, pasted the front side to the thin tape width of 20 mm. Excess tape cropped. As adhesive used a pencil adhesive, pre-lubricating them and the sticker and the place where it glues. As far as it is reliably, I do not know yet.
Now the pros and cons of this scheme.
Plus, the scheme does not contain scarce and expensive parts and is collected literally on the knee. It is also possible to drive from a USB port, which is not enough for novice radio amateurs. No need to break your head, where to power the scheme. Despite the fact that the scheme is very simple, this method Charging is used in many industrial chargers.
You can also make a slightly complicating scheme to implement charging current switching.

Selection of R1, R3 and R4, you can set a charging current for different batteries, thereby providing the recommended charging current for a given battery, which is usually 0.1C (C-capacity of the battery).
Now minuses. The largest, this is the lack of stabilization of the charging current. I.e
When the input voltage changes, the charging current will change. Also with an error in the installation or short closure Schemes There are a high probability of burning a USB port.

Features of charging NI─MH batteries, charger requirements and basic parameters

Nickel-metallohydride batteries gradually apply to the market, and the technology of their production is improved. Many manufacturers gradually improve their characteristics. In particular, the number of cycles of charge-discharge increases and the NI─MH self-discharge of the batteries is reduced. This type of batteries was produced to replace the NI─CD batteries and gradually they displacing them from the market. But there are some areas of use, where nickel-metallicidride batteries cannot replace cadmium. Especially where high discharge currents are required. And the other type of batteries to extend the service life require competent charging. We have already talked about charging nickels ofkadmium batteries, and now it has come to charge ni─mh batteries.

In the process of charge in the battery there is a number of chemical reactions that part of the supplied energy goes. Another part of energy is converted to heat. The efficiency of the charging process ─ is the part of the energy supplied, which remains in the "reserve" at the battery. The efficiency of the efficiency may differ depending on the charge conditions, but it never happens to be 100 percent. It is worth noting that the efficiency when charging the ni─cd batteries is higher than in the case of nickel-metallium-chidride. The process of charging NI─MH batteries occurs with high heat release, which imposes its limitations and features. Read more about, read in the article on the specified link.

• Drip (charge current 0.1C);
• Fast (0.3C);
• Accelerated (0.5─1c).

By and large, charging types are only two: drip and accelerated. Fast and accelerated is almost the same thing. They differ only by the method of stopping the charge process.

In general, any charge of NI─MH batteries current is greater than 0.1C is fast and requires tracking some criteria for the end of the process. Drip charging this does not require and may continue indefinitely.

Types of charging nickel-metallohydride batteries

Now, let's consider the features different species Charging more.

Drip charging NI─MH batteries

It is worth saying that this type of charging does not contribute to an increase in the service life of Ni─MH batteries. Since drip charging is not turned off even after complete charge, the current is chosen very small. This is done so that when the battery does not exceed a long-time charging. In the case of NI─MH batteries, the current value can even be reduced to 0.05c. For nickel okadmiyev will suit 0.1C.

With drop charging, there is no characteristic maximum voltage and the restriction of this type of charging can only be time. To estimate the necessary time, you will need to know the capacity and the initial charge of the battery. To calculate the charging time more accurately, you need to discharge the battery. This will exclude the influence of the initial charge. The efficiency with drip charging NI─MH batteries is at 70 percent, which is below the other types. Many nickel-metallic battery manufacturers do not recommend using drip charging. Although B. lately Everything appears more information The fact that modern models ni─mh batteries do not degrade during drip charge.

Fast Charging Nickel Model Hydride Batteries

The batteries ni─mh manufacturers in their recommendations lead the charge characteristics in the range of 0.75─1C. Focus on these values \u200b\u200bwhen you choose how to charge ni─mh batteries. The values \u200b\u200bof the charge current above these values \u200b\u200bare not recommended, as this can lead to the opening of the emergency valve for resetting pressure. A quick charge of nickel-metallohydride batteries is recommended at 0─40 degrees Celsius and voltage of 0.8─, 8 volts.

Efficiency of the process fast charging much more than drip. It is about 90 percent. However, by the end of the process of the efficiency, the efficiency decreases sharply, and energy goes into heat release. Inside the battery, the temperature and pressure rises sharply. Have an emergency valve that can open with an increase in pressure. In this case, the properties of the battery will be irretrievably lost. And the high temperature itself has a detrimental effect on the structure of the battery electrodes. Therefore, you need clear criteria for which the charge process will stop.

Requirements for the charger (memory) for NI─MH batteries, we will be submitted below. So far, we note that such stages are charged on a specific algorithm. Stage of this algorithm in general Next:

• determining the presence of a battery;
• battery qualification;
• pre-charging;
• transition to fast charging;
• fast charging;
• refreshing;
• support charging.

At this stage, a current is 0.1C and the voltage check is performed on the poles. For the start of the charge process, the voltage should be not more than 1.8 volts. Otherwise, the process does not start.

It is worth noting that checking the availability of the battery is carried out at other stages. This is necessary in case the battery is removed from the charger.

If the logic of the memory defines that the voltage value is greater than 1.8 volts, it is perceived as the lack of a battery or its damage.

Qualification of the battery

It defines an approximate battery charge assessment. If the voltage is less than 0.8 volts, then the battery charge cannot be launched. In this case, the charger will turn on the pre-charging mode. With normal operation, NI─MH batteries are rarely discharged to voltage below 1 volt. Therefore, pre-charging is included only in the case of deep discharges and after long-term storage of batteries.

Pre-charging

As mentioned above, pre-charging is included with a deep discharge of ni─mh batteries. The current at this stage is set at 0.1─0.3c. In time, this stage is limited and amounts to about 30 minutes somewhere. If during this time the battery does not restore the voltage of 0.8 volt, then the charge is interrupted. In this case, the battery is most likely damaged.

Transition to quick charging

At this stage there is a smooth increase in the charging current. Current extension occurs smoothly within 2─5 minutes. At the same time, as on other stages, temperature control is maintained and the charge shutdown at critical values.

The charge current at this stage is in the range of 0.5─1c. The most important thing at the rapid charging stage is the timely shutdown of the current. To do this, when charging NI─MH batteries uses control over several different criteria.

For those who do not know, when charging, the method of controlling voltage is used. In the process of charging, it is constantly growing, and at the end of the process begins to fall. Usually the end of the charge is determined by a voltage drop by 30 mV. But this method of controlling with nickel-metallohydride batteries is not working very well. In this case, the drop voltage is not so much expressed, as in the case of Ni─CD. Therefore, it is necessary to increase the sensitivity to trigger the shutdown. And with high sensitivity, the likelihood of false response increases due to the noise of the battery. In addition, when charging several batteries, the trigger occurs at different times and the whole process is smeared.

But still stop charging on the voltage drop is the main one. When charging 1C, the voltage drop for shutdown is 2.5─12 mV. Sometimes manufacturers set detection not by falling, but by the absence of voltage change at the end of the charge.

In this period of the first 5─10 minutes of charging, control over the voltage delta is disabled. This is explained by the fact that at the start of a quick charging, the battery voltage can vary greatly as a result of the fluctuation process. Therefore, at the initial stage, control turns off to eliminate false responses.

Due to the not too high reliability of shutdown charging on the voltage delta, control is used for other criteria.

There is also a method for monitoring the charge process for analyzing the voltage derivative. In this case, no voltage delta is monitored, but the speed of its maximum growth. The method allows you to stop fast charging a little earlier charge completion. But such control is conjugate with a number of difficulties, in particular, more accurate voltage measurement.

Some batteries for NI─MH batteries are used for charge is not a direct current, but a pulse. It is served as a duration of 1 second at intervals of 20─30 milliseconds. As the advantages of such charge, experts refer to a more uniform distribution of active substances in the amount of battery and reducing the formation of large crystals. In addition, reported more accurate measure Voltages in the intervals between current supply. As the development of this method, Reflex Charging was proposed. In this case, when the pulse current is supplied, charge (1 second) and the discharge (5 seconds). The discharge current is lower than charge in 1─2.5 times. As advantages, you can allocate a smaller temperature when charging and eliminating large crystalline formations.

When charging nickel-metallohydride batteries, it is very important to control the completion of the charging process according to various parameters. Emergency completion methods should be provided. To do this, the absolute temperature value can be used. Often this value is 45-50 degrees Celsius. In this case, the charge must be interrupted and resumed after cooling. The ability to accept the charge in ni─mh batteries at such a temperature is reduced.

It is important to establish a charge time limit. It can be estimated by the capacity of the battery, the value of the charging current and the process efficiency. The restriction is set at the level of the estimated time plus 5─10 percent. In this case, if none of the previous control method does not work, the charge will turn off at the time set.

Package stage

At this stage, the charging current is set to 0.1─0.3C. Duration about 30 minutes. A longer recovery is not recommended as it reduces battery life. Package step helps to align the charge of elements in the battery. It is best if after quick charging, the batteries are cooled to room temperature, and then the charging will start. Then the battery will restore the full capacity.

Chargers for NI─CD batteries often after completion of the charge process, the battery is transmitted to drip charging mode. For NI─MH batteries, it will be useful only in the case of a very small current (about 0.005С). This will be enough to compensate for the self-discharge of the battery.

Ideally, charging should have the function of incorporating supporting charging when the voltage is dropped on the battery. Supporting charging makes sense only in the case when there is a sufficiently long time between the charge of the batteries and their use.

Ultrafast Charging Ni-MH Batteries

And it is also worth mentioning about the super-fast charge rechargeable batteries. It is known that when charging up to 70 percent of its capacitance nickel-metallohydride battery has a CPD of charging close to 100 percent. Therefore, at this stage it makes sense to increase the current for the accelerated passage. Currents in such cases are limited to the value of 10C. The main problem here is in determining the most 70 percent of the charge under which the current should be reduced to the usual fast charging. It strongly depends on the degree of discharge with which the battery is charged. The high current can easily lead to overheating of the battery and the destruction of the structure of its electrodes. Therefore, the use of ultrafast charge is recommended only if there are appropriate skills and experience.

General requirements for charger for nickel-metallohydride batteries

Disassemble some separate models for charge NI─MH batteries in this article inexpedient. It is sufficient to note that it can be narrowly charged to charge nickel-metallohydride batteries. They have the sewed charging algorithm (or a few) and on it are constantly working. Is there universal devicesthat allow you to fine-tune charging parameters. For instance, . Such devices can be used to charge various batteries. Including for, if there is a power adapter of the appropriate power.

It is necessary to say a few words about what characteristics and functionality should have a memory for NI─MH batteries. The device must be able to adjust the charging current or its automatic installation Depending on the type of batteries. Why is it important?

Now there are many nickel-metallic batteries models, and many batteries of the same form factor may differ in the container. Accordingly, the charging current must be different. If you charge the current above the norm, there will be heating. If the norm is lower, the charging process will go longer than the laid. In most cases, currents on chargers are made in the form of "presets" for typical batteries. In general, when charging, Ni-MH batteries do not recommend the current installation of more than 1.3─1.5 amps for the AA type, regardless of the tank. If for some reason you need an increase in this value, then you need to take care of the compulsory cooling of the batteries.

Another problem is related to the power outage of the charger in the charging process. In this case, when power is turned on, it will start again from the battery determination stage. The end of the end of a quick charging is not determined by time, but a number of other criteria. Therefore, if it passed, then when turned on it will be skipped. But the recovery stage will pass again if he was already. As a result, the battery receives an unwanted reload and extra heating. Among other requirements for Ni-MH batteries - low discharge when you turn off the power of the charger. The discharge current in a de-energized memory should not exceed 1 mA.

It is worth noting the presence of another important function in the charger. It should recognize the primary sources of current. Simply put, manganese-zinc and alkaline batteries.

When installing and charging such batteries in the memory, they may well explode, because they do not have an emergency valve to reset the pressure. The charger requires that it can recognize such primary current sources and do not include charging.

Although it is worth noting here that the determination of batteries and primary sources of current has a number of difficulties. Therefore, the manufacturers of the memory are not always equipped their models with similar features.

Often there is no need to design complex devices that take into account many parameters of the discharge-charging battery cycle. It is enough to take into account a pair of such parameters as the voltage of the discharge, the stroke voltage and the charging current. The selected cycle parameters prevent excess or insufficient charge of batteries, which later increases their service life.

The device is powered by an unstabilized source with an output current of at least 100 mA, the voltage of which, taking into account the ripples, should be within 11.5 ... 30 V.

Scheme:

Device operation:
At first, the battery is connected from four batteries and then the supply voltage is supplied. While the battery voltage exceeds 4 V (on average 1 V per element) The VT1 transistor is open, the VT2-VT4 transistors, VD1-VD4 diodes and the VS1 trinistor are closed. The VT5 transistor is open and saturated, through it and the R13 resistor battery is discharged. HL2 LED is enabled. The discharge current should not be installed more than 1/10 battery capacity.

When the battery voltage in the process of discharge becomes less than 4 V, the Schmitt trigger switches, the VT1 transistor closes, and VT2 will open. At the exit of the Schmitt trigger, high-level voltage (about 8 V) will be installed. The VD1 diode and the VS1 trinistor open, resulting in the VD3 diode, the VT5 transistor closes, the HL2 LED will go out, the discharge mode will stop. At the same time, the high-level voltage from the Schmitt trigger output will open the VD2 diode and the VT3 transistor, as a result of which the HL1 LED will turn around, the VT4 transistor and the VD4 diode will open through which the battery charging will be charged with a stable current.
By pressing the SB1 button, the device is forcibly switched from the discharge mode into charging mode. This is necessary if Ni-MH batteries are used, which are not subject to the "memory effect" and, accordingly, do not need a preliminary discharge.

In the process of charging, when the battery voltage reaches 5.92 V (on average 1.48 V per element), the Schmitt trigger switches: the VT1 transistor will open, and VT2 closes. The Diode VD2 and the VT3 transistor will close, the HL1 LED will go out, as a result of which the VT4 transistor and the VD4 diode will be closed, and the charging process will stop. But the VS1 trinistor remains open, so the VT5 transistor will not appear and the discharge mode will not turn on. After turning off the power of the device, it is necessary to turn off the battery from it, otherwise it will be discharged.

Installation and components:
CT315B transistors (VT1-VT3) can be replaced with KT315G or CT315E transistors. You can apply other silicon low-power transistors. n-P-N structures With the maximum current collector current of at least 100 mA, but for the Schmitt trigger, it is desirable to choose transistors with a base transmission coefficient of at least 50. VT4 and VT5 transistors - any of the KT814 series, KT816. They are installed on heat sinks of soft aluminum strips with dimensions of 28x8 mm and a thickness of 1 mm, bent in the form of the letter "P". Diodes are any silicon low-power, except VD4, which must withstand charging current. R2 and R5 stroke resistors - multi-turn SP5-2. HL1 and HL2 LEDs are desirable to apply different color of the glow for unambiguous display mode of operation of the device.

Setup:
To establish the device, an auxiliary battery is 21 ... 12 V, to which a variable resistance resistance variable resistance resistance resistance is connected. To facilitate the accurate installation of the required voltage in the rupture of the chain of one of the extreme conclusions of this resistor, it is desirable to include as a restatt of another variable resistor of ten times smaller resistance.

R2 and R5 stroke resistor engines are set to the lower position. Temporarily break the left connection according to the output scheme R1 with a plus output of the device. At the time of establishing, this output becomes the input of the device, which is connected to the engine of an alternating resistor. The minority output of the auxiliary battery is connected to the shared device of the device. The charging battery is not connected to the exit. After turning on the power, you must make sure that the stable voltage 9 V at the output of the DA1 chip.

Then set the switching thresholds. The voltmeter is connected to the Emitter of the VT2 transistor. Initially, the rotor of the trimming resistor R2 is set by the lower threshold of the switching 4 V. When the input voltage is reduced below this threshold by 0.05 ... 0.1 V, the VT1 transistor should be closed and a high voltage voltage is installed on the Emitter of the VT2 transistor. Then the upper shift threshold 5.92 V. The upper voltage threshold is set to an increase in the input voltage above this threshold by 0.05 ... 0.1 V transistor VT2 should be opened and a low voltage level on the Emitter of the VT2 transistor should be installed. Check both shifting threshold.

Next, it is checked that after opening the VT2 transistor, the VS1 trinistor also opens. If this is not so, reduce the resistance of the R6 resistor, achieving a clear opening of the trinistra. To turn off the trinistra briefly turn off the supply voltage.

Finally, the device's output is connected successively connected milliammeter and charged battery. In charging mode, the reduction of the R9 resistor is set to the desired brightness of the HL1 LED, and the selection of the resistor R11 is the desired charging current. Next, turn off the auxiliary battery and restore the left connection according to the output diagram R1 with the plus output of the device. VS1 trinistor is disconnected. The multimeter is connected to the output of the device in voltage measurement mode. Watch the battery charging process and automatic switching Devices in the discharge mode After reaching the output voltage 5.92 V. Next, in the R12 resistor mode, the HL2 LED giltness and the initial current of the discharge of the resistor R13 are installed. Then the VS1 trinistor is connected and the device is switched to charging mode. At the end, it is necessary to make sure that the VS1 trinistor has opened and prevented the inclusion of the discharge mode.

Strong battery heating at the end of charging, suggests that the charging current is too large, it must be reduced, but the charging time will increase.

Voronov, Stavropol "Radio" No. 1 2012.

A simple compact charger for NIMH and NICD batteries with additional useful features, such as automatic shutdown and temperature control.

Analogues that can be replaced by LM393: 1040s1, 1401CA3, AN1393, AN6916.

USB cable can be cut off from the old mouse / keyboard or buy. And perhaps generally the Plug of Yusb solder directly on the fee.

If the LED is powered by powering, but the scheme does not charge anything, then it is necessary to increase the resistance of the current-limiting resistor R6. To verify the normal operation of the scheme between the Earth and the third conclusion of the chip (VREF), there should be about 2.37 volts, and on the second contact (VTMP) LM393 1.6-1.85 volts.

It is desirable to charge two identical batteries so that their capacitance is approximately equal. And then it turns out that one has already charged completely, but the second only half.

Charging current can be independently set by changing the resistance of the resistor R1. Calculation formula: R1 \u003d 1.6 * The desired current.

For example, I want my batteries to charge 200 MA, we substitute:

R1 \u003d 1.6 * 200 \u003d 320 ohms

When heating batteries, charging will be disconnected. It can increase the charge time, so I recommend to set cooling as a small fan.

When banks are fully charged charging current drops to about 10 mA. This current will prevent the natural self-discharge of nickel-metal hydride / camphive batteries. The first has a 100% discharge for the year, and the second type is about 10%.