Method 4. External energy storage with a solar battery

Another interesting option. As daylight hours begin to increase, it is timely to discuss the benefits of solar energy storage. You'll see how to make a portable charger that can be charged from solar energy storage panels.

We have to:

• Lithium-ion energy storage 18650 format,
• Case from the same drives
• 5V 1A voltage boost module.
• Charge board for battery.
• Solar panel 5.5 V 160 mA (any size)
• Wiring for connection
• 2 diodes 1N4007 (others are possible)
• Velcro or double-sided tape for fixation
• Hot melt adhesive
• Resistor 47 Ohm
• Contacts for energy storage (thin steel plates)
• A pair of toggle switches

1. Let's study the basic circuit of an external battery.

The diagram shows 2 connecting wires of different colors. Red is connected to “+”, black to “-”.

1. It is not recommended to solder the contacts to the lithium-ion battery, so we will put terminals in the housing and secure them with hot glue.
2. The next task is to place the voltage increase module and charging board for the battery. To do this, we make holes for the USB input and USB output 5 V 1 A, a toggle switch and wiring to the solar panel.
3. We solder a resistor (resistance 47 Ohms) to the USB output, on the reverse side of the module that increases the voltage. This makes sense for charging an iPhone. The resistor will solve the problem with the same control signal that starts the charging process.
4. To make the panels easier to carry, you can attach the panel contacts using 2 small female-male contacts. Alternatively, you can connect the main body and panels using Velcro.
5. We place a diode between 1 contact of the panel and the energy storage charge board. The diode should be placed with the arrow pointing towards the charge board. This will prevent the solar panel from draining the storage battery.

IMPORTANT. The diode is placed in the direction FROM the solar panel TO the charge board.

How many charges will this Power Bank last? It all depends on the capacity of your battery and the capacity of the gadget. Remember that discharging lithium drives below 2.7 V is highly undesirable.

As for the charge of the device itself. In our case, we used solar panels with a total capacity of 160 mAh, and the battery capacity was 2600 mAh. Therefore, under the condition of direct rays, the battery will charge in 16.3 hours. Under normal conditions - about 20–25 hours. But don't let these numbers scare you. It will charge via miniUSB in 2-3 hours. Most likely, you will use the solar panel when traveling, hiking, or long trips.

Finally

Choose the method that suits you best and build your own portable battery. This thing will definitely come in handy on the road or while traveling. There are a lot of advantages of the device: it has a unique appearance, and also a way to get the power that will satisfy your needs. Using a portable battery, you can charge not only phones, but also tablets, wireless headphones and other small gadgets.

The number of mobile communications devices in active use is constantly growing. Each of them comes with a charger supplied in the kit. However, not all products meet the deadlines set by the manufacturers. The main reasons are the low quality of electrical networks and the devices themselves. They often break down and it is not always possible to quickly purchase a replacement. In such cases, you need a circuit diagram for a phone charger, using which it is quite possible to repair a faulty device or make a new one yourself.

Main faults of chargers

The charger is considered the weakest link in mobile phones. They often fail due to poor quality parts, unstable mains voltage or as a result of ordinary mechanical damage.

The simplest and best option is to purchase a new device. Despite the differences in manufacturers, the general schemes are very similar to each other. At its core, this is a standard blocking generator that rectifies the current using a transformer. Chargers may differ in connector configuration, they may have different circuits of input network rectifiers, made in a bridge or half-wave version. There are differences in small things that are not of decisive importance.

As practice shows, the main faults of the memory are the following:

• Breakdown of the capacitor installed behind the mains rectifier. As a result of the breakdown, not only the rectifier itself is damaged, but also a constant resistor with low resistance, which simply burns out. In such situations, the resistor practically acts as a fuse.
• Transistor failure. As a rule, many circuits use high-voltage high-power elements marked 13001 or 13003. For repairs, you can use the domestically produced KT940A product.
• Generation does not start due to a breakdown of the capacitor. The output voltage becomes unstable when the zener diode is damaged.

Almost all charger housings are non-separable. Therefore, in many cases, repairs become impractical and ineffective. It is much easier to use a ready-made DC source by connecting it to the required cable and supplementing it with the missing elements.

Simple electronic circuit

The basis of many modern chargers are the simplest pulse circuits of blocking generators, containing only one high-voltage transistor. They are compact in size and capable of delivering the required power. These devices are completely safe to use, since any malfunction leads to a complete absence of voltage at the output. This prevents high unstabilized voltage from entering the load.

The rectification of the alternating voltage of the network is carried out by the diode VD1. Some circuits include an entire diode bridge of 4 elements. The current pulse is limited at the moment of switching on by resistor R1 with a power of 0.25 W. In case of overload, it simply burns out, protecting the entire circuit from failure.

To assemble the converter, a conventional flyback circuit based on transistor VT1 is used. More stable operation is ensured by resistor R2, which starts generation at the moment of power supply. Additional generation support comes from capacitor C1. Resistor R3 limits the base current during overloads and power surges.

High reliability circuit

In this case, the input voltage is rectified by using a diode bridge VD1, a capacitor C1 and a resistor with a power of at least 0.5 W. Otherwise, while charging the capacitor when turning on the device, it may burn out.

Capacitor C1 must have a capacity in microfarads equal to the power of the entire charger in watts. The basic circuit of the converter is the same as in the previous version, with transistor VT1. To limit the current, an emitter with a current sensor based on resistor R4, diode VD3 and transistor VT2 is used.

This phone charger circuit is not much more complicated than the previous one, but much more efficient. The inverter can operate stably without any restrictions despite short circuits and loads. Transistor VT1 is protected from emissions of self-induction EMF by a special chain consisting of elements VD4, C5, R6.

It is necessary to install only a high-frequency diode, otherwise the circuit will not work at all. This chain can be installed in any similar circuits. Due to this, the housing of the switch transistor heats up much less, and the service life of the entire converter increases significantly.

The output voltage is stabilized by a special element - a zener diode DA1, installed at the charging output. Optocoupler V01 is used.

DIY charger repair

With some knowledge of electrical engineering and practical skills in working with tools, you can try to repair a cell phone charger on your own.

First of all, you need to open the charger case. If it is dismountable, you will need an appropriate screwdriver. With the non-separable option, you will have to use sharp objects, separating the charge along the line where the halves meet. As a rule, a non-separable design indicates low quality chargers.

After disassembly, a visual inspection of the board is carried out in order to detect defects. Most often, faulty areas are marked with traces of burning resistors, and the board itself will be darker at these points. Mechanical damage is indicated by cracks in the case and even on the board itself, as well as bent contacts. It is enough to bend them back into place towards the board to resume the supply of mains voltage.

Often the cord at the output of the device is broken. Breaks most often occur near the base or directly at the plug. The defect is detected by measuring resistance.

If there is no visible damage, the transistor is desoldered and ringed. Instead of a faulty element, parts from burnt-out energy-saving lamps are suitable. Everything else was done - resistors, diodes and capacitors - are checked in the same way and, if necessary, replaced with serviceable ones.

Everyone brainiacs, Hello! I suppose you all belong to that part of the world's population that uses smartphones, and I think over the past couple of years you have replaced them several times with more advanced ones. All “outdated” smartphones have lithium-ion batteries, which are not possible to use in new models, and thus you are left with good, but useless batteries... Is this true?

Personally, I have accumulated three phone batteries (and I did not change the phones because the batteries were faulty), they did not heat up or swell, and they can be used to power some gadgets. The capacity of an average battery after 2 years of use is about 80% of the original, this is exactly the period during which I usually purchase a new one brainsmartphone. And if you think about the efforts to obtain raw materials, the production of the batteries themselves and the costs of transportation...

All things considered, it would be a real shame to let them slowly "die" or simply throw them away. In this brain article And video I'll tell you how with your own hands do homemade, which allows you to “give new life” to batteries from old phones, that is, make an external battery for gadgets, also known as POWERBANK.

Step 1: Materials

Well, let's start with what you need to create your own external battery. Materials needed:

• lithium-ion battery,
• charging and protection board for lithium-ion batteries, designed for 5V, maximum input current 1A (the less, the longer the “second life” of the battery will be),
• DC/DC boost converter with output values ​​of 5V and max. 600MA
  wires,
• several pin connectors,
• stationery clip,
  a piece of acrylic,
• screws,
• and a switch.

You will also need:

• a pair of pliers,
• stripper,
• soldering iron,
• and a glue gun,
• and also a drill and a drill.

Step 2: How do the boards work?

First, let's take a look at the charging and protection board for lithium-ion batteries. Its three important functions are charging, overcurrent protection and undervoltage protection.

Lithium-ion batteries charge according to a specific pattern - when they are almost fully charged, their current consumption decreases. Brain board recognizes this and as soon as the battery voltage reaches 4.2V, it stops charging. At the output of the board there is a protection circuit that prevents overcurrent and excessive undervoltage. Modern telephone batteries already have such protection built in, but in this case homemade This board will allow you to use unprotected batteries that can be found in older laptops. The charging current of the board can be adjusted using a resistor, and it should be within 30-50% of the rated battery capacity.

The DC converter converts the battery's DC voltage into a square wave and passes it through a small coil. Due to induction processes, a higher voltage is generated, which is converted back to DC and can be used to power gadgets designed for 5V.

Now, more or less knowing what we are dealing with, we can begin the actual assembly brain games.

Step 3: Design

Before you start creating the housing for homemade products, measure the components and make a drawing. So in my brain structure the battery will be secured using a stationery clip, which is screwed to the case, the boards will be located on top of each other, the input/output contacts will be on top in the upper part of the case, and the contacts going to the batteries will be on the bottom.

Some batteries have a non-standard position of the polarity of the contacts, so this “non-standard” must be taken into account in our device, that is, we need to add pin connectors. To do this, take a connector with three pins and tear out the middle one, and bend the pins themselves on one side to make it easier to attach them to the battery contacts. Or take a connector with four pins, connect the outer ones to the positive terminal, and the middle ones to the negative, and thereby change the polarity of the contacts by simply connecting the battery to the left or right pair of pins.

Step 4: Making the Case

Now let's start assembling the body. To do this, take a ruler and use a sharp knife to mark the lines, scratching them about 10 times, so that you don’t have to put a lot of effort on the workpiece and don’t use the ruler anymore. Having scratched the lines to a sufficient depth, we apply pliers to them and bend the workpiece until it breaks along these lines. Having “broken” all the necessary parts in this way braincase, we clean them and adjust them to each other. Then we attach them to a stable surface and, using a drill, make holes and slots for screws, a switch, inputs, outputs and pin connectors.

Step 5: Circuit Assembly

Before you begin assembly brain devices First we assemble the electrical circuit, and focus on the presented diagram. A small switch here is used to turn the DC/DC converter on/off.

Step 6: Final Assembly

Using a glue gun, we glue the boards to each other, and then to one of the body parts. Next, we glue the entire body and screw a stationery clip to it.

We connect the battery through the pin connector and try homemade In action. If it does not work, then connect the charging cable.

Step 7: Use!

Well, now your old phone batteries are back in business!

The version of the case I proposed is of course not ideal, but it will do for demonstrating the whole concept. I can even bet that you will come up with a much better solution :)

That's all, everyone brain success!

Prologue

The idea to build this design was inspired by a flight on an Airbus A380 aircraft, in which there is a USB connector under the armrest of each seat, designed to power USB-compatible devices. But such luxury is not available on all planes, and even more so it cannot be found on trains and buses. And I have long dreamed of rewatching the series “Friends” from beginning to end. So why not kill two birds with one stone - watch the series and brighten up your travel time.

An additional incentive to build this device was the discovery.

Technical task

The Portable Charger must provide the following capabilities.

1. Battery operating time under rated load is at least 10 hours. High-capacity lithium-ion batteries are ideal for this purpose.


2. Automatic switching on and off of the charger depending on the presence of load.


3. Automatic shutdown of the charger when the battery is critically discharged.


4. The ability to force the charger to turn on when the battery is critically discharged, if necessary. I believe that on the road a situation may arise when the battery of a portable charger is already discharged to a critical level, but the phone needs to be recharged for an emergency call. In this case, you need to provide an “Emergency power-on” button to use the energy still available in the battery.


5. The ability to charge the batteries of a portable charger from a network charger with a Mini USB interface. Since you always take a phone charger with you on the road, you can also use it to charge the batteries of a portable power supply before the return journey.


6. Simultaneous charging of charger batteries and recharging of a mobile phone from the same mains charger. Since the network charger from a mobile phone cannot provide sufficient current to quickly charge the battery of a portable charger, the charge can take a day or more. Therefore, it should be possible to connect the phone to charge directly while the battery of the portable power supply is charging.

Based on this technical specification, a portable charger using lithium-ion batteries was built.

Block diagram

The portable memory consists of the following components.

1. Converter 5 → 14 Volt.
2. A comparator that turns off the charge converter when the voltage on the lithium-ion battery reaches 12.8 Volts.
3. Charge indicator – LED.
4. Converter 12.6 → 5 Volts.
5. A 7.5 Volt comparator that turns off the charger when the battery is deeply discharged.
6. A timer that determines the operating time of the converter when the battery is critically discharged.
7. Converter operation indicator 12.6 → 5 Volts - LED.

Switching voltage converter MC34063

It didn’t take long to choose a driver for the voltage converter, since there wasn’t much to choose from. At the local radio market, at a reasonable price ($0.4), I found only the popular MC34063 chip. I immediately bought a couple to find out if it was possible to somehow forcibly turn off the converter, since the datasheet for this chip does not provide for such a function. It turned out that this can be done by applying supply voltage to pin 3, intended for connecting the frequency-setting circuit.

The picture shows a typical circuit of a step-down pulse converter. The forced shutdown circuit, which may be needed for automation, is marked in red.

In principle, having assembled such a circuit, you can already power your phone or player if, for example, the power is supplied from ordinary batteries (batteries).

I will not describe in detail the operation of this microcircuit, but from the “Additional Materials” you can download both a detailed description in Russian and a small portable program for quickly calculating the elements of a step-up or step-down converter assembled on this chip.

Lithium-ion battery charge and discharge control units

When using lithium-ion batteries, it is advisable to limit their discharge and charge. For this purpose, I used comparators based on cheap CMOS chips. These microcircuits are extremely economical, as they operate on microcurrents. At the input they have field-effect transistors with an insulated gate, which makes it possible to use a microcurrent Reference Voltage Source (RPS). I don’t know where to get such a source, so I took advantage of the fact that in microcurrent mode, the stabilization voltage of conventional zener diodes decreases. This allows you to control the stabilization voltage within certain limits. Since this is not a documented inclusion of a zener diode, it is possible that in order to provide a certain stabilization current, the zener diode will have to be selected.

To provide a stabilization current of, say, 10-20 µA, the ballast resistance should be in the region of 1-2 MOhm. But, when adjusting the stabilization voltage, the resistance of the ballast resistor may turn out to be either too small (several kiloohms) or too large (tens of megaohms). Then you will have to select not only the resistance of the ballast resistor, but also a copy of the zener diode.

The digital CMOS chip switches when the input signal level reaches half the supply voltage. Therefore, if you power the ION and the microcircuit from a source whose voltage you want to measure, then a control signal can be obtained at the output of the circuit. Well, this same control signal can be applied to the third pin of the MC34063 chip.

The drawing shows a comparator circuit using two elements of the K561LA7 microcircuit.

Resistor R1 determines the value of the reference voltage, and resistors R2 and R3 determine the hysteresis of the comparator.

Charger switching and identification unit

In order for a phone or player to start charging from a USB connector, it needs to be made clear that this is a USB connector, and not some kind of surrogate. To do this, you can apply a positive potential to contact “-D”. In any case, this is enough for Blackberry and iPod. But, my branded charger also supplies positive potential to the “+D” contact, so I did the same.

Another purpose of this node is to control the switching on and off of the 12.6 → 5 Volt converter when a load is connected. This function is performed by transistors VT2 and VT3.

The design of the portable charger also includes a mechanical power switch, but its purpose is more likely to correspond to the “mass switch” of the battery in a car.

Electrical circuit of a portable power supply

The figure shows a diagram of a mobile power supply.

C1, C3 = 1000µF

C2, C6, C10, C11, C13 = 0.1µF

C14 = 20µF (tantalum)

IC1, IC2 – MC34063

DD1 = K176LA7	R3, R12 = 1k	R27 = 44M
DD2 = K561LE5	R4, R7 = 300k	R28 = 3k
FU=1A	R5 = 30k	VD1, VD2 = 1N5819
HL1 = Green	R6 = 0.2 Ohm	VD3, VD6 = KD510A
HL2 = Red	R8, R15, R23, R29 = 100k	VT1, VT2, VT3 = KT3107
L1 = 50mkH	R10, R11, R13, R26 = 1M	VT4 = KT3102
L2 = 100mkH	R16, R24 = 22M	Are being selected
R0, R21 = 10k	R17, R19, R25 = 15k	R14* = 2M
R1 = 180Ohm	R18 = 5.1M	R22* = 510k
R2 = 0.3Ohm	R20 = 680Ohm	VD4*, VD5* = KS168A

Purpose of circuit nodes.

IC1 is a step-up voltage converter 5 → 14 Volts, which serves to charge the built-in battery. The converter limits the input current to 0.7 Amps.

DD1.1, DD1.2 – battery charge comparator. Interrupts the charge when the battery reaches 12.8 Volts.

DD1.3, DD1.4 – indication generator. Makes the LED flash while charging. The indication is made by analogy with Nikon chargers. While charging is in progress, the LED flashes. The charge is complete - the LED lights up constantly.

IC2 – step-down converter 12.6 → 5 Volts. Limits output current to 0.7 Ampere.

DD2.1, DD2.2 – battery discharge comparator. Interrupts battery discharge when the voltage drops to 7.5 Volts.

DD2.3, DD2.4 – timer for emergency switching on of the converter. Turns on the converter for 12 minutes, even if the battery voltage drops to 7.5 Volts.

Here the question may arise, why such a low threshold voltage was chosen if some manufacturers do not recommend allowing it to drop below 3.0 or even 3.2 Volts on the bank?

I reasoned like this. Traveling does not happen as often as we would like, so the battery is unlikely to have to go through many charge-discharge cycles. Meanwhile, in some sources describing the operation of lithium-ion batteries, a voltage of 2.5 Volts is called critical.

But, you can limit the discharge limit to a higher voltage level if you plan to use such a charger frequently.

Construction and details

I express my gratitude to Sergei Sokolov for his help in finding the design components!

Printed circuit boards (PCBs) are made of foil-coated fiberglass laminate with a thickness of 1 mm. The dimensions of the PP were selected based on the dimensions of the purchased case.

All elements of the circuit, except the battery, are placed on two printed circuit boards. Moreover, on the smaller one there is only a Mini USB connector for connecting an external charger.

The power supply units were placed in a standard Z-34 polystyrene housing. This is the most expensive part of the design, for which we had to pay $2.5.

The power switch pos. 2 and the forced power button pos. 3 are hidden flush with the outer surface of the case to avoid accidental pressing.

The Mini USB connector is located on the rear wall of the case, and the USB connector pos. 4 together with indicators pos. 5 and pos.6 to the front.

The size of the printed circuit boards is designed to fix the batteries in the body of the portable power supply. Between the batteries and other structural elements, a 0.5 mm thick electrical cardboard gasket, bent in the shape of a box, is inserted.

	This movie requires Flash Player 9

And this is a portable power supply unit in assembled form. Drag the image with the mouse to view the power supply from different angles.

Settings

Setting up a portable charger came down to selecting instances of zener diodes and ballast resistors for each of the two comparators.

How it works? Video illustration.

The three-minute video shows how this homemade product works and what is inside. Video format – Full HD.

Hello dear friends!

Today I will tell you how to make a “Portable USB charger” with your own hands.

For this we need:

1. Car USB charger in the cigarette lighter.

2. Four wires.

3. Small on/off switch. I took it from an old table lamp. But it turned out to be impractical and I replaced it with a switch from a lamp.

4. Three Krona batteries.

5. A box of "Fort" coffee, or something else. You need either iron or plastic.

6. Glue gun.

And so: We take our car USB charger into the cigarette lighter, disassemble it, and take out the board. This is the most important part of our portable charging. On one side of this board you will see a spring and a small piece of iron plate. The spring in the middle is always a plus, and the iron plate on the side is always a minus. The spring can simply be soldered to the board or to the wiring and the wiring to the board. It’s the same with this piece of hardware on the side.. If the spring is soldered to the board, then we carefully unsolder it and solder the wires in its place. Then it’s the same with this piece of iron. If the spring is soldered to the wiring, then simply unsolder the spring from the wiring. It’s the same with this piece of hardware. After soldering the wiring to the board, let’s debug it to the side for now. Let's start making the terminal that we will need to connect the battery. The finished terminal can be removed from old children's toys or from anything where a Kron-type battery was attached. Or you can make it yourself. To do this, take one Kron battery, remove the plug from it, turn it over, take soldering flux, soak a cotton swab in it and degrease the contacts. Then we take the wires and solder them to the contacts. After soldering, take a glue gun and apply glue to the place where the wires were soldered. So we're just doing isolation. Then we take our terminal and connect the battery to it. We do this in order to make sure where we have a plus and where we have a minus. When we are sure where the plus and where the minus are, we take our board to which we soldered wires instead of a spring with a piece of iron, and twist the wires minus with minus and carefully insulate the wires that we twisted with electrical tape. And we will let the plus through the switch. To do this, we take our switch; it has two contacts; to one we solder the wiring that comes from our board, and to the other we solder the wiring that comes from the terminal. Now our charger is almost ready. All that remains is to place it all in the case.
To do this, we take our box; in my case, it’s the “Workstation First Aid Kit” box for repairing pneumatic tires.. We make a hole for USB.
Then we make a hole for our switch.

Now let's take our insides. And this is our board, switch, and terminal. And we install it all inside the box. We attach the board to the bottom of the box using a glue gun, just like our switch. We also attach it to the box using a glue gun.
Now we connect our battery and close the box. We connect the phone, turn on the charger and our phone charges. P.S. The input power of car USB chargers into the cigarette lighter is only 12V, so in no case do not connect it to power sources above 12V, otherwise it will simply burn out. The power of the Kron battery that I used for this portable charger is only 9V, which is quite enough to charge a phone, iPhone, camera, tablet, etc. approximately 2-3 times depending on the power of your battery... after which you will have to change the battery. I have a 3000 mAh battery in my phone, so the Kron battery is enough to maintain the battery charge and not fully charge it. Therefore, I replaced the Kron battery with a 12V battery, which is quite enough to charge the phone. To do this, we simply make 2 terminals from Kron batteries, solder one of them to the battery and that’s it, simply connect it to our portable charger. But in order not to buy a new battery every time, I would advise you to buy a charger for Kron batteries and when one battery runs out, you put it on charge and put the other in your portable charger. Or you can make a charger for Kron batteries yourself. But as? I will tell you about this in the next issue. Bye everyone, all the best. If you have any questions, write to my mailbox.