Power bank connection diagram. Homemade power bank? it's simple! Power bank from finger batteries

Good day to all dear friends! In today's article, I would like to show you how to make a portable portable phone charger - Power Bank. Its camping qualities lie in the fact that it can be charged using solar energy. This Power Bank will cost quite cheaply, since secondary batteries and cheap batteries will be used in its assembly. Chinese components from online stores. Oh well, enough long prefaces, let's go!

Of the tools we will also need:
- Soldering iron.
- Super glue.
- Screwdriver.
- Pen (or pencil, marker, etc.).
- Stationery knife.
- Drill.
- Thermal glue.

Before you start building a Power Bank, you should deal with batteries. It was decided to use 18650 batteries, since this is the most common battery format and it will be easy to find a control module for them in Chinese online stores. You can buy these batteries new, which is very good, but you can save money and get these batteries from an old laptop, just like the DIY author did. But you must understand that the use of old batteries will not have the characteristics of Power Banka, there will be slow charging, small capacity, etc.

Cut out a window for the display. The MTF panel is quite soft and in order to cut a window for the display, we need a clerical knife. We simply draw several times with a knife along the marked contour, using force.

Seeing that the LED from the control board interferes a little, the author decided to make holes so that its indication could be seen and the LED did not rest. And also glued to the body.

Since our solar battery is smaller than the Power Bank case and it will not be enough to use the wall. For the last wall of the case, we will cut out a small rectangle from the MTF panel, and glue it with super glue to the indicated place as in the photo.

The device, in itself, is quite useful, when it’s not quite Chinese, and it costs 2 times more. This one was ordered just for experiments and improvements. About a month later, the device crawled to the local post office, and then fell into our hands:

Such is the unremarkable black glossy case. At the top is some kind of button and what should be a level indicator. On one end of the case there is a miniUSB connector for charging the device, and on the other - two USB connectors for connecting mobile equipment. The Chinese promise them 5V with currents of 1A and 2.1A.

A few days later, he was subjected to ruthless disassembly, for this, in principle, he was ordered. It turned out to be quite easy to disassemble this miracle of technology, the Chinese tightly sealed the case around the perimeter. And now, after half an hour of torment, the following picture appeared before our eyes:

Inside there were 4 18650 batteries, the same as in laptop batteries (just such batteries were prepared before ordering the device), while only two of them turned out to be connected. As it turned out later, the unconnected batteries showed no signs of life and had already begun to rust under the plastic wrap. In this connection, they were immediately sent to the trash.

Between the batteries, the control board was comfortably attached, which contained:

• boost STEP-UP converter on some unknown chip with a rating 8628 (d Atashit on it could not be found);
• a voltage level control circuit to prevent overdischarge of batteries and, in combination, a charger on two DW01 microcircuits (control microcircuit) and 8205A (two MOSFET transistors);
• a pair of transistors to turn on the "charge level indicator";
• "charge level indicator", which actually turned out to be four LEDs connected in parallel.

We did not touch the converter circuit, because enough to charge your phone. In addition, there is overcurrent protection. Yes, the USB connectors marked 5V 1A and 5V 2.1A are connected in parallel. But the control / charging circuit was taken up closely. It turned out to be standard, these are put on ordinary lithium batteries. It looks like this:

MOSFET transistors M1 and M2 are just the 8205A chip. From further use of it as a charger had to be abandoned. Firstly, when 4 batteries were connected, it heated up quite strongly, and secondly, about 5V was supplied to the batteries themselves. Yes, and charging 4 batteries connected in parallel, and even without temperature control, is not the best idea. Therefore, the search for an alternative solution began. The choice fell on microchips. Her characteristics are:

• supply voltage from 4 to 8V. (typical 5V.);
• configurable charge current. maximum current 1A;
• battery charging voltage level 4.2V;
• temperature control with a NTC thermistor;
• minimum external components.

Scheme of inclusion infrom this (taken from the datasheet):

It turns out a very convenient thing, you only need to set the charging current level with the Rprog resistor and apply power, and the microcircuit will take care of the rest. The Chinese, by the way, produce ready-made modules for charging lithium batteries, but there is no provision for connecting a thermistor, which is a huge minus.

The chips themselves were ordered from the same ebay, in the amount of 5 pieces. At first it was supposed to make a separate channel for each battery, but due to space limitations, I had to limit myself to two channels and connect the batteries in pairs (especially in a laptop battery it was done in exactly the same way). As a result, this scheme was born:

As you can see, in addition to the charger circuit, two indicator LEDs were added to the device. HL1 lights up when the charging process is completed by both microcircuits, i.e. as long as one of them continues charging and the end signal is not issued, the LED will not light. The HL2 LED lights up if one of the microcircuits stops signaling normal operation (i.e., overheating, breakage, dead battery, etc.). In the meantime, both microcircuits say that everything is fine, the LED is off. Pairs of batteries are connected through diodes to exclude the influence of microcircuits on each other during operation. The diode should be selected with the lowest junction resistance, otherwise the output voltage will be noticeably lower than the battery voltage and the control circuit will turn off the converter too early. I took the S30SC4M diode assembly from computer block power supply, the voltage drop was 0.25V. A fairly good result, although not ideal. The charge current is adjusted based on the parameters of the charger. As it turned out, none of the ones we have gives a current of more than 1A. Therefore, the charging current for each pair of batteries is limited to 0.5A. It is just comfortable for microcircuits to work, but with a higher current, you will have to think about cooling the microcircuits. The thermistors were soldered from a laptop battery. At room temperature, they had a resistance in the region of 8K. The microcircuit considers the situation an emergency if the voltage at the first output becomes less than 45% of the supply (2.25V) or above 80% of the supply (4V.). Based on this, the values ​​​​of the resistive divider at pin 1 of the microcircuits were selected.As a result, at room temperature, about 3V comes to the TEMP pin. at room temperature.

The whole thing was assembled on this board:

It can not be called a masterpiece, but it was, frankly, too lazy to redo it. Moreover, this board works fine, there are no breaks or short circuits on it, and a couple of blurry tracks have not bothered anyone yet. The "burdocks" on both sides of the board are thermistors and just fit conveniently under the batteries. Yes, 0.5 ohm resistors could not be found, so I soldered two 1 ohm resistors. parallel to the "sandwich".

Now it's time for the most interesting point, the connection of two boards - Chinese and ours. Before starting the merging procedure, some modifications must be made to what was originally installed in the device. Firstly, for some incomprehensible reason, the Chinese made it so that when external power was supplied to the board, the converter started up and threshed into an empty one. Secondly, the LEDs of the "level indicator" began to glow, which interferes quite strongly at night. So, we take the board and begin to solder unnecessary elements from it:

Namely, a diode (so that there is no unnecessary voltage drop, and it did not warm up weakly, later a resistor with a rating of R470 was removed), and a 100K resistor. (Just through it, the fact of supplying the supply voltage was controlled). At the same time, we change the resistors in the DW01 harness in accordance with the datasheet - 470 Ohm to 100 Ohm, and 2K to 1K. (they are not changed in the photo). On the back of the board, we also make some changes:

Separate input and output land. Now the control of the voltage supply to the converter is completely dependent on the DW01 chip. and solder the wires:

Left wire +, right wire -. Accordingly, later, after excluding the resistor R470, the positive wire is soldered to the pad near the miniUSB connector. The resistor itself performed a purely protective function, but since. we have a separate 0.5 ohm resistor on each chip, this one is superfluous.

Later it turned out that it was necessary to make one more revision of the board:

I had to connect the button directly to the minus of the batteries. This is due to the fact that the circuit has overcurrent protection (as mentioned above). It is all built into the same DW01 chip and with two dead batteries it worked fine (when the load increased, the current on the batteries simply sagged), but miracles began with four. It turned out that if you connect two phones for charging at once, the control circuit immediately disconnects the batteries from the converter. But he does not want to turn it back into any. It helped either reconnecting the batteries, or a short-term supply of minus power, bypassing the control circuit. Naturally, the second method is much simpler and more convenient. Therefore, the button was connected directly to the minus of the batteries, with reverse side the 1A transistor was removed (connected just parallel to the button, it launched the "level indicator" when external power was connected), which can be seen just below the throttle, and a series-connected diode and a 470 Ohm resistor are soldered in its place. We solder the diode cathode to the collector pad (bottom in the photo), and the resistor to the emitter pad (left in the photo). The junction of the resistor and the diode very conveniently fell on the base site, which, after removing the resistor by 100K, remained absolutely free. A resistor and a diode are needed to protect the circuit (maybe we have a short circuit at the output, but we directly feed the minus). Now, after the protection is triggered, it is enough to turn off the load and press the button.

Now everything is ready for the reunion. In our board, the pads are displayed exactly opposite the pads on the Chinese board. Batteries were previously connected to these sites. I just took and drilled holes in them. Then I soldered two thick leads left after soldering the diode bridge to my board, and then soldered them to the main board, soldered the LEDs, wires from the batteries and power (the minus of the batteries is connected to the same place where it was originally, near USB connectors and minus the power supply from the miniUSB connector goes there too). I think that in graphical form it will be clearer, because it is better to see once than ...

In reality, it all looks like this:

In this form, the whole thing was checked for two days, and then it was packed back into the case:

Holes were drilled for the LEDs near the miniUSB connector. The left LED indicates the end of charging, and the right one indicates the presence of an accident. The additional fee has become perfect, as if the Chinese had left a place for it

We connect the charger, but not what came in the kit, but a normal one, honestly giving out 1A. 5V. at the exit. Waiting a while and...

Charging completed, you can use. A full charge is enough for 3-4 full charges of the phone. Despite the fact that at that time they use this very phone and the batteries were not installed new. The goal is achieved, the output is a full-fledged portable charger.

List of radio elements

Today you will not surprise anyone with the presence of a smartphone, tablet or camera. Every person has all these special gadgets, but quite often there are situations when it is not possible to recharge them using a charger through the mains.

In this case, you will definitely need a power bank or an external battery that is used for recharging portable devices, for example, while hiking. Of course, you can buy a ready-made power bank, but why spend money if you can make it yourself.

We bring to your attention several do-it-yourself power bank construction schemes.

1. Power bank from rechargeable batteries mobile phones

So, let's look at how to make a power bank with your own hands using several mobile phone batteries. For this you will need:

A few common mobile batteries(preferably six or nine) with a capacity of 1020 mAh each.

We install the batteries parallel to each other and wrap them lengthwise with adhesive tape, and across with electrical tape. Please note that the terminals must be open, to which the wires will later be soldered.

We solder our batteries together by connecting two terminals: “plus” and “minus”. The central terminals of the battery or the temperature sensor can be omitted, since they are only needed to show the remaining charge level of this device.

We make control measurements and attach everything with hot glue.

And voila, you're all set!

This Power bank will be enough for you for four or five full recharges of your phone.

2. An external battery from a simple flashlight

To build a Power bank from a flashlight, we need:

Directly the flashlight itself with a 3.7 volt battery;

Voltage converter with built-in USB output, which allows the 3.7 Volts of the flashlight's lithium-ion battery to be converted to 5 Volts;

charge controller.

a) Dismantle the device.

B) Remove one of the lamp resistors (an LED must be soldered to it). This will allow you to replace one of the bright glow modes with new mode- Power Bank.

C) In the place where the plug for recharging the flashlight is located, we place our converter with a USB output.

D) We solder "plus" and "minus" from the battery to the battery charge controller. After that, we solder a 5V converter to the OUT + / OUT- contacts of this controller.

Please note that you first need to release one switch contact and solder the converter to it.

E) Now we check the performance of the converter, if necessary, solder it.

E) So, if everything works, use epoxy glue to glue the controller and the converter.

G) We collect a flashlight and can use it.

Now you will always be in touch and in the light, the main thing is not to forget to charge the flashlight battery!

3. Power bank from simple batteries 2200 mAh 3.6 V

For this Power bank you will need:

Lithium-ion batteries themselves (preferably 8 pieces);

There can be all sorts of situations in life - an empty smartphone battery and the lack of power outlet for recharging nearby - a frequent occurrence. That is why we decided to make our own powerful power Bank from an old laptop battery, with USB power. Of course, you can buy Chinese, but their 10,000 and 20,000 mA is a big exaggeration! This article will show you how to assemble a device consisting of a Lithium Battery Charger Module, a USB Boost Converter, and a Power Bank Battery Status LED.

Where to get lithium batteries

It’s better not to buy the batteries themselves (it’s expensive and there are a lot of weak ones), but to use them from an old laptop. Inside this, which is in the photo - 3 packs of two parallel assemblies of lithium 18650 type 2200 mAh, which are connected in series.

In our design, we will use all 3 packages in parallel, having previously checked whether they hold a charge well for a sufficiently long time.

As a last resort, if some banks are already quite weak, put one double package - then the bank will become lighter and smaller, albeit weaker.

Modules Power Bank

The next important part of the USB Powerbank is the charging board. For this, a cheap one was chosen. Additionally, it disconnects the load if the lithium battery voltage drops below ~3.7 Volts, thereby protecting battery from deep discharge.

Now we take a circuit that increases the voltage from the batteries to 5 volts (to power the USB output). This is any boost converter to USB.

How to connect it to each other -. Naturally circuit diagram will have a small toggle switch to enable Power Bank. The toggle switch is needed because the boost converter is always powered by the battery (and draws a small amount of current), even if no device is connected to the USB.

Housing for homemade Power Bank

It is better to take a non-metallic case - a suitable plastic box, cable channel, and so on. For this project, a non-standard and environmentally friendly material was used - wood, more precisely fiberboard. Two covers and walls along the perimeter, all this is connected with screws.

Once again, the topic of the article is devoted to PowerBanks. Today you can see a simple good scheme without any microcircuits, only on some transistors.

The circuit is a simple stabilized step-up, which is able to increase the voltage from a power source, for example, from a lithium battery, to a level of 5 V. This voltage will already allow you to charge tablets and smartphones.

Of course, such a boost converter module can be purchased in China for about $ 1, but the operation of a device assembled by oneself brings much more pleasure. In addition, this scheme practically does not require any financial costs, and you do not have to wait a month, as in the case of ordering goods from China.

A few words about the scheme and the principle of its operation.

There is a multivibrator as a pulse generator. In the presented version, it is tuned to a frequency of about 30 kHz.

The principle of operation of the scheme does not differ from its relatives. The initial pulse from the multivibrator, entering the base of the composite transistor, opens it. At the moment the transistor closes, self-induction EMF pulses arise from the inductor, which are rectified by the fast diode D1 and smoothed out by the capacitor C1. The output voltage is stabilized, and it is set by selecting the Zener diode VD1.

Transistor VT2 opens when the output voltage from the converter exceeds the specified stabilization voltage. The base of the transistor VT1 is shorted to ground through its open junction. As a result, the latter is closed.

Coefficient useful action this converter can reach up to 70-75%. And this is very good. But in order to achieve such efficiency, you will have to spend more than one hour rewinding the throttle, because a lot depends on it.

The maximum current value that could be obtained at the output was about 1 A. The stabilization works as it should. The device is suitable for real use.

A lot of time was also spent on the creation of the board. It is compact and looks very nice.

You can download the board at the end of the article.

It's time to talk about element base and schema setup. Transistor VT1 is recommended to take composite. The experiments were carried out with different transistors, but in the end the most suitable ones turned out to be KT829, KT972 or something from imported ones, for example, BD677, etc.

The inductor is wound on a dumbbell-type ferrite core. It was removed from the computer power supply board. You can also use powdered iron rings or a core core. The number of turns and the diameter of the wire were selected through experiments. Ultimately, the inductor was wound with 8 mm wire (deviation up to 20% is possible). The number of turns was 25.

Adjusting the converter is reduced to obtaining the desired output voltage and the minimum current consumption at idle. In the described example, the minimum no-load current is 40 mA and depends on the inductor. This is a lot when compared with ready-made Chinese modules. But nothing can be done - you should not expect more from a banal multivibrator.

The stabilizer is also subject to selection. The stabilization voltage is selected in the range of 4.7-6.2 V. In the example, a zener diode of 5.1 V is used.

The composite transistor is still bipolar, and it can be heated during operation, so a small heat sink in the form of an aluminum sheet will be very useful.

Do not forget to check the device for operability. The wattmeter on the Chinese USB tester is a little "buggy" - the real voltage is approximately 5 V and can "walk" in a small limit, which is completely normal. The charge current will also change.

Now take a look at the design of the PowerBank as a whole. The converter is powered by two 18650 (Li-ion) batteries connected in parallel. They were removed from the laptop battery. The working capacities of both should be as close as possible to each other.

Also, the batteries were supplemented with a protection board that turns them off when the voltage drops below 3.2 V. .

To do this, the following charge board is involved in the device:

Such boards already come with a battery protection circuit. Such boards are easier to buy than to make, because their price is only 30-50 cents.

Now assembly. The first step is to prepare the batteries. Soldering them is undesirable, but possible. The main thing is not to overheat.

The number of batteries can be any. In the example, there are 2 of them. The larger their capacity, the longer the PowerBank's operating time. All batteries are connected in parallel.

The PowerBank case came from an old laptop power adapter.

It remains to place all the details in the case, add a power switch, bring out the USB connector for charging phones, miniUSB for charging the PowerBank itself, and also bring out a couple of LEDs that are on the controller board. One of them lights up when charging is in progress, and the second lights up when it is completed.

Attached files: .

Charger for lithium batteries do-it-yourself