Power bank from a phone battery. Homemade power bank? it's simple! Assembly process and diagram
Once again the topic of the article is devoted to PowerBanks. Today you can see a simple good circuit without any microcircuits, just transistors.
The circuit is a simple stabilized step-up that is capable of increasing 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 yourself is much more enjoyable. In addition, this scheme requires practically no 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 circuit 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 circuit is no different from its relatives. The initial pulse from the multivibrator, arriving at 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 transistor VT1 is short-circuited to ground through its open junction. As a result, the latter closes.
The efficiency of this converter can reach 70-75%. And that's very good. But 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 was obtained at the output was about 1 A. Stabilization works as expected. The device is suitable for real use.
A lot of time was also spent on creating 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 the element base and circuit setup. It is recommended to take a composite transistor VT1. Experiments were carried out with different transistors, but in the end the most suitable were KT829, KT972 or something imported, for example, BD677, etc.
The inductor is wound on a dumbbell-type ferrite core. It was removed from the computer's power supply board. You can also use powdered iron rings or a rod core. The number of turns and diameter of the wire were selected through experiments. Ultimately, the inductor was wound with a wire with a diameter of 8 mm (deviation up to 20% is possible). The number of turns was 25.
Setting up the converter comes down to obtaining the required output voltage and 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 shouldn’t expect more from a banal multivibrator.
The zener diode 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 heat up during operation, so a small heat sink in the form of an aluminum sheet will be very useful.
Don't forget to check the device's functionality. The wattmeter on the Chinese USB tester is a little “buggy” - the actual voltage is approximately 5 V and can “walk” within a small limit, which is completely normal. The charging current will also change.
Now take a look at the PowerBank design as a whole. The converter is powered by two 18650 (Li-ion) batteries connected in parallel. They were taken from a laptop battery. The working capacities of both should be as close as possible to each other.
The batteries were also supplemented with a protection board that turns them off when the voltage drops below 3.2 V.
To do this, the device uses the following charge board:
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. It is not advisable to solder them, but it is 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 housing for the PowerBank came from an old laptop power adapter.
All that remains is to place all the parts in the case, add a power switch, bring out a 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 charging is complete.
Attached files: .
DIY charger for lithium batteries
In this article I will tell you how you can assemble a very cheap power bank from all sorts of rubbish that you should definitely have on hand. More precisely, something similar to a power bank, but it will perform its main function quite well. This portable charger for a smartphone will operate on a battery or Krona battery, 9 or 12 volts.
What is needed for assembly
- Ballast housing for fluorescent lamps
- Crown terminal
- Battery or battery Krona
- USB socket
- Toggle switch or button
- Voltage stabilizer 7805
- Two 100n capacitors
Preparing the case for the power bank
The ballast housing for fluorescent lamps is very convenient for such homemade products, at least it’s just right for my power bank. The crown and USB socket fit into it very well. By the way, you can take any socket; I had a broken car USB charger lying around and I took it from there. The socket is triple and installed on the board, the board itself is exactly the right size for my case, you can see this in the photo below. You can also take a single socket, make a hole for it in the case and fix it with hot glue!
So, there were a lot of unnecessary parts in my case, and using a hacksaw and a blade, I successfully got rid of them. Namely, I cut off one of the fastenings of the case with the base, and on the other side I removed only the fastening.
Next, we make a small hole in the case to output wires to the USB connector and on the other side another hole for the toggle switch. Well, or in any other place, it all depends on the size of the button used, I had a large one, so it fit right there.)
The body preparation is complete, now let's move on to assembly!
Power bank assembly
First we need to assemble a voltage stabilizer, the heart of our bank! To assemble the stabilizer I used the following diagram:
The circuit is very simple, I think it will be easy to assemble. Any 7805 can be used as a stabilizer; I took the KIA7805. We also need two 100n capacitors, but that’s basically it. We solder the circuit by surface mounting, immediately solder two thin insulated wires to the output and a terminal for the crown to the input. Please note that the terminal must be soldered into the gap on the toggle switch so that our power bank can be turned on and off!
We place the assembled circuit in the case. I glued the stabilizer with hot glue near a small hole in order to bring the wires to the USB socket.
After installing the toggle switch, I realized that the crown would not fit into one of the compartments, where it fit very well, and I had to cut off the partition.
Next, we pass the wires through a small hole and solder them to the USB socket. Be careful not to reverse the polarity!
We glue the socket itself to the end of the case using hot glue.
Close the back cover and that’s it, our bank is ready!))
It turned out very compact and neat! Believe it or not, with the help of one new Krona battery, I was able to charge a completely dead smartphone battery and recharge it a couple of times from half charge.
This is the best DIY power bank you've ever seen!
And now you can make your own. All examples of electrical parts and housing are described here. I'm sure you can come up with your own ideas for creating the case, but feel free to use mine.
This power bank has 4 high current USB outputs giving a total of 10A and a real capacity of 30000mAh from a 1S1P lithium polymer battery. And... it can be charged in just 1 hour! Charge all your devices from one source!
Watch the video for all the specifications and some instructions on how to make a power bank.
Step 1: Ingredients
To get started, you need:
- Battery
- Battery Management System (BMS)
- Charging module
- DC-DC Boost Converters
- Various small things (USB connectors, wires, fuses, banana plugs...)
- Frame
Step 2: Battery
First, of course, we will deal with the battery. The part that powers our entire external battery. If you want a powerful device, it needs to be big. This circuit is designed for one lithium battery. I used a battery from Kokam. I was satisfied with the 30000mAh figure. You can choose a larger or smaller capacity option depending on what you want to achieve.
Kokams are quite hard to find and expensive, but don't worry. If you could not find such a power bank, you can connect several smaller batteries in parallel to obtain the same capacity. The voltage will remain the same. Thus, all small batteries used for remote control models and toys will fit. Just connect them as in the photo. 18650 batteries will also work for our needs!
Don't forget the fuse. I used a 40A fuse, since in my case the current in fast charging mode is 30A. If you don't plan on charging it as quickly, you can use smaller fuses.
Step 3: Battery Management System (BMS)
Lithium batteries cannot be “overcharged” or “overdischarged”. To protect them from such cases, we use a simple 1S BMS board, which can be found cheaply on Ebay. Just find a BMS that can handle enough current. Mine is rated at 10A. Connect everything as shown in the photo.
Step 4: Charger
I have two options for charging: fast and slow. You can choose one or the other, but I wanted both to be available.
The first and slow option allows you to use any micro USB charger to charge the external battery slowly. To do this, you need to adapt a charging board that will lower the voltage to 4.2V and charge the battery. (search on Ebay: 1s lithium battery charging module TP4056). The current will be limited by the charger's output current (usually up to 2.1A). This module can also support 3A current, so it will charge from a 3A charger as long as it supports that output current. Connect everything as shown in the photo.
If you have an external lithium battery charger, you can add a fast charging input. Simply add two banana plugs and connect them as shown in the photo. Your charging limit is now limited by the amperage of your external charger. I use a 30A Reaktor charger so I can charge my battery in just 1 hour.
Carefully! In the photo, the banana connectors are connected after the BMS board. Do the same if your external charger does not produce more than 10A. If it charges more than 10A, connect the banana plugs immediately after the + and - fuse of the battery before the BMS. This is how my external battery is assembled. Only do this if you know what you are doing. Unprotected charging may cause a fire!
Step 5: Switch
Use the switch to turn your power bank on and off.
It is only used for power bank mode (DC modules and display), so you can charge your power bank even when it is turned off.
Step 6: DC-DC Boost Converters
DC-DC boost converters will raise the voltage to 5V. This is what you need to charge your USB devices.
Converters can be found on Ebay, I used 2 pieces of 5A LM2587.
Carefully! Please follow the instructions in my photo before connecting them to your power bank. You need to set the voltage at their output to 5-5.3V, otherwise you may damage the device you connect to charge.
Step 7: Putting it all together
Once the DC/DC boost converters are set to the correct voltage, connect them as shown in the photo. Add as many USB ports as you need. 2 ports per 5A DC module is the best option to quickly charge all your devices.
Here's another video that includes all the previous instructions and photos to help you get it right.
It took me a little time to make this case. I designed his model in Autodesk Inventor. Then I found someone who could cut it out of aluminum. I sanded the outer surface, painted it and finally engraved it. This case fits the battery I used. And you can make the body from any material and any shape you like. The main thing is that all parts and the battery fit well inside. My first thought was to make the body out of wood, but I changed my mind and made it metal :)
Happy charging to you!
A power bank can be not only a useful device that allows you to urgently charge a mobile gadget, but also a beautiful accessory. This material provides an overview of a video on making an original Power bank in an apocalyptic style.
We will need:
- USB charger for car;
- 9 volt crown battery;
- battery holder;
- switch;
- deodorant can;
- plastic;
- aerosol paint;
- acrylic paints
The first step is to open the device and disassemble it, removing the case and leaving only the circuit.
Now let's move on to making the box. To do this, you need to attach all the components of the charger along with the battery holder to the can, measure approximately how much space is needed inside and saw off the excess part of the can.
We also saw off the lower part, finishing everything with a file.
Cut a circle along the diameter of the can to close the can. You will also need another circle for the cover, which will allow you to replace the battery.
At this stage, you need to solder the battery holder and switch to the charger board, and also bring the LED light bulb out. Note that the positive contact is located near the spring of the charger, and the negative contact is located near a small iron part.
We check the charger for functionality.
We will attach the circuit to a round piece of plastic. To do this, mark the places that need to be cut, that is, the places for the USB connector and switch, as well as the hole for the LED.
We secure all parts with a glue gun. The long board from the charger can be additionally secured with small pieces of plastic.
Glue the round part to the can, placing all the components inside.
We carefully handle all the irregularities and additionally secure them with cold welding.
We glue a second circle to the lid of the can, which you can decorate at your own discretion.
If desired, you can make beautiful contours by cold welding, adding originality to the Power bank.
We also decorate the can with copper wires running along it.
Next, paint the can with green spray paint.
Now you can give the workpiece a slightly rusty appearance. This can be done using acrylic paints.
It is also necessary to make small splashes on the sides to make the rust look more realistic. You can do this with an old toothbrush.
There are many ways to provide your mobile device with an external source of energy. Flagship smartphones today are equipped with proprietary wireless charging modules. Some people take it simpler and purchase additional batteries for their phone or tablet. Others use solar powered external batteries.
All these methods are good, but sometimes they cost a lot. Therefore, we will use a life hack and create our own power bank from improvised means:
- regular batteries;
- smart flashlight;
- old batteries.
Which one to choose is up to you, but they are all very simple and reliable in their design.
First way
For assembly you will need:
- 4 AA batteries, 1.5 V each.
- Plates.
- Wire.
- USB connector.
- Empty match boxes.
- Glue.
- Suitable size container for the entire structure.
We take empty boxes and bend them on one side so that a pair of batteries fits in each.
We install metal plates at the bottom of the boxes, thereby connecting the “+” and “-” batteries.
We connect the “+” and “-” of the two pairs to each other in a serial circuit, and connect the USB connector wire to the free contacts.
For convenience, the entire structure can be packed in a suitable container. The device is ready for use.
Important so that the output parameters correspond to the current consumed by your device (at least 1A in total, otherwise the device will take a long time to charge).
Second way
We disassemble the flashlight and connect a 5 V voltage converter to the terminals, observing the polarity. It can be removed from the old mains charger with a micro-USB connector. Solder the wires. We tie the structure with electrical tape for strength and compactness.
As a result, we get 2 in 1: both a flashlight and an external charger for a smartphone.
Third way
This design is prepared on the basis of old batteries from all kinds of household appliances. The total voltage should not exceed 5V. We solder only the side contacts together, since the central ones, as a rule, are responsible for exchanging information with the controllers. Then, as in the case of a flashlight, we solder a current power converter to the resulting powerful monolithic battery.
It is advisable to pack the entire structure in a compact container - a cream box or a soap dish.
Thus, you have made another external charging unit for your device.
