For skilled hands - a homemade battery. For skilled hands - a homemade battery How to make a battery more powerful
The first lead-acid battery was invented and tested by the French physicist Gaston Plante. He twisted two lead plates into a roll, after placing a separating cloth between them. The roll was placed in a vessel and filled with salt water. As a result, if you apply voltage to the plates, it will charge. And then, if you connect a light bulb or something else to it, then it could give up the stored energy for some time to burn this light bulb. Also, after charging, the energy in such a battery could be stored for a long time without loss. This marked the beginning of the era lead acid batteries.
But the most main drawback such a roll-on battery has a small capacity. Subsequently, it was found that if such a battery was charged and discharged several times, changing the polarity (+-), the capacity increased. This is explained by the fact that a layer of lead oxide formed on the plates, and the plates softened, becoming like a sponge. The acid could now penetrate deeper into the plates, thereby allowing more lead to participate in the chemical process.
These charge-discharge cycles, changing plus to minus and back again, were called plate forming. To build up a thick layer of lead oxide, a lot of energy and time had to be spent. But later, one young man who worked as Plante’s assistant decided to do it differently. He decided to immediately apply lead oxide to the plates, thereby immediately obtaining a more capacious battery. Subsequently, this technology was slightly improved. They began to make lead gratings, which were coated with lead oxide in the form of a paste. The paste was prepared from lead oxide, to which a little water or electrolyte was added and mixed until a thick consistency.
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After more than 100 years, battery manufacturing technology has not changed in principle. In production, lead gratings are also made by casting or stamping, and they are spread with a paste consisting of lead oxide, plus additional additives that prevent the paste from disintegrating and give other required properties. Also, the separating gaskets between the plates are made from modern materials, which prevents the grease from falling out of the gratings and prevents the plates from connecting to each other. In every factory, and for various types batteries (traction, starter, etc.) have their own subtleties, but in general the technology is the same.
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Now you can think about whether you can do lead acid battery at home so that it is profitable and effective. Firstly, it's about lead, where to get it? In unusable batteries, but if you melt down one car battery, the output will be only about 1.5 kg of lead, and it will become clear that extracting lead in this way is not profitable. To melt all the lead contained in the battery, some of which is in the form of oxide, sulfate and other elements that are contained in the coating of the grates, then you need a melting furnace and additional chemistry and conditions, so at home on a fire you will get tin lead and a whole heap of slag.
Then you can buy lead, there is sheet lead, and in ingots, it is not expensive. If you make it from sheet lead, you can roughly estimate the cost of one battery. If you delve into the literature, you can find out that from one square meter plate area, you can get a capacity of approximately 5-10Ah. Then for one can with a capacity of 50-100Ah you need 10 sq.m of lead. Since 12 volts requires 6 cans, then about 60 sq.m of lead is accordingly needed. The thinnest sheets on sale are 0.5 mm; the weight of one square meter of such lead sheet is 5.7 kg. Since the sheet area works on both sides, it means that we no longer need 60 sq.m. for the battery, but 30 sq.m. Then it turns out that for a battery with a capacity of 50-100Ah you need 30 * 5.7 = 171 kg of lead, the cost for 1 kg is about 150 rubles, and the price for lead alone will be about 25,000 rubles, which is 5-6 times more expensive than a factory battery with a capacity of 100Ah.
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It is possible to increase the capacity of the plates by molding, using charging and discharging, swapping plus and minus, but it is not known how many cycles need to be done to significantly increase the capacity. Plante molded the plates using electricity for three months. During this time, a lot of energy will be spent on molding, and as a result, the battery will only become more expensive. From all this it is clear that it is not economically profitable to make a battery from sheet lead.
Yes, by the way, about the durability of the battery with plates made of sheet lead. Such a battery will last much longer, since the plates are solid and from deep discharges, high discharge currents, there will be no grease coming off, which is simply not there, but the sulfation of the plates will be exactly the same as with a regular battery, so this one will essentially last longer than usual the battery will not last. True, it can be disassembled and cleaned white plaque(sulfate) and it will continue to work.
The problem is that sheet lead does not have an oxide layer, or rather there is, because of it the lead becomes dark gray, but this layer is too thin. Oxide is lead oxidized by oxygen; it is produced in different ways in production. But it is difficult to obtain this dust at home. You can, of course, try moistening the plates with water so that they oxidize fresh air, but what layer of oxide can be built up in this way and how long it will take is not known, so you can forget about a roll-up battery made of sheet lead.
A good battery will turn out if you use lead foil instead of plates. This way you can increase the area several times with the same weight, but you can’t make foil at home, and there is no pure lead foil on sale, and it would cost several times more than sheet lead of the same weight. Therefore, the good option with foil is no longer available. Or install a rolling machine at home and make foil yourself.
You can try to make the plates as they do at the factory; casting the gratings is not difficult. They are thick and the casting mold is easy to make. But the problem is the spread, it consists of lead oxide, but how can you make it at home? For example, use something to wash lead into dust or small shavings, then pour water or electrolyte on it and constantly stir it in some container so that it oxidizes in oxygen, but this is difficult and pointless to do at home, since a ready-made battery will be much cheaper.
That's probably all I wanted to say in brief. For myself, I concluded that DIY lead battery is possible, but labor-intensive and not profitable, so we can safely put a big and fat point on this matter. Having also read a lot of information about other types of batteries, I came to the conclusion that nothing normal can be achieved at home using accessible and cheap materials. If you have questions or any conclusions, please leave comments.
A battery is an energy storage device that usually operates on the principle of reversibility chemical reaction. The simplest battery has a simple structure; its idea was first tested in practice by Ritter in 1803; it was a column of 50 copper plates, lined with a damp, dense cloth.
How to make a battery with your own hands? Build from copper plates? There are more simple methods creating an electricity storage device from improvised means. You can make either an acid homemade battery or an alkaline type device.
Acid and lead
The simplest design is the lead-acid design for storing electricity. To assemble it you need:
- stable container, with the possibility of tight closure lid;
- electrolyte – a solution of battery acid and distilled water;
- lead plate - you can use a flattened piece of lead from cable insulation or purchased at a hunting or fishing store;
- two metal pins - electrodes, which must be driven vertically into the lead plates.
Next, we present the manufacturing process of this device. Lead plates are placed on metal pins, with a small distance between them. After which the structure is immersed in a container filled with electrolyte. The lead must be completely under the solution. The contact ends of the pins are passed through the lid of the container and securely fixed to it. An electricity consumer can be connected to the ends of the electrodes. The container is placed on a stable surface, after which the device is charged. By complicating the design, rolling the lead plates into a roll and, accordingly, increasing their area, with a small volume, you can achieve good performance of such a device. The same principle is used to make rolls in modern gel energy storage devices.
Important! When working with homemade electronic storage devices, follow safety rules: the acid used in the electrolyte is a rather aggressive substance.
Salt, coal and graphite
This device does not require acid as it uses an alkaline reaction. How to make this type of battery? The basis of this type of energy storage device is a container with an electrolyte in the form of a solution of water and sodium chloride - table salt. To create it you need:
- graphite rods, with a metal cap for soldering the contact;
- activated or charcoal, crushed into crumbs;
- fabric bags for storing coal powder;
- container for electrolyte with a tight lid for fixing the ends of the electrode.
The electrodes are a graphite rod coated with dense carbon. Graphite can be used from deteriorated batteries, and charcoal can be used from charcoal or activated carbon from gas mask filters. To create a dense lining, coal can be placed in a water-permeable bag, then a graphite rod can be inserted inside, and the fabric of the bag can be wrapped with thread or wire with an insulating coating.
To increase the performance of this type of design, you can create a battery of several electrodes placed in one container.
Important! Storage capacity and contact voltage homemade devices for storing electricity are relatively small, but at the same time they are quite enough to connect a low-power light source or other purposes. A battery of several electrodes has more high performance, but they are more bulky.
Lemons and oranges as a container for electricity
Lemon is not only tasty and healthy fruit, but also a natural battery. To use it, just combine several lemons into series circuit, through metal electrodes. After which you can connect the “fruit” drive to the charger. Instead of lemons, you can use other citrus fruits that contain acid, which will serve as a natural electrolyte. The more citrus fruits are involved, the higher the parameters of the “natural” battery.
Lemon juice, acid or its solution can be used separately. To do this, just pour them into a jar small size and install a copper and steel electrode there. The voltage of the natural energy storage device is low, but, nevertheless, it is enough for a low-power lighting source.
Even in the absence of a factory-made energy storage device, you can easily make a battery with your own hands. To create it, you only need knowledge of the basics of physics and chemistry, as well as the presence of any type of acid or alkali on hand. Almost any metals that are available can be used as electrodes, but best option– this is the use of steels with a high content of iron, as well as copper and its alloys.
Video
How often there are situations when, on a hike, at the dacha, or somewhere else, we need to recharge the phone, or use a little light. Most often on a hike, when necessary save batteries, you need to call or do something else. So, let's let's make a battery from what we have on hand!
1. Saline battery
1) A large vessel (a bucket, maybe even one with holes, or something like that, you can even use plastic bags)
2) Zinc and copper plate. If there are no plates, then you can simply use zinc and copper wire, but the plates have larger area, and give more current.
3) Earth. Yes, you can just dig up some soil.
4) Saline solution. I won’t give any exact recommendations here. Half a pack of salt is enough for a bucket of water.
It’s simple - we fill it with soil, stick in the electrodes, water it, and at the ends of the electrodes you will see a voltage of about 0.5-1V. Of course, not much, but what’s stopping you from making a battery of such elements? Enough to charge a mobile phone. Pour it in, pour it in and go about your business!
A good option for a homemade element is an air-aluminum one.
To do this, you need to take aluminum cathode foil, soak a napkin with salt (or sea water), I also tried to take acidic flux, a pile of carbon powder as an anode, I took toner from cartridges laser printer. The voltage is 0.5-1.0V at a current of 10mA
2. Battery made from fruits and vegetables
To make a galvanic cell we need: two electrodes, an oxidizing agent, a reducing agent and an electrolyte.
Let's take three plates: copper, iron and magnesium - they will serve as electrodes. To measure voltage, we need a voltmeter; a digital (or analog) tester is quite suitable for these purposes. And as a “glass” with electrolyte we use a large and beautiful... orange. Fruit and vegetable juice contains dissolved electrolytes - salts and organic acids. Their concentration is not very high, but that suits us quite well.
So, let's put an orange on the table and stick our three electrodes (copper, iron and magnesium) into it. Pre-attach a wire to each of the electrodes (it’s convenient to use alligator clips for this). Now connect the tester contacts to the copper and iron electrode. The device will show a voltage of about 0.4-0.5 V. Disconnect the contact from the iron electrode and connect it to the magnesium one. Between the copper and magnesium electrodes there will be a potential difference of about 1.4-1.5 V - approximately the same as that of a finger-type battery. And finally, the iron-magnesium galvanic cell will give a voltage of about 0.8-0.9 V. If you swap the contacts, the sign of the device will change ("+" to "-" or vice versa). In other words, current will flow through the voltmeter in the opposite direction.
Instead of an orange, you can use grapefruit, apple, lemon, onion, potato and many other fruits and vegetables. It is curious that batteries made from orange, apple, grapefruit and onion gave fairly close voltage values - the difference did not exceed 0.1 V. The reducing agent in our case is iron or magnesium, the oxidizing agent is hydrogen ions and oxygen (which are contained in the juice). Note that the iron in a copper-iron cell is negatively charged, while the iron in an iron-magnesium cell is positively charged. If you do not have magnesium, the experiment can be carried out with two electrodes - copper and iron. Instead of iron, you can take zinc or a piece of galvanized sheet. A zinc electrode should give a larger potential difference with copper and a smaller one with magnesium.
In the case of citrus fruits, the experiment looks especially beautiful if you cut the fruit crosswise so that the “slices” are visible and insert electrodes into them (usually this is how a lemon is cut). If the fruit is cut lengthwise, it will not look so impressive.
The figures given should not be taken as absolute. The voltage of our battery depends on the concentration of hydrogen ions (as well as other ions) in the juice of fruits and vegetables, the rate of oxygen diffusion, the condition of the surface of the electrodes and other factors. The voltage of the battery you make may differ significantly from what was observed in this experiment. You can connect several fruit batteries in series - this will increase the voltage in proportion to the number of fruits taken.
The same materials are suitable for a potato battery, but it produces less voltage, so it is recommended to add a little salt inside the potato, the effect will be much greater.
3. Coffee battery (Nespresso battery)
In an attempt to show the world the importance of collecting and recycling valuable aluminum materials, designers at Mischer "Traxler from Vienna have developed batteries from 700 used aluminum cans and coffee grounds to power a quartz watch. The developed design is called the "Nespresso Battery", the installation is made from old aluminum cans, coffee grounds , strips of copper and salt water.
In the photo below:
- watch as a testing device
- salt
- ground coffee
- wires
- copper plates
- aluminum plates
- cup
- plastic bottle separator
In a glass we put a copper plate (textolite, coin, thick wire) and aluminum slices (from beer cans). To prevent copper and aluminum from coming into contact, we place a separator between them made of any dielectric (plastic from a bottle, coffee grounds), and it should not interfere with the free flow of water. We connect wires to the plates, one to copper and one to aluminum. Now take water and add a few tablespoons of salt there, mix them until the salt is completely dissolved. Pour this solution into a glass. The battery is all done.
The coffee grounds here are purely for decoration, and so that a beautiful name can be given. And so its function can be used to separate conductors, you can completely abandon coffee grounds.
4. Baghdad battery
(Parthian battery)
A small Parthian vessel was found at Khuzhut Rabu, in the vicinity of modern Baghdad (now Iraq), once part of the western territories of Greater Iran. In June 1936, a new railway- and the workers discovered an ancient burial place. Subsequent excavations revealed that it belongs to the Parthian period (c. 250 BC - 250 AD).
One of the finds was a clay vessel with an asphalt “stopper”. An iron rod passed through the “plug”. Inside the vessel, the rod was lowered into a copper cylinder.
This vessel was first described by the German archaeologist Wilhelm König in 1938 - he considered it very similar to an electric battery, and published an article on this topic in 1940.
By similar principle You can assemble your own battery. We take a “vessel” that can be made from: clay, plasticine, a bottle, a jar, a glass, insert into it a copper plate twisted into a cylinder, and insert a nickel-plated nail into this cylinder. These plate and nail are electrodes, they should stick out a little from the can. To secure them in the body of the “vessel” you can use: epoxy glue, plasticine, window putty, etc.
Now we need to make an electrolyte. It can be alkaline or acidic. For alkali, you need to make a concentrated solution of: water + salt or water + soda. For acidic, diluted acetic or oxalic acid in water is suitable, or you can use citrus juice.
Pour the electrolyte inside the jar and carefully seal the “vessel”. The Baghdad battery is ready.
When such a model is filled with electrolyte, it can produce voltage. In general, depending on the type of electrolyte, the voltage supplied by the “battery” varies from 0.5 to 2 volts.
Unfortunately, due to the destruction of many Iranian literary sources and libraries during enemy invasions of Iran over the centuries, there are no written records of what exactly such vessels were used for. Everything we know about them today is just guesswork.
5. Solar battery
Having read on the endless expanses of the Internet about homemade solar cells, I decided to conduct my own “experiments” in this area. I'll tell you about the most in a simple way making solar panels with your own hands.
To begin with, I decided to decide on the element base. For a solar cell we need P-N transitions. They are found in diodes and transistors. It was decided to choose KT801 silicon transistors. They were produced in a metal case and therefore they can be opened without damaging the crystal. It is enough to press the lid with pliers and it will break off.
Now let's look at the parameters. With average daylight, each of our transistors produces 0.53V (Base is plus, and Collector and Emitter are minuses). And then there is one nuance. Transistors from 1972 have a large white crystal, and produce about 1.1mA. Transistors from 1973 to 1980 releases have big crystal with a green coating, and output about 0.9mA. Transistors released later have small crystals and produce only 0.13mA.
For the experiment, I used a battery of two parallel chains of 4 transistors. Under load it produced about 1.8V, 2-2.5mA. These are rather modest parameters, but as they say, “for free”. You can power this battery with Chinese ones wrist watch, or charge the battery and power the LED, bug, etc.
For ease of mounting and measurements, you can mount the transistors on a printed circuit board as in the figure below. My device is wall-mounted, as this speeds up assembly.
6. Coin-energy battery
It seems that the design is standard, zinc-copper contacts and salted water, but the design of the battery itself is interesting.
We will need:
Ice tray
- copper/copper alloy coins
- coins made of nickel/aluminum bronze/zinc
- paper clips
- salt
- water
- LED (for checking)
To get a battery, you need to connect coins into electrodes and fill them with electrolyte. In each cell of the tray it is necessary to place two coins from different alloys, for example copper and nickel. Next, we connect all the cells in series using a paper clip. Pressing against one side of the wall copper coin, and on the other nickel we secure them with a paper clip. After this, you need to fill each tray with electrolyte: salt + water. Pay attention to the ends of the tray, since the cells are in two rows, on one side we need to connect them, and on the other they should remain unconnected.
Now we check the performance of the battery using a diode or a multimeter; to do this, we close two unconnected cells with it.
One cell produces electricity with a voltage of 0.5 V, and those connected into one battery produce 2 V and 110 mA. Therefore, it is desirable to have one electrolyte for all cells, and not heterogeneous ones.
Peculiarities:
1. The cell should be completely filled with electrolyte, but contact should only be with a coin, not a paper clip.
2. One of the pairs of cells should not be shorted to each other.
3. Zinc coins are used as positive electrodes, and copper coins are used as negative electrodes.
4. Coins must be made of different metals/alloys (copper and nickel), it is also desirable that they do not contain the same impurities in the alloys.
7. Homemade battery
Now we will make a fairly simple device, or rather a power source - a homemade voltage battery. As is known, two different metals immersed in an electrolyte solution are capable of accumulating electric current. It was decided to use copper and aluminum foil as electrodes (in my opinion, they are the most affordable).
In addition to foil, we also need a sheet of paper, transparent tape and the vessel itself in which we will place the battery jar (it is very convenient to use a glass vessel made from naphthysine or valerian tablets).
Let's look at the photographs.
The foils are almost the same size, only aluminum foil a little longer, there is no reason for this, it’s just easier to apply solder to copper foil than to aluminum foil and the wire is not soldered to the foil, just rolled into it and then clamped with pliers.
Next, both foils were wrapped in a sheet of paper. It is not permissible for metals to touch each other; a sheet of paper serves as a barrier between them. Then the foils need to be taken together and wrapped in a circle and wrapped with thread or transparent tape.
Then the completed package must be placed in a vessel. After this, take 50 ml of water and dilute 10 - 20 grams of salt into it. Mix the solution thoroughly and heat until all the salt has melted.
After melting the salt, pour the solution into a vessel where we have a ready-made blank for our homemade battery. After filling, wait a few minutes and measure the voltage on the battery wires.
I forgot to specify the polarity of the battery, copper foil is a plus for power supply, aluminum foil is a minus. Measurements will show a voltage of the order of 0.5-0.7 volts. But the initial tension doesn't mean anything. We need to charge our battery. You can charge from any DC source with a voltage of 2.5-3 volts, charging lasts half an hour. After charging, we measure the voltage again, it increased to 1.3 volts and can reach up to 1.45 volts. The maximum current of such a homemade battery can reach up to 350 milliamps.
You can make several of these batteries and use them as a backup power source for, say, an LED panel or flashlight. To increase the power of the battery, you can use large foil, but of course such a homemade battery will not hold a charge for very long (the charge will run out within one week), another disadvantage is the short service life (no more than 3 months), since oxide forms on copper During the charge-discharge process, the aluminum foil begins to corrode and will gradually separate into small pieces, but I think for experiments it’s worth trying to assemble such a simple battery.
8. DC adapter
Having a little free time and desire, it is easy to assemble an adapter from scrap materials to power various gadgets from external source nutrition. What I liked about this article is the simplicity of this adapter. I will describe the manufacturing technology in more detail. I think it will be useful to someone else, especially since there is absolutely nothing complicated here.
I didn’t even go anywhere to get the material. It was just lying on the table old card MTS. It was not in vain that he paid a hundred rubles. I tried it on, it’s exactly suitable for making a model of one battery for a camera.
Cutting cardboard:
There are even very few scraps left.
The cardboard is exactly what you need - hard, about 0.25 mm thick. I made markings and cut along the seams. The cardboard was not cut all the way through, but about a little more than half the thickness, to make it easier to bend and glue. For contacts I riveted 1.5 copper wire square millimeters. It turned out something like this.
This is what the contacts look like from the inside:
I soldered the wires and double-glued all the seams with Moment STOLYAR PVA glue. The seams are thin, so I had to smear them patiently, drop by drop, with the tip of a toothpick... Although, if you can’t wait, you can glue them together with tape.
We connect to the “vampire” and work:
Connected it, everything worked.
So far, only one inconvenience has been discovered - the wire. He’s fat, reaching for the camera and the “vampire little one.” Therefore, I decided to attach to the camera the same battery as in the “vampire little one,” only with protection. By the way, it is not necessary to install batteries with protection here, because The camera already has a built-in charge level meter and if the battery is low it simply will not turn on.
And don't forget to observe polarity!!!
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You will need
- - Lemon
- - Glass or shot glass
- - Copper and iron pins
- - 2 pieces of installation wire in insulation
- - 2 wooden sticks
- - 2 pushpins
- - Drill
- - Soldering iron
- - Knife
Instructions
Insert copper and iron pins into the pulp at a distance of 0.5 - 1 cm. They will serve as electrodes in the battery. The negative electrode is iron, the positive electrode is copper. This must be taken into account when you connect, for example, to a camera.
Solder pieces of wire to the pins. If the device for which you are making a battery has an external input for a power source, you can connect the resulting battery to the device using this connector, having previously selected required quantity elements. The elements must be connected in series using wires and soldering.
If the device does not have an external connector, take 2 wooden sticks and cut them to the shape and size of the batteries that you usually use. Drill through them lengthwise so that you can thread the wires coming from the battery. The easiest way to make contacts is from metal push pins, to which the leads are soldered, after which the buttons are secured to the ends of the sticks.
Insert the sticks into the battery compartment, observing the polarity. Press the contacts to contact group. In this case, the container must remain open while the device is operating.
The disadvantage of a lemon battery is that it produces little current. In order to build more powerful device, you need a few lemons and a few pieces of wire. But you can rummage around in the shed and find other things that can also be used to make a power source. Try to make the simplest galvanic cell of the Leclanche type. Pairs of electrodes in this case can be pairs of zinc-copper or aluminum-copper plates. The larger their area, the better. Solder the wires to the electrodes. If you have an aluminum plate, the wire will have to be tied or riveted to it. You will also need the most ordinary glass glasses. Place a pair of electrodes into the glass so that they do not touch each other. You can put a plastic or wooden spacer between them. Prepare a solution for 100 g of water - 50 g of ammonia (ammonium chloride), or a 20% solution of sulfuric acid. Acid must be poured into water, and not vice versa. Carefully pour the solution into the vessel with the electrodes so that there is at least 2 cm of dry space left to the edge of the vessel and to the top of the electrodes. One such element gives an initial voltage of 1.3-1.4V. By connecting the elements into a battery, you can obtain a powerful current source sufficient to power mobile device. In this case, it is best to supply power through an external connector (through which a mobile phone is usually charged). Pay close attention to the polarity of the switch.
In this article, a DIYer will guide us through all stages of battery assembly, from choosing the material to final assembly. RC toys, laptop batteries, medical devices, electric bicycles and even electric cars use batteries based on the 18650 battery.
18650 battery (18*65mm) is the size of lithium ion battery. For comparison, regular AA batteries have a size of 14*50 mm. The author made this particular assembly to replace the lead-acid battery in a homemade product he had previously made.
Video:
Tools and materials:
- ;
- ;
- ;
- ;
-Switch;
-Connector;
- ;
-Screws 3M x 10mm;
- Spot resistance welding machine;
-3D printer;
-Stripper (insulation stripping tool);
- Hairdryer;
-Multimeter;
-Charger for lithium-ion batteries;
-Safety glasses;
-Dielectric gloves;
Some tools can be replaced with more affordable ones.
Step one: choosing batteries
The first thing you need to do is choose correct batteries. There are different batteries on the market ranging from $1 to $10. According to the author, the best batteries are from Panasonic, Samsung, Sanyo and LG. They are more expensive than others, but they have proven themselves good quality and characteristics.
The author does not recommend buying batteries with the names Ultrafire, Surefire and Trustfire. These are batteries that did not pass quality control at the factory and were purchased at a bargain price and repackaged under a new name. As a rule, such batteries do not have the declared capacity and there is a risk of fire during charging and discharging.
For his homemade product, the master used Panasonic batteries with a capacity of 3400 mAh.
Step Two: Selecting Nickel Strip
Nickel strips are needed to connect the battery. There are two products on the market: nickel plated metal and nickel strips. The author recommends using nickel strips. They are more expensive, but have low resistance and therefore heat up less, which affects the life of the batteries.
Step Three: Spot Welding or Soldering
There are two methods for connecting batteries: soldering and spot welding. Best choice spot welding. At spot welding the battery does not overheat. But a welding machine (like the author’s) costs approx. 12 t.r. in a foreign online store and approx. 20 t.r. in a Russian online store. The author himself uses welding, but has prepared several recommendations for soldering.
When soldering, keep contact between the soldering iron and the battery to a minimum. It is better to use a powerful soldering iron (from 80 W) and quickly solder than to heat up the solder area.
Step Four: Check the Batteries
Before connecting the batteries, you need to check each of them separately. The voltage on the batteries should be approximately the same. New high-quality batteries have a voltage of 3.5 V - 3.7 V. Such batteries can be connected, but it is better to equalize the voltage using charger. For used batteries, the voltage difference will be even greater.
Step five: battery calculation
For the project, the master needs a battery with a voltage of 11.1 V and a capacity of 17,000 mAh.
The 18650 battery capacity is 3400 mAh. When connecting five batteries in parallel, we get a capacity of 17,000 mAh. Such a compound is designated P, in this case 5P
One battery has a voltage of 3.7 V. To get 11.1 V, you need to connect three batteries in series. Designation S, in this case 3S.
So, to obtain the necessary parameters, you need three sections, each consisting of five parallel-connected batteries, connected in series. Package 3S5P.
Step Six: Battery Assembly
To assemble the battery, the master uses special plastic cells. Plastic cells have a number of advantages over connecting them, for example, using a glue gun.
1.Easy assembly of any quantity.
2. There is space between the batteries for ventilation.
3. Vibration and impact resistance.
Collects two 3*5 cells. Installs, in the cell, the first package of 5S batteries with the plus side up, the next five with the minus side up, and the last five batteries again with the plus side up (see photo).
Places the second cell on top.
Step seven: welding
Cuts four nickel strips to parallel connection, with a margin of 10 mm. Cuts ten strips for serial connection.
Places a long strip on the + contacts of the first (when turned over, it will remain first) parallel 5P cell. Welds the strip. Welds the strips with one end to the + of the third cell and the other to the - second. Welds a long strip to the + third cell (on top of the plates). Flips the block. Welds plates with reverse side taking into account that now we connect the third in parallel, and the first and second sections in parallel and in series (considering that it was turned over).
Step Eight: BMS (Battery Management System)
First, let's understand a little what BMS is.
BMS (Battery Management System) is an electronic board that is installed on the battery to control the process of its charge/discharge, monitor the condition of the battery and its elements, control temperature, the number of charge/discharge cycles, and protect the components of the battery. The control and balancing system provides individual control of the voltage and resistance of each battery element, distributes currents between the components of the battery during the charging process, controls the discharge current, determines the loss of capacity from imbalance, and guarantees safe connection/disconnection of the load.
Based on the received data, the BMS balances the cell charge and protects the battery from short circuit, overcurrent, overcharge, overdischarge (high and excessively low voltage of each cell), overheating and undercooling. The BMS functionality allows not only to improve the operation of batteries, but also to maximize their service life.
Important parameters board is the number of cells in a row, in this case 3S, and the maximum discharge current, in this case 25 A. For this project the master used board with the following parameters:
Model: HX-3S-FL25A-A
Overvoltage range: 4.25~4.35V±0.05V
Discharge voltage range: 2.3~3.0V±0.05V
Maximum operating current: 0~25A
Operating temperature: -40 ℃ ~ + 50 ℃
Solders the board to the ends of the battery according to the diagram.