How welding is done from a battery. Ultra budget lithium battery spot welding at home 12 volt battery welding

Batteries are used in many household appliances and tools. Sometimes, it is necessary to replace one or more elements. They are connected to a block of a certain voltage, and the poles are welded together with a metal strip using spot welding.

The soldering method is not suitable here, since with this method of connection, the inside of the battery heats up strongly, which leads to its failure. Therefore, if you need to independently repair lithium-ion batteries, you need to purchase a spot welder (spotter) or make it yourself.

The easiest way is to weld the batteries with the battery itself. This will require:

In the field, a battery, charging wires, a piece of solid wire and electrical tape are enough to weld a nickel plate to a battery.

Two electrodes are made from the wire. Their ends are cleaned, leveled and fixed with electrical tape. There should be a distance of 2-3 mm between the ends of the wires, the ends are in the same plane.

The other ends of the monolithic wire are hooked using the clamps of the charging cable. The pre-charging cable is connected to the terminals of the working battery. Polarity doesn't matter.

Spot welding is ready. The nickel strip is mounted on a lithium battery. The ends of the electrodes, which are energized, are pressed to the tape.

A short circuit will occur and the metal at the point of contact will melt. Remove the electrodes quickly to avoid burning through the nickel plate.

At home

For convenience and improve the quality of welding at home, additional elements are used.

The stranded power wire is connected with clamps to the working battery, and the other ends to the normally open contact of the relay and to the tip of the soldering iron.

The second contact of the relay is connected to the second sting. The result is such a scheme that when the relay contacts are closed at the ends of the stings (electrodes), the working battery voltage will be present.

A large capacitor, resistor and switch are used to control the relay. The capacitor and resistor are connected in series. One terminal of the capacitor is connected to the battery. The common terminal of the switch is connected to a resistor.

In the initial state, the switch should be in the position when it is closed to the working battery. The capacitor will charge. The relay control winding is connected with one contact to the output of the capacitor connected to the battery, and the second is connected to the free output of the switch.

When switching, the voltage from the capacitor goes to the control windings. While the capacitance is discharging, the relay is closed, and current can flow through it if the circuit is closed.

For welding, it is enough to put a nickel connecting tape on the lithium battery cell, two stings on it, press and press the switch. The relay contacts will close, voltage will appear on the electrodes.

Since they are closed through the plate, a short-circuit current will flow through it, which will cause the metal to melt between the touching points of the electrodes. Welding completed.

Using a resistor, you can adjust the duration of the control pulse. The adjustment can be done empirically. It is necessary when the voltage of the working battery and the thickness of the welded material change.

From the transformer

Spot welding for batteries can be done by hand from a transformer. It can weld not only batteries, but also any thin metal products.

For welding batteries, a high-power transformer is not required, 300-500 W is enough. The main thing is to be able to rewind the secondary winding.

The primary winding must be 220V 50 Hz. An insulated copper wire of large diameter must be used as a winding wire on the secondary winding. It is required to make three to four turns.

The body of the spot welding machine can be made of plexiglass or plywood. Plexiglas is of course preferable. The base of the case must be large enough to accommodate the transformer with connecting wires, a button and a lever with electrodes.

The lever is attached to the axis between the aluminum corner posts, which in turn are fixed to the base of the device with self-tapping screws. The length of the lever is made in such a way that the electrodes attached to it reach the working platform of the base of the device. The diameter of the electrodes should be 3-5 mm. Their ends are sharpened and aligned.

The secondary winding of the transformer is connected to the electrodes using a stranded copper wire with a cross section not less than the cross section of the electrodes. The length of the wires from the secondary winding to the working part should be minimal. It is better to weld the connections to reduce the resistance of the circuit or connect through the screw terminal blocks.

The operating button is installed on one of the terminals of the secondary winding. Springs are installed on the lever and button. They are needed for their quick return to their original state.

To set a specific duration of the welding pulse, instead of a button, you can use a thyristor or a power relay controlled by an RC circuit. The resistor must be variable, and the capacitance of the capacitor is large enough to allow changing the pulse duration in the range from tens to hundreds of milliseconds.

There are many for rechargeable batteries. Much depends on the materials available. The schemes can be changed to increase the functionality of the device, improve its consumer properties, but the essence remains the same.

Capacitor apparatus

The device will require 8 capacities of 15,000 uF for a voltage of 25 V. Capacitors must be connected in parallel so that the total capacity becomes 120,000 uF.

For charging, you can use any voltage source of 12-24 V. It is connected through a switch. Electrodes are also connected to the capacitor terminals through a copper cable with a cross section of 16-30 mm2.

The electrodes are placed parallel to each other at a distance of three millimeters. The ends are turned and leveled. The welding process is as follows.

The capacitors are being charged, the switch disconnects the charging source. The nickel connection plate is mounted on the battery. The electrodes are pressed against the plate, closing the capacitor leads through it.

While the capacity is being discharged, the welding process is going on at the contact point. To adjust the pulse duration, you can use a thyristor controlled by an RC circuit with specified parameters.

Spot welding for batteries differs from conventional spot welding in low power and shape of working elements. In conventional machines, the workpiece to be welded is between the electrodes, while in battery welding, the electrodes are located on one side of the workpiece to be welded.

I heard about welding from car batteries for a long time, there is also a video on YouTube confirming this. And in principle, I had no doubt about this, since the characteristics of the batteries allow you to do this. Firstly, there is a large current, up to 600A from a 55Ah battery, and with a battery of a larger capacity, an even greater maximum current, therefore, even a large overcurrent is obtained rather than its shortage. But in general, a year ago I needed to weld the motorcycle frame and the side trailer to it, and there is nowhere to connect the welding inverter in the country.

At my dacha I have my own electricity, a small solar power plant is installed, and there is a 12-220 volt converter with a maximum power of only 1 kW, and naturally it will not pull welding. But at that time I had four batteries in the power station, two 65Ah each, and two more 90Ah each, so I decided to make sure myself that it is possible to cook from a battery. In general, I brought two batteries to the welding site and connected the battery in series with 24 volts. The electrodes were 2.5 mm in diameter.

I will say that I succeeded in brewing, and pretty good, but most likely there was not enough tension since the arc ignited very badly and good penetration did not work, since the arc barely burned and often simply extinguished. But at the same time, what surprised me was that if the electrode sticks, it heats up to red in a second and melts. With conventional welding, I did not observe this, but here you have to be careful, when the electrodes stick, they burn out in a swing.

Most recently, in early February (2016), I needed welding again, but I already had three 90Ah batteries. I cooked a frame for a wind generator. With three batteries connected in series welding turned out to be excellent and with a large overcurrent. I started to cook with 2 mm electrodes, and at first I even burned a few holes in the metal because there was too much current. Then I cooked with 2.5 mm electrodes, but still there was too much current and I had to cook very carefully so as not to burn through thin 3 mm metal. I even cut such metal freely with electrodes. Then I didn't have any other electrodes, but I think 4 mm electrodes would go freely under such a current. Generally cooks great except that the current is too large, which has nothing to limit. But you get used to it, and it is quite normal to brew something even serious.

Only it is better not to discharge the batteries deeply, otherwise they will deteriorate quickly, but they will not get anything from a large current. I will say that 15-20 electrodes can be easily burned from three 90Ah batteries and the batteries are not very discharged, and this number of electrodes is already decent.

This is how, in general, the batteries themselves look like, connected in series, I have 35kv welding wires.

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These are the actual electrodes 2 mm

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Electrodes 2.5 mm

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In this photo you can see the penetration from the back side, I did not specifically photograph the welding process itself, therefore I did not capture the welding quality more specifically, but in general it cooks well.

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And here is the result of welding, the frame for the wind generator is welded.

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If anyone is interested about the wind generator itself and about welding, then I wrote an article about making a wind generator and there is a video where you can see what I did there and how I cooked with such welding. That's all, if there is something new, I will unsubscribe in the following articles.

In the life of every "radio killer" there is a moment when it is necessary to weld together several lithium batteries - either when repairing a laptop battery that has died from age, or when assembling power for another craft. Soldering lithium with a 60-watt soldering iron is inconvenient and scary - you will overheat a little - and you have a smoke grenade in your hands, which is useless to extinguish with water.

Collective experience offers two options - either go to the trash heap in search of an old microwave, knock it out and get a transformer, or spend a lot of money.

I absolutely did not want to look for a transformer for several welds a year, saw it and rewind it. I wanted to find an ultra-cheap and ultra-simple way to weld batteries with electric current.

A powerful low-voltage DC power supply available to everyone - this is an ordinary used device. Battery from the car. I bet you already have it somewhere in the closet, or you will find it at your neighbor's.

I suggest - the best way to get an old battery for free is

wait for frost. Go to the poor fellow who does not start the car - he will soon run for a new fresh battery to the store, and the old one will give you just like that. In the cold, the old lead battery may not work well, but after charging the house in the warmth it will reach its full capacity.

To weld batteries with current from a battery, we will need to deliver current in short pulses in a matter of milliseconds - otherwise we will not get welding, but burning holes in the metal. The cheapest and most affordable way to switch the current of a 12-volt battery is an electromechanical relay (solenoid).

The problem is that conventional 12 volt automotive relays are rated for a maximum of 100 amperes, and the short-circuit currents during welding are many times higher. There is a risk that the relay armature will simply be welded on. And then, in the vastness of Aliexpress, I came across a motorcycle starter relay. I thought that if these relays withstand the starter current, and many thousands of times, then it will work for my purposes. Finally, this video convinced me, where the author is testing a similar relay:

My relay was bought for 253 rubles and reached Moscow in less than 20 days. Relay characteristics from the seller's website:

• Designed for motorcycles with 110 or 125 cc engine
• Rated current - 100 amperes for up to 30 seconds
• Winding excitation current - 3 amperes
• Designed for 50 thousand cycles
• Weight - 156 grams

The relay arrived in a neat cardboard box and, upon unpacking, gave off a wild stench of Chinese rubber. The culprit is a rubber casing on top of a metal case, the smell has not disappeared for many days.

The unit pleased with the quality - two copper-plated threaded connections were brought out under the contacts, all the wires were filled with a compound for waterproofing.

Hastily assembled a "test stand", closed the relay contacts manually. The wire used a single-core, with a cross section of 4 squares, the stripped terminals were fixed with a terminal block. For safety reasons, I supplied one of the terminals to the battery with a "safety loop" - if the relay armature decided to burn and arrange a short circuit, I would have had time to pull off the terminal from the battery for this rope:

Tests have shown that the machine works for a solid five. The armature knocks very loudly, and the electrodes give clear flashes; the relay does not burn. In order not to waste a nickel strip and not to practice on dangerous lithium, I tormented the blade of a clerical knife. In the photo you can see several high-quality dots and a few overexposed ones:

Overexposed dots are also visible on the inside of the blade:

First, he piled up a simple circuit on a powerful transistor, but quickly remembered that the solenoid in the relay wants to eat as much as 3 amperes. I rummaged in the box and found an IRF3205 MOSFET transistor instead and sketched a simple circuit with it:

The circuit is quite simple - in fact, a MOSFET, two resistors - 1K and 10K, and a diode that protects the circuit from the current induced by the solenoid when the relay is de-energized.

First, we try the circuit on the foil (with joyful clicks, it burns holes through and through through several layers), then we take out a nickel tape from the storage box to connect the battery assemblies. We briefly press the button, we get a loud flash, and we consider the burnt hole. The notebook also got it - not only the nickel burned, but also a couple of sheets under it :)

Even a tape welded with two points cannot be divided by hand.

Obviously, the scheme works, it's up to fine-tuning the "shutter speed and exposure". If you believe the experiments with the oscilloscope of the same friend from YouTube, from whom I spied the idea of \u200b\u200bthe starter relay, then it takes about 21ms to break the armature - from this time we will dance.

YouTube user AvE tests the rate of fire of the starter relay versus SSR Fotek on an oscilloscope

We supplement the scheme - instead of manually pressing the button, we will entrust the count of milliseconds to Arduin. We will need:

• arduino itself - Nano, ProMini or Pro Micro will do,
• Sharp PC817 optocoupler with a 220Ω current-limiting resistor - to galvanically isolate the Arduino and the relay,
• A voltage-reducing module, for example XM1584, to turn 12 volts from the battery into 5 volts safe for Arduina
• we also need 1K and 10K resistors, a 10K potentiometer, some kind of diode and any buzzer.
• And finally, we will need a nickel tape, which is used to weld batteries.

Putting together our simple scheme. We connect the release button to the D11 pin of the Arduino, pulling it to “ground” through a 10K resistor. MOSFET to pin D10, buzzer to D9. I connected the potentiometer with extreme contacts to the VCC and GND pins, and with the middle contacts to the A3 pin of the Arduino. If you wish, you can connect a bright signal LED to the D12 pin.

Fill the Arduino with some tricky code:

Const int buttonPin \u003d 11; // Shutter button const int ledPin \u003d 12; // Pin with signal LED const int triggerPin \u003d 10; // MOSFET with relay const int buzzerPin \u003d 9; // Beeper const int analogPin \u003d A3; // Variable resistor 10K for setting the pulse length // Declare variables: int WeldingNow \u003d LOW; int buttonState; int lastButtonState \u003d LOW; unsigned long lastDebounceTime \u003d 0; unsigned long debounceDelay \u003d 50; // minimum time in ms to wait before triggering. Made to prevent false alarms when the release button contacts bounce int sensorValue \u003d 0; // read the value set on the potentiometer to this variable ... int weldingTime \u003d 0; // ... and based on it we set the delay void setup () (pinMode (analogPin, INPUT); pinMode (buttonPin, INPUT); pinMode (ledPin, OUTPUT); pinMode (triggerPin, OUTPUT); pinMode (buzzerPin, OUTPUT) ; digitalWrite (ledPin, LOW); digitalWrite (triggerPin, LOW); digitalWrite (buzzerPin, LOW); Serial.begin (9600);) void loop () (sensorValue \u003d analogRead (analogPin); // read the value set on the potentiometer weldingTime \u003d map (sensorValue, 0, 1023, 15, 255); // convert it to milliseconds in the range from 15 to 255 Serial.print ("Analog pot reads \u003d"); Serial.print (sensorValue); Serial.print ( "\\ t so we will weld for \u003d"); Serial.print (weldingTime); Serial.println ("ms."); // To prevent false triggering of the button, first make sure it is held down for at least 50ms before starting welding: int reading \u003d digitalRead (buttonPin); if (reading! \u003d lastButtonState) (lastDebounceTime \u003d millis ();) if ((millis () - lastDebounceTime)\u003e debounceDelay) (if (reading! \u003d buttonState) (buttonState \u003d reading; if (buttonState \u003d\u003d HIGH) (WeldingNow \u003d! WeldingNow;))) // If the command is received, then start: if (WeldingNow \u003d\u003d HIGH) (Serial.println ("\u003d\u003d Welding starts now! \u003d\u003d"); delay (1000); // Output three short and one long beeps to the speaker: int cnt \u003d 1; while (cnt<= 3) { playTone(1915, 150); // другие ноты на выбор: 1915, 1700, 1519, 1432, 1275, 1136, 1014, 956 delay(500); cnt++; } playTone(956, 300); delay(1); // И сразу после последнего писка приоткрываем MOSFET на нужное количество миллисекунд: digitalWrite(ledPin, HIGH); digitalWrite(triggerPin, HIGH); delay(weldingTime); digitalWrite(triggerPin, LOW); digitalWrite(ledPin, LOW); Serial.println("== Welding ended! =="); delay(1000); // И всё по-новой: WeldingNow = LOW; } else { digitalWrite(ledPin, LOW); digitalWrite(triggerPin, LOW); digitalWrite(buzzerPin, LOW); } lastButtonState = reading; } // В эту функцию вынесен код, обслуживающий пищалку: void playTone(int tone, int duration) { digitalWrite(ledPin, HIGH); for (long i = 0; i < duration * 1000L; i += tone * 2) { digitalWrite(buzzerPin, HIGH); delayMicroseconds(tone); digitalWrite(buzzerPin, LOW); delayMicroseconds(tone); } digitalWrite(ledPin, LOW); }
Then we connect to Arduin using the Serial monitor and set the length of the welding pulse by turning the potentiometer. I empirically selected the length of 25 milliseconds, but in your case the delay may be different.

By pressing the release button, the Arduino will squeak several times, and then turn on the relay for a moment. You will need to lime a small amount of tape before you can find the optimal pulse length - so that it will weld and not burn the hole through.

As a result, we have a simple, artless welding machine that is easy to disassemble:

A few important words about safety:

• When welding, microscopic metal spatter can fly to the sides. Do not show off, wear safety glasses, they cost three pennies.
• Despite the power, the relay can theoretically "burn" - the relay armature will melt to the point of contact and will not be able to return back. You will get a short circuit and fast heating of the wires. Consider in advance how you will pull off the terminal from the battery in such a situation.
• You can get different degrees of welding depending on the battery charge. To avoid surprises, adjust the welding pulse length on a fully charged battery.
• Think in advance what you will do if you pierce a lithium 18650 battery - how you will grab a hot element and where you will throw it to burn out. Most likely, this will not happen for you, but with video the consequences of spontaneous combustion of 18650 better read in advance. At a minimum, prepare a metal bucket with a lid.
• Control the charge of your car battery, do not allow it to discharge strongly (below 11 volts). This is not useful for the battery, and you will not help out a neighbor who urgently needs to "light" the car in winter.

It is no secret that when performing welding work, our electrical networks at a load of 3.5 kW. immediately give a voltage drop of 30 volts or more.

Of course, you can purchase a separate power plant for welding, but you can do it differently - do homemade welding machine from car batteries.

Welding machine manufacturing

Take several 3-4 car batteries with a capacity of 55-190 A / hour (the more the better) and connect them in series (with improvised means, using ignition wires, wires, wire cutters, clamping clips)

Note: Used batteries can be used

It brews excellently, including in the field. The main thing is to check the electrolyte level at least once a week. During the day of operation, the batteries become very hot, especially on hot summer days, and the water evaporates.

Homemade welding machine can be supplemented by making a homemade charger to it (so as not to charge the batteries separately), we put it on charge at night, and work quietly during the day.

The current that develops when welding with a 3mm electrode. 90-120 amperes for the battery is not even half the load, and the electrolyte has excellent heat capacity.

The output voltage depends on the number of batteries used and is 42-54 V

The current strength is 10% of the capacity of 1 battery in the unit, that is, if you have 55 amperes / hour, then no more than 5 amperes of charging current.

Many people, working in the garage or in the country, were faced with the need to weld parts together without having a welding machine. Battery welding is possible in some situations. It is not always acceptable, as it has a number of limitations. However, the indisputable advantage of such work is the simplicity and availability of welding.

Welding from the battery can also be carried out by inverter devices that are connected to the battery. Some car owners specifically purchase batteries for welding. At the same time, spot welding performed with the help of a battery is much more durable than soldering. How to perform welding work from a car battery, what parts and materials are needed for this, will be described below.

Brief description of welding methods

People who do welding quite often regularly face the problem of voltage drops in networks at high welding loads, which occur both when using old welding transformers and new inverter machines. Often when connecting welding devices, the voltage drops by at least 30 volts. Such a fall is serious and may affect the performance of household appliances.

Therefore, before starting welding, according to the legislation of the Russian Federation, it is necessary to warn all neighbors that are powered from the same line. This creates a lot of inconvenience, moreover, neighbors may refuse to carry out such work. The way out of this situation is welding from a battery.

When and where she first appeared is unknown, but the first documented (filmed) process was in the 60s of the last century.

The physics of this process is no different from conventional welding. Just like ordinary welding, welding from the battery occurs when an electric arc is formed. In this case, the permanent welding joint also occurs at the molecular level - the heated metal begins to melt, forming a seam.

At the moment, such welding can be performed in three ways (conditional division):

1. Spot welding using bare contact wires. Requires a minimum of preparation, materials, labor. It happens very quickly, the connection is much weaker than a conventional weld. In the process of performing such welding, copper wires will protrude with electrodes.
2. Connecting multiple batteries to a storage battery. This will allow welding with small diameter carbon electrodes (up to 3 mm). In this case, the diameter of the electrode depends on the maximum current delivered by the battery.
3. Connecting several batteries to a battery and connecting an inverter welding machine to it. In this situation, welding is performed as standard, only the power source is changed.

The choice of welding method depends on the materials of the parts to be welded. So, the connection of non-ferrous and alloyed metals must be performed by spot welding (item 1) or carbon electrodes (item 2).

Ferrous metal connections are made only by welding inverters (point 3). Inverters can also weld non-ferrous metals, but since the welding process with inverters is not new, there will be no detailed description here. The only thing worth noting is the need to connect 3-4 batteries of the same capacity and the same output current into one battery. It is worth noting that the inverter quickly drains the battery from which it is powered. Therefore, it is necessary to constantly monitor the charge level by connecting a measuring device to the battery.

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Advantages and disadvantages

All these processes have their advantages and disadvantages, therefore, the practical use of batteries for welding depends on specific conditions, financial capabilities and the availability of the necessary materials. The positive aspects include the following:

1. Ability to carry out welding work in extreme conditions. For example, on the road, in the field, etc.
2. The ability to perform welding in the absence of specialized equipment. However, in the absence of an inverter, only non-ferrous metals can be cooked.
3. No voltage drops in networks. Since the process is carried out using an autonomous energy source, it does not harm the operation of the network.
4. The ability to work under almost any external conditions With the correct connection of the equipment, welding can take place both in heat and cold (temporary), during precipitation, etc. To do this, you must strictly follow some rules for performing such work.
5. Depleted batteries can be reused after recharging.

However, this process has several disadvantages:

1. The main disadvantage is that the battery drains quickly. Therefore, it is very important to monitor its capacity. For this, a measuring device is installed in the circuit.
2. Intensive discharge of batteries will significantly reduce their service life. Therefore, it is necessary to constantly monitor the battery's ability to hold a charge and to replace batteries that do not hold a charge.
3. Financial expenses. Whereas only one car battery is needed for spot welding, a minimum of three batteries are required for welding with carbon electrodes or for connecting an inverter, which are connected in series.
4. Many people, using batteries for welding, often neglect safety rules. However, despite all the seeming simplicity of such work, it is possible to get various injuries when performing them.

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Spot welding

Spot welding with a battery is considered the most primitive. To complete it, you will need one battery, wires, a pair of terminal blocks. But let's take a closer look

Before performing welding work (this applies not only to spot welding), it is necessary to observe some safety rules. The first is the protection of the organs of vision. Naturally, in the field, a person will not have a welding shield (mask), as most motorists do not have it in garages. However, sunglasses can provide minimal protection for short-term work. The next important point is the insulation of the wires. It must be whole and not destroyed. Since these welding jobs require a minimum current of 150 amperes, you must protect yourself from electric shock. The latter - as with any complex work, care and accuracy are required.

To assemble the spot welder, insulated wires with a cross section of at least 5 mm must be connected to the battery terminals (the choice of the cross section depends on the battery current), the correct selection of the wire cross section is controlled during operation - the wires must not get warm. The conclusions of the wires should be brought to the terminal block (Soviet BZN are suitable) with a rated current of about 200-250 amperes. Next, wires are connected to the terminals, which will act as electrodes. They must be rigid, their cross-section must match the cross-section of the output wires, it is necessary that they be insulated. Further, their conclusions are located at a distance of up to 3 mm from each other (however, they should not contact) and fix the wires in this position with improvised materials (well suited for fixing household feedthrough terminals). The ends of the wires are stripped of insulation, and the device is ready for use.

To weld 2 parts, they should be connected to each other, and cleaned wires of the apparatus should be attached to the connection on one side. Important: only the ends (cross-section) of the wires are applied for welding, while it is necessary to ensure an even cross-section of each wire (for this, u.x is equal to the file).