How to disassemble the battery of a Makita screwdriver

How to disassemble the battery of a screwdriver yourself?

We take the battery and begin to carefully cut with an ordinary, but very sharp knife at the junction in the battery.

Then, in order to tear off the layer of glue located lower, I scrolled along the entire length with a self-tapping screw. This must be done carefully, because the body may crack and then you will have to get a haircut as a monk 🙂

When you feel that the battery begins to “crunch”, you need to start tapping the joint with a flat screwdriver

So, my dear hands, I myself disassembled the battery of the Makita screwdriver. Of course, my method is not a panacea, but I know for sure that it works 🙂

How to disassemble a screwdriver battery?

Batteries on screwdrivers are collapsible, but they are not collapsible. It is clear that it is more profitable for the manufacturer to make non-collapsible ones, since the failure of the battery automatically implies the purchase of a new battery, only there is one small “НННООО”!

The thing is that the price of a new rechargeable battery for “Shurik” reaches up to a third of the cost of the screwdriver itself! Therefore, as a true Patriot of our country and a level 80 handshake, I didn’t even have a thought about buying a new battery or some fucking Chinese analogue (sorry for my French).

An immediate decision was made. I will disassemble the battery of the screwdriver with my own hands.

How to correctly and quickly disassemble the battery of a Makita screwdriver

Greetings, my dear readers.

I hasten to share with you two interesting news that have not so sickly changed my way of life that has developed over the years:

December 16, 2015 my son was born. Yaroslav :))) Now I have a daughter and two sons.
2. Shortly before the birth of his son, a terrible thing happened. the battery on the Makita screwdriver “died”, which had been plowing with faith and truth for almost five years 🙁

Of course, the first event is much more important for me, but I will introduce you to it in the next article of my blog 🙂

But the news that the battery of the screwdriver came to an end not sickly so undermined my already shaken health, since the “deceased” was immediately buried and a certain amount of alcohol was consumed for the repose of his 14-volt soul. Yes, Megavolt will be with him.

Of course, for all the years of his construction and repair career, your humble servant has “shoved” a huge number of screwdrivers, but Makita has become a real godsend for me. Its ergomics, its reliability. I was captivated by it at first sight!

In general, I could not come to terms with the loss and decided at all costs to repair the screwdriver battery.

After reading a huge amount of literature, graduating with honors from the courses “Novice Warlock”. the department of applied necromancy, that is, the revival of the dead. I got down to work, but from the very first steps I realized that in order to restore the screwdriver battery it was necessary to disassemble it.

Dismantling the battery of the Makita screwdriver. video

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How to disassemble a battery from a Makita screwdriver

The battery for the Makita screwdriver is disassembled in order to replace one / several cans (batteries), or to transfer it to another type of nutrient elements. Work must be carried out with the utmost care, movements must be precise, careful so that the case, banks, electronic boards and wires are not damaged, and the module, after assembly, functioned properly and safely.

How to disassemble the battery of a Makita screwdriver 12 V, sealed with glue

The glue seam should be disconnected especially carefully so that cracks and splits do not appear on the plastic, and when assembled, the case completely covers all the electronic parts and ensures safety. To do this, it is rational to use a mallet with a rubber striker, or another hammer made of soft material.

Around the entire perimeter of the seam, blows are applied, applying medium force, ensuring that the gun slightly bounces off the body. The procedure is not short-term, it takes from 10 minutes. and more should be done without haste. In its course, the halves of the body are periodically pulled slightly apart from each other, helping them to separate. The adhesive layer collapses with a characteristic sound, when specific clicks become more frequent, you can help the separation with a thin knife blade, or a similar tool, trying to open the seam with it.

Another way to gently unfasten the glued module is with a thin knife, flat screwdriver. It lasts a little longer, work must be done with caution, since the risk of injury and plastic cracking is very high. With a blade, gently loosen the seam around the entire perimeter, then insert a screwdriver tip into it and slowly separate the halves of the module.

Before disassembling the battery of the Makita 12 volt screwdriver, you can warm up the glue layer using a construction hair dryer, which will speed up and facilitate the work. Having placed the battery module at a safe distance, a hot stream is directed to the connection, warming it up around the perimeter. When the glue has softened, the case will be easy to open.

Important: gloves used during work will help avoid burns.

Types of fasteners, preparation for work

The battery module can be fastened with:

• glue;
• latches;
• screws.

It is not uncommon for a combination fastener to be used with the simultaneous use of different types of fasteners such as screws and glue.

Before disassembling the battery from the Makita screwdriver, you should measure the voltage issued by the battery pack. This figure will help determine the number of faulty cans. After assembly, the measurement is carried out again, checking the correctness of the work done.

Connection with screws, latches

Loosening a screw fastener also requires care. Pick up a screwdriver with a suitable tip shape, rod length. They remember from which holes each screw was unscrewed, and during assembly they are screwed strictly into place. This must be done due to the fact that the hardware can be of different lengths. A short screw screwed into a deep hole will not be able to ensure a reliable connection, and a long screw placed in a short opening can pierce the wall of the case, power elements and even an electronic board. If, as a result, the electrolyte leaks out, the microcircuits and nearby banks will be damaged, and in case of unfavorable development of events, an explosion is possible.

The module, fastened with latches, is easy to open: you just need to find them and open them with moderate force. Most often, one latch is used, or two side.

The first step of disassembling the battery of a Makita screwdriver

The Japanese developer offers two types of batteries. collapsible and non-collapsible. Of course, the second option is much more common, since its breakdown automatically implies the purchase of a new element. By the way, the cost of the battery is about a third of the price of the entire tool. We will go the other way. As practice has shown, with a strong desire, even the most non-separable element can be carefully disassembled.

So, we install the screwdriver on a flat surface. Remove the battery and set the tool aside. Now we will work directly with the battery itself.

For disassembly, we need a knife. Use the sharpest possible tool, as otherwise you will only damage the surface of the battery, but you will not achieve the desired result.

Place the battery vertically and slide the knife along the junction in the cell, applying good pressure.

Then the usual self-tapping screw is used. We use it to remove a layer of glue that the knife did not reach. Scroll with a self-tapping screw around the entire perimeter of the joint. Do this as carefully as possible. Otherwise, you risk severely damaging the plastic, and in this case, of course, you will not be able to assemble the battery back.

When figuring out how to disassemble the Makita screwdriver battery without screws, you should understand that the case is attached to the glue. Therefore, you will have to work “by eye and ear.” Scrolling the self-tapping screw around the perimeter, you will hear a slight crunch. This means that the battery is ready for further manipulation. Next, you need to make the parts of the element move away from each other. To do this, use a regular screwdriver. Tap the element along the seam contour, as shown in the example below:

After these processes, you will see that the parts are no longer attached to each other as they were originally. In addition, the body has become more wobbly. After using a screwdriver, your device should look something like this:

As you can see, now nothing prevents you from simply bringing what you started to the end. Gently grasp the two parts of the battery with both hands. Press on both sides and break the battery. The main thing here is not to overdo it. If you feel that the device does not give in to any pressure, you should not put pressure on the force. Better to repeat the process with a screwdriver and finally knock out the second part. You end up with:

Detailed instructions for disassembling the Makita battery are offered at

How to assemble one battery from two

It so happens that the best way out of the situation when both batteries are “hooked” is a way to assemble one full-fledged battery of two. Using any of the proposed methods, you can disassemble both blocks in order to understand which elements are suitable for further use, and which should be discarded.

For this you will need:

• two batteries;
• Charger;
• any thin and flat screwdriver;
• scalpel;
• a piece of sandpaper;
• two wires;
• load resistance (two are possible);
• voltmeter for voltage measurements.

Charging the batteries

Before disassembling the blocks, be sure to charge them well. With subsequent voltage measurements, this is exactly what will make it possible to understand which batteries are “live” and which are not. Before charging the batteries, it is recommended to clean the internal contacts of the charger with emery paper, because any contact resistance can “give out” an incorrect charging process.

When you charge both batteries alternately, pay attention to how fast they charge. If the battery is charged quickly, and the charge indicator signals the end of the process after just a few minutes, this means that there are definitely faulty cells in the battery. And of course, when the battery charges too slowly, or does not take current at all, it should definitely be disassembled and “tested” all the batteries that are inside. Read more about the charging time of the screwdriver battery →

After you charge and disassemble your battery pack, you will see that there are several elements inside it. cans. The number may vary depending on the voltage level of your instrument. Banks are connected in a certain series. Inside there is a thermal sensor brought out to the contact plates.

If the signal from the temperature sensor going to the charger is incorrect, then the battery will receive either an undercharge or an overcharge. Both are highly undesirable for the battery and adversely affect its performance. This is why it is strongly recommended to clean the contacts before charging both batteries.

How to disassemble a battery from a Makita screwdriver

Soldering banks

Soldering should be done by spot welding using a regular aspirin tablet. It is impossible to solder one element directly to another: any heating causes evaporation of the electrolyte and a rise in temperature, which can be critical for the battery.

When disassembling the bundle and soldering, it is important not to lose metal particles, which may be indispensable when soldering the elements together. To be on the safe side, you can take care of how to make blanks of spare plates from bending metal in advance. It is important to remember the following: the better I solder, the better the battery will work.

Aspirin gives off a lot of corrosive fumes, so work in a well-ventilated area. A soft fusible composition with flowing properties is taken as a solder. The solder is sprinkled with aspirin powder, so it flows between the plates and connects them securely, and aspirin helps to fix the composition in the right place.

The assembled battery is installed in the case, and the operation of the screwdriver is checked. If the tool is running, the newly assembled battery is charged as usual and its functionality is checked again. If no drop in RPM is observed for the instrument, this means that the experiment was successful. Since nickel-cadmium batteries work for a long time with proper operation, there is a chance that a new bundle assembled by yourself will not fail, and a self-made screwdriver battery will work properly.

How to disassemble a screwdriver battery?

So, the first step is to take the battery and place it on a hard surface. Personally, the kitchen table came up to me, besides, in parallel with disassembling the battery, you can “grind” something tasty.

Batteries on screwdrivers are collapsible, but they are not collapsible. It is clear that it is more profitable for the manufacturer to make non-collapsible ones, since the failure of the battery automatically implies the purchase of a new battery, only there is one small “НННООО”!

The thing is that the price of a new rechargeable battery for “Shurik” reaches up to a third of the cost of the screwdriver itself! Therefore, as a true Patriot of our country and a level 80 handshake, I didn’t even have a thought about buying a new battery or some fucking Chinese analogue (sorry for my French).

An immediate decision was made. I will disassemble the battery of the screwdriver with my own hands.

What is the load for?

Let’s work with the load resistance. As already mentioned, you can take two, each with a nominal value of 1 ohm. If we put both of them in parallel, then the total resistance we get 0.5 Ohm. It is not necessary to adhere to these ratings, but the lower the resistance, the better.

What is the role of load resistors in qualitatively replacing the battery pack? If we take any electrical appliance and measure the voltage in its battery, we will get a certain value. However, this value does not show how well a particular battery can give its energy. If we measure the voltage under load, we will have what is called “voltage drop”. It is just from it that you can judge how good or bad the battery is.

The load resistance in the form of two small metal blanks and wires connected in parallel to each other is carefully connected to a voltmeter. This loading method is acceptable only if the output voltage of your battery is 12 volts or less (safe voltage level).

The wires are neatly fixed in the “sockets” of the voltmeter with probes, and a constant voltage threshold of 20 volts is set on the voltmeter. This indicator is quite enough to measure U for the entire bunch of elements as a whole and for each element separately, which is especially important.

Fault definition

We figured out the purpose of the battery structure elements, now we will consider how to determine the malfunction, this is part 2 of the screwdriver battery repair. We note right away that all the elements cannot fail at once, and since our circuit is sequential, when one element fails, the whole circuit does not work. So, our task is to determine where we have the weakest link in the chain.

For this, we will need a multimeter, and for the second method of troubleshooting a 12V lamp, if your battery for a screwdriver is also 12 volt. The procedure is as follows:

Note. The difference between the cells in the battery of 0.5. 0.7V is considered significant, this means that the cell becomes unusable.

Thus, we have found candidates for “resuscitation” or “amputation” and replacement with new elements.

If your screwdriver operates on a voltage of 12 or 13V, you can search with a simpler method. We disassemble the fully charged battery and connect a 12 volt lamp to the contacts “” and “-“. The lamp will be a load and will drain the battery. Next, we take measurements on the battery cells, where the voltage drop is strongest, there is also a weak link.

There are other ways, instead of a lamp, you can choose a resistance, but for this you already need the basics of electrical engineering, and it is doubtful that a resistor with the necessary resistance would be at hand.

Other faults are very rare. For example, loss of contact at the soldering points of the batteries or the power contacts of the unit, failure of the thermistor. This problem is more inherent in fakes. Due to the rarity, we will not focus on the battery elements.

With the “problem” elements sorted out, it is necessary to repair. How to repair a screwdriver battery? In general, there are 2 ways available for repair, so to speak. This is the restoration and replacement of elements that have become unusable.

Is it possible to “reanimate” the elements and how?

Let’s proceed to part 3 of repairing a screwdriver battery and immediately make a reservation that the concept of “resuscitation” for lithium. ion batteries is not applicable. There is no memory effect in them, most likely, lithium decomposition has occurred, and nothing can be done about it. In such batteries, it is necessary to find out what the cause of the malfunction is: the element itself or the control circuit. There are two options here:

• we change the control scheme from another, but similar to ours, battery, if it helps, we find a replacement and change it;
• apply 4V to a cell with a current of about 200mA, this requires an adjustable charger. If the voltage on the element rises to 3.6V. the element is working properly, the problem is in other elements, or in the control circuit.

Screwdriver battery refurbishment is available mainly for Ni-Cd batteries, but they are usually the most common in household screwdrivers.

So how to reanimate a screwdriver battery? There are two types of “resuscitation” for these types of batteries:

• The method of compaction or compression (it will work in cases where the electrolyte is still present, but the volume is lost);
• “Firmware” voltage and current greater than the nominal. This method allows you to eliminate the memory effect, and although not completely, but restore the lost capacity.

This method is shown below in the video.

Note. As a rule, in a nickel. cadmium battery, the main reason for the loss of capacity is the boiling off of the electrolyte, and if it is critically small, no “firmware” will help.

This method, if its result is positive, will not solve the problem of failure of elements. Rather, it will only postpone the replacement of those that have become unusable and in the future you will still need to repair the battery of a Makita screwdriver or any other.

• Screwdriver battery: design and types
• Fault definition
• Is it possible to “reanimate” the elements and how?
• Repair and replacement of screwdriver battery cells

Screwdriver battery: design and types

It should be noted that regardless of the brand of the screwdriver and the country of the manufacturer, the batteries have an identical structure. The assembled battery pack looks like this.

If we disassemble it, we will see that it is assembled from small elements that are assembled sequentially. And from the school physics course, we know that elements that have a serial connection harmonize their potentials.

Note. The sum of each battery gives us the total voltage at the contacts of the battery.

Typesetting parts or “cans”, as a rule, have a standard size and voltage, they differ only in capacity. Battery capacity is measured in Ah and is indicated on the cell (pictured below).

For the arrangement of screwdriver batteries, the following types of elements are used:

• nickel. cadmium (Ni. Cd) batteries, with a nominal voltage on the “banks” of 1.2V;
• Nickel-metal hydride (Ni-MH), cell voltage. 1.2V;
• lithium-ion (Li-Ion), with voltage. 3.6V.

Let’s consider in more detail the advantages and disadvantages of each type.

• The most common type due to its low cost;
• Low temperatures, such as Li-Ion batteries, are not scary;
• Stored in a discharged state, while retaining its characteristics.

• Produced only in third world countries, due to toxicity during production;
• Memory effect;
• Self-discharge;
• Small capacity;
• A small number of charge / discharge cycles, which means that they do not “live” for a long time with intensive use.

• Environmentally friendly production, there is an opportunity to purchase a high-quality branded battery;
• Low memory effect;
• Low self-discharge;
• High capacity compared to Ni. Cd;
• charge / discharge cycles.

• Price;
• Loses some of its characteristics during long-term storage in a discharged state;
• Does not “live” for a long time at low temperatures.

• No memory effect;
• Self-discharge is almost absent;
• High battery capacity;
• The number of charge / discharge cycles is several times greater than that of previous types of batteries;
• To set the required voltage, fewer “cans” are required, which significantly reduces the weight and dimensions of the battery.

• High price, almost 3 times in comparison with nickel. cadmium;
• After three years, there is a significant loss of capacity, because Li decomposes.

We got acquainted with the elements, let’s move on to the rest of the elements of the screwdriver battery pack. Disassembling the unit, for example, for repairing the battery of the Hitachi screwdriver (pictured below), is very simple. unscrew the screws around the perimeter and disconnect the case.

The body has four contacts:

• Two power, “” and “-“. for charge / discharge;
• Upper control, it is switched on through a thermal sensor (thermistor). A thermistor is necessary to protect batteries, it cuts off or limits the charge current when a certain temperature of the cells is exceeded (usually in the range of 50. 600C). Heating occurs due to high currents during forced charging, the so-called “fast” charging;
• The so-called “service” contact, which is connected through a 9K ohm resistance. It is used for complex charging stations that equalize the charge on all battery cells. In everyday life, such stations are useless, due to their high cost.

That’s actually the whole design of the battery. Below is a video on how to disassemble a block.

Tools

The cost of a new screwdriver is about 70% of the cost of the battery for it. Therefore, it is not surprising when, faced with a battery failure, we ask ourselves the question. what’s next? Buy a new battery or screwdriver, or maybe there is an opportunity to repair the screwdriver battery with your own hands and continue working with an already familiar tool?

In this article, which we will conditionally divide into three parts, we will consider: the types of batteries that are used in screwdrivers (part 1), their possible causes of failure (part 2) and available repair methods (part 3).

Repair and replacement of screwdriver battery cells

A more effective way to repair batteries for a screwdriver is to replace elements that we have identified as faulty.

Note. When purchasing a new element, make sure that its capacity and dimensions coincide with the native elements.

We also need a soldering iron, a low-corrosion flux (preferably an alcohol flux for rosin) and tin. We are not talking about spot welding, since there is hardly a need to purchase or assemble it for a one-time battery repair.

In the replacement itself, there is nothing complicated, especially if at least some. then there is experience in soldering. The photographs show everything in sufficient detail, we cut off the faulty element, instead of it we solder a new one.

Several nuances should be noted:

• When soldering with a soldering iron, try to solder quickly, so that the battery does not heat up, because risk spoiling it;
• if possible, implement the connection using native plates, or use the same copper plates, this is important because the charging currents are large and if the cross-section of the connecting wires is incorrect, they will heat up, respectively, the thermistor protection will be triggered;
• in any case, do not confuse the plus of the battery with the minus. the connection is sequential, which means that the minus of the previous can goes to the plus of the new can, and the minus of the new one. plus the next.

After the new elements have been soldered, it is necessary to equalize the potentials on the “banks”, since they are different. We carry out a charge / discharge cycle: we set it to charge overnight, give it a day to cool down and measure the voltage on the elements. If we did everything correctly, the picture will be something like this: on all elements the same indicator of the multimeter, within 1.3V.

Next, we proceed to discharge the battery, insert the battery into the screwdriver and load it “in full”. The main thing is to spare the screwdriver itself, otherwise you will have to repair it too. We bring it to full discharge. We repeat this procedure two more times, i.e. charge and fully discharge.

It should be noted that the procedure for erasing the “memory effect” should be carried out every three months. It is carried out by analogy with the above-described training.

Such a not very tricky procedure will prolong the work of your screwdriver, at least until you have to change it to a new one.

Charging the batteries

Before disassembling the blocks, be sure to charge them well. With subsequent voltage measurements, this is exactly what will make it possible to understand which batteries are “live” and which are not. Before charging the batteries, it is recommended to clean the internal contacts of the charger with emery paper, because any contact resistance can “give out” an incorrect charging process.

When you charge both batteries alternately, pay attention to how fast they charge. If the battery is charged quickly, and the charge indicator signals the end of the process after just a few minutes, this means that there are definitely faulty cells in the battery. And of course, when the battery charges too slowly, or does not take current at all, it should definitely be disassembled and “tested” all the batteries that are inside. Read more about the charging time of the screwdriver battery →

After you charge and disassemble your battery pack, you will see that there are several elements inside it. cans. The number may vary depending on the voltage level of your instrument. Banks are connected in a certain series. Inside there is a thermal sensor brought out to the contact plates.

If the signal from the temperature sensor going to the charger is incorrect, then the battery will receive either an undercharge or an overcharge. Both are highly undesirable for the battery and adversely affect its performance. This is why it is strongly recommended to clean the contacts before charging both batteries.

How to disassemble a battery using a regular mallet

In order to disassemble the battery from a Bosch screwdriver, Metabo or any other tool of 12 volts or more, you need to make some effort. If you just rip open the edges of the battery pack adjacent to each other with a screwdriver, it will turn out to be sloppy. In addition, there is a greater risk that the fragile plastic structure will simply break.

Therefore, it is recommended to take a mallet and begin to slowly tap on the edge of the seam until characteristic sounds appear, meaning that the seam itself begins to weaken on the sly. It will take a long time to knock, and it will take time and patience. But it is in this way that you can ensure that the disassembly of the battery from the Makita screwdriver will be crowned with success, without unnecessary breakdowns and losses.

After a while, you will hear a crack of a breaking seam. The batteries themselves inside from such manipulations will not be damaged. Only the seam that holds the block will break, and the “cans” and the two halves of the plastic case will remain unharmed.

When we disassemble the block, knock the body with a mallet lightly, without applying any special efforts, so that it bounces slightly off the surface. From time to time, between tapping, you can try to slowly pull back the bottom cover of the block, thereby checking how much the seam has loosened. In such cases, the mallet itself will be slightly damaged, but there is nothing wrong with that.

When the clicks when tapping become regular, you should check the block with some thin knife, carefully inserting it between the halves of the case. When the two parts of the case begin to open, it will be visible. it means that we have almost achieved our goal.

It is worth warning right away that the battery packs of the 12-volt Makita screwdriver are often extremely sturdy and difficult to disassemble. But if you slowly work with a mallet, the seam on the glue will gradually crumble. This may take ten minutes or more in time. But for a person with experience, the whole process takes no more than six minutes.

This is how, gradually and carefully, you can disassemble the screwdriver battery, which the manufacturer intentionally made “non-removable”. with the aim not to change the batteries in it, but immediately run after a new one, which is expensive. Of course, this will require some skill and accuracy. But it will also save money, and at the same time learn how to disassemble the battery from the Makita screwdriver with your own hands.

How to assemble one battery from two

It so happens that the best way out of the situation when both batteries are “hooked” is a way to assemble one full-fledged battery of two. Using any of the proposed methods, you can disassemble both blocks in order to understand which elements are suitable for further use, and which should be discarded.

For this you will need:

• two batteries,
• Charger,
• any thin and flat screwdriver,
• scalpel,
• a piece of sandpaper,
• two wires,
• load resistance (two are possible),
• voltmeter for voltage measurements.

How to disassemble and remake a battery from a screwdriver with your own hands

Everyone knows that the battery of a screwdriver sooner or later begins to lose its former performance and needs to be replaced. Usually only a couple of elements in a common bundle “sit down”, but this negatively affects the entire battery. Therefore, it becomes necessary to either replace several elements with new ones, or still change the battery pack completely. Since the complete set of any screwdriver. “Hitachi”, “Makita” and other models. includes two batteries, if you wish, you can try to assemble a whole homemade battery from two. The owners of power tools, who use them all the time, sooner or later begin to wonder how to convert the battery of a screwdriver to lithium. As for the newcomers who were first puzzled by this goal, they first of all have a question about how to disassemble the battery from the Makita screwdriver or any other, so as not to damage the fragile plastic box.

Experienced electronics enthusiasts assemble different types of batteries, including power supplies for an uninterruptible power supply (UPS). This is much more difficult than disassembling the battery of an electric drill. Any drill is often produced with so-called “non-separable” battery packs, which are either firmly sealed with tape around the perimeter, or their two parts fit so tightly to each other that, at first glance, it is impossible to disconnect them without causing forced external damage. However, among the craftsmen, you can also find people who have already thoroughly “got their hands on” with such batteries and can happily share their secrets with everyone.

• How to disassemble a battery using a regular mallet
• We disassemble the battery with a spatula or a stationery knife
• How to assemble one battery from two
• Charging the batteries
• What is the load for?
• We measure the voltage
• Soldering banks
• A little about how to convert a battery from cadmium to lithium and who needs it

What is the load for?

Let’s work with the load resistance. As already mentioned, you can take two, each with a nominal value of 1 ohm. If we put both of them in parallel, then the total resistance we get 0.5 Ohm. It is not necessary to adhere to these ratings, but the lower the resistance, the better.

What is the role of load resistors in qualitatively replacing the battery pack? If we take any electrical appliance and measure the voltage in its battery, we will get a certain value. However, this value does not show how well a particular battery can give its energy. If we measure the voltage under load, we will have what is called “voltage drop”. It is just from it that you can judge how good or bad the battery is.

The load resistance in the form of two small metal blanks and wires connected in parallel to each other is carefully connected to a voltmeter. This loading method is acceptable only if the output voltage of your battery is 12 volts or less (safe voltage level).

The wires are neatly fixed in the “sockets” of the voltmeter with probes, and a constant voltage threshold of 20 volts is set on the voltmeter. This indicator is quite enough to measure U for the entire bunch of elements as a whole and for each element separately, which is especially important.

We disassemble the battery with a spatula or a stationery knife

For those who are not used to working with a mallet and want to make the battery disassembly process look quieter and more gentle, you can suggest using a small metal spatula or a utility knife. The main thing is that they do not have sharp edges, like a large screwdriver, which can easily damage plastic.

First, you should completely walk around the perimeter of the entire block with a knife to loosen the seam, and only after that you can begin to “pick” the flexible plastic with a small screwdriver. The method is no less painstaking than the first, and if the person is not experienced enough, damage may remain on the plastic case. However, if you work as carefully as possible, it is possible to do without “losses” and in this case.

If, when disassembling the battery pack, you still have cracks or other damage, you should not be upset, because this type of plastic lends itself well to gluing with dichloroethane.

Soldering banks

Soldering should be done by spot welding using a regular aspirin tablet. It is impossible to solder one element directly to another: any heating causes evaporation of the electrolyte and a rise in temperature, which can be critical for the battery.

When disassembling the bundle and soldering, it is important not to lose metal particles, which may be indispensable when soldering the elements together. To be on the safe side, you can take care of how to make blanks of spare plates from bending metal in advance. It is important to remember the following: the better I solder, the better the battery will work.

Aspirin gives off a lot of corrosive fumes, so work in a well-ventilated area. A soft fusible composition with flowing properties is taken as a solder. The solder is sprinkled with aspirin powder, so it flows between the plates and connects them securely, and aspirin helps to fix the composition in the right place.

The assembled battery is installed in the case, and the operation of the screwdriver is checked. If the tool is running, the newly assembled battery is charged as usual and its functionality is checked again. If no drop in RPM is observed for the instrument, this means that the experiment was successful. Since nickel-cadmium batteries work for a long time with proper operation, there is a chance that a new bundle assembled by yourself will not fail, and a self-made screwdriver battery will work properly.

We measure the voltage

Before measuring the voltage of the cells, prepare a simple pencil with which you will write down the value of U issued by each battery in the bundle. Since in most cases “walking” screwdrivers are equipped with nickel-cadmium batteries packed in dense cardboard layers, it is important to ensure that the batteries are accessible from both sides.

Now it remains to turn on the voltmeter (or multimeter) and start measuring. When measuring, we make each battery an exposure for five seconds and see if the voltage drops (usually, it is normally about 1.2 volts for each battery separately). We fix the indicators with a pencil. It is impossible to keep the probes on batteries for a long time, because the resistance increases, and they can simply burn out.

Practice shows that one has only to fail one element from the entire bundle, this negatively affects the operation of all batteries. If the voltage indicator on any “bank” is 1 volt or less, it has already exhausted its resource. In order to finally make sure of this, you should check the self-discharge level of each battery in the bundle.

Repeated measurements are taken after 15 minutes. When measuring, be sure to check the primary U values ​​with repeated ones. If it turns out that there are batteries, the voltage of which after the initial measurements dropped sharply during the second measurement, it means that they have a high self-discharge, and it is these elements that have already become completely unusable.

After the unusable elements are “calculated”, we disconnect them from the rest with a scalpel, and in their place we put usable batteries from a spare battery. So we redo the whole block, collecting one full-fledged from two.