The cadmium battery is a popular source of energy, which is used to complete household appliances. They are classified as alkaline types. They are equipped with those units and devices into which other models cannot be included.

Nickel-cadmium batteries contain negative and positive conductive terminals, for the separation of which a separator is used. Interior filled with alkaline electrolytic composition. The housing for nickel-cadmium batteries is prepared from a special metal and hermetically sealed.

In order to ensure best contact, to prepare the electrodes, foil is used, which is not very thick. To construct a separator, which is concentrated between the terminals in nickel-cadmium batteries, woven raw materials are used. After all, it does not interact with alkaline electrolyte.

Borne is used to connect the battery to other nickel-cadmium power sources. The nickel-cadmium battery design includes welded joints to ensure a tight connection.

Advantages of Nickel Cadmium Power Supply

The number of discharge and charge cycles reaches 1,000 or more.
The storage period for such devices is long. At the same time, the degree of charge of the unit does not affect this indicator.
The technology for charging nickel-cadmium batteries is relatively simple. Novice motorists can also implement it.
Such power supplies can also be used in winter period, in harsh conditions.
The capacity does not decrease even at sub-zero temperatures.

Negative sides

The devices have a property called a “memory effect”. To eliminate it, there is a need to carry out certain measures.
The level of self-discharge is increased.
If you compare CD batteries with other power sources, you can highlight their low energy density.
Toxic components were used for preparation. Therefore, some states do not use such batteries and do not manufacture them.
To dispose of such units, appropriate equipment is used. In our country, installations for recycling and recycling are being prepared for nickel-cadmium units.

Charge and discharge of nickel-cadmium batteries

Discharge process

The discharge parameters of the power source largely depend on the design features, characteristics of the electrodes and current leads. They also predetermine the magnitude of voltage and internal resistance.

Bit parameters depend on:

Features and structures of the separator.
Build quality.
The amount of electrolytic composition with which the housing is filled.
Other.

When discharging a nicd source for a long time, experts recommend using disk batteries, which are supplemented with large-sized pressed leads. Therefore, with a slight increase in current, the discharge capacity, as well as the voltage, decreases. In order to optimize this indicator, the thickness of the leads is reduced and the number is increased.

The maximum capacity value is observed at room temperature. Further increase in temperature does not affect this parameter. Negative temperature provokes a decrease in discharge voltage and an increase in discharge current.

The use of screwdrivers equipped with nickel-cadmium power supplies in winter requires caution.

Charging process

When charging ni cd batteries, it is necessary to introduce charge restrictions. After all, during the recharging process, the pressure inside the case increases, oxygen is produced, and the current application coefficient decreases.

How to charge ni cd battery? In order to fully restore the charge, a capacity of 150–160 percent must be provided. Temperature range – 0-+35 degrees. If you do not take into account the temperature range, the pressure will increase. An oxygen mixture will be released through the emergency valve. Therefore, it is important to determine in advance how to properly charge the battery.

A discharged nickel-cadmium battery is charged in various modes. The charging time depends on which mode is selected.

Current of 0.2 of the total capacity for 7 hours.
A current of 0.3 of the total capacity for no more than 4 hours.

When charging the unit in accelerated mode (with a current of 0.4 of the available capacity), overcharging is prohibited, as this will lead to a decrease in capacity. You can set how much the power source is charged using appropriate devices. When working with currents, an ammeter is used. To determine the number of volts, use a voltmeter or multimeter.

Charger for nickel-cadmium batteries

To charge ni cd batteries, reversible and automatic chargers are used.

The automatic ni cd charger is easy to use. With its help you can recharge 2–4 batteries for a screwdriver or other household appliances. After placing the battery in the memory, the mode and number are set. After this, the unit is connected to the network.

Automatic models are equipped with indicators that help determine the state of the charging power sources when working with current. Such devices are also suitable for discharging ni cd batteries.

Pulse chargers differ more complex design. They can be used when working with significant current. Since they are classified as professional units, before use you learn how to charge the power source and how to set the required parameters.

Reverse (pulse) models are suitable for cyclic supply of charge and discharge current. During discharge and charging, the parameters of current and voltage are determined in advance.

Features of use

Long-term operation affects the functioning and performance of cadmium-nickel batteries. Performance deterioration and failure are caused by:

The working surface of the conductive terminals is reduced.
The active mass of the conductive terminals is significantly reduced.
The alkaline electrolytic composition changes composition and is incorrectly redistributed throughout the power source.
Leakage occurs along conductive elements. As a result, the discharge of a charged power source occurs quite quickly.
The consumption of liquid and oxygen increases. If oxygen is released excessively, the process becomes irreversible.
Organic compounds begin to disintegrate.

Reconditioning of nickel-cadmium batteries

The procedure for restoring nickel-cadmium batteries, which are used to complete a screwdriver or other portable unit, takes some time. Since the cost of such batteries is high, the features should be studied before implementation.

Essentially, we restore the nickel-cadmium battery of the screwdriver with a pulsed current, which is supplied for 2-4 seconds. The current value exceeds the capacitance parameters by 10 or more times.

Before restoring the battery, certain elements and tools are prepared:

Efficient power supply with strong current ratings. A car battery is used as a battery.
Clamps.
Wires.
A multimeter that monitors voltage.
Protective items.

The recovery procedure includes certain activities:

The positive and negative terminals of a portable tool unit or a separate battery are determined.
Using clamps or alligator clips, as well as pieces of wire, the cons are attached.
The other end of the wire is pressed to the positive contact. The duration of wire contact is 1–2 seconds (can be increased to 3 seconds). Such actions take a little time. When making contact, make sure that the wires do not stick to the unit or battery.

After one cycle, the voltage level is measured using a multimeter. As soon as the voltage has been restored, they proceed to increasing the capacity. In order to restore and repair the power supply, 2–4 cycles are performed.

This technique brings the expected effect only on short term. This is because the electrolytic composition changes, and its volume also changes. As a result, batteries cannot be used as sources for a long time.

Modernized technique

In order to restore nickel-cadmium batteries with your own hands, as well as ensure their long-term operation, perform the following steps:

All batteries are carefully checked and the voltage is measured. Those elements on which the voltage is close to zero are removed.
Using an appropriate tool, holes are prepared in the body to fill 1 cm3 of distilled water.
The power sources are allowed to settle for a short period of time, after which they are recheck voltage.
If the functionality of the battery is restored, then the formed holes are treated with sealant and soldering.
The unit is equipped with batteries and is rechargeable. The portable instrument is ready for use as soon as the indicator on the charger changes color. For these purposes, it is worth using pulse chargers, which are distinguished by extensive functionality and high-quality equipment.
At zero voltage, distilled water is reinjected into the battery.
The procedure is repeated until a positive result is achieved.

Storage Features

Operating instructions for cadmium batteries have been prepared by specialists. The instructions describe how to store power supplies. Several basic rules have been highlighted.

Ni cd sources can only be stored when completely discharged. For these purposes, chargers that are equipped with the appropriate function are used. For emptying, incandescent lamps with the appropriate number of amperes are also used.

Batteries that are properly prepared can be stored for a long time. Temperature changes do not affect the condition and performance.

Premises are used to store nickel-cadmium batteries. After all, temperature fluctuations do not provoke discharge or the launch of irreversible processes.

Although nickel-cadmium batteries are stored for a long time, at a certain stage there is a need for disposal. To do this, you should contact an organization that performs similar processes.

The efficiency of nickel-cadmium batteries is difficult to overestimate. They are equipped with portable tools used in everyday life and in industry. With proper handling, compliance with safety precautions and operating conditions, the period of use exceeds five years.

Video about Nickel cadmium batteries

Electric screwdriver, a necessary household and industrial tool for small construction work, installation and removal of hardware. The use of batteries instead of mains power supply allows you to work in any conditions, in the absence of energy. Most often, the storage battery of the tool is equipped with Ni-Cd batteries resembling AA batteries. Under proper operating conditions, these components can withstand up to 1000 charging cycles. In some cases, screwdriver batteries need to be rebuilt.

Features of operation of nickel-cadmium and nickel-metal hydride batteries

For a screwdriver, it is important to choose a battery that matches the voltage of the tasks being performed and has good capacity. All assemblies are made from standard components with a voltage of 1.2 V and a capacity of 2000 mAh, regardless of the country of origin of the instrument. To obtain the required operating voltage, the package is assembled with a series connection of elements, each of which works independently. The owner's responsibility is to properly maintain the tool.

The battery may lose capacity under the following conditions:

At the beginning of operation, the battery was not “boosted” - eliminating the “memory effect”.
The tool is recharged at a time convenient for the owner, without waiting for full energy production.
Charging does not reach maximum level, stops earlier, contributing to a decrease in capacity.

Therefore, from time to time it is necessary to use firmware as a method of restoring the memory of Ni batteries.

A screwdriver with a nickel-cadmium battery can be stored for a long time in a discharged state. The reason for the loss of capacity of a non-working battery is the drying out of the internal active part. The capacity will be restored if water is added to each jar in a special way.

However, over time, the deadline for disposing of batteries with toxic filling comes. It was this aspect that forced European countries to switch to less harmful Ni-Mh (nickel metal hydride) batteries. Their technical specifications and memory effect are identical to nickel-cadmium, but have fewer charge-discharge cycles and do not work at sub-zero temperatures. The method of restoring the capacity of Ni-Mh batteries differs from nickel-cadmium batteries.

Ni-Cd batteries – capacity restoration

For the restoration of nickel-cadmium batteries roll type pulse currents are used. In this case, the current parameter exceeds the capacitance by 10 or more times, the pulse lasts 2-4 seconds. In order not to damage the structure of the elements, you must follow the instructions and follow the sequence of operations.

First of all, it is necessary to identify elements with zero charge in the assembly. These elements must be desoldered and restored separately. There is no reading on the multimeter, because inside the can there was a break in the contact between the housing and the positive plate. The reason is the absence or lack of moisture inside the case. In such batteries it will be necessary to restore the water-salt balance:

completely remove the element body from the packaging;
drill a hole in the groove and inject about 1 ml of water into the cavity with a syringe, slowly and gradually, if the water is not absorbed at all, discard the cell;
let the water soak in, do the initial recharging of the element with a pulsed current;
Charge each battery to 1.2 V and leave for several days.

After making sure that the cells hold a charge, you need to solder the holes on the cases. Assemble a new battery, replacing the rejected cells.

It happens that one cube of water is not enough, the capacity in the element is not fully restored. You can repeat the operation as long as the hole is open. There are other ways to resuscitate a screwdriver battery, but this one restores the cells for a long time.

We suggest watching the described method in the video.

The battery life is relatively short, on average 5 years. After the set period has expired, the battery suddenly stops working. In such a situation, it is not always possible to quickly purchase a new power source, so home handyman I have to solve the problem of how to restore the battery of a screwdriver, at least for a short time. In some cases, after a successful recovery, the batteries work normally for quite a long time.

Structural elements of a screwdriver

A screwdriver is rightfully considered an indispensable universal tool. Modern market screwdrivers presented big amount models equipped with a battery. Despite the variety of brands and modifications, all batteries have the same structure and only differ slightly from each other.

Each of them consists of individual elements connected in series with each other. All of them are made according to standard sizes and have the same voltage level. Certain types of elements differ only in capacity, measured in A/h and indicated in the labeling.

The tool body contains 4 contacts that perform various functions. Including two are power ones, designed for charging and discharging. In addition, in the upper part there is a control contact included in the circuit along with a special temperature sensor. It protects the battery, cuts off the charging current and limits it to a set value by changing the temperature regime.

The fourth contact is located separately, connected together with a resistance. It is necessary when using highly complex charging stations capable of equalizing the charges of all battery cells. Such stations are rarely used in everyday life due to their high cost. A regular 12-volt screwdriver does not require such stations.

One of the reasons why a screwdriver fails is a faulty battery, that is, it individual element. In such cases, when serial connection the entire circuit fails. Therefore, it is very important to accurately determine the faulty location. As a rule, this happens after the specified service life has expired. This problem can be resolved in two ways: purchasing a new battery or repairing and restoring the old battery.

What batteries are used in screwdrivers?

Correct diagnostics requires knowledge of the main types of batteries used in screwdrivers and the design features of each of them. Each battery consists of mini batteries connected in series to form a single chain. Depending on the material of manufacture, they are nickel-cadmium (Ni-Cd), nickel-metal hydride (Ni-MH) and lithium.

The first option, Ni-Cd, is the most widely used. In these batteries, each cell has a voltage of 1.2 volts, for a total of 12 volts with a capacity of 12,000 mAh. They differ from lithium ones in their ability to be restored, since they have a known memory effect, which is a reversible loss of capacity.

Due to design features batteries, not all methods are suitable for restoring them. For example, lithium cells cannot be restored using Imax B6 charging, since lithium gradually decomposes, loses its qualities and does not hold 18 volts. The same method is not always suitable for Ni-Cd batteries, since in some cases the electrolyte in them may completely boil away. However, there are many options for recovery.

Different types of batteries also differ in their own operating voltage of the cells. This difference is due to the materials used to make a particular battery. This factor also affects the capacity, which ensures long-term operation of the tool without additional charging. Therefore, when initially opening the case, the type of elements placed inside is first determined. The fact is that it is not allowed to replace lithium mini-batteries with nickel-cadmium ones, since their operating voltages are significantly different. Accordingly, the methods of repair and restoration will differ.

To repair the battery you will need measuring instruments- 2 A, 2 and 15 V, tester, and milliammeter. Manipulations with the body are performed using a screwdriver, scissors and pliers. A magnifying glass may be needed to detect defects.

While solving the problem of whether the battery can be repaired, the faulty element is searched for and then replaced. A standard scheme is used for verification, and based on the data obtained, the condition of individual parts is analyzed. It should be remembered that not only the mini-batteries, but also the terminals of the screwdriver itself may be faulty.

Determining the causes begins with measuring the voltage using a tester on each individual battery. All non-working elements are marked and separated from serviceable ones. If the battery suffers fast discharge, you should not immediately disassemble it. First, you can try to restore the battery capacity of the screwdriver. For this purpose, the battery is fully charged and deeply discharged over several cycles. In most cases, capacity is restored almost completely.

Often a screwdriver stops working due to terminal failure. During operation, they gradually unbend, as a result of which the contact is broken and the battery is not fully charged. To repair the charger, you must first disassemble it and then carefully bend each terminal. After this, you need to check the charging quality using measuring instruments.

If Taken measures did not help, you just need to replace the faulty part. If a specific cause of the malfunction is discovered, it is recommended to use the recovery methods below.

How to eliminate the memory effect

When a battery is undercharged and then discharged very frequently, it experiences a so-called memory effect. That is, the battery gradually remembers the minimum charging and discharging limit; as a result, its capacity is not fully used and gradually decreases further and further.

This problem is typical mainly for nickel-cadmium batteries and affects nickel-metal hydride batteries to a lesser extent. In any case, it is necessary to restore the battery capacity. The memory effect does not apply to lithium-ion batteries at all.

In order to solve the problem of whether the element can be repaired, it is recommended to completely discharge and charge the battery using a 12-volt light bulb. The positive and negative wires are soldered to it, which are connected to the battery contacts. This procedure is repeated five times or more.

How to add distilled water correctly

Distilled water only evaporates from nickel-cadmium batteries when they overheat during operation. Therefore, to eliminate the problem and restore their functions, water must be added.

This procedure is performed in the following sequence:

After disassembling the battery, mini batteries will be found inside. Their number may vary, depending on the brand of the instrument. The faulty element is determined by a multimeter. In a working battery, the voltage is 1-1.3 V. If this figure is lower, then the element is faulty and needs to be repaired.
Next, carefully remove faulty parts without destroying the connecting plates. They will be needed later for reassembly.
A hole no larger than 1 mm is drilled in the side. It is not located in the middle, but closer to the bottom or top of the battery. You only need to drill the wall, without going deep into the element.
You need to fill the syringe with distilled water. The needle is inserted into the hole and through it the battery is completely filled with water. After this, it should stand in this position for at least a day.
After a day, the battery is charged using a special device, and then left in a charged state for another 7 days.
A week later, the capacity and voltage are checked again, and if it has not dropped, the hole in the case is sealed or sealed with silicone.

After all the manipulations, the batteries are assembled into one unit and inserted inside the battery case. The connecting plates are soldered or spot welded. Then the functionality of the entire battery is checked again, after which it is completely discharged using small loads. The charging and discharging process is performed at least 3 times.

Replacing old batteries

This method can be used to repair the battery of any screwdriver. The repair procedure itself is not particularly difficult and begins with disassembling the battery. Using a multimeter, faulty elements are determined whose voltage will be below normal. Then they are carefully removed and exactly the same mini-batteries are purchased instead.

New parts are installed in place and connected by existing plates. Soldering or spot welding. In this case, you need to ensure that the battery does not overheat. Therefore, the work must be done carefully and quickly using flux or rosin.

Battery Bleeding

This repair method concerns elements lithium-ion batteries. During the period of operation, they overheat, as a result of which the electrolyte evaporates from some batteries. Because of this, gases accumulate inside the battery, causing swelling, accompanied by bending of the plate. After this, you have to restore the screwdriver battery.

The solution to this problem is carried out in the following order:

Disassembling the battery and finding a faulty battery using a multimeter. Usually there is no voltage in such elements.
After this, the battery is removed and gas is released from it. In the first case, you will need some kind of flat tool, curved at the end. It is brought under the positive contact and the swollen plate is gently pressed down. The gas finds its way on its own, making a hole and exiting. In this case, you restore functionality only for a short time, since the electrolyte will evaporate completely through the hole and the battery will stop working again.
In the second case, the positive contact is disconnected using wire cutters, after which it is slightly bent, but not completely cut off. After this, an awl is inserted under the curved plate and gradually pushed inward. That is, the plate is disconnected from the edge of the battery and the gas comes out. After this, it is inserted into its place, and the hole is sealed as close as possible. in a convenient way. All that remains is to solder the contact that was disconnected at the very beginning.

The performance of Ni-Cd batteries (like any other) deteriorates over time and after some time they can reach a “zero” discharge state. However, charging cannot affect this condition in any way. They simply refuse to accept the charge. At the same time, the batteries still have enough resources for further use. Therefore, over time, some ways to restore them have emerged. It's up to you to decide whether to buy a new nickel-cadmium battery or restore an old one. We just tried to summarize the data that we were able to find on the Internet about the restoration and repair of Ni-Cd batteries.

When using Ni-Cd, the voltage and discharge capacity gradually decrease. The following are the main factors driving these processes:

reduction of the working surface of positive and negative electrodes;
loss of active mass, as well as its redistribution among the electrodes;
the occurrence of current leaks due to the formation of dendrites of metal Cd;
processes resulting in irreversible consumption of water and oxygen;
change in the composition and volume of the electrolyte.

Similar processes occur when they are exploited. The only difference is in the electrode materials used.
During the operation of Ni-Cd batteries, due to the redistribution of the active mass over the electrodes, a change occurs mechanical strength and the volume of the nickel oxide (positive) electrode. As a result, the contact between the active mass and the electrode deteriorates. All this causes a decrease in conductivity and a drop in capacity. IN running version the contact between the positive and negative electrodes is simply broken. As a result, the battery stops showing signs of life.

All these changes in the nickel oxide electrode are caused by constant recharges, during which the process of oxygen release occurs in the space of the positive electrode. The more batteries go through charge-discharge cycles, the more the crystals of the active mass of the positive electrode become larger. Therefore it decreases working surface, and, therefore, the battery capacity.

On a cadmium electrode, the degradation process is determined mainly by the migration of the active mass. As a result, some loss occurs. In addition, the active mass clogs the pores in the surface layer of the negative electrode. This makes it difficult for the electrolyte to reach the deeper layers. The result of migration of the active mass is the growth of dendritic bridges through the separator to the positive electrode. These lead to numerous short microcircuits and increase self-discharge. On the cadmium electrode during operation, crystal growth and an increase in the volume of the active mass also occur.

In addition to the processes described above, oxidation processes occur in Ni-Cd batteries various additives, which are present in the battery. The cermet of the positive electrode gradually oxidizes with the consumption of water. And another unpleasant process that leads to loss of performance is the selection of electrolyte from the separator. This occurs due to a change in the porous structure of the electrodes and leads to an increase in the internal resistance of the nickel-cadmium battery.
The composition of the electrolyte also changes during operation. In particular, the volume of carbonates is growing. The electrical conductivity of the electrolyte decreases and all parameters of the Ni-Cd battery drop when discharged. The picture becomes especially noticeable when low temperatures. What to do in such cases?

Common method for reconditioning Ni-Cd batteries?

There are quite a lot of articles and videos on the Internet on the topic of restoring Ni-Cd batteries. Most of them concern the recovery of batteries from screwdrivers and other portable tools. This is not surprising, since such batteries are quite expensive and often still need to be looked for. Basically, when restoring nickel-cadmium batteries, one technique is used, which we will now describe.

The image below shows the assembled screwdriver battery and its contents.

And the next photo shows one battery of this assembly.

In short, the recovery method involves applying high current to a Ni-Cd battery in short pulses for a few seconds. In this case, the current must be much greater than the battery capacity (tens of times).

The recovery technique is suitable for nickel-cadmium batteries. Not to be confused with nickel metal hydride. It was tested on roll-type models. In principle, it is suitable for batteries of any age, even leaking ones. Of course, the older the battery, the less likely it is to be restored.
What you will need during the recovery procedure:

another working battery with strong current. It could be the battery from the source uninterruptible power supply, car battery, etc.;
crocodiles, pieces of wire. The pieces of wire should have a length of about 10 centimeters and a cross-section of at least 1.5 mm 2;
multimeter for voltage monitoring;
protective equipment (gloves, goggles).

Attention! Don't neglect your protective equipment. Be sure to wear safety glasses and gloves to protect your eyes and hands.

Ideally, the procedure should be carried out on each battery (1.2 volts) separately, and not on the entire assembly at once. In this case, the recovery procedure will be more efficient and the second battery can be used with less power (a standard car battery or a battery from an uninterruptible power supply will be sufficient).

So, in order, what needs to be done:

Find the plus and minus on the battery being restored (or on the entire screwdriver unit, if you are restoring the whole unit);
Then, using a piece of wire and crocodiles, connect the negatives;
Then a second piece of wire is attached to one of the positive contacts;
After this, you need to quickly touch the remaining free positive contact with the free end of the wire. Here it is important to make touches quickly and briefly (2-3 touches per second). This procedure lasts 3-4 seconds. It is important to avoid welding the wire at the point of contact.

After one cycle of such touches, the voltage on the restored battery is measured. If it doesn’t appear, then do another cycle. After voltage appears on the battery, it is charged until it reaches its capacity. Most likely, it will be less than face value. It is also recommended to do several charge-discharge cycles to train the battery. Read more about this at the given link.

After reading reviews about this recovery method, it became clear that it only provides a short-term improvement in the condition of the battery. The battery actually began to work, charge, discharge, gain capacity, but fell into a coma for a while. As I understand it, this is due to the fact that the source of the problem has not been eliminated. As a result of burning, the dendrites that caused microcircuits were eliminated, and the battery came to life. But since the composition and volume of the electrolyte were disrupted, everything returned to its original state.

Improved battery recovery method

The author of the method disassembled several battery cans during the process and noticed a break in the positive contact with the negative case. He assumed that this was caused by electrolyte degradation and he was right. As mentioned above, during operation there is an oxidation process with water consumption. As a result of the decrease in water in the composition of the alkaline electrolyte, its operational characteristics also changed.

What was suggested:

before carrying out any manipulations with the supply of pulsed current and charging, the author of the method selected elements from the assembly whose voltage was zero;
a hole was made in their body with a microdrill and a thin drill;
a cubic centimeter of distilled water was pumped into the hole of each element;
After this, the batteries stood for some time and their voltage was measured. Elements with zero voltage were “invigorated” with a pulsed current;
then the cells were charged;
After this, it is recommended to leave them for a few days and then check the voltage again;
if the elements are alive, then the holes are sealed with sealant or sealed. The battery is assembled, charged and the screwdriver is ready for use;
if the voltage is again zero, then another “cube” of distilled water is added, and the process is repeated until successful completion.

You might be interested in an article about batteries for a screwdriver.

On the Internet you can also find recommendations for restoring nickel-cadmium batteries by freezing. In this case, they are placed in the freezer for a couple of hours, and then they are quickly and sharply knocked on the battery case. The idea here is that dendrites in a frozen state become brittle and are destroyed by impact. The comments on this recovery method say that it is recommended if the electric shock method does not help. However, I could not find any reviews about the results of its use.

That's all I wanted to say on the topic of restoring Ni-Cd batteries. If you have corrections or additions to the article, write them in the comments. Additionally, we recommend reading the material about.

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How to restore and repair Ni─Cd batteries

The performance of Ni─Cd batteries (like any other) deteriorates over time and after some time they can reach a “zero” discharge state. However, charging cannot affect this condition in any way. They simply refuse to accept the charge. At the same time, the batteries still have enough resources for further use. Therefore, over time, some ways to restore them have emerged. It's up to you to decide whether to buy a new nickel-cadmium battery or restore an old one. We just tried to summarize the data that we were able to find on the Internet about the restoration and repair of Ni─Cd batteries.

When using Ni─Cd, the voltage and discharge capacity gradually decrease. The following are the main factors driving these processes:

reduction of the working surface of positive and negative electrodes;
loss of active mass, as well as its redistribution among the electrodes;
the occurrence of current leaks due to the formation of dendrites of metal Cd;
processes resulting in irreversible consumption of water and oxygen;
change in the composition and volume of the electrolyte.

Similar processes occur when they are exploited. The only difference is in the electrode materials used.

During the operation of Ni─Cd batteries, due to the redistribution of the active mass among the electrodes, a change occurs in the mechanical strength and volume of the nickel oxide (positive) electrode. As a result, the contact between the active mass and the electrode deteriorates. All this causes a decrease in conductivity and a drop in capacity. In the neglected version, the contact between the positive and negative electrodes is simply broken. As a result, the battery stops showing signs of life.

All these changes in the nickel oxide electrode are caused by constant recharges, during which the process of oxygen release occurs in the space of the positive electrode. The more batteries go through charge-discharge cycles, the more the crystals of the active mass of the positive electrode become larger. Therefore, the working surface is reduced, and, therefore, the battery capacity.

In addition to the processes described above, Ni─Cd batteries undergo oxidation processes of various additives that are present in the battery. The cermet of the positive electrode gradually oxidizes with the consumption of water. And another unpleasant process that leads to loss of performance is the selection of electrolyte from the separator. This occurs due to a change in the porous structure of the electrodes and leads to an increase in the internal resistance of the nickel-cadmium battery.
The composition of the electrolyte also changes during operation. In particular, the volume of carbonates is growing. The electrical conductivity of the electrolyte decreases and all parameters of the Ni─Cd battery drop during discharge. The picture becomes especially noticeable at low temperatures. What to do in such cases?

A common method for regenerating Ni─Cd batteries?

There are quite a lot of articles and videos on the Internet on the topic of restoring Ni─Cd batteries. Most of them concern the recovery of batteries from screwdrivers and other portable tools. This is not surprising, since such batteries are quite expensive and often still need to be looked for. Basically, when restoring nickel-cadmium batteries, one technique is used, which we will now describe.

The image below shows the assembled screwdriver battery and its contents.

And the next photo shows one battery of this assembly.

In short, the recovery method involves applying high current to a Ni─Cd battery in short pulses for several seconds. In this case, the current must be much greater than the battery capacity (tens of times).

another working battery with strong current. This could be a battery from an uninterruptible power supply, a car battery, etc.;
crocodiles, pieces of wire. The pieces of wire should have a length of about 10 centimeters and a cross-section of at least 1.5 mm 2;
multimeter for voltage monitoring;
protective equipment (gloves, goggles).

Attention! Don't neglect your protective equipment. Be sure to wear safety glasses and gloves to protect your eyes and hands.

So, in order, what needs to be done:

Find the plus and minus on the battery being restored (or on the entire screwdriver unit, if you are restoring the whole unit);
Then, using a piece of wire and crocodiles, connect the negatives;
Then a second piece of wire is attached to one of the positive contacts;
After this, you need to quickly touch the remaining free positive contact with the free end of the wire. Here it is important to make touches quickly and briefly (2-3 touches per second). This procedure lasts 3-4 seconds. It is important to avoid welding the wire at the point of contact.

After searching on the Internet, another, more advanced method for Ni─Cd recovery was found batteries. We also advise you to read the material about.