What you need to know about nickel-cadmium batteries. How to restore and repair Ni-Cd batteries Ni ca batteries how to assemble

09.03.2020

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In the second half of the twentieth century, some of the best rechargeable chemical sources current were rechargeable batteries manufactured using nickel-cadmium technology. They are still widely used in various fields thanks to its reliability and unpretentiousness.

Contents

What is Nickel Cadmium Battery

Nickel-cadmium batteries are galvanic rechargeable current sources that were invented in 1899 in Sweden by Waldmar Jungner. Until 1932 they practical use was very limited due to the high cost of the metals used compared to lead-acid batteries.

Improvements in their production technology led to a significant improvement in their performance characteristics and made it possible in 1947 to create a sealed, maintenance-free battery with excellent parameters.

Operating principle and design of Ni-Cd battery

These batteries produce electrical energy through the reversible process of interaction of cadmium (Cd) with nickel oxide-hydroxide (NiOOH) and water, which results in the formation of nickel hydroxide Ni(OH)2 and cadmium hydroxide Cd(OH)2, which causes the appearance of electromotive force.

Ni-Cd batteries are produced in sealed cases containing electrodes separated by a neutral separator containing nickel and cadmium in a solution of a jelly-like alkaline electrolyte (usually potassium hydroxide, KOH).

The positive electrode is a steel mesh or foil coated with nickel oxide-hydroxide paste mixed with conductive material

The negative electrode is steel mesh(foil) with pressed porous cadmium.

One nickel-cadmium cell is capable of producing a voltage of about 1.2 volts, so to increase the voltage and power of batteries, their design uses many parallel-connected electrodes separated by separators.

Technical characteristics and types of Ni-Cd batteries

Ni-Cd batteries have the following technical characteristics:

the discharge voltage of one element is about 0.9-1 volts;
the rated voltage of the element is 1.2 v; to obtain voltages of 12v and 24v, a series connection of several elements is used;
full charge voltage – 1.5-1.8 volts;
operating temperature: from -50 to +40 degrees;
number of charge-discharge cycles: from 100 to 1000 (in the most modern batteries - up to 2000), depending on the technology used;
self-discharge level: from 8 to 30% in the first month after a full charge;
specific energy intensity – up to 65 W*hour/kg;
service life is about 10 years.

Ni-Cd batteries are produced in various cases of standard sizes and in non-standard designs, including disk and sealed form.

Where are nickel cadmium batteries used?

These batteries are used in devices that consume high current and also experience high loads during operation in the following cases:

on trolleybuses and trams;
on electric cars;
on sea and river transport;
in helicopters and airplanes;
in power tools (screwdrivers, drills, electric screwdrivers and others);
electric shavers;
in military equipment;
portable radios;
in radio-controlled toys;
in diving lights.

Currently, due to stricter environmental requirements, most batteries of popular sizes (, and others) are produced using nickel-metal hydride and lithium-ion technologies. At the same time, there are still many NiCd batteries of various sizes in use that were released several years ago.

Ni-Cd cells have a long service life, which sometimes exceeds 10 years, and therefore this type of battery can still be found in many electronic devices, except those listed above.

Pros and cons of Ni-Cd battery

This type of battery has the following positive characteristics:

long service life and number of charge-discharge cycles;
long service life and storage;
opportunity fast charging;
ability to withstand heavy loads and low temperatures;
maintaining performance in the most unfavorable conditions operation;
low cost;
the ability to store these batteries in a discharged state for up to 5 years;
average overcharge resistance.

At the same time, nickel-cadmium power supplies have a number of disadvantages:

the presence of a memory effect, manifested in loss of capacity when charging the battery without waiting for complete discharge;
the need for preventive maintenance (several charge-discharge cycles) to reach the full capacity;
complete restoration of the battery after long-term storage requires three to four full charge-discharge cycles;
high self-discharge (about 10% in the first month of storage), leading to almost complete discharge of the battery within a year of storage;
low energy density compared to other batteries;
the high toxicity of cadmium, due to which they are banned in a number of countries, including the EU, the need to dispose of such batteries using special equipment;
greater weight compared to modern batteries.

Difference between Ni-Cd and Li-Ion or Ni-Mh sources

Batteries with active components including nickel and cadmium have a number of differences from more modern lithium-ion and nickel-metal hydride power sources:

Ni-Cd elements, in contrast to the variants, have a memory effect and have a lower specific capacity with the same dimensions;
NiCd sources are more unpretentious and remain operational at very high temperatures. low temperatures, many times more resistant to overcharge and strong discharge;
Li-Ion and Ni-Mh batteries are more expensive, they are afraid of overcharging and strong discharge, but they have less self-discharge;
service life and storage Li-Ion batteries(2-3 years) is several times less than Ni Cd products (8-10 years);
Nickel-cadmium sources quickly lose capacity when used in buffer mode (for example, in a UPS). Although they can then be fully restored by deep discharging and charging, it is better not to use Ni Cd products in devices where they are constantly recharged;
The identical charging mode of Ni-Cd and Ni-Mh batteries allows you to use the same chargers, but you need to take into account the fact that nickel-cadmium batteries have a more pronounced memory effect.

Based on the existing differences, it is impossible to make an unambiguous conclusion about which batteries are better, since all elements have both strengths and weaknesses.

Operating rules

During operation, a number of changes occur in Ni Cd power supplies, which lead to a gradual deterioration in performance and, ultimately, to loss of performance:

decreases effective area and mass of electrodes;
the composition and volume of the electrolyte changes;
the separator and organic impurities decompose;
water and oxygen are lost;
Current leaks appear due to the growth of cadmium dendrites on the plates.

In order to minimize damage to the battery that occurs during its operation and storage, it is necessary to avoid adverse effects on the battery that are associated with the following factors:

charging an incompletely charged battery leads to a reversible loss of its capacity due to a decrease total area active substance as a result of crystal formation;
regular strong overcharging, which leads to overheating, increased gas formation, loss of water in the electrolyte and destroys the electrodes (especially the anode) and the separator;
undercharging leading to premature battery depletion;
long-term operation at very low temperatures leads to changes in the composition and volume of the electrolyte, increasing internal resistance battery and deteriorate performance characteristics, in particular, the capacity drops.

With a strong increase in pressure inside the battery as a result of rapid charging with a high current and severe degradation of the cadmium cathode, excess hydrogen can be released into the battery, which leads to a sharp increase in pressure that can deform the case, disrupt the assembly density, increase internal resistance and reduce operating voltage.

In batteries equipped with an emergency pressure relief valve, the risk of deformation can be prevented, but irreversible changes chemical composition batteries cannot be avoided.

Ni Cd batteries must be charged with a current of 10% (if fast charging in special batteries is necessary - with a current of up to 100% in 1 hour) of their capacity (for example, 100 mA with a capacity of 1000 mAh) for 14-16 hours. Most best mode discharging them with a current equal to 20% of the battery capacity.

How to restore Ni Cd battery

Nickel-cadmium power supplies in case of loss of capacity can be almost completely restored using a complete discharge (up to 1 volt per element) and subsequent charging in standard mode. This battery training can be repeated several times to fully restore their capacity.

If it is impossible to restore the battery by discharging and charging, you can try to restore them using short current pulses (tens of magnitude more capacity element being restored) for several seconds. This effect eliminates the internal short circuit in the battery cells that occurs due to the growth of dendrites by burning them out with a strong current. There are special industrial activators that carry out such an effect.

Complete restoration of the original capacity of such batteries is impossible due to irreversible changes in the composition and properties of the electrolyte, as well as degradation of the plates, but it makes it possible to extend the service life.

The recovery method at home consists of the following steps:

a wire with a cross-section of at least 1.5 square millimeters connects the minus of the element being restored to the cathode powerful battery, such as automobile or UPS;
a second wire is securely attached to the anode (plus) of one of the batteries;
for 3-4 seconds, the free end of the second wire is quickly touched to the free positive terminal (with a frequency of 2-3 touches per second). In this case, it is necessary to prevent welding of the wires at the connection point;
a voltmeter is used to check the voltage on the source being restored; if it is absent, another restoration cycle is performed;;
when an electromotive force appears on the battery, it is charged;

In addition, you can try to destroy the dendrites in the battery by freezing them for 2-3 hours and then sharply tapping them. When frozen, dendrites become fragile and are destroyed by shock impact, which theoretically could help get rid of them.

There are also more extreme restoration methods that involve adding distilled water to old elements by drilling out their housing. But fully ensuring the tightness of such elements in the future is very problematic. Therefore, you should not save money and expose your health to the risk of poisoning with cadmium compounds due to the gain of several cycles of operation.

Storage and disposal

It is better to store nickel-cadmium batteries in a discharged state at a low temperature in a dry place. The lower the storage temperature of such batteries, the lower their self-discharge. High quality models can be stored for up to 5 years without significant damage technical specifications. To put them into operation, it is enough to charge them.

The harmful substances contained in one AA battery can pollute about 20 square meters territories. To safely dispose of NiCd batteries, they must be taken to recycling points, from where they are transported to factories, where they must be destroyed in special sealed ovens equipped with filters that trap toxic substances.

Adding distilled water to nickel-cadmium batteries

One of the most common problems Ni-Cd batteries - evaporation of distilled water. Most often occurs when the battery overheats. To solve the problem you need to:

Disassemble the battery.
There will be small batteries inside (about 14 pieces, depending on the screwdriver model). Using a multimeter you need to find the failed part. The voltage on the working “barrel” will be in the range from 1 to 1.3 volts. Anything below this mark requires repair.
Faulty items are carefully removed. The plates that attach them to other batteries will be useful for assembly later.
On the side, closer to the top or bottom of the battery, there is a bend where you need to make a hole with a diameter of no more than 1 mm. You only need to drill the wall, without going inside.
Now you will need a syringe with a needle and distilled water (in no case ordinary tap water). The syringe is inserted into the hole made, and the battery is filled to the brim. It is advisable for it to remain in this state for a day.
The device charges nickel-cadmium batteries (IMAX is suitable), after which the battery must be allowed to sit for another week.
After 7 days, check to see if the voltage has dropped. If all is well, you need to seal the holes using silicone or a soldering iron.
Next, the batteries are assembled in reverse order and placed in the battery case. Used for soldering spot welding or a regular soldering iron.
After checking the functionality, the battery is completely discharged under light loads and charged again at least three times.

Replacing batteries

Disassemble the battery.
Use a multimeter to find faulty elements. On nickel-cadmium and nickel-metal hydride batteries, the voltage should be around 1.2 volts, on lithium-ion batteries – around 3.6 volts.
Faulty elements are carefully removed and exactly the same batteries must be purchased in their place.
New elements are put in place of old ones. Old plates are used for connection.
Soldering is done with a soldering iron or spot welding. You need to work with a soldering iron very carefully and quickly so as not to overheat the battery. It is advisable to use flux, or, in extreme cases, rosin.

Release of gas from lithium-ion batteries

IN lithium-ion battery There are several separate batteries. During operation, one or more of them may overheat, which will lead to evaporation of the electrolyte. Thus, inside the battery will accumulate a large number of gas and it will swell, bending the thermal plate. To solve the problem you need to:

Disassemble the battery.
Use a multimeter to find the dead battery. Its voltage will be 0.
Next, you need to remove it from the chain and release the gas. This can be done in two ways:

Take scissors with a curved end or any other similar tool, place them under the positive contact and gently press the swollen plate down. In this case, the gas will make a hole somewhere to find its way out. In fact, this method Only restores battery functionality for a short time. Subsequently, through the hole made by the gas, all the electrolyte will evaporate, without which the battery will not work.
Take small wire cutters and disconnect the positive contact so that it can be bent (no need to cut off completely). Next, you need to use an awl with a blunt end, which is inserted under one of the edges of the curved plate and gradually push it inward (disconnect the plate and the edge of the battery). When the gas comes out (it will be audible), the swollen plate must be pressed into place, and the hole made must be soldered with a soldering iron or covered with silicone. And also solder the contact that was disconnected at first.

Now you need to charge the battery using the IMAX device.

Battery excitation

The method is suitable for all types of batteries. Necessary:

Disassemble the battery.
Use a multimeter to find dead batteries.
Excite them using a pulse discharge. Suitable for this: 12 volt battery, power supply, spot welding, etc. The impulse should be short-lived and should not be repeated many times. It is enough to excite the battery so that it can be seen Charger.
Reassemble all the cells (if they were disassembled) and place them in the battery case.

This method is imperfect, since after some time (from a week to a month) the voltage of the batteries will drop again. This is especially true for nickel-cadmium batteries.

A significant part of the price of a new autonomous screwdriver is the cost of the power supply. This is due to the peculiarities of the production of power elements. This situation forces users to repair the screwdriver battery. on our own. It is important to understand what difficulties you will encounter. However, as a result you will be able to win.

Express methods for repairing a screwdriver battery

Before you undertake battery repair, it is worth determining what type of power is installed in the power tool. Modern manufacturers are constantly improving their technologies, so equipment produced in different years, there may be a variety of types of batteries.

Batteries for power tools

The most popular options are:

nickel metal hydride type;
nickel-cadmium type;
Lithium-ion type.

Each of the element blocks has its own characteristics and is designed for a specific operating mode.

They have an operational drawback in which they dry out after the expiration date. Owners of NI-CD blocks will be able to revive their equipment with simple conditions- it is enough to refill them. However, not all owners decide to repair the screwdriver battery with their own hands using such a radical technique.

Battery cells 34x22 mm NI-CD 1.2v 2000mAh, cans for battery repair

Most in a frequent way repair battery with similar structure considered an option in which they try to replace outdated banks with new ones. For battery of this type The memory effect is also characteristic, which is considered one of the main disadvantages of this type. Often you have to reflash the battery itself in order to restore functionality.

Lithium batteries

Repair lithium batteries A screwdriver is often required after operation at subzero temperatures, which is undesirable according to manufacturers. Such batteries are modern conditions are considered the most suitable for construction and other tools, since they do not have a negative memory effect.

Lithium-ion batteries

Li-Ion power supply for the latest generations of electrical appliances are the most common use case. Failure occurs only when lithium decomposes internally or after mechanical damage.

Nickel-metal hydride batteries

This option can be classified as problematic elements for restoration in the battery. Most often, you have to remove the old ones and solder new batteries into the existing case with contacts.

Many online stores offer not only blocks of elements, but also individual components. By folding them and soldering them together, you can assemble new battery.

VIDEO: How to sort out a screwdriver battery

Method for restoring the capacity of nickel-cadmium batteries

Such restoration of a screwdriver battery with your own hands is appropriate in a situation where it has not been allowed to dry out. If an undesirable process has begun, then such food must be disposed of. For determining current state We carry out testing: we simply charge it for 1-2 hours. If the result is zero, then we send them all to the trash bin.

The batteries for the screwdriver will have to be impacted using great strength current and high voltage. Step-by-step algorithm consists of the following points:

We completely disassemble the screwdriver battery along the body joint line. Next, take out the existing elements.
We are preparing the charger. It is advisable to choose equipment for this experiment with the ability to adjust the output parameters (current and voltage). They often use car charging equipment.
Initial setup is being carried out. It is important to consider that the battery in construction power tools uses elements designed for a voltage of 1.2 V and a small current. The voltage on the supply device is set so that it exceeds the consumer rating three times.
We start the fast charging process, which should last no more than 2-3 seconds.
At the next stage, we test the level of changes with a multimeter in the voltmeter stage. On every separate element the expected voltage is 1.4V or close to it. When this result is achieved, the screwdriver batteries will gain charge.

The load can be a 12 V and 40 W light bulb.

Identification and replacement of used containers

At the initial stages of repair, the problem for inexperienced craftsmen is how to disassemble the screwdriver battery. Manufacturers seal the block tightly. This is to a greater extent marketing ploy to show the inseparability of the design and the need to purchase a new unit. It is important to use a flathead screwdriver to determine where the seam is located. Before disassembling, it is recommended to charge a weak battery for 2-3 hours. Next we proceed according to plan:

Carefully open the case to remove the components

The case of any battery is collapsible. Consists of two parts that are connected with small screws or glue

We carry out testing for each element, marking them in advance with markers in order, for the degree of charge, and write down the result

The banks are connected in series, that is, one faulty one is enough for the entire circuit to not work. Your job is to find that weak link.

We connect the load on the entire battery, connecting it to the consumer for a while.
We discard the consumer and retest each element separately, identifying the most discharged ones.
We get rid of the “weak link” by replacing it with new banks. We purchase the same separate batteries by reading the markings on the old ones

We solder the entire system in series (plus to plus minus to minus).

When soldering, work very quickly to avoid overheating the battery. Otherwise, it will not be subject to restoration.

For a new or renewed battery, overclocking is recommended. In this case, you need to charge the power tool to the maximum value, and then completely discharge it. Repeat everything 2-3 times. This operation is standard for all nickel-cadmium products. It is recommended to carry it out approximately once every six months to keep the equipment in good shape.

The negative effect of NI-CD is the so-called “memory effect”. You should not charge a battery that is not completely discharged, since it “takes” this point as a zero charge value and the next time it will not accept power from the current source during charging when this level is reached.

For better subsequent operation, craftsmen recommend making the body collapsible. This will allow unlimited amount times to repair the screwdriver battery with your own hands.

Topping up boiled-off electrolyte

Some technicians use forced battery charging, which leads to negative consequences. The existing electrolyte boils inside the cans. Some of it may evaporate, which leads to exposure of the connecting plates present in the structure.

We use a multimeter to determine the problematic components of the block by soldering it into parts. We dismantle the selected cans and use a punch with a pointed end. Using it, we make a small hole on the minus side. It is desirable that it is not in the middle and has a diameter for the penetration of a medical needle.

Add 0.5-1 mm of distilled water inside using a small syringe. Important on next stage seal the hole. For this, an epoxy compound is used. We return the reanimated part to the block.

Using a 1.5 V light bulb, we discharge all the banks to the same level. At the next stage, we carry out five to six charge/discharge cycles to the maximum. After this, you can use the equipment again for a long time.

VIDEO: The real way restore the screwdriver battery to 100%

Well, tell me, who doesn’t have dead batteries?

Where will they go? Well, yes, to the landfill. By the way, nickel-cadmium batteries contain cadmium, heavy metal, which is extremely harmful to people.
How many millions of batteries end up in landfills?
How much cadmium is sent to the soil, water, and to our table?

You will need a disposable camera.
If there is one, then there is a holder for the battery, but if not, there are alligator clips.
Charging switch
Button.
You can borrow a camera for free at any photo center, they throw them away.
Let's move on.

Here is the diagram you will need.

here it is on the other side.
It may be different, depending on the model. It doesn’t matter, any will do.
Important. Short-circuit the capacitor with a screwdriver, there will be a spark and a small pop.
If you do not do this, then while working on the circuit you may get a little electric shock.
330 volts, unpleasant....

Break off this plate.

and solder two wires there. This will be for charging the capacitor.

That's about it.

That's it, it's ready.

Please note that the gray stripe is the negative electrode!
The minus of the battery that you will restore will then go to it.

That's about it.
If the battery is large, as is the case with a drill (there are a lot, from 12 to 15 elements), then it is more convenient to make crocodiles. Disassemble the battery and restore element by element.

Very important.
ISOLATE the circuit. It's 330 volts, it can give a lot of shock.

Ready scheme.
Charge the capacitor, press the discharge button and give the battery “shock therapy”.
The dendrite crystals inside are destroyed by high voltage and your element works again!
Congratulations, you've just saved yourself a new battery and saved yourself the cadmium that would have come to your table if the battery had been thrown away.

Yesterday I restored an 8 year old battery from a drill.
Didn't hold a charge at all.
I disassembled it, found 6 bad elements, each of them was restored using the above method.
Two "shocks" for each element. The battery is like new and holds a charge remarkably well.

ADDITION.
After treating the battery, perform two charge and discharge cycles.
You need to discharge the element to approximately 0.6 volts and charge it with a full charge.
This will help restore the structure of the element.
How much this method restores batteries, 100% or 80%, I don’t know.
I haven’t done any research and I don’t have any evidence with graphs.
And from experience, a battery with a declared capacity of 1.2Ah was restored after 8 years of service (1 year “on the shelf”)
up to 85-90% approximately from the original (discharged while measuring current consumption).
In general, according to experts from the CADEX company, about 50-70% nickel cadmium batteries(of those that are sent to a landfill) can be restored.

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 task is to fulfill proper maintenance 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.

Screwdriver with nickel-cadmium battery can be stored 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 is this aspect that has 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. Capacity restoration method Ni-MH batteries differs from nickel-cadmium.

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.