DIY ni cd battery repair

In detail: do-it-yourself repair of ni cd batteries from a real master for the site my.housecope.com.

In the price of a new self-contained screwdriver, a significant part is the cost of the power supply. This is due to the peculiarities of the production of feeding elements. This situation forces users to repair the screwdriver battery on their own. It is important to understand what difficulties you will have to face in this case. However, as a result, you will be able to win.

Before starting to repair a battery, it is worth determining what type of power is installed in the power tool. Modern manufacturers are constantly improving their technologies, therefore, equipment released in different years may have a variety of types of batteries.

Power Tool Batteries

The most popular options are:

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

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

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

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

The most common way to repair a battery with a similar structure is considered to be the option in which they try to replace outdated banks with new ones. This type of battery is also characterized by a memory effect, which is considered one of the main disadvantages of this type. Often you have to reflash the battery itself in order to reanimate the performance.

Video (click to play).

Repair of lithium screwdriver batteries is often required after operation at low temperatures, which is undesirable in the opinion of manufacturers. In modern conditions, such batteries are considered the most acceptable for construction and other tools, since they do not have a negative memory effect.

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

This option can be attributed to the problematic elements for recovery in the battery. Most often, you have to remove the old and solder the new batteries into the existing housing with contacts.

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

VIDEO: How to sort out a screwdriver battery

Such a do-it-yourself screwdriver battery restoration is appropriate in a situation where drying out was not allowed. If the undesirable process has begun, then such food must be disposed of. To determine the current state, we carry out testing: we simply put it on charge for 1-2 hours. If the result turns out to be zero, then we send them all to the trash can.

The batteries for the screwdriver will have to be influenced with the help of high amperage and high voltage. The step-by-step algorithm consists of the following points:

We completely disassemble the battery of the screwdriver along the line of the joint of the case. Next, we take out the existing elements.
Preparing the charger. It is advisable to choose equipment for this experiment with the ability to adjust the output parameters (current and voltage). Often they use car charging equipment.
Initial setup is in progress. It is important to take into account that the battery in the construction power tool uses cells 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 rating of consumers 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 at the voltmeter stage. For each individual cell, 1.4 V or so is expected. When this result is achieved, the battery of the screwdriver will be charged.

A 12 V and 40 W light bulb can act as a load.

At the initial stages of repair for inexperienced craftsmen, the problem is how to disassemble the screwdriver battery. Manufacturers seal the block tightly. This is more a marketing ploy to show that the structure is not separable and the need to purchase a new unit. It is important to determine with a flat screwdriver where the seam is located. Before disassembling, it is recommended to set a weak battery to charge for 2-3 hours. Next, we act according to the plan:

We carefully open the case to extract the component parts

The case of any battery is collapsible. Consists of two parts, which are connected with fine screws or glue

We carry out testing for each element, having previously marked them with markers in order, on the degree of charge, and the result is written down

The banks are connected in series, that is, one faulty one is enough so that the entire circuit does not work. Your task is to find this weak link.

We connect the load on the entire battery by connecting it to the consumer for a while.
We discard the consumer and re-test each element separately, determining the most discharged ones.
We get rid of the "weak link" by replacing it with new banks. We purchase the same individual batteries by reading the markings on the old ones

When repairing a screwdriver battery with your own hands, replacing cells is considered more effective than restoring them

We solder the entire system sequentially (plus to plus minus to minus).

When soldering, work very quickly so as not to overheat the battery. Otherwise, it will not be subject to restoration.

For a new or renewed battery, a distillation is recommended. In this case, you need to charge the power tool to the maximum value, and then completely discharge it. Repeat all 2-3 times. This operation is standard for all nickel-cadmium products. It is recommended to carry out it about 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 put on a charge a not completely discharged battery, since it "takes" this point for a zero charge value and the next time it will not take power from the current source during charging when this level is reached.

For better subsequent operation, craftsmen recommend making the case collapsible. This will allow you to repair the screwdriver battery with your own hands an unlimited number of times.

Some craftsmen use a forced battery charge, which leads to negative consequences. The electrolyte present boils inside the cans. Some of it can evaporate, which leads to the exposure of the connecting plates in the structure.

We determine the problematic component parts of the block with a multimeter, having unsoldered it into parts. We dismantle the highlighted cans and use a punch with a pointed end. With its help we make a small hole from the "minus" side. It is desirable that it is not in the middle and has a diameter for the penetration of a medical needle.

Inside, add 0.5-1 mm of distilled water with a small syringe. It is important to seal the hole in the next step. 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 cans to the same level. At the next stage, we carry out five to six charge / discharge cycles to the maximum. Then you can use the equipment again for a long time.

VIDEO: A real way to restore 100% battery of a screwdriver

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To begin with, there are a lot of videos on the Internet on recovering batteries from screwdrivers, and they are all the same as a mirror, a brief description of the recovery process that these people offer is that we take the battery, push it with a power supply or another battery, then charge and we use it, and it’s strange that someone doesn’t look, but what kind of stress will be on him when he lies down for a week or two. I propose a completely different way to restore

Which does not just charge and use until the battery dies again. And the one that you did and use as a new battery until the need arises. This method was filmed in draft about a month ago, but I never dared to post it on the site, I just didn't want to reshoot it for a more correct explanation. And frankly speaking, I have very little free time lately.

But now the time has passed, which has shown that the recovery option that many people on the network offer to use are not destined to live for more than a certain period of time. And my version, even after 2-1 month of inactivity, as if nothing had happened quietly works and charges, I still tried to shoot a new video clip, where I will try to tell everything.

In fact, everything turned out to be very simple, and in this I was helped by the NI-CAD 1.2V battery I disassembled, which showed me that even with all the zeros on the outside of the device, the patient inside is rather alive than dead and feels very good.

An attempt to regenerate the bus relative to the collector plate was made using distilled water, and the process was quite successful, as a result of which I came up with the easiest way to restore them even without disassembling the batteries!

It is enough to drill a hole in the accumulator in the place behind the + rollers and pour 20-40 ml of distilled water into it. after a couple of cycles, the hole is slightly covered with silicone.

Before repeating, I recommend watching the video, where I tried to describe the process in more detail.

If you are not sure or afraid of ruining a damaged battery, for example, you can do this with one battery.

If your batteries have voltage and are within the operating range, then you may have a problem with the following:

- faulty charger

- the thermal protection of the battery pack has worked

- there is one battery in the battery pack that has dropped to 0 Volts.

Also, if you notice that the drill began to work somehow sluggishly and at the same time works as long in time after charging, then you most likely have a problem in one or more batteries that are at zero!

A very interesting effect on the battery capacity, it was equal to or slightly more than the indicated battery capacity after restoration by this method.

The performance of Ni-Cd batteries (like any other) deteriorates over time and after a while they can come to a state of "zero" discharge. At the same time, charging cannot affect this state in any way. They simply refuse to accept the charge. At the same time, the batteries still have enough resources for further operation. Therefore, over time, there were some ways to restore them. Whether to buy a new nickel-cadmium battery or restore an old one is up to you.We just tried to summarize the data that we could find on the Internet about the restoration and repair of Ni─Cd batteries.During the operation of 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 over the electrodes;

current leakage due to the formation of metal Cd dendrites;

processes resulting in irreversible consumption of water and oxygen;

changes in the composition and volume of the electrolyte.

Similar processes occur when Ni-MH batteries are in use. The only difference is in the used electrode materials. All these changes in the oxide-nickel electrode are caused by constant overcharges, in which oxygen is evolved 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 grow larger. Therefore, the working surface is reduced, and, therefore, the capacity of the battery.At the cadmium electrode, the degradation process is mainly determined by the migration of the active mass. As a result, there is some loss of it. In addition, the active mass clogs the pores in the surface layer of the negative electrode. Because of this, the access of the electrolyte to the deep layers is difficult. The migration of the active mass results in the growth of dendritic bridges through the separator to the positive electrode. This leads to numerous short microcircuits and increases self-discharge. On the cadmium electrode, during operation, crystals also grow and the volume of the active mass increases.In addition to the processes described above, oxidation processes of various additives that are present in the battery take place in Ni-Cd batteries. The cermet of the positive electrode gradually oxidizes with the consumption of water. And another unpleasant process that leads to the loss of performance of the Ni─Cd battery is the selection of electrolyte from the separator. This is 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 electrolyte composition also changes during use. In particular, the volume of carbonates is growing. The electrical conductivity of the electrolyte decreases and all parameters of the Ni - Cd battery fall during discharge. The picture becomes especially noticeable at low temperatures. What to do in such cases?

The cost of a new screwdriver is approximately 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 a screwdriver, or maybe there is an opportunity to repair a screwdriver battery with your own hands and continue working with an already familiar tool?

In this article, which we 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).

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 (shown 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), voltage across elements - 1.2V;
lithium-ion (Li-Ion), with a voltage of 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;
It is 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;
More charge / discharge cycles.

Price;
Loses some of its characteristics during long-term storage in a discharged state;
It 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, a smaller number of "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's battery pack. Disassembling the unit, for example, for repairing the battery of a Hitachi screwdriver (pictured below), is very simple - we unscrew the screws around the perimeter and disconnect the case.

The housing has four contacts:

Two power ones, "+" 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.

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. Immediately, we note that all the elements cannot fail at once, and since our circuit is sequential, when one element fails, the whole circuit does not work. Hence, 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:- We put the battery on charge, wait for the signal of a full charge.- We disassemble the case and measure it on each battery bank. For Ni - Cd, we should have 1.2 - 1.4V, in lithium - 3.6 / 3.8V.- Check all "banks" in which the voltage is less than the nominal one. For example, most Ni - Cd cells have a voltage of 1.3V, and one or more - 1.2 / 1.1V.- We collect the battery and work until a noticeable loss of power.- We remove, disassemble and measure the voltage drop across the "banks" of the battery. On the marked elements, the voltage "sag" will be greater than on others. For example, they are no longer 1.2V, but 1.0V or even lower.Note. The difference between the cells in the battery of 0.5 - 0.7V is considered significant, which 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.We have dealt with the "problem" elements, they need to be repaired. How to repair a screwdriver battery? In general, 2 methods are available for repair, so to speak. This is the restoration and replacement of elements that have become unusable.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 primarily for Ni - Cd batteries, but these 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.

The ability to work with a tool such as a screwdriver without connecting it to the mains is convenient, practical and, most importantly, necessary. After all, it is often necessary to perform any work in those places where it is almost impossible to reach the network cable. Construction tool stores offer a wide variety of screwdrivers, including Bosch, as well as the popular Hitachi and Makita. But, unfortunately, the battery life of any drill or similar tool is short - a maximum of 5 years. It happens that the screwdriver's battery is no longer charged even after a shorter period of time. It is not profitable to buy a new battery urgently. A new screwdriver can be purchased for the same amount. Therefore, it is worth trying an option such as restoring the battery of a screwdriver with your own hands.

As you know, the battery of any screwdriver includes several batteries, which are connected in one chain in a certain sequence. There are nickel-cadmium (Ni-Cd), nickel-metal hydride (Ni-MH) and lithium cells.

Nickel-cadmium batteries, in this case, are the most popular and commonly used. The voltage of each individual cell is 1.2 volts and the capacity is 12,000 mAh if we have a 12 volt instrument. It should be noted right away that, unlike lithium ones, they are subject to recovery, because they have the so-called "memory effect" in the form of a reversible loss of capacity.

As for batteries containing lithium, the popular Imax B6 charger is unlikely to restore their capacity due to the fact that lithium tends to degrade over time.

Rebuilding a screwdriver battery in a similar manner may also fail for cadmium batteries. Such a battery differs in that the electrolyte in them sometimes completely boils away. However, in the case of cadmium batteries, the chances of "reviving" them are much greater. But at the same time it is important not to rush and not to use rashly common methods of "quick recovery" of Ni Cd batteries. Read more about which battery is better for a screwdriver →

There are a large number of videos on the Internet in which, for example, the battery recovery of a Hitachi screwdriver using the Imax B6 is clearly shown. It consists in "reanimating" nickel batteries by supplying high currents. Supporters of the express method of recovery propose to revive the battery using the simple settings of Imax B6. The mode is set to nickel-cadmium, and the battery can be reanimated in this mode.

However, pulsing warm-up and subsequent charging are rather risky methods for nickel-cadmium batteries. The broken connection in the element cannot be restored with high currents. In addition, if there is little or no electrolyte inside the battery, high currents will finally "kill" the battery. Therefore, in order to prevent irreversible damage to the batteries, it is recommended to first replenish their electrolyte supply with distilled water and only then charge with the Imax B6.

There is an extreme option, how to restore the nickel-cadmium battery of a screwdriver - you can "pull" them with a high current. They will start charging, but not for long. Electronics enthusiasts who criticize this method assure that there was not a single case when the impulse current restored the battery capacity for a long time. As a rule, it will rise for a very short time, and then, after a few days, the battery "sits down" again.

Whether it is possible to use the impulse current method is up to the owners of the batteries. There are many videos on the Internet on how to recover a Ni Cd battery from a screwdriver. But there is an opinion that in reality, quick methods work for a very short time. For example, if the electrolyte inside any battery has boiled away from the bundle or dried out, the impulse current will “kill” the cell completely.

If possible, you can carefully disassemble each nickel-cadmium battery and see the state of the electrolyte. If it turns out to be dry, you can use the method of adding a small amount of distilled water through a syringe.

To drill a neat hole in the battery, you need a small drill. The hole should be made farther from the center, preferably in the upper side of the element, where there is a small depression. Then fill the battery with distilled water using a syringe to the last.

After that, the battery can be fully charged Imax B6 and let it "settle". The procedure is long. Recovery of 8-, 12-, 14-battery "cans", depending on the voltage, can take a long time. Ideally, you should not charge them right away, but give time to the "cans" of water to stand for a day. You cannot charge the batteries one at a time, it is better that there are at least three or four of them in a bundle, for even distribution of voltage.

Short-term current pulses through a 40 Ohm resistance at 12 V should be applied after water has been poured into the element to be reanimated, and not on the "dry" one, as is often done.

After the batteries have stood for a day, you can start charging them. Do not close the openings yet. Connect to Imax so that the device "sees" them. Charge and let "settle" again if any one battery has not recovered. Find the weak element in the bundle with a multimeter and add water to it again.

The main essence of this meticulous method of repairing a screwdriver battery is to restore the connection of the battery plates with their contact-adapter buses (The internal structure of Ni-Cd is similar to the scheme according to which solar panels are made). The main reason for the termination of batteries is the detachment of the positive contact from their inner part.