How to properly store a screwdriver battery + review of popular mistakes

A screwdriver is one of the most popular power tools in home and professional use. It allows you not only to tighten and unscrew various types of fasteners, but also to drill holes. Based on the method of power supply, devices are divided into mains-powered and battery-powered. Models with batteries are practically not inferior in performance to tools operating from a 220 V network. At the same time, they can be used to perform work operations in offline mode. It is also convenient that the power cord does not restrict movement. But you should charge and store your screwdriver battery properly to ensure it lasts a long time. Many problems with the battery pack can be fixed yourself by using a multimeter to identify the cause of the problem.

Screwdriver battery device

The battery is the source of energy for cordless screwdriver models. Due to the occurrence of physical and chemical processes (electrolysis), this element accumulates electricity and then produces a constant voltage of the required value at its corresponding outputs. Voltage and capacity are the main parameters of any drive. The first shows the potential difference between the cathode and anode of the battery. Voltage is measured in volts. Capacity determines the amount of current produced by the battery in 1 hour, so this parameter is measured in ampere-hours.

For different models, the battery pack (battery) looks and is designed in a similar way. It consists of the following structural elements:

• housings with contacts located on it;
• power supply elements (batteries);
• temperature sensor circuit (thermistor), which performs the function of protecting the unit from overheating (range is from 50 to 600 degrees).

Not all models are equipped with thermistors. The case is usually a plastic box consisting of two parts. It usually houses about 10 batteries inside, and sometimes there are more. In this case, the batteries are connected to each other in a chain. The free terminals of the outer cans are connected to the contacts located on the body, designed to power the tool’s electric motor and connect to charging equipment. The output voltage of the battery is determined by summing this parameter of all batteries connected in a single circuit.

There are 4 contacts on the battery case:

• 2 power (“+”, “-”), intended for charging and discharging;
• one upper control connected to the thermistor;
• one contact used for charging from special stations that are capable of equalizing the amount of charge for all batteries included in the unit.

Based on the type of battery, battery storage devices are divided into the following types:

• nickel metal hydride (designated NiMh) with an output voltage of 1.2 V;
• nickel-cadmium (marked NiCd) also produces 1.2 V at the output;
• lithium-ion (denoted by the symbols Li-Ion), in which the voltage depends on the number of power elements in the battery and can be in the range of 1.2-3.6 V.

Lithium-ion batteries have a control board. At the same time, a special controller monitors the operation of the batteries.

A separate battery consists of the following structural elements:

• positive and negative contacts;
• electrode with a positive charge;
• external covering of the body;
• electrolyte;
• negative electrode.

Nickel-cadmium energy storage devices are most widespread due to their affordable price, compact size and large capacity. They can be recharged more than 1 thousand times.

Operation and storage of lithium-ion (Li-ion) tool batteries

People often write in reviews of a new tool that “the tool itself is good, but the battery died after only six months,” or “I only used it twice, but the battery died.”

The list of similar messages can be continued, but the main point is that people did not really have time to use the tool when something irreparable happened.

Moreover, often, purchasing a new battery is either completely impossible (go and find them for some Chinese), or its price turns out to be comparable to buying a new tool.

Of course, the tool manufacturer is immediately blamed. However, this is only a small part of his fault.

This short article will help you avoid joining the ranks of “deceived buyers,” and will also tell you what to do if everything has already happened.

Let's start with the main thing - in most cases, the tool manufacturer has nothing to do with the manufacturers of the battery cells found in its battery packs.

He simply buys them from those who, in his opinion, offer good value for money.

In other words, the battery cells in the batteries for the Bosch tool and some nameless “Chinese” will most likely be from the same manufacturer, for example, the Japanese company Sanyo or Samsung.

The most commonly used battery cells are 18650 size with a typical voltage of 3.6-3.7 V. These cells are universal and are used wherever possible: from laptop batteries to electric vehicles.

If we are talking about a 10.8-volt battery for a tool, this means that it contains three such elements. In 14.4-volt - four. In 18-volt - five. In 22-volt there are already six, and so on.

Here is a photo of a 14.4V Hitachi BCL battery without the cover. It can be seen that the base part houses four battery cells (by the way, made by Sanyo), and the control circuit is located in the “leg”.

If the Li-ion battery has died for a long time

So, if trouble has already happened and your battery pack shows no signs of life, then you just need to buy the required number of battery cells of the same type and install them into the unit yourself. A couple of notes: they are all rare in Russia, but you can order them from China or the States (Aliexpress.

com and Ebay.com to help you) with free shipping for $4-5 each; You will also have to remember your soldering skills. In addition, battery cells should not be changed selectively. Just everything at once.

After all, the charge controller will consider them all the same, which will lead to overheating of the old ones, which may even catch fire or explode.

And one more thing: the electronics in the battery pack can also be damaged, so before buying new “cans”, first “ring” the old ones. Suddenly everything is fine with them, and it’s not their fault at all.

What needs to be done to make a Li-ion battery last longer than two months

In other words: what to fear from lithium-ion batteries. In household use in power tools, they are afraid of only one thing - long-term storage during deep discharge.

When the charge remains less than 10%, the battery begins to degrade quickly. If you completely discharged the battery and forgot to charge it, but remembered about it a couple of months later, don’t blame me.

Most likely you will have to buy a new one.

The situation is aggravated by the fact that many power tool manufacturers, for reasons of economy, do not do two things. First, the cheapest tool may not have a system to protect the battery from deep discharge.

The second is that if this system is present, it often allows for a deeper discharge than the battery cell manufacturer regulates. This is done to squeeze out every last drop and in such a way that the user will not delay for a long time in installing the battery for charging.

In other words, if you have finished work and think that the battery is more than two-thirds discharged, put it on charge.

That's all the wisdom for those who don't want to delve into the details. If you are one of those people, then you don’t need to read any further.

But if you're interested in the details, or if you use the tool regularly, there's still more to tell.

For those who use the tool regularly

There are a few other tips to help you extend the life of your lithium-ion batteries.

1. As mentioned above, always try to immediately charge the battery if it is completely or almost completely discharged. At the same time, avoid deep discharge-charge cycles. This table will show how many charge-discharge cycles will follow before losing 50% of the capacity, depending on the depth of battery discharge:

2. Do not charge batteries in sub-zero temperatures. They will lose capacity.

3. Do not store batteries at temperatures above 30 degrees. This plate shows how much the capacity will decrease depending on the storage temperature and the state of charge of the battery:

4. If the battery will be stored for a long time, do not charge it completely. The optimal charge level would be 35-50%.

What you need to know about charging lithium-ion batteries

This is a complex process. Each type of battery has its own strategy, but in general terms it is called CC-CV and consists of two main stages - charging with constant current and increasing voltage, then recharging with constant voltage. There may also be additional stages, for example, the whole process may look like this:

1. The battery is first checked electronically to determine its current state and state of charge, as well as its suitability for a fast charge cycle. In the first minutes, a low voltage and low current are applied. If the voltage on the battery does not increase (i.e. it accepts a charge well), then everything is in order, you can charge in fast mode;

2. then comes the main charging phase, which lasts about an hour, where the voltage gradually increases with a consistently high current;

3. then the final phase begins (recharging), where the voltage is kept at the maximum permissible level (usually 4.2 V), and the current gradually decreases. It can last about two hours.

It is extremely important for lithium-ion batteries to prevent overcharging. It also negatively affects the battery life, as does storing it in a discharged state. In addition, the battery can simply overheat and explode. Therefore, the controller strictly monitors this process and stops charging at the appropriate moment.

But unscrupulous manufacturers can cheat a little. If you slightly increase the charge voltage (by 0.1 V, to 4.3 V), this will slightly speed up the process, and most importantly, it will increase the amount of energy stored in the battery by 10%. The consequences of this approach are reflected in this graph:

Please note that the ordinate scale is non-linear, and the graph itself reflects only the number of recharge cycles at which the battery capacity will be halved.

And here we see that at a voltage of 4.2 V the battery degrades extremely slowly, and the number of cycles until the capacity “halves” can be about 1000.

But if the voltage is increased by just 0.1 V, the degradation rate will increase fourfold.

Ultra fast charging

Typically, the manufacturer recommends charging battery cells with currents equal to 0.7 or 1 of the capacity divided by time (i.e., for a 1500 mAh battery cell, the recommended charge current is 1.5 A).

Some manufacturers allow charging at significantly higher currents, which speeds up the process significantly.

However, this leads to accelerated degradation of the battery, plus at the same time you have to monitor its temperature and stop the process if the battery heats up to 40 degrees (the exact value is determined by the battery manufacturer). Early overheating is common with aging batteries.

Here is a graph of capacity loss of lithium-ion batteries depending on the magnitude of charge and discharge currents:

The blue line is charging and discharging with currents equal to capacity/time (for 1500 mAh batteries this is 1.5 A). Green – doubled charge and discharge current relative to capacity (for 1500 mAh batteries – 3 A). Red – triple current (for 1500 mAh batteries – 4.5 A).

In other words, fast charging modes will lead to accelerated battery degradation.

Parameters of typical battery cells

Finally, as background information, we present the official characteristics of the same popular Sanyo UR18650W2 battery cells that were mentioned above:

—

Lower orange line – operation at -20°C.

Well, to be sure that the Sanyo UR18650W2 are not some kind of exception to the general rule, let’s lay out their 10 A discharge graph in comparison with two other batteries produced by Samsung and AW:

Prepared from BatteryUniversity

Article rating: ( 7 , 4.43 out of 5) Loading…

Source: https://dacha.news/li-ion-accumulators/

General rules for battery charging

In order to properly charge the screwdriver battery, a certain external temperature must be provided. The optimal air temperature is considered to be from 10 to 40 degrees. An undesirable point is the possible overheating of the battery pack during charge accumulation. To avoid possible negative consequences of this phenomenon, it is necessary to disconnect the battery from the charger for cooling.

After the batteries reach full capacity, it is not recommended to leave them in a disconnected charger or insert them into a screwdriver, which will then not be used; it is better to place them in a tool case.

It is recommended to recharge battery packs that are not used for a long period of time once a month.

The recommended battery charging time ranges from 30 minutes to 7 hours and depends on its type. For a specific model of power tool, it is indicated in the operating instructions. These instructions must be followed carefully to ensure a long service life of the product. Most chargers are equipped with indicators that show what stage the process is at. In such cases, by the lighting of LEDs of a certain color, it is not difficult to determine exactly how long the batteries need to be charged. Once the full capacity level is reached, the process must be stopped immediately.

General information

The most popular screwdrivers are those that have built-in types of batteries, where the nominal voltage is 12 V. When working with such devices, you should keep in mind the fact that you can only talk about ideal performance, as well as the service life of the tool, if you use only the type of battery pack that is specified in the official passport of the device. If a battery with a lower voltage is supplied, the screwdriver will have insufficient performance. If you install a battery with a higher voltage, the engine will wear out prematurely, and then completely break down. So, let's look at how to store the battery from a screwdriver.

The nuances of charging batteries of various types

Charging different types of battery packs has its own characteristics. They are related to the properties of the materials from which the batteries are made. To regularly recharge battery packs, pulse or conventional chargers are used. Professional power tools are equipped with adapters of the first type, and models for domestic use are equipped with adapters of the second type. New or discharged drives must be properly charged before use, taking into account their characteristics.

Thus, nickel-cadmium batteries are characterized by a pronounced “memory effect”. For the first time, it is recommended to charge them three times in a row, each time completely discharging them. Only in this way will the maximum (operating) capacity of the storage batteries be achieved. Afterwards, you will need to regularly connect the screwdriver to the charger when its power drops to a minimum.

Nickel-metal hydride batteries also have a “memory effect”. Before first use, it is recommended to repeat the full charge/discharge cycle 4-5 times. During further operation, the charge is replenished as necessary.

If nickel-cadmium and nickel-metal hydride batteries are not initially charged correctly, their battery capacity will gradually decrease.

Lithium battery packs are the least demanding. There are no special rules for them, because there is no “memory effect”. Lithium-ion power cells are able to maintain their original operating capacity levels for a long time. It is not necessary to bring them to full charge/discharge each time.

What is the problem when using 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 Ni-MH batteries are used. The only difference is in the electrode materials used.

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, 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 the loss of performance of a Ni─Cd battery 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?

Charging methods without using a special charger

When a standard charger is missing or simply broken, you can do without it. Craftsmen have come up with different ways to replenish battery charge from different sources. To charge a screwdriver battery without a conventional charger, you can use:

• car charging;
• universal type charger;
• external sources of electricity.

The best option for car charging is a device with the ability to regulate voltage and current . The main thing in such cases is to avoid overcharging. To do this, the charging current is set within such limits that the process runs from 0.5 to 0.1 A*h, depending on the size of the total capacity. For example, if it is 1.3 A*h, then the current should be from 650 to 130 mA.

When the current values ​​are too large, and it is impossible to set smaller values ​​with the regulator, additional resistance is used, for example, a car lamp. It is connected in series to the battery pack.

Universal chargers are convenient in practice. They have many additional settings that allow you to optimally select the appropriate current parameters for recharging batteries from different power tools.

External power sources are used mainly for worn-out screwdrivers, for which it is not economically feasible to purchase new batteries. In such cases, the power tool is upgraded in a certain way, and an appropriate connection diagram is developed. An example is a converted USB charger, additionally equipped with a fuse.

What to do after diagnosis

Having established reliably which equipment is faulty, you need to choose a way to solve the problem.
The simplest action is to replace the faulty unit. This path is not always optimal for economic reasons - batteries and chargers are not cheap, and it is irrational to throw them away due to a cheap breakdown. And it’s not always possible to purchase components, especially for older models. In many cases, the functionality of electrical equipment can be restored. If oxidized or rusty terminals of the charger are found, they must be cleaned with fine sandpaper. Better yet, replace the contact plates by taking them from the faulty donor charger.

Replacing charger contacts.

To do this, you will need a soldering iron, and with it solder and rosin-based flux (acid-free). The same applies to damaged battery pack contacts.

If the charger board does not receive mains voltage, then the power cord must be replaced. You can take it from any other device or make it yourself by purchasing a plug and a piece of wire.

An example of a screwdriver charger circuit.

If everything is in order, and the charger does not blink the LEDs and does not output voltage, then the control board is faulty. You can try to fix it. This requires certain qualifications and equipment (at least a multimeter and an oscilloscope). The charger diagram can be found on the Internet.

The parameters of the battery and charger are marked on the device body.

If the battery is faulty, you can try to revive it, and the restoration method depends on the type of battery elements. For NiCd batteries, you need to open the plastic casing of the unit and remove all the elements. Next, you should carry out a visual inspection, which will help identify leaking, oxidized, damaged elements. They need to be unsoldered and replaced with new ones. If there are none, you need to measure the voltage on each element.

Battery cells without outer casing.

Lagging banks or elements with zero voltage must be unsoldered and set aside separately. If the voltage is zero, then we can assume that the electrolyte has dried out. In this case, you need to drill a hole in the battery case and try to gradually introduce about 1 milliliter of distilled water inside using a syringe. If water is not absorbed, the element cannot be restored.

Adding water inside the NiCd element.

If you manage to saturate the internal cavity with water, then you must try to recharge each faulty element (including lagging banks) with a pulsed current to a voltage of 1.2 volts. The essence of the method comes down to charging with a current exceeding the capacity by 10+ times in pulses of 2-4 seconds. If the operation is successful, you need to solder the hole in the element body and let it sit for several days. Then the battery must be soldered again and collected in a plastic case.

Nickel-metal hydride elements can be restored by training. Experience shows that for batteries that have not been deeply discharged, the chances of success are high. To do this, the lagging elements must be individually discharged to a level of 1 volt by loading them onto a light bulb or resistor. Then charge it again to nominal, and repeat this cycle several times.

From the video you will learn: Why the battery of the Riobi screwdriver stopped charging.

It is impossible to restore the capacity of a Li-ion battery, but the battery may lose functionality if one or more cells are deeply discharged. In this case, the control circuit assumes the elements are faulty and blocks their charge. You can try to “pull up” the batteries to their nominal value so that the balancer does not turn them off when charging. To do this, remove the discharged element (it can be found by measuring the voltage on each battery) and assemble a simple circuit.

Lithium-ion battery recovery scheme.

The voltage must be raised from zero until a current reaches approximately 0.2 of the battery capacity. In this mode, the element must be charged to 3.7 volts, and then turned off and the voltage on it monitored for several days. If it decreases due to self-discharge, then the element must be rejected. If not, you can carry out a charge-discharge control cycle. It must be borne in mind that even if performance is restored, this effect is temporary. The element will soon fail, so you need to be prepared to completely replace the battery.

If it turns out that the screwdriver is not charging, then this problem can in many cases be solved. But the approach must be conscious, otherwise the situation will only worsen and lead to financial losses.

Recommendations for storing batteries

It is recommended to store batteries of any type disconnected from the screwdriver. Each type of battery also has its own characteristics in this regard:

• nickel-cadmium batteries must be discharged before storage to such an extent that the screwdriver does not work at its full power;
• Nickel-metal hydride batteries are recommended to be kept fully charged, but a small discharge is still allowed;
• Before storing a lithium-ion battery, it also needs to be discharged, but only half.

After a long period of storage, nickel-metal hydride batteries, which can withstand 200 to 300 recharge cycles without loss of capacity, must be recharged within 24 hours. Blocks of this type are distinguished by a significant self-discharge parameter.

As mentioned above, lithium-ion power cells do not have a “memory effect”. They have a large capacity and the lowest self-discharge rate. You can replenish their charge at any time, regardless of the degree of discharge.

Li-Ion batteries should not be completely discharged, because this may cause the built-in electronic temperature or voltage protection system to turn off.

To achieve the 50% charge required for proper storage, lithium-ion batteries must be charged from near zero for a period of about 65% of the time it takes to reach full capacity.

Compliance with the simplest recommendations for storing and charging different types of battery packs will allow you to use up the entire lifespan of the batteries included in them by the manufacturers.

Features of battery types + (Video)

The battery is the most important part in a screwdriver. If the tool begins to work poorly, then one of the reasons is the failure of the batteries. A new battery pack costs slightly less than the screwdriver itself. And you have to make a serious choice - buy a new block or a new tool. Not a cheap pleasure.

But, if a person created it, then a person can repair it. The main thing is that the head works and the hands have the right source. You can repair batteries with your own hands, which will then work for many more years.

Rechargeable batteries consist of several elements. They are very similar to regular batteries, but can be recharged. The number of charge cycles determines the basic price of the cells. By type of material, battery cells are divided into:

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

They are arranged in the list by frequency of use. Nickel - cadmium elements (Ni-Cd) are most often found in screwdrivers of different brands. This is due to its comparative cheapness. But they have a low output voltage and the number of charge-discharge cycles is also low. The voltage on one such battery is about 1.2 V. If a screwdriver requires 12 V to operate, then the battery must consist of at least 12 such elements.

They are stored for a long time in an uncharged state and are not afraid of temperatures. But the level of self-discharge forces the battery to be charged frequently, which is the reason for failure. The environmental friendliness of the production of such batteries is not acceptable in every country in the world, but perhaps that is why they are cheaper.

Lithium – ion (Li – Ion) batteries have the best performance. The voltage on a separate copy reaches 3.6 V. High charge capacity. Four pieces are enough to operate the tool. This is very pleasing to the hands, because the instrument must be carried and held in the hands at any height. The number of charge cycles is high, but the price is also not low. But the battery has no “memory” of its charge level. And the self-discharge is small. In a word, everything is good except the price.

Nickel-metal-hydride (Ni-MH) batteries have almost all the disadvantages of previous brands. Given the quality of nickel-cadmium elements, their price is equal to the cost of lithium-ion ones. Application in practice is very low where there are low temperatures. Low temperatures damage the entire battery at once.

You can repair a battery yourself, but this does not mean that you can repair one element. You can try to restore one element, and if restoration does not help, then you just need to replace it. All battery elements can be replaced. This is the best option - buy new elements and make replacements. But this is not always fast, and the tool is needed now.

Checking the battery condition with a multimeter

Not always, when the battery runs out quickly or does not function at all, it is necessary to buy a new one or take the unit to the service center specialists. In many cases, even an inexperienced electrician can independently find the cause of the malfunction after familiarizing himself with the search algorithm. To do this, you will need to use a multimeter or similar measuring devices. In addition to this device, you will also need the following tools:

• screwdriver;
• soldering iron with soldering kit;
• knife;
• pliers.

To accurately determine the cause of battery problems, it is necessary to determine the performance of each individual power element. But first it is recommended to check the charger. Using a multimeter this is done this way:

• turn on the device;
• set the switch of the measured values ​​of the multimeter to constant voltage;
• install the probes into the corresponding sockets of the multimeter and touch them to the contacts (“+” and “-”) of the charger;
• compare the value displayed on the device display with the output voltage of the charger indicated in the operating instructions or on the case;
• if the values ​​do not match, then repair the adapter or buy a new one.

Whenever possible, select the measurement range on the device used that is closest to the output voltage indicated on the charger.

To check the battery of a screwdriver with a multimeter, perform the following steps:

• fully charge the battery pack;
• check the output voltage of the battery with a multimeter, setting the device switch to its constant value, and touching the plus and minus with probes;
• if it is determined that the measured parameter does not correspond to the value specified in the operating instructions, then disassemble the battery pack and remove all the batteries;
• when there are no damaged banks (leaking or swollen), then check the voltage at the terminals of each battery with a multimeter, having previously soldered the circuit using a soldering iron;
• a load is connected to the batteries in turn for the same amount of time (for example, a light bulb of the appropriate voltage);
• Whichever battery experienced the greatest drawdown is the one that is damaged.

To check, nickel-metal hydride and nickel-cadmium energy storage devices are completely discharged - this is done to avoid the “memory effect”.

When checking batteries, it should be taken into account that for nickel-cadmium and nickel-metal hydride types of batteries, the output voltage should be in the range from 1.2 to 1.4 V, and for lithium batteries - from 3.6 to 3.8 V.

Having found a defective battery, you can replace it with a new one or try to temporarily restore it. You can also measure the current strength with a multimeter: if it grows and exceeds 1 A in the first hour, then the battery is considered operational.

If there is no voltage at the battery output, then there is a high probability of a violation of the integrity of the circuit inside the unit. At the same time, they also disassemble the block and first look for the break point visually and then using a multimeter.

Where to start repairing a faulty battery

The first thing you need to do is recharge the battery, and then open the case, inside of which the cans are located. If they are not soldered together, but have the shape of an ordinary AA battery, then you should try bending the terminals. Sometimes it helps. If not, you'll have to use a multimeter.

PHOTO: motonoob.ruA multimeter is an indispensable thing for such repairs

Use the switch to set the desired voltage (constant) and check each of the cans. If there are no differences, then the problem is a “memory effect”. A faulty can will have a significantly lower charge. It will have to be changed, although there is a way to try to resurrect the jar, provided that it is nickel-cadmium, but more on that a little later.

PHOTO: izdoski.com So a faulty can has been found, you need to put it aside and try to restore it

It is clear that buying cans is also quite expensive. However, if time does not play a big role for the home craftsman at the moment, you can order them on Chinese resources. Prices there are much lower, especially if you buy in batches of 10 pieces. packaged. After all, such things will always come in handy. And nickel-metal hydride cells are also suitable for most laptop batteries, which are also designed in a similar way.

PHOTO: seven.dealsNickel-metal hydride cells can be ordered from China in approximately these packages

Related article:

How to revive a battery

Since the battery of a cordless screwdriver consists of many individual batteries, failures can be caused by several reasons.

1. Failure or malfunctions in the control system of the element block (charge controller, voltage level).
2. Change of parameters or failure of one of the batteries.

Determining that a battery requires diagnostics and resuscitation is quite simple. Problems with the controller manifest themselves in the form of charging failure, its continuity until the entire battery pack overheats, or lack of voltage.

Problems of individual units are diagnosed in a more varied manner, from complete failure of the battery to various cases of changes in its voltage and useful capacity. The method of resuscitation depends, first of all, on the type of individual batteries.

Lithium-ion

A standard test for lithium-ion batteries looks like this.

1. The control board is dismantled. In its place is installed a working one, removed from another block of the same type.
2. Individual batteries are removed and tested. Using an adjustable power supply, each is supplied with 4V with a current of 200 mA. If the voltage increases, the unit is working.

If the battery does not work due to the failure of one element, it will not be difficult to find and replace the culprit. But batteries of this type have other problems.

Lithium-ion batteries have a standard technological feature: the charge carrier in them decomposes . Therefore, despite the lack of memory and a stable set of voltage limits, during normal operation after three years the product’s capacity drops by 2 times.

However, there is another problem within the entire battery. It's called power supply imbalance. It manifests itself in the form of a gradual decrease in useful capacity and operating time of the screwdriver. The imbalance can only be determined by disassembling the battery. All power units are removed. It is advisable to do this after the battery is fully charged. Each battery is tested. If the voltage on some is less than others, it is necessary to eliminate the imbalance.

This problem is known to users of electronic cigarettes. There are many charger options on the market today that can correct an unbalanced lithium-ion battery bank. However, at home, you can use a cheaper method: each of the elements is charged separately. It is recommended to find data from the manufacturer on rated currents and charging times. By using a regulated power supply, the cells can be discharged to the same level.

Balancing board for lithium-ion batteries

Nickel-cadmium

Nickel-cadmium batteries have a slight memory effect, can withstand negative temperatures, and store a charge for a long time without a noticeable decrease in performance. However, their design features also create some negative failure factors.

First, nickel-cadmium batteries have an electrolyte. It evaporates over time. As a result, no resuscitation methods will help. The battery must be replaced.

Secondly, nickel-cadmium batteries are sensitive to mechanical stress. This is the basis of one of the pair of basic methods of resuscitation. The item can be restored:

• deforming or vice versa, returning the original shape to the element;
• supplying increased voltages and currents using an adjustable power supply.

The latter method should be used carefully. It is recommended to find rated current data for a specific battery class. It is useful to study the experiences of other users with similar resuscitation measures.

How to determine what kind of battery you have

Determining whether a battery belongs to a particular technology is not difficult. If there are letter markings on the battery, you can accurately determine the type of power source. If there are no indicators, but the battery weighs very little, then most likely the product is made using lithium technology.

If the battery has a significant weight and the presence of a memory effect is clearly noticeable during its operation, then we can assume that the element belongs to the group of nickel-cadmium products.

Nickel-metal hydride batteries are free of such disadvantages and do not contain heavy metals that are hazardous to the environment, so such a battery will have an average weight and a long service life.

Operating rules

In order for the battery to last as long as possible, you need to charge it correctly and follow the operating instructions.

How to properly charge your battery

To increase service life, make sure the battery is completely discharged before charging. If the discharge is incomplete during operation, the effective area of ​​the electrodes will decrease. By discharging the battery to 0.9-1 Volt each time, you can preserve the battery parameters for a longer time.

Before using the battery for the first time, you need to train it - conduct several complete charge-discharge cycles. Usually five is enough, but on some models manufacturers recommend doing more, so follow the recommendations in the operating instructions. So the battery will start working at the stated parameters.

Also, the training cycle should be carried out after storage for longer than six months.

How to store batteries

If you do not plan to use a Ni-Cd battery, you do not need to charge it, nor can it be stored in a discharged state. When stored charged for a long time, battery performance begins to decline.

What is a protection board?

The protection board (or PCB - power control board) is designed to protect against short circuit, overcharge and overdischarge of the lithium battery. As a rule, overheating protection is also built into the protection modules.

For safety reasons, it is prohibited to use lithium batteries in household appliances unless they have a built-in protection board. That's why all cell phone batteries always have a PCB board. The battery output terminals are located directly on the board:

These boards use a six-legged charge controller on a specialized device (JW01, JW11, K091, G2J, G3J, S8210, S8261, NE57600 and other analogues). The task of this controller is to disconnect the battery from the load when the battery is completely discharged and disconnect the battery from charging when it reaches 4.25V.

Here, for example, is a diagram of the BP-6M battery protection board that was supplied with old Nokia phones:

If we talk about 18650, they can be produced either with or without a protection board. The protection module is located near the negative terminal of the battery.

The board increases the length of the battery by 2-3 mm.

Batteries without a PCB module are usually included in batteries that come with their own protection circuits.

Any battery with protection can easily turn into a battery without protection; you just need to gut it.

Today, the maximum capacity of the 18650 battery is 3400 mAh. Batteries with protection must have a corresponding designation on the case (“Protected”).

Do not confuse the PCB board with the PCM module (PCM - power charge module). If the former serve only the purpose of protecting the battery, then the latter are designed to control the charging process - they limit the charge current at a given level, control the temperature and, in general, ensure the entire process. The PCM board is what we call a charge controller.

I hope now there are no questions left, how to charge an 18650 battery or any other lithium battery? Then we move on to a small selection of ready-made circuit solutions for chargers (the same charge controllers).

Resuscitation methods

Using higher current

One of the most effective methods for restoring a Ni-Cd battery is the use of increased currents that exceed the battery capacity by 30-40 times. They are served for 5-8 seconds. Due to design features, this method is effective only for Ni-Cd batteries.

By applying increased pulses, you can restore even completely discharged and damaged batteries. It is recommended to connect each element of the battery bank to the circuit - this will reduce the required current power. Tools and materials you will need:

Power supply and multimeter.

• element for supplying pulses;
• cables with terminals for connecting battery sections;
• multimeter for measuring power;
• gloves and glasses for protection;
• battery disassembled into sections.

The process of resuscitating a Ni-Cd battery using powerful pulses includes the following steps:

1. Disassemble the battery by disconnecting the sections from the common circuit. Find the positive and negative contacts, measure the power on each section.
2. Connect the negative terminal to the current source using a cable. It is recommended to use a lead-acid battery from a car with a nominal voltage of 12 V.
3. Connect the second wire to the positive terminal on the battery section.
4. Turn on the power supply, applying amplified current to the positive output at a frequency of up to 3-4 times per second. At the same time, make sure that the wire does not weld to the contact surface. To reduce the risk, it is recommended to install a plate at the output of the current source.
5. Measure the voltage of each section of the Ni-Cd battery. If the characteristics do not increase, apply current again. After power appears at the terminals, replenish the battery capacity by performing several charge and discharge cycles.

Adding distillate

This method allows you to prevent electrolyte degradation, which occurs due to high distillate consumption during operation of the Ni-Cd battery. Due to its reduction in the composition of the working solution, the battery parameters drop significantly. The essence of the improved method is to add distillate through special holes, which leads to the restoration of voltage and other characteristics. The process includes the following steps:

Adding distillate to the battery.

1. Remove the zero-voltage sections from the battery assembly.
2. Make a small hole in their body using a screwdriver and a thin drill.
3. Pour 1 cm2 of distillate into the hole made.
4. After a few hours, measure the voltage in these sections.
5. When the required power is reached, recharge the batteries.
6. Let the distillate sections sit for 2-3 days, then measure the voltage again.
7. If the batteries are restored, seal the holes with sealant.
8. Reassemble the Ni-Cd battery and restore full capacity using a charger.

Freezing method

The method of restoring a Ni-Cd battery by freezing is recommended for batteries that could not be revived by applying current or pouring distillate. To begin, place the battery cells in the freezer for 1-2 hours. After this, take them out and knock on the body of each section with sharp and short blows.

The essence of the method is that when frozen, the crystals that appear during the degradation of the electrolyte become brittle and are easily destroyed upon impact. It is recommended to use a small but heavy object for this, such as a hard plastic handle or a small hammer. You need to repeat the cycle 5-6 times until the voltage is completely restored.

Nickel-cadmium batteries should be used in accordance with the manufacturer's instructions. Due to the nature of the composition, they must be discharged to zero before charging.

Reconditioning a nickel-cadmium battery must be carried out with precautions and in a well-ventilated area.

Design features

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

In order to ensure better contact, foil, which is thin in thickness, is used to prepare the electrodes. 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 sources can also be used in winter, 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.