Replacing the batteries in the screwdriver battery

Screwdriver battery recovery

Most modern models of power tools are equipped with a rechargeable battery, which increases the comfort of their use. The device with a rechargeable battery can be used even in places where it is not possible to connect to an outlet. That is why, in the event of a battery failure, it is extremely important to quickly eliminate the malfunction. This is especially true for the restoration of the battery of a screwdriver and drill.

Screwdriver battery repair. features of the power tool battery

The screwdriver, like most handheld power tools, uses a standard battery design. Several battery cans are placed in a plastic case. They are connected to each other in series by means of spot welding or by means of sliding contacts. The number of batteries may differ based on the output voltage of the instrument.

In complex models of batteries, there are controller boards that monitor the charge level and temperature of the cans. Similar boards can be found in branded products with li ion battery sections.

Repairing a screwdriver battery involves disassembling the device and the power system itself. As a rule, the parsing procedure is quite simple, regardless of the device model. However, they meet with batteries, which can be difficult to disassemble. they require special tools. In any case, this task must be entrusted to specialists who will do everything without risk to the device and in compliance with safety measures for humans.

Screwdriver battery repair. what types are repaired

The following types of batteries are used in power tools:

• Ni-Cd. Used in budget models, work well at low temperatures. At the same time, they are environmentally unsafe. Repair of batteries of this type of screwdriver is often carried out due to low capacity, tendency to self-discharge.
• Li-ion. They are used more often than other types, including in budget-level power tools. They can be recharged at any time, have a large capacity in a compact size. Designed for a huge number of recharge cycles. Restoring a li ion battery in a screwdriver is important in the case when the battery starts to get hot, swells up, and also when its capacity decreases.

Restoring the battery capacity of the screwdriver

The workshop employees carry out the restoration of the battery of power tools of the following brands:

• Bosch;
• Hitachi;
• Dewalt;
• Bison;
• Einhell;
• Makita;
• Metabo.

Contact Batteries if you encounter any battery malfunction. Any problem will be promptly resolved here, while you will be pleased with reasonable and high quality services.

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

Screwdriver battery: design and types

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

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

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

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

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

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

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

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

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

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

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

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

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

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

The housing has four contacts:

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

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

Tools

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

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

Fault definition

We figured out the purpose of the battery structure elements, now we will consider how to determine the malfunction, this is part 2 of the screwdriver battery repair. 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. So, our task is to determine where we have the weakest link in the chain.

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

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

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

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

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

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

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

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

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

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

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

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

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

This method is shown below in the video.

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

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

Repair and replacement of screwdriver battery cells

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

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

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

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

Several nuances should be noted:

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

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

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

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

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

Replacing cans in a screwdriver battery

To repair the battery, you need to purchase cans of the same voltage. They can be taken either from an old and faulty battery, or you can purchase new ones. per can.

It is important to know! The purchased item must match in capacity and dimensions with the rest of the banks.

At home, you can replace a faulty element with a soldering iron and tin. In production, such a connection is carried out using spot welding. Buying such a device for repairing a screwdriver battery is irrational. After the defective element is replaced, you can assemble the battery and check the quality of the repair, for this you need to put it to charge until it is fully charged. After that, and a few hours after the device has cooled down, you will have to disassemble it again and measure the voltage on each bank. Voltage values ​​should correspond to 1.2-1.3V.

What operations does the repair process consist of?

The process of repairing the device is the removal of a faulty can, which is possible by using side cutters, and to connect the battery, you will need to use a soldering iron and its accessories: rosin and tin. Instead of a removed jar, you should solder a serviceable one. However, before proceeding with soldering work, it is important to know the following:

• Soldering must be done quickly so that the battery does not have time to warm up.
• To solder a new can, use the same size connection plates.
• When soldering, it is important to control the correct connection of the pros and cons.

After replacing the faulty can, we check the quality of the soldering, and, if necessary, remove the remaining flux. Banks must be assembled, then positioned in the device case, and assemble the case.

How to repair a screwdriver battery

The question of repairing a screwdriver battery is one of the most relevant among the owners of this type of tool. The reason for this is the rather high cost of batteries for screwdrivers, which fail over time. If the battery on the screwdriver has become unusable, then you should not rush to dispose of it. In this case, you can repair the battery of the screwdriver, and what is required for this, we will find out further.

Fault definition

Repairing a screwdriver battery is a replacement for a faulty can. All banks cannot fail immediately, therefore, when the battery is not being charged, the reason lies mainly in the malfunction of only one battery cell. To repair the battery, you should find this faulty item.

It is possible to determine the malfunction of a failed bank by performing the following manipulations:

• Initially, you need to charge the battery until it is fully charged.
• We disassemble the case of the device, after which the voltage of each can is measured using a multimeter. The voltage value should be in the range from 1.2 to 1.4 Volts, and for lithium-ion. 3.6-3.8 Volts.
• When taking measurements, you can sign the values ​​on each jar with a pencil.
• After taking measurements, you should reassemble the battery, and then discharge it until the charge is completely lost.
• We proceed to disassemble the case again, and again we check the voltage readings on each element.
• If in any bank the voltage drop exceeds the threshold of 0.5 Volts and above, then this indicates the failure of this element.

This popular method is used by many to find a faulty battery cell. There are also other types of battery malfunction testing, but the above is the most popular.

It is important to know! Other types of battery malfunctions are very rare and are often associated with poor product quality.

After the faulty elements are found, they begin to repair them, which is quite realistic to do at home on your own.

Screwdriver battery: design and types

Despite the external design differences between screwdriver batteries, inside these devices have the same structure. Each device is based on a set of small cylindrical elements that are interconnected in a sequential manner. Such elements are called “banks”, the external image of which is shown below.

Such “cans” are made of various materials, which affects the cost of the screwdriver. These materials include:

• Nickel metal hydride (Ni – MH) elements. The nominal voltage of each can does not exceed 1.2 volts. The final nominal value of the battery voltage depends on the number of such cans.
• Lithium-ion. The voltage of each can is 3.6 volts, therefore, to achieve the same rating with metal hydride cans, 2 times fewer cans are required.

Rarely enough, you can already find another type of battery for screwdrivers, which have the abbreviation Ni – Cd. This means that nickel-cadmium cans are installed in such a device. They are already almost ousted from the market by more modern and better-performing types of batteries. Lithium batteries are currently the most popular. The main advantages of lithium devices are the absence of self-discharge, less weight, and a large number of cycles for charging and discharging. Such advantages are reflected in the cost of products, the price of which is 3 times higher than nickel-metal hydride.

Repair and replacement of screwdriver battery cells

It should be noted initially that all types of batteries, both nickel-metal hydride and lithium-ion, are subject to repair. Not many people know how to repair a screwdriver battery, so very often faulty batteries become the reason for buying a new tool.

It is not possible to repair a can that does not hold a charge, so it will have to be disposed of after being removed from the circuit. It is irrational to repair the battery with a screwdriver in which more than 4 faulty cans are found. In this case, it is easier to purchase a new battery entirely, or find a used device.

In conclusion, it should be noted that most screwdrivers are equipped with two batteries, so if one fails, then the second will have to be used more intensively during its repair. This will allow you not to lie idle with the tool, and you can try to repair the product at a convenient time.

Wiring diagram for converting a screwdriver for Li-Ion batteries

Before replacing batteries in a screwdriver, it is recommended to prepare the correct assembly diagram. To exclude the failure of any components, it is necessary to accurately observe the polarity of the connection.

Important! When drawing up a diagram, it is recommended to mark the positive polarity in red on it, and negative polarity in blue.

BMS protection board selection

Lithium-ion batteries require careful handling and compliance. The role of protection is performed by the BMS board. It is this element that does not allow an excess of voltage of more than 4.2 V and a decrease of less than 2.55 V per battery during charging. In addition, the cell keeps the maximum allowable current under control and maintains the necessary balance between the batteries.

The main parameters when choosing is the number of elements connected in series. On the Internet, you can see a table in which all the necessary parameters are indicated and with its help choose a suitable board.

You can even make a replacement at home, the main thing is to follow the sequence

Choosing a Li-ion battery

Manufacturers offer lithium-ion and lithium-polymer cells. The latter are smaller and safer, but they also cost more. At the same time, they are not able to deliver large currents to work. Therefore, experts recommend taking conventional lithium-ion cans.

Replacing nickel-cadmium batteries in a screwdriver with lithium

Do-it-yourself screwdriver batteries are replaced with lithium batteries by calculating their number, provided that one cell requires 3.7 V. For example, for a product with a capacity of 14.4 V, it is necessary to prepare 4 cans of Li-Ion of 18650 standard.

It is also worth considering the difference in size. To change the battery, you will need to purchase a charge-discharge controller, which is installed additionally in the case with banks. In addition, it is possible that the charger will have to be replaced.

Lithium battery capacity indicator

Indicators are LED and digital. The latter are cheaper, but not convenient to use. Better to choose LED options based on the number of batteries connected in series.

How to change batteries in a screwdriver with your own hands

A screwdriver is one of those tools that every man needs. The device can operate both from the mains and from special chargers. Therefore, it is recommended that every owner of such a product know how the batteries are replaced in a screwdriver. The process is simple, but some models may have certain features.

For each product, the number of cans in the battery may be different

Fault definition

Before eliminating the malfunction, it is required to find out whether it is really present. To this end, the following actions are performed:

• Disconnect the battery from the product, while it must be fully charged.
• Disassemble the battery case with a screwdriver.
• Remove all cans from the product.
• With the help of a voltmeter, the voltage is measured on each bank. For nickel-cadmium products, an indicator of 1.2 Volts is considered normal, for lithium products. from 3.6 to 3.8 Volts.
• After taking measurements, it is determined on which part the voltage is least of all, it is it that will be of poor quality.
• The battery must be assembled and installed in the tool, then completely discharged.
• After that, you need to disassemble the part again, and then re-measure. The element with the lowest scores needs to be changed.

Important! Replacing low-quality elements is quite simple, they are connected in the usual sequence, taking into account the pros and cons. This applies to all models Makita, Bosch, Bison, Metabo, Devolt, Interskol, Diold, AEG.

Ready-made 18650 battery assemblies

Varieties of batteries for a screwdriver

There are 3 types of rechargeable batteries on the power tool market:

• (NiCd) nickel-cadmium;
• (NiMH) nickel metal hydride;
• (Li-Ion) lithium-ion.

Replacing batteries with similar ones

On some units, you can see the mounting screws that need to be removed. But on most battery packs there are no self-tapping screws, since the body is glued together. To open such a block, you need to carefully insert a screwdriver into the gluing place (shown by an arrow in the photo) and press lightly so that the walls of the case are disconnected. The same actions need to be done around the entire perimeter.

After opening the block, you will see the batteries in it.

• You need to solder quickly, not allowing the battery to heat up, as it may become unusable.
• For connections, you need to use the “native” plates, desoldering them from the old batteries (they have the desired cross-section and resistance).
• It is important to correctly connect the plus and minus of the battery. The elements must be connected in series: the minus of the previous battery must be connected to the plus of the new one, and the minus of the new battery to the plus contact of the next battery.

After connecting all the elements, it is necessary to equalize the potentials on all batteries, since they are different. Carry out one charge-discharge cycle: connect the charger to the battery overnight, then let it cool down for a day and measure the output voltage in turn on all cells. If everything went well, then on all batteries the indicator will be the same. within 1.3 V.

Now the battery needs to be discharged by inserting it into a screwdriver and loading the latter to the maximum. The main thing is not to overheat the engine of the tool. Give him a little rest. Bring the battery to full discharge. Repeat this procedure 2 more times (full charge and full discharge).

Which battery for a screwdriver is better to choose

A cordless screwdriver is a fairly convenient and demanded tool. The independence of the power supply makes this device mobile and allows you to work in hard-to-reach places. But despite all the advantages, the rechargeable battery (AKB) is the weak link in a screwdriver. Therefore, when choosing a power tool, you first need to understand what types of batteries exist, what is their difference, the pros and cons of different types of batteries.

Replacement with lithium batteries

Replacing NiCd cells with Li-Ion is also not difficult. It is known from the school course that if the batteries are connected in series, then their voltage ratings will be summed up. For example, your screwdriver runs on a battery with a voltage of 14.4 V, which means that it can be replaced with four 3.3 V finger batteries. This voltage will be enough, because the lithium batteries do not “sag too much” when starting the device.

It is recommended to buy batteries from well-known manufacturers, for example, Sistem A123. The LiFePO4 battery of this company has a capacity of 2400 mAh, sufficient for the normal functioning of the screwdriver. If you buy batteries via the Internet, then they will cost you less. around 900 rubles for 3 pieces.

When buying batteries, pay attention to whether there are copper strips on their contacts. If they are, then the soldering process is much easier.

You will also need to purchase soldering acid instead of alcohol flux. In this case, overheating of the batteries will be minimized. The soldering iron must have a power within 65W.

You can learn more about how batteries are replaced with lithium batteries by watching this video.

How can you replace the “native” battery in a screwdriver

If the batteries in your screwdriver are worn out, they can be easily replaced. There is such a thing as battery interchangeability. For example, under the PowerPlant brand, batteries are produced that are compatible with most popular brands of power tools. They cost much less than the “native” batteries and are quite efficient.

But if this option does not suit you, then the batteries themselves in the unit can be replaced with new ones. To do this, you will have to disassemble the battery pack and remove the elements that make up it.

Nickel-cadmium batteries

Nickel-cadmium batteries have the following advantages.

• Durability. With proper operation, the battery can last 8-10 years.
• Ability to work at low temperatures. The battery power is practically not reduced, which allows using the tool in the winter outdoors.
• High degree of reliability and unpretentiousness to working conditions.
• The battery can withstand a thousand charge-discharge cycles.
• The battery can be stored for a long time in a discharged state.

Since NiCd batteries are not “afraid” of full discharge, you can work with the tool until it stops completely, that is, until the battery is deeply discharged. Only then can you put it on charge, without fear that the battery capacity will decrease.

However, nickel-cadmium batteries are not without their drawbacks. Toxicity of internal battery filling causes disposal problems.

In some European countries, the operation of nickel-cadmium batteries is prohibited in order to preserve the environment.

Batteries of this type are quite heavy when compared to other types of batteries. In addition, they have a “memory effect”. This phenomenon occurs in a nickel-cadmium battery when it is prevented from fully discharging. If you turn on such a battery for recharging, then it will “remember” this value and during further work it will be discharged exactly to this mark. This will lose a significant portion of the battery’s capacity. The figure below clearly demonstrates how the “memory effect” appears.

Lithium-ion batteries

Li-Ion batteries significantly outperform other types of batteries. The advantages of lithium-ion batteries include the following:

• almost complete absence of the “memory effect”;
• You can recharge the lithium-ion battery at any stage of discharge, without fear of loss of capacity;
• no power loss at low battery charge;
• effective service life is 5-8 years;
• low self-discharge;
• takes little time to charge;
• there are no toxic elements;
• high power with small dimensions.

Cons of lithium-ion batteries:

• sensitivity to impacts (may explode with strong impacts);
• the battery does not tolerate full discharge and overcharge. this causes the battery to fail;
• discharges quickly at low temperatures;
• high price;
• service life is lower than that of nickel-cadmium batteries.

It is difficult to say unequivocally which battery is better. Mainly, you must decide for what purpose you are going to purchase a screwdriver. If for home use, which implies infrequent switching on with long interruptions in work, then you need to choose a tool with a nickel-cadmium battery.

This can be explained by the fact that during long-term storage without recharging the NiCd battery does not lose its properties, provided that it has been completely discharged.

Lithium-ion batteries are the professional choice. They are designed for continuous, long-term and uninterrupted operation. The recharge time of the battery is also important for a professional tool. But it’s worth remembering one rule: a lithium battery cannot be brought to full discharge.

How to restore a screwdriver battery?

Determine the malfunction of the screwdriver battery

Charge the battery to full level, remove from charge and disassemble to access the cells.
2.With a multimeter we measure the voltage (in DCV mode) of each cell (battery).
3. In good condition, Ni-Cd and Ni-MH give out 1.2-1.4 V, and Li-Ion. 3.6-3.8 V.
4. Collect the battery and discharge it until an obvious slowdown in the rotation of the screwdriver.
5. Disassemble and measure again. a voltage drop to the level of 0.4-0.8 V indicates the wear of such a cell.

What you need to know before you start rebuilding a screwdriver battery?

Most batteries in a power tool have the same design features (series connection of compact cells).
2. It is necessary to pay attention to the type of battery (Ni-Cd, Ni-MH and Li-Ion) and capacity (in mAh).
3. When disassembling the battery pack, observe the polarity (/.) of the connections.
4. “Banks” are protected from overheating by a thermistor with a soldered resistor.
5. It is impossible to restore a Li-Ion battery (how to determine its serviceability, see below).

Complete replacement of the battery with a new one

Can the battery of a screwdriver be restored? 4 methods

You can restore the screwdriver battery on your own. You will save up to 30% on the total cost of your tool if you follow these instructions.

The manual will help to restore the autonomy of any models of screwdrivers (18 volts, Makita 12 volts, Makita 14.4, Metabo, Hitachi, iMax B6 and so on) with Ni-Cd (NiCd), Ni-MH and Li-Ion batteries. You should carefully consider the recommendations and clarifications regarding the different designs of the power tool.

Partial replacement of worn-out cells

It will be more economical to replace each cell separately if you have free time. Here you need the skill of spot welding. soldering the cells with an ordinary soldering iron can change their characteristics and spoil!

Elimination of the “memory effect”

If, after a full charge, the screwdriver quickly consumes battery power and after a while continues to work a little, then you are faced with the “memory effect” of Ni-Cd or Ni-MH.

To eliminate the “memory effect” in a screwdriver, its calibration (training) will help:
charge up to 100% (with low current as possible);
completely discharge the tool with a low power rotation feed for a long time;
repeat this procedure 3-5 times, and the battery will come back to life.

An exotic method for the pros

Batteries for a screwdriver wear out due to the loss of electrolyte substance. it simply boils away with active use of a power tool. By cutting the connection plates and punching a hole in the cell, the chemical composition can be added. After sealing the case, the battery is ready for operation again.

If you know more ways, then write them in the comments or send a message to us on @NeovoltRu.

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Ni. MH batteries

Positive aspects: low charge memory effect; small spontaneous discharge; high capacity, relative to Ni. Cd; more charge-discharge processes.

Negative sides: with a small charge, it loses some of its parameters when it is in storage; price range; short service life when used at low temperatures.

Battery Repair Tips

The recommendations below will help you avoid mistakes when repairing batteries for a screwdriver:

• batteries should be purchased according to the nominal voltage and capacity, as well as size;
• the batteries are spot welded at the factory. Replacing the battery is done by soldering. When performing soldering, you will need to do it quickly so as not to damage the battery by overheating;
• The connection is made using factory plates or using copper plates of the same size, since a large current flows during charging (operation). Observe polarity.

After repacking the screwdriver batteries, you need to equalize their potentials by charging the cans for 8-10 hours. After cooling down, the voltage on the elements is measured. If everything is done correctly, the voltage will be in the range of 1.3-1.4 V. Then the cans are discharged to the end by using a screwdriver (it is necessary to charge-discharge 3 times). This procedure is recommended to be carried out once every 3 months to eliminate the memory effect.

Identification of faulty elements and their replacement

This will require the following tools:

• Phillips and flat screwdriver;
• multimeter;
• soldering iron;
• tin;
• flux;
• hydrochloric acid for soldering.

Battery repair procedure:

• Charging cans to full charge.
• Disassembling the case.
• Measuring voltage with a multimeter on the elements, one by one.
• Identification of cells with a voltage below the nominal (nominal voltage of the Ni. Cd cell 1.2-1.4 volts, the voltage of the lithium cell 3.6-3.8 volts).
• Identified elements marking.
• Assembling the case.
• Working with a screwdriver under load until power is reduced.
• Disassembling the case.
• Measuring the voltage on the marked elements (the voltage will be lower than that of others), for example, for serviceable elements, the voltage will be 1.1 V, and for faulty ones. 0.8 V and below.

This method identifies faulty 12-18 V battery cells, which must be replaced or restored.

In Li-Ion batteries, defective cells are identified in two ways:

• Replacing the control circuit from another battery that is suitable for the parameters of the battery, if a malfunction is detected, a replacement is made.
• With a charger with adjustable voltage and current. The voltage is set equal to 4 V, the current is equal to 200 mA. The battery is connected. If the voltage rises to 3.6 V, the battery cell is good. Then the rest of the elements are checked.

Li. Ion batteries

• there is no charge memory effect;
• almost imperceptible spontaneous discharge;
• the highest capacity batteries;
• the number of charge-discharge processes is much higher compared to the types of batteries listed above;
• the voltage of one battery cell is higher than in other types, in connection with this, the weight and dimensions of the battery are reduced.

• the price range is almost 3 times higher compared to Ni. Cd;
• after three years, the capacity decreases significantly, since lithium tends to decompose. It is not possible to reanimate such a battery;
• can not be used in low temperatures.

Recovery of nickel cadmium batteries

You can always restore the battery’s performance if the battery is not dry. Otherwise, it will have to be disposed of. How to revive a screwdriver battery is discussed below. The battery will need to be disassembled.

Recovery methods: by compression (if there is electrolyte, but at the same time there is a high risk of volume loss); by supplying voltage and current, for each element significantly higher than the nominal.

DIY screwdriver battery repair

With prolonged use of the screwdriver or its storage, after a certain time, the battery of the screwdriver becomes unusable. Further use of the tool becomes impossible. The consumer has to consider the option of purchasing a new battery or screwdriver. This solution to the problem is the simplest way out of this situation, in comparison with replacing the batteries in an old battery.

The cost of a new battery is about 60% of the cost of a screwdriver. Each battery contains the same cell type, also sold separately. You can try to fix the battery. Its repair is not considered a very difficult process, but in case of an unsuccessful attempt, the user can purchase a new battery. The article below will discuss in detail the issues of repairing a screwdriver battery with your own hands.

Battery types

Today, there are screwdrivers on sale with the following types of batteries: nickel-cadmium; nickel metal hydride; lithium ion.

A separate species has its own advantages and disadvantages. We will conduct a detailed review of each type.

12V cordless drill battery cell changing

Ni. Cd batteries.

• the ability to use in low temperatures;
• storage at low charge allows you to save the parameters of the tool;
• quite common type of batteries;
• low cost.

• charge memory effect;
• spontaneous discharge;
• small capacity;
• small number of charge-discharge cycles.

Replacing an old Ni-Cd screwdriver battery with a Li-Ion cell

It happened in my case as well. The RYOBI CMD-1202 screwdriver was purchased by me on the occasion of repairs in the kitchen and served with faith for 3 years, after which the battery charge was enough to screw in a pair of medium screws. This screwdriver was equipped with two 12 V, 1.7 Ah Ni-Cd rechargeable batteries. The cost of two new batteries turned out to be more than the cost of a new screwdriver of the same class with two batteries included. The latter was purchased for household needs. The old screwdriver went to a well-deserved rest in the closet.

Recently, on the Internet, I came across an article about replacing the nickel-cadmium battery cells of a screwdriver with lithium-ion (Li-ion) batteries in the 18650 format. Fortunately, the latter have accumulated in a decent amount, mainly from licked laptop batteries. After spending several hours studying the issue, it turned out that there are several options for implementing such a replacement.

Simple daisy chain connection of the required number of 18650 cells and use the native charger. A superficial knowledge of the peculiarities of charging batteries connected in series is sufficient to exclude such an option. Without delving into technical terms, we can say that Li-ion batteries cannot be strongly discharged and recharged, only work within 2.5. 4.2 V guarantees a long and safe battery life. Charging a battery converted in this way with a native charger will quickly disable Li-ion cells, and their destruction as a result of overheating is also possible.

Connection of elements with the addition of additional balancing wires, which are output to a separate socket. Smart chargers such as iMAX B6 and Turnigy Accucel-6 are used for charging. The charging process in this case turns out to be “correct”, however, as in the first case, the discharge of the batteries is not controlled in any way, and their excessive discharge will significantly reduce the battery life. In addition, it becomes necessary to purchase and use a special charger, which is extremely inconvenient in a construction site.

There are also extremely exotic implementations of this idea. Some people build miniature voltmeters into the battery case, according to the readings of which they determine the state of charge. Experienced radio amateurs design and manufacture charge and balancing controllers. These solutions are either difficult to replicate or do not provide adequate control and the required reliability.

Having decided on the terms of reference: using a native charger for charging batteries, no additional connectors and wires, the presence of charge control and balancing of elements, I began to look for implementation options. As always, our Asian friends did not disappoint, they offer many options for charge control modules, both single and connected Li-Ion batteries. At this stage, we need to choose the nominal voltage for our Li-ion battery. Option 3S Li-ion batteries with a voltage range of 12.6. 7.5 V is not suitable for power engineering, since under heavy load there is a strong voltage drop even on a fully charged battery. Rechargeable battery of 4S Li-Ion batteries with a voltage range of 16.8. 10 V will provide the maximum continuous operation, and a slight excess of the operating voltage is not critical. The option suitable for me (bought here) has the following characteristics:

Charge and protection controller BMS 4S for 4 x Li-Ion 18650 batteries
Charging voltage limiting: 4.25 V
Discharge cut-off: 2.5 V
Maximum charging current: 3A
Peak discharge current: 30A
Discharge working current: 15 A
Short circuit protection
Overcharge / overdischarge protection
Overcurrent protection

We proceed directly to the alteration

We disassemble the old battery and remove the Ni-Cd cells, as in most of these batteries, the contact pad is fixed directly on one of the cells, so as not to “farm” with the contacts in the future, we glue them together with this element using hot glue.

We collect 4 elements Samsung ICR18650-26C 2600 mAh in such a way as to provide the most convenient location in the case. We connect the individual elements by soldering the wires; this must be done as quickly as possible so as not to overheat the battery. We connect the resulting battery with the protection board according to the connection diagram.

We install the battery into the case. Battery ready.

The weight of the old batteries with Ni-Cd cells was 560 grams, the new Li-Ion battery “lost” 180 grams. and weighs 380 gr. At the same time, the energy capacity was almost doubled from 20.4 Wh (12V x 1.7 Ah) to 38.48 Wh (14.8 V x 2.6 Ah). A screwdriver converted in this way will serve as a faithful assistant for many more years in our service center.

Screwdriver battery repair

First charge

The initial stresses on the elements are 3.85. 3.95 V, we charge it with a native charger. To control the current consumption, a multimeter is connected in the current measurement mode between the battery contact and the charge controller in the wire break. The voltage of the storage battery and a separate cell is controlled by two miniature digital voltmeters. Just in case, using an infrared thermometer, we control the temperature of the batteries and transistors on the charge controller board. Charging results are shown in the table and graphs.

After the completion of the charging process, the voltage across the cells is 4.15. 4.17 V, battery voltage in general. 16.63 V. During charging, the battery temperature did not rise above 34.5 ° C, the charge controller board did not heat up at all.

“Reanimation” of storage elements

Immediately it is worth making a reservation, trying to “reanimate” ionic batteries is useless. This type of battery cannot have a memory effect, and therefore, the reason for their failure lies in the decomposition of lithium. But first, it’s worth finding out. perhaps the control scheme is wrong. Two methods can be used here.

• The control scheme should be changed. If the batteries are working, then the circuit itself needs to be repaired.
• The battery is supplied with a regulated charger at 4 V with a current of approximately 200 mA. An increase in the voltage on the “bank” to 3.6 V indicates the health of the element and, therefore, either the control circuit or another battery is to blame for the malfunction.

To “reanimate” the battery of the screwdriver battery, two methods are used:

• Restoring the performance of “cans” by compression or compaction.
• Supply of high voltage and current to the storage element. In this case, it will be possible, although not completely to eliminate the lost capacity and get rid of the “memory effect”.

However, these methods cannot completely solve the problem of battery failure. They will only delay the inevitable. Sooner or later, you will have to change banks anyway.

Checking by resistance value

The normal functioning of each battery can be verified by comparing the internal resistance of the “banks”. The value is determined by dividing the operating parameters voltage by current and deducting the load resistance.

Operating voltage is measured necessarily under load. As a load, you should take a resistor with a resistance of 10 ohms and a power of 25 watts. Each battery is tested. Measure the working amperage and voltage.

Cordless screwdriver battery replacement and test (before and after)

For a better understanding, here are some approximate calculations. Let’s say, during the measurement under load, data were obtained for one “can”: operating voltage. 1.19 V and operating current. 112 mA. Before making a calculation, do not forget to convert the current value from mA to A. 0.112 A. We perform the appropriate actions (1.19 / 0.112). 10 = 0.63 Ohm. Recall that the subtracted in our expression is the load resistance of the resistor (10 Ohm).

VOTO 12 Volt Lithium-ion Battery Cordless Screwdriver – Battery Replacement

Checking the Drive Batteries

So, let it turn out that with the help of preliminary checks, the presence of faulty elements in the drive was established. Then it is necessary to disassemble the battery and remove the batteries connected in series. “banks”. As mentioned above, the battery consists of 10-12 such cells with a voltage of 1.2 V.

First, a visual inspection of the joints of the elements is carried out for violations. They can degrade the overall battery performance.

After inspection, you should measure the voltage of each of the “cans”. The voltage of one cell should not be less than 1.2 V. During measurements, the battery cells should be disconnected from the connections with any kind of sensors. The measuring device is connected to the battery poles. “Banks” with reduced voltage must be replaced. If a simple measurement did not reveal faulty elements, you should try on the “banks” under load.

Checking under load

To answer the question for how long the battery will be discharged, you should check the drive under load. The load must be selected based on the capacity of the drive. If it is unknown, then it is considered that the load power is equal to half the product of the current that is given to the battery during operation by the voltage of the drive. As a rule, this value is taken equal to 35-40 watts. Thus, you can use a car headlight (35 W) as a load or use a 12 V spot lamp with the same power.

For battery measurements, the battery is connected to the load through an ammeter. Readings are taken with a voltmeter. Banks are connected for 2-3 minutes. The measured voltage must be greater than 12.4 V. If the readings fall within the range of 12 to 12.4 V, then this means that there is a damaged cell in the battery. The presence of faulty batteries can also be indicated by a decrease in the brightness of the lamp used as a load. If the lamp goes out in the allotted time period, it means that the drive is discharging very quickly. it has a very small capacity.

Screwdriver repair: checking and replacing battery cans

The most expensive and important part of a screwdriver is its battery. Therefore, when the electrical storage fails, you do not want to buy a new tool. How to check the battery and make repairs in the event of a battery malfunction can be read below.

Inspection tools

The electrical storage can be checked using:

• DC voltmeter 15 V;
• ammeter and DC voltmeter;
• tester;
• multimeter.

From the tools you should acquire:

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

Replacing the “cans” in the screwdriver battery

The task itself is simple. It is good if you have experience in soldering. In the connection of the elements, the faulty battery is cut off, a good one is put in its place, then soldering is performed. As you can see, nothing complicated.

However, in this case, several important nuances should be taken into account:

• you need to solder quickly so that the “banks” do not heat up. this may affect their performance;
• to connect the elements, it is better to use native plates, or copper, but of the same dimensions;
• when attaching a new element to an old one, do not confuse plus and minus. When connected in series, the minus from the previous battery goes to the plus of the new battery.

After soldering, you should carry out a charge-discharge cycle, and then measure the voltage on the “banks”. It should be around 1.3V.

Checking the screwdriver battery

To determine the real basic parameters of the battery, a check is carried out.

When carrying out actions aimed at checking battery cells, one should not forget about the influence of such a factor as the “memory effect”. The phenomenon itself is that, due to frequent charging of the storage device, the battery cells can change their capacity. This is due to the charges left over from the previous charge. Nickel-cadmium “banks” are more susceptible to this phenomenon than other batteries.

The screwdriver battery is checked when fully charged. Full verification takes place in several stages.