How to fix screwdriver batteries with your own hands

A screwdriver is a fairly popular tool that greatly simplifies the process of screwing in and out of screws. Most of these tools operate on rechargeable batteries, which periodically fail. Many people who have encountered such a breakdown are interested in how to repair a battery for a screwdriver and what needs to be done for this.

A screwdriver is a tool that is often used in the household.

What you need to know before you start repairing a screwdriver battery

Before you try to restore the battery at home, you need to familiarize yourself with the basic recommendations:

• before starting repair work, it is necessary to determine the type of battery used;
• in the process of disassembling the battery case, it is necessary to find out the polarity of the connections;
• all “banks” installed in batteries to protect against overheating are equipped with a soldered resistor and therefore must be removed very carefully;
• Lithium-ion batteries cannot be repaired.

Additional Information! Almost all elements in Bosch, Interskol and Vikhr power tools have a serial connection.

Structural elements of a screwdriver

People who decide to repair a power tool should familiarize themselves with its main structural elements:

• Electrical engine;
• planetary gearbox for transmitting rotation from the motor to the spindle;
• a clutch that regulates torque;
• electronic control unit;
• battery;
• a clamping chuck with which the working attachments are secured.

If the screwdriver is used incorrectly, each of the listed components may fail.

Video description

Video about repairing a failed screwdriver battery:

• The series connection of the batteries must be such that “+” is in contact with “-”. Otherwise it simply won't work.

If you change only some of the batteries in the screwdriver battery, a potential difference will arise between those already used and those not yet used. It can be eliminated through the alignment procedure. To do this, the following series of actions are taken:

1. The assembled battery is placed on a full charge - 8-10 hours.
2. The battery is left alone for a period of 24 hours.
3. Next, the voltage on the banks is measured. It should be approximately the same everywhere.
4. After this, the battery is charged and the device turns on at full power. In this case, the load factor on the screwdriver itself is taken into account so that it does not deteriorate.
5. Then the “charging-discharging” cycle is repeated 2 more times.

Recommendation! To extend the battery life, it is necessary to erase the memory effect once every 3 months, using several consecutive charge-discharge cycles.

Checking the screwdriver battery

A multimeter is often used when testing batteries.
Before you start repairing the tool, you need to familiarize yourself with the features of testing the battery.

Checking the battery for functionality

To make sure that the charger is working, you need to perform the following sequence of actions:

1. Connect the unit to a power source.
2. On the multimeter, turn on the DC current measurement mode.
3. Connect the probes to the minus and plus of the charger.
4. Review the results of the measurements taken.

If the values ​​differ from the parameters located on the battery case, then you will have to repair it or buy a new one.

Checking battery capacity with a multimeter

Before repairing the battery, it is necessary to check its capacity. This is done like this:

1. Fully charge the battery.
2. Connect the multimeter probes to the battery contacts.
3. Check the indicators on the device display.

If, after testing, the battery capacity is lower than declared, you will have to remove all batteries from the structure and test each of them.

The design and principle of operation of a screwdriver battery

The battery is a separate device, housed in a plastic case with fastening elements to the screwdriver. There are several battery cells located inside. Depending on the brand of screwdriver, there may be several of them, they may vary in composition and quality.

There aren't many cells inside the battery

The principle of battery operation is simple. Since it is rechargeable, it must be charged before use. After the battery is installed in the screwdriver, the charge accumulated in it is transferred to the electric motor of the tool, which, in turn, rotates the chuck with the drill or bit installed.

Related article:

Cordless screwdriver : why you need it, types, which one is better to choose, which brand model to prefer, average prices and repair tips will help our detailed review.

General recommendations before checking the battery

To properly test the battery, you need to familiarize yourself with the basic recommendations for testing different types of devices.

Nickel-cadmium

Nickel-cadmium batteries are most often used in screwdrivers.
This is the most common type of battery. They are most often installed in screwdrivers from Bosch. Among the advantages of these batteries are their resistance to external influences and durability.

Before checking such batteries, they must be fully charged. This will allow you to obtain the most accurate measurements and ensure the functionality of the device. If you check a discharged battery, you will not be able to obtain accurate data.

Lithium-ion

Such batteries are most often installed in the most expensive models of power tools. They have a large capacity and a small percentage of loss of available charge. However, they also have a serious drawback, which is that they cannot be left discharged for a long time. The fact is that their crystals quickly degrade and because of this the battery stops working.

Before testing lithium-ion batteries, they must be fully charged and discharged three times. This is done to eliminate the “memory effect” and obtain the most accurate test results.

Background of the issue

As you know, I try to do all or almost all household chores myself. This not only saves me a lot of money, but also gives me a lot of pleasure, and for some time now even allows me to expand my social circle and find my fans on the Internet. Of course, I can’t do without a screwdriver in my life. I had a lot of screwdrivers. Many of them are probably still working. However, they were all very cheap and did not last long. A year and a half at most. And then one day, five years ago, my wife and her mother-in-law decided to give me a gift. They bought me a whole suitcase from Hitachi. The suitcase contained an 18V screwdriver, a flashlight and two batteries. This pleasure cost around 5 and a half thousand rubles. I won’t lie, I was delighted with the gift and immediately put the screwdriver to work and haven’t put it down until today. But here's the problem! Over the years that have passed since its purchase, one battery has become completely dead, it is even impossible to charge it, and the second is frail, but you can work for a couple of hours. At the market, I even once saw a tent “repairing tools” and asked the person who works there - why is one completely dead, and the second more or less? He answered me that he doesn’t sell 18-volt Hitachi batteries and, by the way, never has, and as for sets of screwdrivers with two batteries, that’s the case for everyone. I can also thank the company for the fact that one battery lasted me more than a year.

This is a wonderful kit!

Nevertheless, we need to work! And I went on the Internet. Do you know how much a new battery costs? 3 and a half thousand rubles! Obviously, it makes sense to buy a new screwdriver for 5 thousand! But, as they say, “Knowledge is a hard nut to crack!” But we are not used to retreating!” It's never too late to buy a new one! I took a screwdriver and, out of grief, unscrewed all the screws that I found on the battery.

Experimental battery

Common faults

A short circuit is one of the most common faults.
Owners of screwdrivers who decide to repair the battery themselves should familiarize themselves with the most common types of faults. There are several reasons why batteries stop functioning normally:

• destruction of plates;
• short circuit;
• electrolyte contamination;
• reversal of poles;
• degradation of crystals due to long-term storage in a discharged state.

Additional Information! It is quite difficult to cope with the consequences of such breakdowns on your own. This is why many people decide to entrust battery repair to professionals.

Options for selecting new cells

Choosing new elements is simple - in terms of design, dimensions and capacity, you need to choose exactly the same cans as the old ones. Then there should be no problems with installation, charging and operation. Due to the improvement of technology, elements with similar mounting dimensions but larger capacity may appear on sale. It is undesirable to use them, since they will require more energy replenishment time at the same current and will operate under different conditions. In this option, you can replace all the banks with new ones at once.

How to determine if repair is possible

Before you repair a screwdriver battery at home, you need to figure out whether it is possible to repair it at all. To understand this, you will have to disassemble the power tool and carefully remove the battery “cans” from it.

The extracted cells must be sorted out and laid out in a row in front of you. After this, you need to check each element one by one with a multimeter. The voltage should be about 1.4 V. If on one of the components this value differs by 0.5 V up or down, then this element must be replaced. Therefore, such a battery can be repaired.

Battery cell recovery

Here I will give a story from Master Sergei on the restoration of a nickel-cadmium screwdriver battery. The owner began to complain about the short operating time of the electric screwdriver and that “the battery doesn’t hold up.” Disassembling the battery case showed that there are factory Ni-Cd banks from Liang with a capacity of 1000 mAh.

You can restore a Ni-Cd battery in a fairly simple way. You need to do several deep discharge and charge cycles. In such extreme modes, hard-to-reach areas of battery charge accumulation begin to operate, the output of which has deteriorated due to the memory effect, violation of operating or storage conditions.

Such problems arise not only with screwdrivers. The battery-powered radio-controlled model industry has long ago solved the problems of automated discharge/charge. There are special chargers for this.

Master Sergey had a Vista Power AK610AC. This is a charger with a charge function of 90 W and a load discharge of 20 W. This is a wonderful professional device with a touch screen! This can be found on Avito for about 5,000 rubles.

Instead of such a charger, you can use something more Chinese, for example, at a price of about 2000 rubles.

It is best to start cyclic battery recovery by deeply discharging the battery and then immediately charging it.

After the first cycle, the discharge capacity was 707 mAh, and the charging capacity was 879 mAh. As you can see, the capacity decreased by 30% relative to that declared by the manufacturer.

The second discharge/charge cycle showed figures of 781 mAh / 937 mAh. As you can see, this is 10% more than the previous values.

The third battery recharge cycle showed minor deviations from the previous second recharge. So this is enough. If you see on your batteries that the capacity is increasing, then you can continue.

Upon restoration of the battery, it was possible to restore about 8% of the originally declared capacity of the screwdriver. In principle, not bad, but I would advise replacing the battery banks with new ones.

List of required tools

Screwdrivers may be needed to disassemble the battery case or screwdriver.
To carry out repair work, you may need the following tools:

• Multimeter. This device is necessary for measuring AC and DC voltage.
• Curly and flat screwdrivers. Useful for disassembling the screwdriver body.
• Soldering iron. Inexpensive models with a power of about 40 W are suitable for repairs.

Additional Information! To use a soldering iron, you will need consumables such as solder and tin.

What tools will we need?

When restoring a battery for a screwdriver, you will need:

• screwdriver;
• multimeter;
• tin;
• special flux;
• soldering iron, preferably with a power of at least 100 W.

At the factory, spot welding is used to connect contacts with minimal heat. Therefore, high speed is required when soldering to avoid damaging the battery cell.

How to determine if a screwdriver battery is faulty

Determining a malfunction of a power tool is carried out as follows:

1. Fully charge the battery.
2. Disconnect the device from the network and remove the battery.
3. Carry out a visual inspection and check for visible defects on the surface.
4. Check the voltage of the “cans”.
5. Connect a 24 V or 12 V car light bulb to the battery with wires.
6. Turn off the lamp after 20-30 minutes and measure the voltage of the “cans” again.

If the capacity of the “cans” has sagged significantly, then they need to be replaced with new ones.

Calculation of "used" cans

The first thing to do after removing the elements is a visual inspection. Banks that have:

• swelling on the body;
• traces of deep corrosion;
• electrolyte leaks.

These elements cannot be restored, and damaged lithium battery banks are also a potential fire hazard. The rest of the batteries, which appear to be in good working order, should be checked with a multimeter - measure the voltage without load. It should be close to nominal.

Measuring the voltage of each element.

If the voltage of the bank is below the nominal value, but within the normal range, the cell may not have charged due to faulty batteries. For example, if there is a break in the bank, the charging circuit of consecutive elements will break. We must try to charge these elements from an external power source with a current of 0.1..0.3 of the capacity of a single battery. It is not necessary to separate the elements for this.

Single cell charging circuit.

Important! Measuring the voltage of lithium-ion cells must be done with the balancer board disconnected. If the controller has a faulty key (or several), it can bypass a working bank. It is also highly undesirable to charge these elements uncontrollably from random power supplies, as this can lead to a fire or explosion.

If the voltage is restored (without load it should be close to the upper limit value, and after some time return to the nominal value), the batteries that have passed this stage proceed to the next test - for actual capacity. To do this, each element is alternately loaded onto a resistor, the resistance of which is calculated using the formula: R = Ubank/C, where:

• R – required resistance;
• Ubanks – rated voltage of a fully charged cell;
• C – battery capacity in ampere hours.

So, for a nickel-cadmium battery with a capacity of 1.2 Ah, the resistance will be equal to 1 Ohm. With this resistance, the new battery will be discharged to the minimum voltage in about an hour. If you take a resistance of 2 Ohms, then in 2 hours, 5 Ohms - in 5 hours, etc. It is not advisable to use light bulbs as a load, because their resistance depends on the current . We must remember that:

• the capacity depends on the discharge current, therefore, strictly speaking, the indicated linear dependence of the discharge time on the load resistance will not exist, and the calculated discharge time is approximate;
• The declared capacity refers to new elements, therefore, for batteries that have worked for a long time, the actual capacity will be obviously lower than what is written on the case.

Cell control discharge circuit.

During the process, you need to monitor the voltage on the element to prevent a deep discharge. After completing the procedure, you need to record the resulting time for each jar. Those cells whose discharge time is less than that of most cans are rejected.

Faulty cells must be removed. To do this, you need to cut off the connecting bars. They should be shortened as little as possible to facilitate the process of installing new cans.

Screwdriver battery repair

Before you start repairing the battery yourself, you need to figure out how to do it correctly.

Disassembling the case

A mallet will allow you to disassemble the glued battery case.
The battery case consists of two parts. Most often they are connected with screws. However, sometimes they are held together with superglue. In this case, the gluing areas should be carefully tapped with a mallet. After this, the glued parts will be much easier to separate.

Determination of defective cans

Identifying damaged “cans” is quite simple. To find them, you need to do the following:

• Conduct a visual inspection of the elements.
• Remove components with traces of swelling and particles of leaked electrolyte.
• Check the output voltage of each bank.

It is necessary to check components with a multimeter several times to obtain the most accurate measurement results.

Important! It is better to replace all banks whose voltage readings deviate greatly from the norm with new ones.

Recovering items

Anyone can restore battery “banks” on their own. This is done like this:

• Disassemble the battery and remove each component. It is impossible to charge all the cells well in a common battery.
• Apply a voltage of 3-4 V to each of the “cans” for five seconds.
• Measure the output voltage. If it is at 1.4 V, then the components have been restored.

Sometimes the above steps do not help restore the battery. In this case, you will have to replace it with a new one.

Battery assembly

Defective battery “banks” must be replaced with new ones.
When all components have been restored or replaced, the structure can be assembled. To do this, you need to install all the components back into the case. After this, the parts of the structure must be reconnected with screws or glue.

Restoration with distilled water - fact or fiction?

Many craftsmen who are capable of restoring power tools claim that dried-out power sources cannot be “reincarnated.” Others say that it is possible to restore batteries; all you need is distilled water, a tool and 30-40 minutes of free time.

The sequence for restoring batteries with distilled water is:

• Using a thin bit and drill, make a small hole in the top of the battery can. If you drill into the middle of the element or the bottom, you can damage the power source. It will be impossible to restore it later.
• Using a syringe, fill the battery with distilled water to the maximum.
• Leave the battery in a clean and warm place for 1-2 days, do not cover the hole.
• Connect the cells filled with distilled water into one battery.
• Place the battery on charge until capacity is fully restored. After charging, check the voltage on each jar and, if necessary, add distilled water.
• After checking, close the holes with a glue gun. It is strictly forbidden to solder the holes - this can damage the battery cell.
• Place the battery back into the case, close the lid and recharge.

The home method with electrolyte works, but not always. Sometimes the internal structure of the battery is so damaged that even distilled water does not give a positive result.

Replacement of defective elements

Replacing a defective battery component is fairly easy. To do this, you need to get rid of the broken “can” by disconnecting it from the common plate with side cutters. A new component is then soldered to the ends of the contacts. After this, you need to check with a multimeter whether the installed element is working correctly.

The battery of a screwdriver is a part that often fails. If necessary, a broken battery can be repaired at home. However, before you do this, you need to figure out how to do it correctly.

Complete replacement and erasing of battery “memory”

In rare cases, for example, if the battery is too old, then all the elements fail. Buying a new battery will still be more expensive than replacing all the batteries. Therefore, it makes sense to order separate power supplies via the Internet, solder them into the battery, and then place them in the old case.

There is a little secret to extending the life of new power supplies. To do this, you need to remove the factory settings from the cans, which are set by several charge/discharge cycles. The operation to extend the lifespan should be carried out only on new elements, and in the future they should be charged correctly.

A new battery bank is discharged to a voltage of 1 V. It is important to monitor this parameter, since below one volt the battery may become unusable, after which it will be impossible to restore it. For discharge, it is best to use an adjustable load, on which the current is set to 1 A.

After complete discharge, all cells must be recharged using the rated current and voltage. After a full charge, you can solder the power supplies into the battery and install them on a screwdriver.

Disassemble the battery with a spatula or utility knife

For those who are not used to working with a mallet and want the process of disassembling the battery to look quieter and gentler, you can suggest using a small metal spatula or a utility knife. The main thing is that they do not have sharp edges, like a large screwdriver, which can easily damage the plastic.

This is interesting: What to do if the battery on your phone is swollen?

First, you should completely go around the perimeter of the entire block with a knife to loosen the seam, and only after that you can begin to “pick” the flexible plastic with a small screwdriver. The method is no less painstaking than the first, and if a person is not experienced enough, damage may remain on the plastic case. However, if you work as carefully as possible, it is possible to avoid “losses” in this case as well.

If, when disassembling the battery pack, you still experience cracks or other damage, you should not be upset, because this type of plastic lends itself perfectly to gluing with dichloroethane.

Preparation for repair

To repair a screwdriver battery with your own hands, you will need to prepare the following tools and materials:

A multimeter is needed to determine DC and AC voltage, resistance, current or open circuit.

• new batteries;
• flux, soldering iron, tin for connecting new cans into a single circuit;
• multimeter;
• screwdriver;
• long nose pliers;
• insulating tape.

Battery won't charge

A screwdriver sometimes fails after prolonged use. Its working element may stop charging, which will lead to the impossibility of fulfilling the functional capabilities of the tool; the tool, roughly speaking, will “die”.

In order to extend the life of the instrument so that you do not have to remove it from visibility, you can try three methods in turn. Each subsequent one is considered more complex and costly. They are:

• restoration and increase in capacity after its reversible loss (memory effect);
• adding distilled water to the electrolyte;
• replacing some or all of the battery packs.