In detail: do-it-yourself repair batteries for a screwdriver from a real master for the site my.housecope.com.
There comes a time when a reliable home assistant - a screwdriver - stops working. Batteries are out of order, and regular recharging no longer helps. Do not rush to buy new batteries, another way out of the situation is possible.
The cost of batteries is about 70% of the price of a new tool, so it is logical to try to repair the battery of a screwdriver. Before proceeding with the operation, you should familiarize yourself with the features of the voltage sources, find out what type of battery is used on your tool. Their structure is absolutely the same and does not depend on the country of manufacture and brand. Inside the plastic box are serially connected elements of a standard size. On each element there is an indication of the type and capacity in ampere-hours (A / h).
Screwdriver battery
Batteries are equipped with elements of the following types:
lithium-ion (Li-Ion) - with an element voltage of 3.6 V;
nickel-cadmium (Ni-Cd) - 1.25 V per element;
nickel-metal hydride (Ni-Mh) - 1.2 V.
Evaluating lithium-ion power supplies in terms of quality and service life sets them apart from the competition. They practically do not lend themselves to self-discharge, high capacity, they can be recharged many times, several times more than other types of batteries. The cell voltage is three times higher than that of other types, which allows you to complete batteries with fewer cans, reducing weight and dimensions. They do not have a memory effect, which makes them an ideal device of this kind.
But the ideal does not exist in nature, and lithium-ion power supplies also have some drawbacks. They cannot be used at sub-zero temperatures, as manufacturers honestly say. But practical use has revealed another drawback: when the operational life of such a battery ends (three years), lithium decomposes, no means of making a reverse reaction bring results. The price of such batteries is three times higher than other power sources for a screwdriver.
Video (click to play).
Nickel-cadmium batteries are the most common due to their low cost. They are not afraid of negative temperatures, like lithium-ion voltage sources. If a screwdriver is rarely used, such elements are ideal, because they can be stored discharged for a long time, while maintaining their characteristics. Such batteries have a lot of disadvantages: they are of small capacity, toxic, so their production is concentrated in underdeveloped countries. The tendency to self-discharge, short life expectancy with intensive use - also belong to the disadvantages of these batteries.
Nickel-cadmium batteries dry out at the end of their useful life. Those who know about this feature refill them, but this operation is not easy to perform, so few decide on such an action, preferring to replace individual battery banks. If the cause of failure is the memory effect, which is considered a big disadvantage of nickel-cadmium batteries, it is possible to restore their performance by flashing.
VIDEO Nickel-metal hydride batteries are environmentally friendly, high quality, produced by the world's leading companies. Compared to Ni-Cd, they have clear advantages:
slow self-discharge;
the memory effect is small;
resistant to multiple discharge-charge cycles;
relatively large capacity.
But during long-term storage without work, some of the characteristics are lost, they do not like low temperatures, and besides, they cost a lot.And the main disadvantage is that they cannot be repaired.
If you have elements installed on the screwdriver in the battery that, in principle, can be repaired (except for nickel-metal hydride), we proceed to disassemble the case. It has two parts connected with screws or glue. In the first case, no difficulties are foreseen - we unscrew the screws and separate the parts. If the connection is glued, we insert a knife between the parts at the junction, then we screw a self-tapping screw into this place. Carefully, so as not to damage the elements, we pass the knife along the joint, separating the parts of the case.
We check the elements on a fully charged battery.
Having disassembled the case, we will see banks connected in series, which means that a malfunction of even one bank can lead to poor battery performance. The main task during the repair is to find a weak point in the circuit. We remove the cells from the body and lay them out on the table so that there is convenient access to all contacts. With a multimeter, we measure the voltage of each element, write down the indicators on paper or directly on the case. The voltage indicator on a nickel-cadmium battery should be 1.2-1.4 V, on a lithium-ion battery - 3.6-3.8 V.
Types of malfunctions and methods for their elimination
Having measured the voltage, we assemble the cans into the case, turn on the screwdriver and work until it loses power. Again we disassemble and re-take the voltage indicators, again we fix. Cells with the lowest voltage, once fully charged, will again show a significant drop in voltage. A difference of 0.5–0.7 V is considered significant. Such elements will soon become completely unusable, they are candidates for resuscitation or complete amputation.
If you have a 12-volt tool, you can use a simpler method for troubleshooting, eliminating the double disassembly-assembly. First, we also measure the voltage of each fully charged element, fix the indicators. We connect the load to the banks laid out on the table - a 12 V light bulb, which will discharge the battery. Next, we are again interested in voltage. Where there is the strongest drop - a weak area.
You will either need cans from an old battery, in which serviceable elements remain, or you will have to buy new ones, they are inexpensive. When buying, pay attention to the dimensions and capacity - they must match the existing elements. We throw out the bad cans, solder new ones in their place. It is desirable to connect using native plates or copper ones that are suitable in size. Compliance with the cross section is important - when charging, a large current passes through the contacts. If the area is insufficient, they heat up, the protection works.
Replacing battery cells
We pay special attention to the connection sequence - the minus of one can is connected to the plus of the other.
On the assembled battery, we equalize the potentials, since they are different. We put on charging for the whole night, let the battery rest for a day, then measure the voltage. Ideally, all elements should have the same indicator. We turn to the discharge of the battery until it is completely depleted. We repeat the procedure twice more. It should be said that such training is necessary not only for repairs, it should be carried out every three months in order to extend the life of the battery.
A method acceptable for nickel-cadmium batteries when the cells are not dry. You can verify this using the method below, if it does not help, then the electrolyte has boiled away. The essence of the method is in charging using high current and voltage. You will need a charger with the ability to regulate, charging for car batteries is suitable. We will charge each element separately, for which we remove the battery from the case and disconnect the banks from one another.
Battery firmware
We set the charging voltage to three times the nominal voltage - 3.6 V.We connect to the charger and turn it on for 3-5 seconds. If the voltage test with a multimeter showed 1.4 V or a little lower, everything is in order. We collect the battery and use it. The method relieves batteries from the memory effect. It is not suitable for completely dead cans.
As already noted, the main reason for the failure of nickel-cadmium batteries is the drying of the cans. The procedure for topping them up is not very pleasant, but not so complicated that it cannot be performed. We do everything, as always - we disassemble the case, take out the elements. We remove the paper with which the banks are wrapped. From some it is removed easily, whole, on some it has to be cut. We examine the body of the cells - some without any signs of corrosion, others can be seriously damaged, but the main thing is that the shell is intact.
With a thin drill at the top of the element, where there is a recess in a circle, we make a hole. You will need distilled water. We draw it into a syringe, insert the needle into the hole and pump water very slowly. It is not known how much it will enter, it is impossible to determine visually. If liquid flows from the can from the very beginning of water input, throw it away, it cannot be resuscitated, it is necessary to replace it with a new element. Some kind of reaction occurs there, which indicates the unsuitability of this element for repair. But this happens very rarely. Further procedures are usual - assembly, several charge-discharge cycles.
VIDEO
Lithium-ion batteries can also be recycled, but this operation is unhealthy due to the toxicity of the contents. The reason for their failure is most often a violation of the contact between the internal filling and the exit to the case. To check the suitability for repair, insert an awl into the hole at the top of the element so that it touches the inside. We connect a multimeter and look at the readings. If there is current, the reason is a broken contact, you can continue the repair.
With wire cutters we cut off a part of the metal on the cover protruding from the top of the element. We bend it upwards, and opposite the body metal we press it so that it touches the inside of the element. Now comes the turn of the most critical part of the operation - soldering. We use solder that has a flux inside, it is faster and more convenient to solder with it, especially in such a situation. We solder quickly so as not to overheat the element. If you don’t know how to do this, don’t take it - in this situation you won’t learn, but ruin everything. Then we close the gap in the case with sealant - and for charging.
Do-it-yourself repairs are real if you use one of the above methods!
The use of screwdrivers has firmly entered the construction business. Cordless drills allow you to perform tasks in places where there is no external power source or it is difficult to connect an extension cord. But over time, batteries fail. Some have found it possible and easy to repair the battery of a screwdriver with their own hands. What is needed for this and is it possible to restore existing elements? To answer this question, you need to understand the varieties of existing batteries.
Screwdriver manufacturers use batteries in their models that are incompatible with competitor products. But this concerns the external structure, the internal components are the same and can be of several different types. Among them are:
lithium-ion;
nickel-cadmium;
nickel-metal hydride.
Each of these options has its own advantages and disadvantages. Most often, the inscription Ni-Cd can be found on the battery case. She says that inside there are elements that have a nickel-cadmium composition. Previously, such batteries were also used in mobile phones. This is due to the low cost of cells for such batteries. In terms of service life, they are inferior to the other two groups. This is due to a small number of discharge / charge cycles. Typically, the voltage on one bank is 1.2 volts.To achieve a voltage of 12 volts, you will need to use 12 cans for one battery.
This negatively affects the weight and dimensions of the battery. For an 18 volt battery, you need 18 cells. Positive properties are endurance to deep discharge. They can also be stored unloaded, which does not affect their recoil. If you leave a charged battery for a long time, then after a while it will lose its charge. The production of such elements is not environmentally friendly, therefore it is not allowed in every country.
Nickel-metal hydride batteries were developed as a replacement for the previous type. They have been widely used in the domestic sphere. Conventional finger-type rechargeable batteries are made on the principle of nickel-metal hydride batteries. Such products have practically no memory effect. This means that you can charge them until they are completely discharged. But there are some limitations, which are the length of stay in a partially discharged state. If the battery has been in it for more than a month, then it will need to be completely discharged before charging. Their production does not cause such harm to the environment as nickel-cadmium.
Products are able to hold a charge longer, but their cost is two or more times higher than that of the first option. Batteries that contain nickel-metal hydride cells can withstand up to 300 charge / discharge cycles. In addition, this type of battery self-discharge rate is also several times higher. Not so long ago, elements were developed that are subject to less self-discharge. The voltage of one cell is also 1.2 volts. Manufacturers advise charging standard cells with a small current for a long time.
Recently, lithium-ion batteries have become widespread. They are used not only in screwdrivers, but also in most appliances and electronics that are powered by a portable source. Such elements are identified by an inscription on the Li-Ion package or case. One such element has a voltage three times greater than that of one can of the previous two, it is 3.6 volts. Elements can be of various capacities. At the same time, their dimensions remain small, which reduces weight and makes the screwdriver more compact. The number of cycles has been increased to 500. The element has no memory effect, so it can be charged at any time when it is needed. The production of such batteries is more expensive, so equipment with them also has a large price tag.
To correctly identify a malfunction, it is worth understanding that the energy source consists of separate cans that are connected to each other in series. For nickel-cadmium and nickel-metal hydride batteries, the charge controller is installed in the charger, and in lithium-ion batteries, it is most often located in the batteries themselves. If the battery is not charging from the charger, then you need to check what voltage the device produces. To do this, a voltmeter is connected to it and measurements are taken. If everything is in order, then the reason lies in the elements themselves. Typically, components do not fail together. One or more jars have lost their capacity.
To check this, you will also need a multimeter, which is switched to voltmeter mode to measure direct current. It is also necessary to disassemble the battery to gain access to individual banks. But before that, you need to include the discharged product in the charger and wait for the end of the cycle. When it is signaled that a full charge has been reached, then you can proceed to disassembly. Most often, the body is made non-separable. This means that you will have to use your imagination and observation to open it without damaging the internal components. Often the halves can be glued together, so you can use Kalosh gasoline and a syringe with a needle.It is necessary to apply a small portion to the joint and wait until the degreaser dissolves the adhesive.
Now, using a multimeter, it is necessary to measure the voltage on each element. It is important not to confuse the probes in places, as the readings may be incorrect. In a charged state, lithium-ion batteries can have a voltage of up to 4.2 volts, if it is below 3.5, then we can assume that there is a problem with the cell. In the other two types of cells, the voltage of a charged can is in the range of 1.2 and higher. After taking measurements on good banks, you can put a “+” sign, and “-” on those that have lost capacity. You can choose any convenient designation. After the verification, you can collect the source. Glue the body halves is not worth it. You can rewind them with electrical tape, because one more disassembly is required.
The battery must be put into operation until it becomes clear that it has lost capacity or is discharged. After that, the source housing can be dismantled again and measurements can be made on individual elements that were marked as failed. If the voltage on them dipped by 0.5 volts from the nominal lower threshold, then the elements were identified correctly and their further maintenance or replacement will be required. After disassembling the battery, it is necessary to carefully inspect all connection and soldering nodes. If there is a bad contact on any of the elements, then it may be to blame, and the bank will be in order.
Restoring elements that have lost capacity is not an easy task that does not always bring results. In most cases, the procedure can slightly extend the life of the jar, but subsequently a replacement will be required. Lithium-ion batteries are not recoverable, so don't even try. Most often, when they fail, they swell, deforming the internal components, and nothing can be done about it. The first method that can be applied is the selection of a different control system. You can rearrange the banks from a non-working battery to a working one and see if anything changes. If that helps, then the issue is resolved. But the donor battery must be of a similar model. For nickel-cadmium cans, you can try recovery with several charge and discharge cycles. If after that a normal set of capacity occurs, then you can use it for a while.
To repair the screwdriver battery, you will need the same or the same cans as in your own battery. You need a soldering iron, a flux that does not have a corrosive effect on the material, tin and a wash that will remove flux residues.
The soldering iron for work must be of sufficient power to warm up the plates well. Damaged items are removed and thrown away. It is better to hand them over to recycling points so as not to harm the environment. According to the existing scheme, new cans are substituted and connected with native plates. It is worth working quickly so as not to overheat the battery cells too much, this can cause them to fail. It is important to carefully look at the marking of the elements so as not to confuse the polarity. The flux is applied first, and then the tin. After assembling the battery, it is necessary to allow new banks to gain the required capacity. For these purposes, it is necessary to carry out several cycles of full discharge and charge of the battery. For more information on battery repair, see the video.
VIDEO
Repairing a battery for a screwdriver is a simple task if you know about the nuances that were described in the article. The main problem may be the selection of suitable cans that would correspond to the current parameters and fit the specific battery in size.
The cost of a new screwdriver is approximately 70% the cost of the battery to it.Therefore, it is not surprising when faced with a battery failure, we ask ourselves the question - what's next? Buy a new battery or a screwdriver, or maybe it is possible to repair the battery of a screwdriver 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: types of batteries that are used in screwdrivers (part 1), their possible causes of failure (part 2) and available repair methods (part 3).
It should be noted that regardless of the brand of the screwdriver and the country of manufacture, 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 balance their potentials.
Note. The sum of each battery gives us the final voltage at the battery contacts.
Type-setting parts or "cans", as a rule, have a standard size and voltage, they differ only in capacity. Battery capacity is measured in Ah and is indicated on the cell (shown below).
The following types of elements are used for the layout of screwdriver batteries:
nickel - cadmium (Ni - Cd) batteries, with a nominal voltage on the "banks" of 1.2V;
nickel-metal hydride (Ni-MH), voltage on the elements - 1.2V;
lithium-ion (Li-Ion), with a voltage of 3.6V.
Let us consider in more detail the advantages and disadvantages of each type.
The most common type due to low cost;
Not afraid of low temperatures, such as Li-Ion batteries;
It is stored in a discharged state, while retaining its characteristics.
Produced only in third world countries, due to toxicity during production;
memory effect;
Self-discharge;
small capacity;
A small number of charge / discharge cycles, which means that they do not “live” for a long time with intensive use.
Environmentally friendly production, it is possible to purchase a high-quality branded battery;
Low memory effect;
Low self-discharge;
Large capacity, in comparison with Ni - Cd;
More charge/discharge cycles.
Price;
Loses some of the characteristics during long-term storage in a discharged state;
At low temperatures, it does not "live" for a long time.
No memory effect;
Almost no self-discharge;
High battery capacity;
The number of charge / discharge cycles is many times greater than that of previous types of batteries;
To set the required voltage, a smaller number of "cans" is needed, 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 battery pack of the screwdriver. Disassembling the unit, for example, to repair the battery of a Hitachi screwdriver (shown below), is very simple - we unscrew the screws around the perimeter and disconnect the case.
The housing has four contacts:
Two power, "+" and "-", for charge / discharge;
The top control, it is switched on through a temperature sensor (thermistor). The thermistor is necessary to protect the batteries, it turns off or limits the charge current when a certain temperature of the elements 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 9Kom 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 the block.
VIDEO
We figured out the purpose of the battery design elements, now let's look at how to determine the malfunction, this is part 2 of repairing the battery of a screwdriver. We note right away that all elements cannot fail at once, and since our circuit is sequential, when one element fails, the entire circuit does not work. So, our task is to determine where we have the weakest link in the chain.
To do this, we will need a multimeter, and for the second troubleshooting method, a 12V lamp, if your screwdriver battery is also 12 volt. The procedure is as follows:
- We put the battery on charge, we are waiting for a signal about a full charge.
- We disassemble the case and measure on each bank of the battery. For Ni - Cd we should have 1.2 - 1.4V, in lithium - 3.6 / 3.8V.
- Mark all "banks" in which the voltage is less than the nominal. For example, most Ni - Cd cells have a voltage of 1.3V, and one or more - 1.2 / 1.1V.
- We assemble the battery and work until a noticeable loss of power.
- We remove, disassemble and measure the voltage drop on the "banks" of the battery. On the marked elements, the “sagging” of the voltage will be greater than on the others. For example, they are no longer 1.2V, but 1.0V or even lower.
Note. The difference between the cells in the battery in 0.5 - 0.7V is considered significant, which means that the cell becomes unusable.
Thus, we found candidates for "resuscitation" or "amputation" and replacement with new elements.
If your screwdriver is powered by 12 or 13V, you can search using a simpler method. We disassemble a fully charged battery and connect a 12-volt lamp to the “+” and “-” contacts. The lamp will be a load, and will drain the battery. Next, we take measurements on the battery cells, where the voltage drop is the strongest, there is a weak link.
There are other ways, instead of a lamp, you can pick up resistance, but this already requires 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 in the places of soldering batteries or power contacts of the unit, failure of the thermistor. This problem is more inherent in fakes. In view of the rarity, we will not focus on, we will limit ourselves to battery cells.
With the "problem" elements sorted out, it is necessary to repair. How to repair a screwdriver battery? In general, 2 methods are available for repair, so to speak. This is the restoration and replacement of elements that have become unusable.
Let's proceed to part 3 of repairing the battery of a screwdriver 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 has decomposed, and nothing can be done about it. In such batteries, it is necessary to find out what is the cause of the malfunction: 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 the cell with a current of about 200mA, this requires a regulated charger. If the voltage on the element rises to 3.6V, the element is working, the problem is in other elements, or in the control circuit.
Screwdriver battery refurbishment is available mainly for Ni - Cd batteries, but they are usually the most common in household screwdrivers.
So, how to reanimate the battery of a screwdriver? There are two types of "resuscitation" for these types of batteries:
Compaction or compression method (it will work in cases where the electrolyte is still available, 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 to restore the lost capacity.
This method is shown in the video below.
VIDEO
Note.As a rule, in a nickel-cadmium battery, the main reason for the loss of capacity is the boiling of the electrolyte, and if it is critically low, no “firmware” will help.
This method, if its result is positive, will not solve the problem of failure of the elements. Rather, it will only delay the replacement of those that have become unusable and in the future you will still need to repair the battery of the Makita screwdriver or any other.
A more effective way to repair screwdriver batteries is to replace elements that we have identified as faulty.
To carry out repairs, we need either a battery - a “donor”, in which some of the elements are in good condition, or new “banks”. It will not be difficult to buy them, even on the Internet you can easily find a dozen stores that are ready to send these items by mail. The price does not particularly bite, for example, a nickel-cadmium cell with a capacity of 2000 mAh costs around 100 rubles.
Note. When purchasing a new element, make sure that its capacity and dimensions match the native elements.
We also need a soldering iron, a low-corrosion flux (preferably an alcohol flux on rosin) and tin. We are not talking about spot welding, since for a one-time battery repair there is hardly a need to purchase or assemble it ...
There is nothing difficult in the replacement itself, especially if there is at least some experience in soldering. In the photographs, everything is shown in sufficient detail, we cut off the faulty element, instead of it we solder a new one.
It is necessary to note several nuances:
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 copper plates of the same size, 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 work;
in no case do not confuse the plus of the batteries with the minus - the connection is serial, which means that the minus of the previous can goes to the plus of the new can, and the minus of the new one goes to the plus of 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 all night, 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: all the elements have the same multimeter indicator, within 1.3V.
Next, we proceed to discharge the battery, insert the battery into the screwdriver and load it “to the fullest”. The main thing is to spare the screwdriver itself, otherwise you will have to repair it too. We bring 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 training.
Such a not very tricky procedure will extend the life of your screwdriver, at least until you have to change it for a new one.
VIDEO
Why is the battery not holding a charge? How to work if after charging the screwdriver works no more than 10 minutes? Such questions arise among users whose cordless tool has been in operation for more than one year. There are several ways to solve this problem. You can, for example, contact the service center. There, most likely, you will be offered to buy a new battery, since specialists do not officially repair failed elements. But what if such models are no longer produced and it will not be possible to find a suitable analogue? Do you really have to part with your favorite tool and buy a new one, with a new battery and charger? With current prices, not everyone can afford it. Therefore, many craftsmen undertake to repair the battery of a screwdriver with their own hands. By the way, not all of them are chasing savings.For some, this is an occasion for creativity - an opportunity to breathe new life into an old instrument. After all, you can’t do worse, but it’s worth a try!
In preparing this article, we studied many examples of do-it-yourself screwdriver battery repair. Some users restore only cells, others create a completely new battery based on cheap Chinese batteries. However, these approaches are not always good. For example, lithium-ion battery cells cannot be restored. When restoring nickel-cadmium, sometimes a cell firmware is required, which means a special device. The universal way is to repair the battery with the replacement of individual cells. Our article will tell about this.
Disassembling the battery case
The body of any battery is collapsible. It consists of two parts, which are connected by small screws or glue. In the first case, everything is simple: you just need to unscrew the screws and separate the parts. If the case is glued, you will have to work hard to carefully get to the cells without damaging them. First you need to stick the knife blade at any point at the junction of the parts, then insert something sharp there, for example, a self-tapping screw. Thus, it will be possible to wedged a separate section. Then you need to carefully walk the blade around the entire perimeter, separating the glued parts. The hull is disassembled. After repair, it will need to be glued again.
We determine the malfunction
When you get to the battery cells, you will see that they are banks connected in series. This means that one faulty element can cause the screwdriver to work poorly. An important step in do-it-yourself screwdriver battery repair is to find this weak link.
The test must be carried out on a fully charged battery. All cells should be removed from the case and, for convenience, lay them out on the table so that free access to the connecting contacts is provided. Using the contact probes of the multimeter, measure the voltage on each bank, be sure to record the readings. For convenience, you can draw a diagram on a piece of paper and write down the indicators taken there. You can mark them directly on the cells.
Helpful information: for nickel-cadmium batteries, the voltage of each cell should be within 1.2 - 1.4 V, for lithium-ion batteries - within 3.6 - 3.8 V.
After measuring the voltage, the battery is assembled and worked with a screwdriver until power is lost. Then again disassemble and make repeated measurements, which are recorded again. The cells that had the lowest voltage values during the first measurement show the highest losses. It is worth noting that 0.5 - 0.7 V is considered a significant difference in the voltage of the cans. Such elements should be replaced.
On a note! When repairing a screwdriver battery with your own hands, replacing cells is considered more effective than restoring them. The fact is that the restored banks will not last long, and soon they will still have to be replaced. So it is better not to do double work, but to immediately make a replacement.
Replacing damaged cells
With the upcoming self-repair of the screwdriver battery, many users have the question of where to get new cans. You can find an old battery, for example, from friends or visitors to thematic forums. Use it as a donor and select working cells from it. You can buy items separately. They are sold in radio and electrical stores or on classifieds sites. Some craftsmen order batteries from Chinese sites. The price of one can is from 100 to 200 rubles. Agree, this is not so much money compared to buying a new battery.
Advice: when choosing, pay attention to the fact that the new cells in terms of dimensions and current indicators should be similar to the elements that you are replacing.
The process of replacing damaged cells is quite simple. It will not cause difficulties for those who have dealt with soldering.First, you should carefully cut off the connecting plate and remove the faulty can. Try to save this plate for attaching a new element. When installing a new jar, observe the correct location of the plus and minus. When connecting in series, position the cell so that the minus of the previous one goes to the plus of the new one. To securely hold the cans, you can fasten them around the perimeter with electrical tape.
Attention! When soldering, try not to overheat the parts and work quickly. This rule is important to observe in order to avoid overheating the battery. Otherwise, there is a risk of spoiling it.
Charging and discharging a repaired battery
After repairing the screwdriver battery, the potentials on the cells will be different, so they need to be aligned. We put the assembled battery on a long charge, for example, overnight. Then we leave it for a day to lie down so that it cools down. After that, we check the voltage on all elements. If all processes are performed correctly, then the indicators on each bank will be the same, for example, 1.2 - 1.3 V.
The next step is to fully discharge the battery. Work with a screwdriver until the charge is gone. Then fully charge the cell. Repeat the charge/discharge cycle 2 more times. This will help prolong the life of the returned battery.
In conclusion, we say that you should not take this article as an exact guide to repairing a screwdriver battery with your own hands. It is just one of the ways to bring the battery back to life. If the topic interests you, study it on the instrumental forums, chat with craftsmen who share their experience, ask them questions. Try to repeat their experience - for sure you will do just as well.
In order for the battery to serve for a long time and the tool to effectively cope with its task, proper operation is important. These articles will help.
Here are the resources that we focused on when compiling the article. In these publications, users share their experience in repairing batteries for a screwdriver.
Screwdrivers are used in various conditions and the degree of load they have is different. Therefore, they differ in their power, which directly depends on the battery. If an element breaks down, you need to be able to carry out prompt repairs with your own hands.
By design features, batteries are distinguished in the form of sliders and clips.
But these are minor differences compared to battery types. Both the slider and the clip are used in different types of batteries.
There are three types of screwdriver batteries:
Nickel - cadmium (Ni-Cd).
Nickel - metal hydride (Ni-Mh).
Lithium - ion (Li-Ion).
Lithium polymer batteries (Li-Pol) are not manufactured for screwdrivers. The main areas of their application: smartphones, cell phones, tablets, laptops, radio-controlled devices, electric vehicles.
Nickel-cadmium batteries the cheapest, fast charging, have over a thousand charge cycles. Batteries are resistant to operation at low temperatures. But they have a memory effect. That is, you can charge them only after complete discharge, otherwise the capacity will fall. They have a high self-discharge current. They are made from toxic materials and are difficult to dispose of. These batteries are the most popular.
Nickel - metal hydride batteries more expensive, non-toxic, have a low memory effect. The self-discharge current is greater than nickel-cadmium. The capacity is higher, the charge cycle is more than five hundred. These batteries are less tolerant of high discharge rates. They are less suitable for maximizing the power of the tool. They need to be constantly recharged.
Lithium - ion batteries more expensive, more powerful, fast charging. They have no memory effect. Low self-discharge current. The voltage of the battery cells is greater, so their number is less. Therefore, the dimensions and weight of such batteries are less than that of nickel ones.But they cannot be completely discharged, otherwise after several such cycles you will have to buy a new one. To improve the quality of lithium-ion batteries, manufacturers install a microcircuit in the battery case or a screwdriver that controls the operation of the battery. A multi-level multi-stage protection is formed:
From high temperature.
From full charge. These batteries are afraid of a full discharge and cannot recover if the discharge is below the permissible norm.
From short circuit.
From overcharging, as an explosion may occur.
From overload currents.
The control board installed in the battery case is more efficient. When the battery is separate from the screwdriver and not in use, the microcircuit monitors its condition and opens the circuit in case of any problems. The battery is fully protected.
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What can be a problem with batteries:
flowing;
not removed;
decreased capacity;
not charging;
the charging and discharging time is reduced.
Nickel batteries can be recycled. And lithium is impossible, since lithium decomposes in them. Here you can only replace unusable batteries.
Be patient and start repairing.
Disassemble the battery carefully. Do not use force to avoid damaging the case.
Remove the battery from the screwdriver. If the buttons are stuck and it won't come off, unscrew the tool body screws and remove the top half. One of the buttons is free. Pull the battery towards you, slightly moving it in different directions, and it will also be removed. Once you have disassembled the battery, position the buttons so that they are easy to press in their grooves.
The battery case consists of two parts and can be collapsible and non-collapsible. In the first case, unscrew all the screws and separate both parts.
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Inside are several successively soldered elements. Such a cassette provides the necessary voltage and current characteristics for the battery. Some nickel batteries have a temperature sensor attached to the cells.
In lithium - ion batteries, everything is more complicated. There is a control board, and the elements are dressed in a protective case or film.
A new battery must be fully charged before use. The average ambient temperature is from 10 to 40 degrees. Chargers have indicator lights. When they show that the battery is charged, you must immediately turn off the process.
New nickel-cadmium batteries must be shaken before first use. Fully discharge and charge three times. The capacity will be maximum. If the instructions for the device say that the buildup should include more charge cycles, then follow these recommendations. During operation, fully discharge the battery before charging.
Nickel-metal hydride batteries have less memory effect, so they can be pumped once before first use.
Lithium-ion batteries do not need to be pumped. Simply charge them up to full capacity.
To discharge the battery, a load in the form of a 12 volt lamp is used. It is connected by crocodiles to the terminals. If the battery is disassembled, then to the terminals of the serial circuit of the batteries. The discharge process will take less than an hour.
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The second way to properly discharge is to use a "smart" charger like imax b6, which is very convenient for pumping batteries. In it, you can adjust the current and voltage parameters for charging and discharging the battery. Set the automatic cycling mode to build up the battery. That is, you do not need to constantly monitor the capacitance and voltage. The device will do it for you. Up to 5 cycles available. And at the end you will be able to see the values of current and voltage after each cycle and analyze the result.
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After fully charged, disassemble the battery. Inspect the elements for swelling and oxidation. Use a multimeter or tester to measure the voltage of all elements. Voltage limits for different batteries:
For nickel - cadmium 1.2 - 1.4 volts.
For nickel - metal hydride 1.2 - 1.4 volts.
For lithium - ion 3.6 - 3.8 volts.
The battery banks are wrapped in paper. Voltage is applied to each element. If all cells have normal voltage, discharge the battery by half the power. Measure the voltage again. Those elements in which the voltage has decreased by 0.5 - 0.7 volts compared to the average are subject to restoration or replacement. About such banks they say "flows".
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If the charger is OK, check the contacts between the battery and the charger. The charger contacts could be bent. This causes the battery to not charge. Disassemble the device and bend the terminals. The second reason may be a failed or soldered temperature sensor. It must be soldered or replaced with a new one.
When the contacts of the battery, charger, and tool are oxidized and dirty, the battery charges and discharges quickly. Wipe the contacts periodically.
The electrolyte boils away due to accelerated charging and overcharging. If the cells are not swollen and show operating voltage after a full charge, they can be restored without replacement. It is necessary to fill the empty volume with distilled water.
After identifying defective cans, cut the connecting metal tape. Unsolder the elements.
Take a punch with a thickness of no more than 1 millimeter. Where the jar has a minus, make a hole in the body.
Pump out air up to 1 cubic centimeter and pour the same amount of water.
Epoxy seal the elements and connect them to the circuit.
If this method does not help, then replace the banks with new ones.
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When you have carried out diagnostics and identified defective cans, you need to purchase their replacement. New elements must completely match in size and technical characteristics.
Cut or solder the old elements from the plates.
Put new ones in their place. For connection, use the same plates or copper conductors of the same section.
To keep the jars from overheating, solder quickly. Observe the polarity of the series circuit. Connect plus with minus and minus with plus.
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Many owners of a screwdriver with a nickel-cadmium battery have encountered such a problem that when you need to use it, the battery is always empty. And constant charging kills it due to the memory effect. Therefore, they convert such a battery to lithium-ion.
Video (click to play).
The source of lithium batteries can be an old laptop battery or you can buy new ones. Notebook and new banks are unprotected. You cannot use them without protection, because you will not be able to charge them and control the discharge. And when reloading, they will safely die. It is allowed to connect in parallel exactly the same batteries, then they will work as one. Purchase a series battery protection module that monitors and takes care of each cell individually. Monitors voltage and current, provides short circuit protection. Such modules are available for one, two, three and four batteries.
