In detail: DIY battery screwdriver repair from a real master for the site my.housecope.com.
There comes a time when the reliable home assistant - the screwdriver - stops working. The batteries are out of order, and regular recharging no longer helps. Do not rush to buy new batteries, there may be another way out of the situation.
The cost of batteries is about 70% of the price of a new tool, so it is logical to try to repair a screwdriver battery. Before proceeding with the operation, you should familiarize yourself with the features of voltage sources, find out what type of batteries is used on your instrument. Their structure is absolutely the same and does not depend in any way on the country of production and brand. Inside the plastic box there are standard-sized daisy-chained elements. Each element has an indication of the type and capacity in ampere-hours (A / h).
Screwdriver battery
Batteries are completed with the following types of elements:
lithium-ion (Li-Ion) - with a cell voltage of 3.6 V;
nickel-cadmium (Ni-Cd) - 1.25 V on each cell;
nickel metal hydride (Ni-Mh) - 1.2 V.
Evaluation of 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 charged repeatedly, several times more than other types of batteries. Cell voltage is three times higher than that of other types, which makes it possible to equip batteries with fewer cans, reducing weight and dimensions. They have no 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 disadvantages. They cannot be used at subzero temperatures, as manufacturers honestly declare. But practical use has revealed another drawback: when the service life of such a battery ends (three years), lithium decomposes, no way to do a reverse reaction brings results. The price of such batteries is three times higher than that of other power sources for a screwdriver.
Video (click to play).
Nickel-cadmium batteries are the most common because of 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 uncharged for a long time, while maintaining their characteristics. Such batteries have a lot of disadvantages: they are small in capacity, toxic, so their production is concentrated in underdeveloped countries. The tendency to self-discharge, short lifespan during intensive use are also among the disadvantages of these batteries.
Nickel-cadmium batteries dry up at the end of the shelf life. Those who know about this feature re-fill them, but this operation is not easy to perform, so few decide on such an action, preferring to replace individual battery banks. If the reason for the 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, manufactured by the world's leading companies. Compared to Ni-Cd, they have clear advantages:
slow self-discharge;
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, moreover, they cost a lot.And the main drawback is that they cannot be repaired.
If you have battery elements installed on your screwdriver that, in principle, can be repaired (except for nickel-metal hydride), we proceed to disassemble the case. It has two parts connected by screws or glue. In the first case, no difficulties are foreseen - we unscrew the screws and separate the parts. If the connection is adhesive, insert a knife between the parts at the junction, then screw a self-tapping screw into this place. Carefully, so as not to damage the elements, we pass with a knife along the joint, separating the parts of the case.
Checking the cells is carried out 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 the weak point in the chain. We remove the cells from the case and lay them out on the table so that there is convenient access to all contacts. We measure the voltage of each element with a multimeter, record the indicators on paper or directly on the case. The voltage indicator for a nickel-cadmium battery should be 1.2-1.4 V, for a lithium-ion battery - 3.6-3.8 V.
Types of malfunctions and how to fix them
Having measured the voltage, we collect the cans in the case, turn on the screwdriver and work until it loses power. We again disassemble and re-remove the voltage indicators, again fix them. Cells with the lowest voltage will again show a significant drop when fully charged. The difference in readings 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, a simpler method can be used to troubleshoot the problem by eliminating double disassembly and assembly. First, we also measure the voltage value of each fully charged element, fix the indicators. We connect a 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 the strongest fall is noted, the weak area.
You will need either cans from an old battery, in which there are serviceable elements, or you will have to buy new ones, they are inexpensive. When buying, we pay attention to the size and capacity - they must match the existing elements. We throw out the unusable banks, and we solder new ones in their place. It is advisable to connect using native plates or copper plates of suitable size. Compliance with the cross section is important - when charging, a large current flows through the contacts. If the area is insufficient, they heat up, protection is triggered.
Replacing Battery Nutrients
We pay special attention to the sequence of the connection - the minus of one can is connected with the plus of the other.
On the assembled battery, we equalize the potentials, since they are different. We put it on charge for the whole night, let the battery rest for a day, then measure the voltage. Ideally, all elements should have the same indicator. We proceed to discharge the battery until it is completely depleted. We repeat the procedure twice more. It should be said that this training is necessary not only for repairs, it should be done every three months to prolong the life of the battery.
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 charging using high current and voltage. You will need a charger that can be regulated; a charger 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 battery firmware
We set up the charging for a voltage three times higher than the nominal voltage - 3.6 V.We connect to the charger and turn on for 3-5 seconds. If the voltage test with a multimeter showed 1.4 V or slightly lower, everything is in order. We collect the battery and use it. The method eliminates the memory effect of accumulators. It is not suitable for completely killed cans.
As already noted, the main reason for the failure of nickel-cadmium batteries is drying out of the cans. The procedure for refilling them is not very pleasant, but not so complicated as not to be performed. We do everything as always - disassemble the case, take out the elements. We remove the paper with which the cans are wrapped. From some it can be removed easily, whole, on some it has to be cut. We examine the body of the cells - some without any traces 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 depression in a circle, we make a hole. You will need distilled water. We put it into a syringe, put the needle into the hole and pump water very slowly. It is not known how much of it will enter; it is impossible to visually determine it. If, from the very beginning of water injection, liquid flows from the can, throw it out, it cannot be resuscitated, it must be replaced with a new element. There is some kind of reaction, 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 refurbished, but this operation is harmful to health 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 the multimeter and look at the readings. If there is current, the reason is the break in the contact, you can continue the repair.
Cut off part of the metal on the cover protruding from the top of the element with pliers. We bend it up, and opposite the metal of the case 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, which 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 do not know how to do this, do not take it - in this situation you will not learn, but ruin everything. Then we seal 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 become part of the construction business. Cordless drills allow you to perform tasks in places where there is no external power source or it is difficult to feed an extension cord. But over time, the batteries fail. Some found it possible and easy for themselves to repair a screwdriver battery with their own hands. What is needed for this and can existing elements be restored? To answer this question, you need to understand the varieties of existing batteries.
Screwdriver manufacturers use batteries in their models that are not compatible with competitors' products. But this applies to 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 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, these 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 the small number of discharge / charge cycles. Typically, the voltage per cell is 1.2 volts.To reach a voltage of 12 volts, you would need to use 12 cans for one battery.
This negatively affects the weight and dimensions of the battery. An 18 volt battery requires 18 cells. Positive properties are deep discharge endurance. They can also be stored uncharged without affecting 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 become more widely used in the domestic sphere. Conventional pen-type rechargeable batteries are based 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 consist in the period 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 harm the environment as much as nickel-cadmium.
Products are capable of holding 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, the self-discharge rate of this type of battery 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 low current for a long time.
Recently, lithium-ion batteries have become widespread. They are used not only in screwdrivers, but also in most equipment and electronics, which are powered from a portable source. Such elements are identified by the inscription on the packaging or the Li-Ion case. One such element has a voltage three times higher than that of one can of the previous two, it is 3.6 volts. Elements can be of very different capacities. At the same time, their dimensions remain small, which reduces weight and allows you to make 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 technology with them also has a high price tag.
To correctly identify a malfunction, it is worthwhile to understand that the energy source consists of separate cans, which are connected in series with each other. For nickel-cadmium and nickel-metal hydride, the charge controller is installed in the charger, and in lithium-ion, it is most often located in the batteries themselves. If the battery does not charge from the charger, then you need to check what voltage the device produces. For this, a voltmeter is connected to it and measurements are taken. If everything is in order, then the reason lies in the elements themselves. Usually, the components do not fail together. One or more cans have lost their capacity.
To check this, you will also need a multimeter, which is switched to voltmeter mode to measure DC current. It is also necessary to disassemble the battery to gain access to individual banks. But before that, it is necessary to plug the discharged product into the charger and wait until 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 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 "Galosha" gasoline and a syringe with a needle. It is necessary to apply a small amount to the joint and wait until the degreaser dissolves the adhesive.
Now, using a multimeter, it is necessary to measure the voltage at each element. It is important not to mix up the probes, 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 are problems with the cell. In the other two types of cells, the voltage of a charged cell is in the range from 1.2 and higher. After taking measurements, you can put a "+" sign on good banks, and "-" on those that have lost capacity. You can choose any convenient designation. After checking, you can collect the source. You should not glue the halves of the case. You can rewind them with electrical tape, since one more disassembly will be required.
The battery must be put into operation until it becomes clear that it has lost capacity or is discharged. After that, the source body can be dismantled again and measurements can be made on individual elements that have been marked as out of order. If the voltage across them sank 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 bad contact on any of the elements, then it may be the fault of everything, and the bank will be in order.
Recovering items that have lost capacity is challenging and not always successful. In most cases, the procedure can slightly extend the life of the can, but later it will need to be replaced. Lithium-ion batteries cannot be repaired, so you shouldn'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 multiple charge and discharge cycles. If after this there is a normal set of capacity, then you can use it for some time.
To repair a screwdriver battery, you will need to have similar 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 the remaining flux.
The soldering iron for work must be of sufficient power to warm up the plates well. Spoiled items are removed and discarded. It is better to hand them over to recycling centers 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, from which they can fail. It is important to look carefully at the markings of the elements so as not to reverse the polarity. Flux is applied first, followed by tin. After assembling the battery, it is necessary to allow the new banks to gain the required capacity. For these purposes, it is necessary to carry out several cycles of complete discharge and charge of the battery. For more information on battery repair, see the video.
VIDEO
Repairing a battery for a screwdriver is not a difficult task if you know about the nuances that were described in the article. The main problem can be the selection of suitable cans, which would correspond to the parameters of the current and would be suitable in size for a specific battery.
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's next? Buy a new battery or a screwdriver, or maybe there is an opportunity to repair a screwdriver battery with your own hands and continue working with an already familiar tool?
In this article, which we conditionally divide into three parts, we will consider: the types of batteries that are used in screwdrivers (part 1), their possible causes of failure (part 2) and available repair methods (part 3).
It should be noted that regardless of the brand of the screwdriver and the country of the manufacturer, the batteries have an identical structure. The assembled battery pack looks like this.
If we disassemble it, we will see that it is assembled from small elements that are assembled sequentially. And from the school physics course, we know that elements that have a serial connection harmonize their potentials.
Note. The sum of each battery gives us the total voltage at the contacts of the battery.
Typesetting parts or "cans", as a rule, have a standard size and voltage, they differ only in capacity. Battery capacity is measured in Ah and is indicated on the cell (shown below).
For the arrangement of screwdriver batteries, the following types of elements are used:
nickel - cadmium (Ni - Cd) batteries, with a nominal voltage on the "banks" of 1.2V;
nickel-metal hydride (Ni-MH), voltage across elements - 1.2V;
lithium-ion (Li-Ion), with a voltage of 3.6V.
Let's consider in more detail the advantages and disadvantages of each type.
The most common type due to its low cost;
Low temperatures, such as Li-Ion batteries, are not scary;
It is stored in a discharged state, while retaining its characteristics.
Produced only in third world countries, due to toxicity during production;
Memory effect;
Self-discharge;
Small capacity;
A small number of charge / discharge cycles, which means that they do not "live" for a long time with intensive use.
Environmentally friendly production, there is an opportunity to purchase a high-quality branded battery;
Low memory effect;
Low self-discharge;
High capacity compared to Ni - Cd;
More charge / discharge cycles.
Price;
Loses some of its characteristics during long-term storage in a discharged state;
It does not "live" for a long time at low temperatures.
No memory effect;
Self-discharge is almost absent;
High battery capacity;
The number of charge / discharge cycles is several times greater than that of previous types of batteries;
To set the required voltage, a smaller number of "cans" are required, which significantly reduces the weight and dimensions of the battery.
High price, almost 3 times in comparison with nickel - cadmium;
After three years, there is a significant loss of capacity, because Li decomposes.
We got acquainted with the elements, let's move on to the rest of the elements of the screwdriver's battery pack. Disassembling the unit, for example, for repairing the battery of a Hitachi screwdriver (pictured below), is very simple - we unscrew the screws around the perimeter and disconnect the case.
The housing has four contacts:
Two power ones, "+" and "-", for charge / discharge;
Upper control, it is switched on through a thermal sensor (thermistor). A thermistor is necessary to protect batteries, it cuts off or limits the charge current when a certain temperature of the cells is exceeded (usually in the range of 50 - 600C). Heating occurs due to high currents during forced charging, the so-called "fast" charging;
The so-called "service" contact, which is connected through a 9K ohm resistance. It is used for complex charging stations that equalize the charge on all battery cells. In everyday life, such stations are useless, due to their high cost.
That's actually the whole design of the battery. Below is a video on how to disassemble a block.
VIDEO
We figured out the purpose of the battery structure elements, now we will consider how to determine the malfunction, this is part 2 of the screwdriver battery repair. Immediately, we note that all the elements cannot fail at once, and since our circuit is sequential, when one element fails, the whole circuit does not work. Hence, our task is to determine where we have the weakest link in the chain.
For this, we will need a multimeter, and for the second method of troubleshooting a 12V lamp, if your battery for a screwdriver is also 12 volt. The procedure is as follows:
- We put the battery on charge, wait for the signal of a full charge.
- We disassemble the case and measure it on each battery bank. For Ni - Cd, we should have 1.2 - 1.4V, in lithium - 3.6 / 3.8V.
- Check all "banks" in which the voltage is less than the nominal one. For example, most Ni - Cd cells have a voltage of 1.3V, and one or more - 1.2 / 1.1V.
- We collect the battery and work until a noticeable loss of power.
- We remove, disassemble and measure the voltage drop across the "banks" of the battery. On the marked elements, the voltage "sag" will be greater than on others. For example, they are no longer 1.2V, but 1.0V or even lower.
Note. The difference between the cells in the battery of 0.5 - 0.7V is considered significant, which means that the cell becomes unusable.
Thus, we have found candidates for "resuscitation" or "amputation" and replacement with new elements.
If your screwdriver operates on a voltage of 12 or 13V, you can search with a simpler method. We disassemble the fully charged battery and connect a 12 volt lamp to the contacts "+" and "-". The lamp will be a load and will drain the battery. Next, we take measurements on the battery cells, where the voltage drop is strongest, there is also a weak link.
There are other ways, instead of a lamp, you can choose a resistance, but for this you already need the basics of electrical engineering, and it is doubtful that a resistor with the necessary resistance would be at hand.
Other faults are very rare. For example, loss of contact at the soldering points of the batteries or the power contacts of the unit, failure of the thermistor. This problem is more inherent in fakes. Due to the rarity, we will not focus on the battery elements.
We have dealt with the "problem" elements, they need to be repaired. How to repair a screwdriver battery? In general, 2 methods are available for repair, so to speak. This is the restoration and replacement of elements that have become unusable.
Let's proceed to part 3 of repairing a screwdriver battery and immediately make a reservation that the concept of "resuscitation" for lithium - ion batteries is not applicable. There is no memory effect in them, most likely, lithium decomposition has occurred, and nothing can be done about it. In such batteries, it is necessary to find out what the cause of the malfunction is: the element itself or the control circuit. There are two options here:
we change the control scheme from another, but similar to ours, battery, if it helps, we find a replacement and change it;
apply 4V to a cell with a current of about 200mA, this requires an adjustable charger. If the voltage on the element rises to 3.6V, the element is working properly, the problem is in other elements, or in the control circuit.
Screwdriver battery refurbishment is available primarily for Ni - Cd batteries, but these are usually the most common in household screwdrivers.
So how to reanimate a screwdriver battery? There are two types of "resuscitation" for these types of batteries:
The method of compaction or compression (it will work in cases where the electrolyte is still present, but the volume is lost);
"Firmware" voltage and current greater than the nominal. This method allows you to eliminate the memory effect, and although not completely, but restore the lost capacity.
This method is shown below in the video.
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.
A more effective way to repair batteries for a screwdriver is to replace elements that we have identified as faulty.
To carry out repairs, we need either a "donor" battery, in which some of the elements are in good order, or new "banks". It will not be difficult to purchase 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 bite too much, 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 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 ...
There is nothing complicated in the replacement itself, especially if you have 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.
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 sequential, 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 one.
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 discharge completely.
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 operation of your screwdriver, at least until you have to replace it with a new one.
VIDEO
Screwdrivers are used in different conditions and the degree of stress 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 their design features, batteries are distinguished in the form of sliders and clips.
But these are not significant differences compared to the types of batteries. Both the slider and the clip are used in different types of batteries.
There are three types of cordless screwdriver batteries:
Nickel - cadmium (Ni-Cd).
Nickel - metal hydride (Ni-Mh).
Lithium - ionic (Li-Ion).
Lithium polymer batteries (Li-Pol) are not available for screwdrivers. Their main areas of application: smartphones, cell phones, tablets, laptops, radio-controlled devices, electric vehicles.
Nickel - cadmium batteries the cheapest, fast charging, have more than a thousand charging cycles.The batteries are resistant to use in low temperatures. But they have a memory effect. That is, they can be charged only after a 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 in the highest demand.
Nickel - metal hydride batteries more expensive, non-toxic, have a low memory effect. Self-discharge current is higher than nickel - cadmium. The capacity is higher, the charge cycle is more than five hundred. These batteries do not tolerate high discharge rates worse. They are less suited to making the most of 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 higher, therefore their number is lower. Consequently, 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 or screwdriver case that monitors battery performance. A multi-level multi-stage protection is formed:
From high fever.
From full discharge. These batteries are afraid of full discharge and cannot recover if the discharge is below the permissible rate.
From short circuit.
Overcharge, as an explosion may occur.
From overload currents.
The control board installed in the battery case is more efficient. When the battery is located separately from the screwdriver and is not used, the microcircuit monitors its condition and, in case of any problems, opens the circuit. The battery is fully protected.
VIDEO
What can be the problem with the batteries:
flows;
not removable;
decreased capacity;
not charging;
the charging and discharging times are reduced.
Nickel batteries can be recovered. And lithium is not allowed, since lithium decomposes in them. Here you can only replace the unusable batteries.
Please be patient and proceed with the repair.
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 cannot be removed, unscrew the screws on the tool body and remove the top half. One of the buttons was released. Pull the battery towards you, slightly wiggling it in different directions, and it will also come off. When you disassemble the battery, position the buttons so that they easily press into 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.
VIDEO
Several sequentially welded elements are located inside. This cassette provides the required voltage and current characteristics for the battery. Some nickel batteries have a thermal sensor attached to the cells.
Things get more complicated with lithium-ion batteries. There is a control board, and the elements are wrapped 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. The chargers have indication lights. When they show that the battery is charged, you must immediately turn off the process.
New nickel-cadmium batteries must be rocked before first use. Fully discharge and charge three times. The capacity will become maximum. If the instructions for the device say that the buildup should include a larger number of charge cycles, then follow these recommendations. During operation, completely discharge the battery before charging.
Nickel-Metal Hydride batteries have less memory effect, so they can be swung once before using for the first time.
Lithium ion batteries do not need to be rocked.Simply charge them up to full power.
A 12 volt lamp load is used to discharge the battery. 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.
VIDEO
The second way to properly discharge is to use a "smart" charger such as imax b6, which is very convenient to swing the batteries. In it, you can adjust the parameters of the current and voltage for charging and discharging the battery. Set the automatic cycling mode to swing the battery. That is, you do not need to constantly monitor the capacity and voltage. The device will do it for you. Up to 5 cycles are provided. And at the end you can see the current and voltage values after each cycle and analyze the result.
VIDEO
After fully charged, disassemble the battery. Examine elements for bulging and oxidation. Measure the voltage of all elements with a multimeter or tester. 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 cans are paper wrapped. The voltage is applied to each element. If all cells have normal voltage, discharge the battery to half the capacity. Measure the voltage again. Those elements in which the voltage has dropped by 0.5 - 0.7 volts compared to the average must be restored or replaced. They say about such banks "flows".
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If the charger is ok, check the contacts between the battery and the charger. The contacts of the charger could be straightened. This prevents the battery from charging. Disassemble the device and bend the terminals. The second reason may be a faulty or sealed temperature sensor. It needs to be soldered or replaced with a new one.
If the contacts of the battery, charger and tool become oxidized or dirty, the battery will quickly charge and discharge. Wipe the contacts periodically.
Boil-off of electrolyte occurs due to accelerated charging and overcharging. If the cells are not swollen and after a full charge show the operating voltage, they can be restored without replacement. It is necessary to replenish the empty volume with distilled water.
After identifying the defective cans, cut the connecting metal tape. Unsolder the elements.
Take a punch no more than 1 millimeter thick. Where the can has a minus, make a hole in the body.
Pump out air up to 1 cubic centimeter and pour in the same amount of water.
Seal the elements with epoxy and connect them to the circuit.
If this method did not help, then replace the cans with new ones.
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When you have diagnosed and identified defective jars, you need to purchase a replacement. New elements must be completely the same in size and technical characteristics.
Cut or unsolder old elements from the plates.
Put new ones in their place. Use the same plates or copper conductors of the same cross-section for the connection.
So that the cans do not overheat, do the soldering 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 faced such a problem that when you need to use it, the battery is always discharged. And constant charging kills her due to the memory effect. Therefore, such a battery is converted to a lithium-ion one.
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Lithium batteries can be sourced from an old laptop battery, or you can buy new ones. Laptop 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 overcharged, they will die safely. It is allowed to connect in parallel exactly the same batteries, then they will work as a whole.Purchase a battery protection module for series-connected batteries 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.
