Replacing the screwdriver battery with a lithium

Alteration of the “Hitachi” 12 V screwdriver for lithium batteries 18640

Features of reworking the 12 V Hitachi screwdriver for lithium batteries. The very compact battery compartment is designed for finger cells. Therefore, you should prepare a place for 18650 cells. It is necessary to cut one side of the partition in order to tightly place 1 element.

You need to get a gumboil, a flat metal connecting tape, hot glue. It is necessary to install lithium batteries in a screwdriver during alteration through a protective controller. It should service 3 18650 cells, 3.7V and rated for 20-30 amps.

Remove the old battery from the socket, carefully disconnect the contacts in the assembly with the temperature sensor and the power indicator. Clean up and sign contacts. They should be brought out to one side, connected with solder to the leads from thick wires and filled with hot melt glue on the assembly.

replacing, screwdriver, battery, lithium

Assemble a power source with one of the 3 cell controllers. Build a serial circuit of 3 Li-ion cells. Connect the controller. The conversion of the 12-volt lithium battery is completed when the structure is installed in the unit, secured, and the charging indicator lights up. After fully charging, the measurements show 12.17 volts in the external network. But this is enough for trouble-free long-term operation of the device.

The meaning and procedure for converting screwdrivers to lithium batteries

Why do nickel-cadmium batteries fail quickly? In a garland of series-connected cans, each one is special. The chemical process is individual, the charge in closed systems is different. In the event of a malfunction in one bank, the design does not provide the required voltage. The control system and charge balancing in individual components is not provided.

  • Each Ni-Cd bank provides 1.2V and Li-ion 18650 3.6V.
  • Lithium battery capacity is 2 times that of nickel-cadmium battery, similar size.
  • An overheated li-ion battery threatens an explosion and fire, therefore, the installation of monitoring the uniformity of the charge in the banks is mandatory. BMS is not installed in nickel-cadmium batteries. the manufacturer is not interested.
  • Lithium cells have no memory effect, unlike Ni-Cd, they can be charged at any time and within an hour.
  • The screwdriver becomes much easier after converting the battery to li-ion, using 18650 cells.

There are only two obstacles to converting a screwdriver for lithium batteries. it is impossible to work with it at minus. The capacity of cans decreases, starting from a decrease already from 10 0 C. Lithium batteries are expensive.

Knowing what input voltage is required for the screwdriver, the charger is reworked, taking into account the placement of the lithium battery cans and control elements in the factory container. You can also do with a flashlight by upgrading the socket for a block of 18650 cells.

Let’s say you need to rework a 12 V screwdriver using Ni-Cd cans on li-ion. If you use 3 cans, the output voltage is not enough: 3.6 x 3 = 10.8 V. With 4 components, the power of the apparatus will be higher: 3.6 x 4 = 14.4 V. This will make the instrument 182 g lighter. its power will increase slightly, capacity. solid pluses. But when dismantling, it is necessary to leave the terminals and the native thermal sensor.

Conversion of a screwdriver to lithium batteries 18650 14 V

When converting screwdrivers of different power and flashlights from Ni-Cd to Li-ion, batteries of the form factor 18650 are more often used. They easily fit into a container or a nest, since instead of two or three relatives, one lithium is installed. Alteration of the screwdriver battery should be carried out taking into account the characteristics of lithium 18650 batteries.

This type of energy source does not tolerate deep discharge and excessive charge. Hence, it is necessary to use voltage control boards. Since each battery has its own character, their charge is corrected by a balancer. The point of reworking a screwdriver with a voltage of 14.4 V lies in creating a device using lithium batteries to facilitate a hand tool and increase its performance. Lithium 18650 batteries are most suitable for these purposes.

When selecting components, it should be taken into account that the starting current of the screwdriver is high, you must select the appropriate BMS for the required number of cans and at least 30 A.

  • Lithium-ion cans in the amount of 4 pcs.
  • 4 cell li-ion battery controller, CF-4S30A-A works well. It has a built-in balancer that controls the charge of each element.
  • Hot melt glue, flux for soldering TAGS, solder.
  • Heat-resistant tape;
  • Connecting jumpers or thick insulated wire with a cross section of at least 0.75 squares, cut for bridges.

The procedure for converting a screwdriver for 18650:

  • Disassemble the case and remove a bundle of 12 Ni-Cd cells from the container.
  • Remove the garland, leaving the connector with the “” and “-” pins. Instead of a temperature sensor, a thermocouple from the controller will be installed.
  • Solder the assembly, considering that you cannot use acid, only neutral flux and pure solder. During the connection period, do not warm up the covers. Work pointwise.
  • Connect the balancing points to the controller according to the diagram. The board has connectors.
  • Connect assembly with plus and minus pins.
  • Check the functionality of the circuit. If everything works, assembled the battery, place the controller in the socket, secure with a sealant.

If the charger is not universal, additional alteration will be required. Screwdrivers for 12 V with a universal charger are assembled in the same way, but a protective connection circuit 3×18650 3.7 V for lithium batteries is used. In the same way, a screwdriver is reworked using a set of 18650 batteries in the amount of 2 elements.

Accumulators and batteries

Energy storage information website

Conversion of the Makita screwdriver to the lithium battery

There is a “Makita” screwdriver with a 1.3 A / h battery and a voltage of 9.6 V. To change the power source to a lithium-ion one, you will need 3 18650 components. The alteration will give the old tool new possibilities: it will increase the operating time on one charge. will add power as the operating voltage rises to 10.8V.

The design will require the use of a BMS, a control controller that maintains the lithium cell operating mode within operating limits. With this breaker, each cell will be charged evenly without exceeding 4.2V, the lower voltage is 2.7V. The built-in balancer is used here.

The parameters of the controller should accompany the operation of the instrument when the operating current rises to 10-20 A. The Sony VTC4 30 A board, designed for a capacity of 2100 A / h, can ensure operation without shutdown. Of the 20 amperes, the Sanyo UR18650NSX accepting 2600A / h energies is suitable. The board is needed for 3 elements, which is marked in the 3S classification. In this case, the board must have 2 contacts, plus and minus. If the conclusions are designated with the letters “P-“, “P”, “C-“, they are intended for later models of screwdrivers.

Step-by-step instructions for converting a Makita screwdriver to lithium batteries looks like this.

  • You can disassemble the battery with glue if you tap the junction with a soft-headed hammer while weighing. Direction of impact downward, butt-joint along the lower part of the body.
  • Take only the contact plates from the old assembly, carefully disconnecting them from the battery. The sensor and the breaker must be left.
  • Solder 3 elements in series using TAGS flux and insulated jumpers. The wire cross-section must be greater than 0.75 mm2.
  • Assemble the circuit with the controller, and connect the power supply to the contact connectors with 1.5 square wires.
  • Check the functionality of the circuit and reassemble the case by placing it on the glue again.

In a screwdriver with an old DC9710 charger, after charging the 18650 lithium battery, the red LED on the panel will turn off. The built-in controller monitors the charge level.

The Makita DC1414 T charger is used to charge 7.2-14.4 V power sources. While charging, the red light is on. But when charging a lithium battery, its voltage does not fit into the standards of salt products, and after 12 V, the charger will flash red and green. But the necessary charging is already there. The screwdriver is ready to work.

Converting a screwdriver to lithium batteries 18650

Alteration of the Interskol screwdriver for lithium batteries 18650

Sooner or later, the nickel-cadmium assembly of 15 cans fails. One or two elements are lazy, and it is no longer possible to get the output voltage. Modern DSh “Interskol” on lithium batteries serve much better. Alteration of a screwdriver for 18 volt lithium batteries mastered by craftsmen.

READ  Convert Bosch Screwdriver Battery To Lithium

It is necessary to purchase a protection board for 5S, 3.7 V and 40-50 A. You will need a balancing board and the energy sources themselves. 5 lithium 18650 batteries, you can leave them with factory thermistors by extending the wires. During installation, create a contact pad, insert the assembly, check the functionality, secure. The assembly features of the wizard’s advice are given in detail in the video. See here for full details on reworking an 18-volt lithium screwdriver

Makita DC9710 charger and lithium-ion battery

Previously, the battery was controlled by the device itself. When the full level was reached, it stopped the process and signaled the completion of charging with a green indicator. But now the BMS circuit we have installed is engaged in level control and power off. Therefore, when charging is complete, the red LED on the charger will simply turn off.

If you have such an old device, you are in luck. Because everything is simple with him. The diode is on. charging is in progress. Off. charging completed, battery fully charged.

DIY: Ni-Cd To Lithium Battery Conversion By Using 18650 Cells

How to disassemble a screwdriver battery

How to disassemble an old battery? There are batteries where the halves of the case are fastened with screws, but there are also glue ones. My batteries are one of the last ones, and I generally believed for a long time that they could not be disassembled. It turned out that it is possible if you have a hammer.

In general, with the help of intense blows to the perimeter of the edge of the lower part of the case (a hammer with a nylon head, the battery must be held in the hand by weight), the gluing site is successfully disconnected. In this case, the case is not damaged in any way, I have already disassembled 4 pieces this way.

The part of interest to us.

From the old circuit, only contact plates are needed. They are permanently spot welded to the upper two elements. You can pick out the welding with a screwdriver or pliers, but you need to pick it as carefully as possible so as not to break the plastic.

Everything is almost ready for further work. By the way, I left the standard thermal sensor and disconnector, although they are no longer particularly relevant.

But it is very likely that the presence of these elements is necessary for the normal operation of a standard charger. Therefore, I highly recommend saving them.

Makita DC1414 T charger and lithium-ion battery

There is a small nuance here that you need to know. This charger is newer and is designed to charge a wider range of batteries from 7.2 to 14.4 V. The charging process on it proceeds as usual, the red LED is on:

But when the battery (which in the case of NiMH cells is supposed to have a maximum voltage of 10.8 V) reaches 12 volts (we have Li-Ion cells with a maximum total voltage of 12.6 V), the charger will blow the roof. Because he will not understand what kind of battery he is charging: either 9.6-volt, or 14.4-volt. And at this moment Makita DC1414 will enter error mode, alternately blinking red and green LEDs.

This is normal! Your new battery will still charge. though not completely. The voltage will be approximately 12 volts.

That is, you will miss some part of the capacity with this charger, but it seems to me that you can survive.

In total, the upgrade of the oBosch battery cost about 1000 rubles. Makitovsky’s new Makita PA09 costs twice as much. over, we ended up with twice the capacity, and further repairs (in the event of a slight failure) will consist only in replacing lithium-ion cells.

Note: This article and the images in it are subject to copyright. Partial or complete reproduction on other resources without consent is prohibited.

The inevitable has come. the batteries in my old Hitachi DS 12DVF3 are completely dead. It was disgusting to hold a charge for a very long time, but the available capacity was enough for small household needs, so I never thought about solving this problem. Until the moment when I needed to drill a hole in a stainless steel kitchen sink, which took me forty minutes! One hole! One battery could not be swung at all, while the other did not work, twists for twenty seconds, charges for about ten minutes. It was then that I realized that it was time to give a new life to my beloved instrument.
It is clear that first it was necessary to familiarize myself a little with the theory in order to understand what in general I have to do. Of course, this topic is not at all new and everyone who is not lazy is engaged in the translation of screwdrivers into lithium. But everyone does it in their own way, depending on their education, the amount of laziness and the concept of beauty. I needed everything to be done absolutely correctly from the technical point of view, so that it did not look scary from the outside and that the batteries could be conveniently used. After re-reading and reviewing a huge amount of material, I took a project from AlexGyver as a basis.

Here you need to carefully break off the upper contact pad, it will be needed later. You will also need nickel jumpers to solder the second unit to the batteries, so I move this stuff aside for now. Next, I try on new components in order to understand the front of the upcoming work.

Energy storage information website

Every craftsman is faced with the problem of reduced tool performance, or complete failure due to the battery. Manufacturers use nickel-cadmium batteries in 12, 14, 18 volt screwdrivers. The sequential assembly of several elements creates the required voltage. Replacing nickel-cadmium batteries with lithium batteries extends battery life by making construction easier. Mandatory BMS board installation adds reliability. Therefore, the conversion of a screwdriver to lithium batteries, mainly to the 18650 form factor, is justified.

Replacing a screwdriver battery with a lithium do-it-yourself

I won’t say anything new in this article, but I just want to share my experience of upgrading the batteries of my old Makita screwdriver. Initially, this tool was designed for nickel-cadmium batteries (which have long since died, just as those bought for replacement have died). The disadvantages of Ni-Cd are well known: low capacity, short lifespan, high price. Therefore, cordless tool manufacturers have long since switched to lithium-ion batteries.

Well, what about those who have an old instrument? Yes, everything is very simple: throw away the Ni-Cd cans and replace them with Li-Ion of the popular 18650 format (marking indicates a diameter of 18 mm and a length of 65 mm).

Conversion of the Makita screwdriver to the lithium battery

There is a “Makita” screwdriver with a 1.3 A / h battery and a voltage of 9.6 V. To change the power source to a lithium-ion one, you will need 3 18650 components. The alteration will give the old tool new possibilities: it will increase the operating time on one charge. will add power as the operating voltage rises to 10.8V.

The design will require the use of a BMS, a control controller that maintains the lithium cell operating mode within operating limits. With this breaker, each cell will be charged evenly without exceeding 4.2V, the lower voltage is 2.7V. The built-in balancer is used here.

The parameters of the controller should accompany the operation of the instrument when the operating current rises to 10-20 A. The Sony VTC4 30 A board, designed for a capacity of 2100 A / h, can ensure operation without shutdown. Of the 20 amperes, the Sanyo UR18650NSX accepting 2600A / h energies is suitable. The board is needed for 3 elements, which is marked in the 3S classification. In this case, the board must have 2 contacts, plus and minus. If the conclusions are designated with the letters “P-“, “P”, “C-“, they are intended for later models of screwdrivers.

Step-by-step instructions for converting a Makita screwdriver to lithium batteries looks like this.

  • You can disassemble the battery with glue if you tap the junction with a soft-headed hammer while weighing. Direction of impact downward, butt-joint along the lower part of the body.
  • Take only the contact plates from the old assembly, carefully disconnecting them from the battery. The sensor and the breaker must be left.
  • Solder 3 elements in series using TAGS flux and insulated jumpers. The wire cross-section must be greater than 0.75 mm2.
  • Assemble the circuit with the controller, and connect the power supply to the contact connectors with 1.5 square wires.
  • Check the functionality of the circuit and reassemble the case by placing it on the glue again.

In a screwdriver with an old DC9710 charger, after charging the 18650 lithium battery, the red LED on the panel will turn off. The built-in controller monitors the charge level.

The Makita DC1414 T charger is used to charge 7.2-14.4 V power sources. While charging, the red light is on. But when charging a lithium battery, its voltage does not fit into the standards of salt products, and after 12 V, the charger will flash red and green. But the necessary charging is already there. The screwdriver is ready to work.

Putting together a lithium-ion battery

Here are the new elements of Sanyo UR18650NSX (according to this article they can be found on Aliexpress) with a capacity of 2600 mAh. For comparison, the old battery had a capacity of only 1300 mAh, half the size.

It is necessary to solder the wires to the elements. The wires must be taken with a cross section of at least 0.75 sq. Mm, because we will have considerable currents. A wire with such a cross section normally works with currents of more than 20 A at a voltage of 12 V. You can solder lithium-ion cans, short-term overheating will not harm them in any way, this has been verified. But you need a good fast-acting flux. I use TAGS glycerin flux. Half a second. and you’re done.

READ  Can The Drill Be Used As A Screwdriver

We solder the other ends of the wires to the board according to the diagram.

I always put even thicker wires of 1.5 mm2 on the battery contacts. because the space allows. Before soldering them to the mating contacts, I put a piece of heat-shrink tubing on the board. It is necessary for additional isolation of the board from battery cells. Otherwise, the sharp edges of the solder can easily rub or puncture the thin film of the lithium-ion cell and cause a short. It is possible not to use heat shrinkage, but at least something insulating to be laid between the board and the elements is absolutely necessary.

Replace Convert Ni Cd With Li Ion Batteries for all drills BOSCH MAKITA DeWALT BLACK DECKER

Now everything is insulated as it should.

The contact part can be fixed in the battery case with a couple of droplets of super glue.

Battery ready for assembly.

It’s good when the case is on the screws, but this is not my case, so I just glue the halves again “Moment”.

The battery is charged with a standard charger. True, the algorithm of work is changing.

I have two chargers: DC9710 and DC1414 T. And they work differently now, so I’ll tell you exactly how.

Conversion of a screwdriver to lithium batteries 18650 14 V

When converting screwdrivers of different power and flashlights from Ni-Cd to Li-ion, batteries of the form factor 18650 are more often used. They easily fit into a container or a nest, since instead of two or three relatives, one lithium is installed. Alteration of the screwdriver battery should be carried out taking into account the characteristics of lithium 18650 batteries.

This type of energy source does not tolerate deep discharge and excessive charge. Hence, it is necessary to use voltage control boards. Since each battery has its own character, their charge is corrected by a balancer. The point of reworking a screwdriver with a voltage of 14.4 V lies in creating a device using lithium batteries to facilitate a hand tool and increase its performance. Lithium 18650 batteries are most suitable for these purposes.

When selecting components, it should be taken into account that the starting current of the screwdriver is high, you must select the appropriate BMS for the required number of cans and at least 30 A.

  • Lithium-ion cans in the amount of 4 pcs.
  • 4 cell li-ion battery controller, CF-4S30A-A works well. It has a built-in balancer that controls the charge of each element.
  • Hot melt glue, flux for soldering TAGS, solder.
  • Heat-resistant tape;
  • Connecting jumpers or thick insulated wire with a cross section of at least 0.75 squares, cut for bridges.

The procedure for converting a screwdriver for 18650:

  • Disassemble the case and remove a bundle of 12 Ni-Cd cells from the container.
  • Remove the garland, leaving the connector with the “” and “-” pins. Instead of a temperature sensor, a thermocouple from the controller will be installed.
  • Solder the assembly, considering that you cannot use acid, only neutral flux and pure solder. During the connection period, do not warm up the covers. Work pointwise.
  • Connect the balancing points to the controller according to the diagram. The board has connectors.
  • Connect assembly with plus and minus pins.
  • Check the functionality of the circuit. If everything works, assembled the battery, place the controller in the socket, secure with a sealant.

If the charger is not universal, additional alteration will be required. Screwdrivers for 12 V with a universal charger are assembled in the same way, but a protective connection circuit 3×18650 3.7 V for lithium batteries is used. In the same way, a screwdriver is reworked using a set of 18650 batteries in the amount of 2 elements.

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

Tools

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

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

Change Old Dead BOSCH Battery/ NI-MH Ni-Cd To Li ion With Test

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

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

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

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

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

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

This method is shown below in the video.

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

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

Fault definition

We figured out the purpose of the battery structure elements, now we will consider how to determine the malfunction, this is part 2 of the screwdriver battery repair. Immediately, we note that all the elements cannot fail at once, and since our circuit is sequential, when one element fails, the whole circuit does not work. So, our task is to determine where we have the weakest link in the chain.

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

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

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

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

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

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

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

Screwdriver battery: design and types

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

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

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

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

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

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

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

  • The most common type due to its low cost;
  • Low temperatures, such as Li-Ion batteries, are not scary;
  • Stored in a discharged state, while retaining its characteristics.
  • Produced only in third world countries, due to toxicity during production;
  • Memory effect;
  • Self-discharge;
  • Small capacity;
  • A small number of charge / discharge cycles, which means that they do not “live” for a long time with intensive use.
  • Environmentally friendly production, there is an opportunity to purchase a high-quality branded battery;
  • Low memory effect;
  • Low self-discharge;
  • High capacity compared to Ni. Cd;
  • charge / discharge cycles.
  • Price;
  • Loses some of its characteristics during long-term storage in a discharged state;
  • Does not “live” for a long time at low temperatures.
  • No memory effect;
  • Self-discharge is almost absent;
  • High battery capacity;
  • The number of charge / discharge cycles is several times greater than that of previous types of batteries;
  • To set the required voltage, fewer “cans” are required, which significantly reduces the weight and dimensions of the battery.
  • High price, almost 3 times in comparison with nickel. cadmium;
  • After three years, there is a significant loss of capacity, because Li decomposes.
READ  Replacing the Oil Pump On a Partner 350 Chainsaw

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

The housing has four contacts:

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

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

Repair and replacement of screwdriver battery cells

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

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

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

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

Several nuances should be noted:

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

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

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

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

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

What else can you test the state of charge besides the controller?

The screwdriver was converted to lithium batteries. The built-in charger is ideal. But the cost of the controller is quite high. The device will cost 30. which is equivalent to the cost of the battery itself.

To test the charge level of a lithium battery on the go without using a charger, you can use the special RC helicopter lipo battery AKKU portable voltage meter tester alarm 2-6S AOK. The cost of the device is very low. It has a balance and charge connector similar to the iMax6. The device is connected to the battery via an adapter. This voltage level monitor is very convenient. It can measure from two to six lithium cells connected in series, and also give the total indicator or the voltage of each element separately with extreme accuracy.

How many cells will fit in the case?

Assembling 4S2P (four serial connections and two parallel) will not work. Converting a screwdriver to 18650 lithium batteries assumes the presence of eight cells. How can they meet four? Each cell will bear the maximum current load.

Choosing the rated voltage

First of all, you should decide on the choice of the voltage rating indicator for a lithium-based device. The choice should be made between the 3S-model (its voltage range is from 12.6 to 7.5 V) and the 4S-Li-Ion battery (voltage range is from 16.8 to 10 V).

How to choose a controller?

So, the screwdriver is being converted to lithium batteries. A regular charger is required for the device. When choosing a controller, keep in mind that the device must meet two parameters:

  • an indicator of the rated operating voltage;
  • indicator of rated operating current.

With the voltage, everything is very clear: if the battery is 11.1 V, then the controller will be with the same voltage.

Rated operational current refers to the protection capacity of the board. Thus, a 4 A controller is designed for a current mark of 4 A, and with an indicator of 8 A, an additional load falls on it. In this case, the protective device will be triggered. All these technical data are stated in the passport of each controller modification. In this case, one modification can have a limiting current indicator of 30 A, and the other. 50 A. And both of these devices will formally be suitable for operation. Also, when creating a lithium battery, there is a limitation in size. Therefore, you should purchase a controller that fits in the case of an old battery.

How to Determine the Choice of Lithium Cells?

In order to make the selection of lithium-based cells, the limiting factors should be outlined. Currently, lithium devices with a permissible load current of 20-25 A are being produced.

Pulse current values ​​(short, up to 1-2 seconds) reach 30-35 A. Battery configuration will not be violated.

Advantages of the second option

The second option is more suitable, because the voltage in the battery drops quite quickly from the maximum to the minimum (from 16.8 to 14.8 V). For an electric motor, which, in fact, is a screwdriver, an excess of 2.8 V is not a critical mark.

The lowest voltage indicator is for the 3S-Li-Ion modification. It is equal to 7.5 V, which is insufficient for the normal functioning of the electrical device. By installing four configurations, we will increase the electrical capacity of the battery.

How long does it take to replace batteries?

Converting the screwdriver to lithium batteries will take approximately 2 hours. If all parameters are checked, then it will take 4 hours.

Everything can be done on your own, without the help of another person. But contact welding and selection of batteries cannot be carried out without specialized equipment.

Disassembly and assembly

Converting a screwdriver to lithium batteries includes the following steps:

  • Open the old battery by unscrewing five screws.
  • Remove the Ni-Mh battery from the housing. It will be noticeable that the contact pad engaging with the contact group of the screwdriver is welded to the negative contact of one of the Ni-Mh cells. The welding points should be cut using a tool with a DREMEL 4000 cut-off stone built into it.
  • Wires are soldered to the contacts, the cross-section of which is at least 2 mm 2 for the power leads and 0.2 mm 2 for the thermistor. The contact pad is glued to the battery case with hot melt glue.
  • According to the indicator of internal resistance, four cells are selected on the meter. The value must be the same for all four fixtures.
  • Lithium cells are glued with hot melt glue so that they are compactly located in the housing.
  • Welding of cells is carried out on a resistance welding machine by means of a welding tape made of nickel (the indicator of its section should be equal to 2X10 mm).