Screwdriver power supply 18v on 18650 elements. Converting a screwdriver to lithium batteries: instructions

If anyone read my previous writings, they may remember that after they gave oak standard screwdriver batteries, and I urgently needed to continue working, I soldered a fairly powerful 8 A converter with a nominal value and up to 15 A short-term load. From 24 volts to 15 V. Two 7 Ah 12 V batteries were connected in series. I have a 14.4v screwdriver.

Having dragged enough and suffered all the last construction season, I decided that in the new season I need normal batteries.

I rummaged around on the Internet, understood the marketing trick of Bosch in relation to my native batteries. One new battery costs like a new screwdriver with two batteries in the set. Buying this shit for that kind of money did not make sense.

There were no lithium-ion batteries for my screwdriver model. New screwdrivers for Li-ion had inadequate cost. Some orgy of divorce suckers.

Then the idea came to me to convert the screwdriver to lithium. Li-ion banks are 3.7 V, and we need 15-16 V. Connect four batteries in series and get 16.8 V in a fully charged version (4.2 V per bank).

If you have a 12 V screwdriver, you can connect three cans in series.

Banks, that is, separate batteries from which our battery is assembled into one large battery, I decided to take the 18650 type.

These are now fashionable to use in flashlights. They are also found in laptop batteries.

This is a Sony vtc4 type battery. Able to give to the load (max) as much as 30 Amperes. Perfect for our purpose.

Everything would be fine, but lithium is a dangerous thing, you can make a boom if you recharge it.

In addition, our individual batteries are connected in series and over time there will be a large imbalance, i.e. some banks will be recharged, while others, on the contrary, will be strongly undercharged. As a result, such a battery will quickly fail.

Our Chinese friends came to my aid again. There is something called a balancer. It controls the voltage during the charging process on each individual bank and, if it is fully charged, turns it off, while the rest continue to charge, and so on until all individual banks in our series battery chain are fully charged.

This thing is worth a penny from the Chinese in general. But I took from them a little more serious thing.

A little more expensive, but it's worth it. The fact is that these batteries do not have any protection. In general, I also ordered a battery controller. This thing includes the balancer mentioned above, as well as a whole set of protections. In particular, it contains: short circuit protection, overheating protection, overcurrent protection, etc.

Board contacts:

• B+: battery +plus;
• B3: 1st battery - minus and 2nd battery + plus;
• B2-: 2nd battery -minus and 3rd battery +plus;
• B1-: 3rd battery - minus and 4th battery + plus;
• B: 4th battery - minus;
• P+: load/charge V+ (to screwdriver +/or charge +);
• P-: load/charge V- (to screwdriver +/or charge +).

Having collected everything in a single heap, I tried the screwdriver in action and oops, nothing works. What the hell, did the Chinese slip me bullshit, but no, they had nothing to do with it. The thing turned out to be that during the assembly process, I apparently shorted something somewhere, in general, the protection worked, completely disconnecting the battery from the load.

To remove the protection (guess the type yourself, this is not in the seller's instructions), you need to apply voltage from the load side, i.e. you can just put the battery on charge. The protection will be removed instantly.

I put everything in a regular battery case, having previously removed the old nickel-cadmium cans from it. Soldered to the contact pads. So that they do not fall out, I filled this case with hot glue.

The resulting battery normally charges regular charging, although the voltage is not enough (recommended 18V), but hands have not reached it yet. No need to worry about recharging. The controller will turn off the banks itself after they are fully charged.

Homemade Li-ion battery for screwdriver turned out to be 2.1 Ah (2100mAh). Against the regular capacity of 1.2 Ah. At the same time, the new battery weighs three times less.

I ran the product on the dismantling of the formwork of the slabs. Just great, very pleased with the result. Works great, does not sit down for a long time, pulls powerfully.

Then I ran into a small downside. When you forget to set the force on the screwdriver (drilling mode), especially when it sits down, then when heavy loads blocking the engine, the protection is triggered. I don't know if this is good or not. If you also take not a balancer, but a full controller, then take more for the load current, otherwise you will get tired of removing the protection. Or look for a controller with auto-detach.

My controller is for a load current of 8 A.

At first, I took the second old Akum with me, connecting to it removed the protection. Then he made a button that switches the circuit to the operating mode directly without a controller and simultaneously removes protection using the voltage of the battery itself.

• Those. you can either remove the protection by briefly pressing the button back and forth (it is with fixation).

• Or turn on bypass mode and at the same time remove protection.

If you want, you can buy jars for a larger capacity, but be careful in this regard, solid fakes. The seller from whom I took and constantly take, I have already been checked and his declared capacity corresponds to the real one.

Finally here:

Happy assembly 🙂

Has the meaning. The advantage is that they have a high electrical density. As a result, by installing such a device in the body of a screwdriver, we can achieve an increase in the duration of the tool many times over. The charging current for high-power lithium batteries, especially for new modifications, it can reach 1-2 C. You can recharge such a device in 1 hour, without overestimating the parameters recommended by the manufacturer and without spoiling the quality of the product.

What do lithium batteries look like?

Most lithium devices are enclosed in a prismatic case, but some models are cylindrical. Rolled electrodes and separators are used in such batteries. The body is made of aluminum or steel. The positive pole goes to the housing cover.

In prismatic configurations, the electrodes are in the form of rectangular plates. To ensure safety, the battery has a device that acts as a regulator of all processes and opens electrical circuit in critical situations. The increased sealing of the case prevents the electrolyte from leaking out and oxygen and moisture from penetrating inside.

What precautions should be taken to avoid damaging the lithium battery?

• Due to technology limitations, the charge indicator of lithium batteries should not exceed 4.25-4.35 V. The discharge should not reach 2.5-2.7. This condition is indicated in the technical data sheet for each specific model. If these values ​​are exceeded, you can disable the device. Special charging and discharging controllers are used, which keep the voltage on the lithium cell within normal limits. Converting a screwdriver to a lithium battery with a controller will protect the device from malfunction.
• The voltage indicator of lithium batteries is a multiple of 3.7 V (3.6 V). For Ni-Mh models, this figure is 1.2 V. This phenomenon is understandable. in lithium devices is stored in a separate cell. The 12 volt lithium battery will never be assembled. The rating will be 11.1V (three consecutive cells) or 14.8V (four consecutive cells). In addition, the voltage indicator of the lithium cell changes when operating when fully charged by 4.25 V, and when fully discharged, by 2.5 V. The voltage indicator 3S (3 serial - three serial connections) will change when the device is operating from 12.6 V (4.2x3) up to 7.5 V (2.5x3). For a 4S configuration, this figure ranges from 16.8 to 10 V.
• Converting a screwdriver to 18650 lithium batteries (the vast majority of products have this particular size) requires taking into account the difference in dimensions with Ni-Mh cells. The 18650 cell has a diameter of 18 mm and a height of 65 mm. It is very important to calculate how many cells will fit in the case. It should be remembered that for a model with a power of 11.1 V, you will need the number of cells in multiples of three. For a model with a power of 14.8 V - four. The controller and switching wires must also fit.
• The lithium battery charger is different from the Ni-Mh charger.

The article will look at how a screwdriver is converted to lithium. The tool is equipped with a pair of Ni-Mh batteries with a voltage rating of 12 V and a capacity of 2.6 Ah. A remake of a Hitachi screwdriver will be considered. Lithium batteries will provide the device with a long service life.

Choosing the rated voltage

First of all, you should decide on the choice of voltage rating 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 (its voltage range is from 16.8 to 10 V).

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 rating 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 mounting four configurations, we will increase the battery.

How to decide on the choice of lithium cells?

In order to select lithium-based cells, limiting factors must be identified. Currently, lithium devices are produced with a permissible current load value of 20-25 A.

Impulse current values ​​(short, up to 1-2 seconds) reach 30-35 A. The battery configuration will not be disturbed.

How many cells will fit in the case?

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

How to determine the maximum current in a screwdriver?

Converting a 12V screwdriver to lithium batteries involves connecting the device to a laboratory power source with a maximum current of 30 A. The limiter regulator is set to the maximum value. Having created the voltage level of the power source close to the nominal value of the future battery, we begin to smoothly pull the trigger. The current consumed by the screwdriver will rise to 5 A. Now you should sharply pull the trigger. This will short out the power circuit. The current will reach a power of 20-30 A. Perhaps its indicator would be much higher, but the power of the power source will not allow this to be fixed. This will be a short load current when you sharply press the trigger of the screwdriver. Any model of such a device will react similarly.

Next, you should clamp the tip of the screwdriver with a vise and observe to what value the current consumption will increase during the operating mode, when the ratchet works in the screwdriver. The current indicator in this case increases to 10-12 A.

So you can determine the magnitude of the load current. In this case, it will be 5 A at idle and 30 A at a sharp start, and at maximum load it will be 12 A. The manufacturer must select lithium cells, the nominal load current of which will be 10-20 A, and the pulse current - 25-30 A.

How to choose a controller?

So, the screwdriver is being converted to lithium batteries. Regular charging for the device is required. When choosing a controller, please note that the device must meet two parameters:

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

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

The concept of "rated operating current" implies the carrying capacity of the board protection. Thus, a 4 A controller is designed for a current mark of 4 A, and with an indicator of 8 A, an additional load is placed on it. In this case it will work protective device. All these technical data are set out in the passport of each modification of the controller. In this case, one modification may 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 will fit in the case of the old battery.

Disassembly and assembly

Converting a screwdriver to lithium batteries includes the following steps:

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

Installing the protection board

This stage can show how lightweight lithium battery design is. The weight of the Ni-Mh device was 536 g. The weight of the new lithium device is 199 g, which will be quite noticeable. We managed to win 337 g in weight. At the same time, an increase in energy capacity is observed.

The battery is mounted in the case. The voids are filled with soft material from the packaging.

Screwdriver connection

• A sharp pull on the trigger triggers the current protection mechanism. But in fact, such a protective mode is unlikely to be needed when using the tool. If you do not provoke protection on purpose, then the operation of the screwdriver will be stable.
• The tip should be clamped in a vise. The power of the battery freely triggers the ratchet, which limits the increase in the number of turns of torsion.
• the screwdriver is discharged by 5A.
• The battery is inserted into the regular memory. The charge current indicator during measurement is 3 A, which is acceptable for lithium cells. For the LG INR18650HG2 configuration, the maximum charge current will be 4 A, which is indicated in the technical specification.

How long does it take to replace batteries?

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

You can do everything on your own, without the help of another person. But resistance welding and the selection of batteries cannot be carried out without specialized equipment.

How else can you test the degree of charge other than the controller?

The screwdriver has been converted to lithium batteries. The standard charger built into the case 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 a special indicator RC helicopter lipo battery AKKU portable voltage meter tester alarm 2-6S AOK. The cost of the device is very low. It has a balancing and charging connector similar to the iMax6 device. The device is connected to the battery via an adapter. This voltage level control device is very convenient. It can measure from two to six lithium cells connected in series, as well as give the total value or voltage of each cell individually with extreme accuracy.

How much will it cost to replace a Ni-Mh with a lithium device?

What cash costs will require conversion of a screwdriver to a lithium battery?

The price of such a device consists of the cost of several components:

• 4S lithium-based battery configuration costs 2200 rubles;
• buying a controller for charging and discharging plus a balancer costs 1240 rubles;
• the cost of welding and assembly is 800 rubles.

It turns out that a do-it-yourself lithium battery costs 4240 rubles.

For comparison, let's take a similar configuration from factory-made lithium. For example, the Makita 194065-3 device is designed for a screwdriver. It has the same settings. The cost of such a device is 6500 r. It turns out that converting a screwdriver to lithium batteries saves 2300 rubles.

Every craftsman faces the problem of tool performance degradation, or complete failure due to the battery. Manufacturers use nickel-cadmium batteries in 12, 14, 18 volt screwdrivers. The series assembly scheme of several elements creates the desired voltage. Replacing nickel-cadmium batteries with lithium batteries increases battery life by lightening the design. The obligatory installation of a BMS board adds reliability. Therefore, the conversion of a screwdriver to lithium batteries, mainly to the 18650 form factor, is justified.

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 desired voltage. The control system and charge balancing in individual components is not provided.

1. Each Ni-Cd bank gives 1.2V, and li-ion 18650 - 3.6V.
2. The capacity of a lithium battery is 2 times that of a nickel-cadmium battery of similar size.
3. An overheated li-ion battery threatens to explode and ignite, so setting charge uniformity control in banks is mandatory. BMS is not installed in nickel-cadmium batteries - the manufacturer is not interested.
4. Lithium cells do not have a memory effect, unlike Ni-Cd, they can be charged at any time and within an hour.
5. The screwdriver becomes much easier after converting the battery to li-ion using 18650 cans.

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

Knowing what input voltage is required for a screwdriver, alteration charger produced, taking into account the placement of 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 elements.

Let's say you need to remake a 12 V screwdriver using Ni-Cd cans on li-ion. If you use 3 banks, the output voltage is not enough: 3.6 x 3 \u003d 10.8 V. With 4 components, the power of the device will be higher: 3.6 x 4 \u003d 14.4 V. This will make the tool lighter by 182 g , its power will increase slightly, capacity - solid pluses. But when dismantling, it is necessary to leave the terminals and the native temperature sensor.

Converting 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 18650 form factor are more often used. They easily fit into a container or nest, since instead of two or three native ones, they install one lithium one. Alteration of the battery of a screwdriver should be carried out taking into account the features of lithium batteries for 18650.

This type of energy source does not tolerate deep discharge and excessive charge. So, it is necessary to use voltage control boards. Since each battery has its own character, their charge is adjusted by the balancer. The point of reworking a 14.4 V screwdriver is to create a device using lithium batteries to lighten a hand tool and increase its performance. Lithium 18650 batteries are the most suitable for this purpose.

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. To convert the charging of the screwdriver to a lithium battery, you need to stock up on a good soldering iron, non-acid flux and thick wires to make jumpers.

Equipment:

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

The procedure for converting a screwdriver under 18650:

• Dismantle the case and remove a bundle of 12 Ni-Cd elements from the container.
• Remove the garland, leaving the connector with the conclusions "+" and "-". Instead of a temperature sensor, a thermocouple from the controller will be installed.
• Solder the assembly, taking into account that no acid can be used, only neutral flux and pure solder. During the connection period, do not heat the lids. Work precisely.
• Connect balancing points to the controller according to the diagram. Connectors are provided on the board.
• Connect the assembly to the plus and minus terminals.
• Check the functionality of the circuit. If everything works, the assembled battery, place the controller in the socket, secure with sealant.

If the memory 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 circuit for connecting 3x18650 3.7 V to lithium batteries is used. In the same way, a screwdriver is remade using a 18650 battery kit in the amount of 2 elements.

Converting a Makita screwdriver to a lithium battery

There is a “Makita” screwdriver with a battery capacity of 1.3 A / h and a voltage of 9.6 V. To change the power source to a lithium-ion one, you will need 3 18650 components. , will add power as the operating voltage rises to 10.8V.

The design will require the use of a BMS, a master controller that keeps the lithium cells operating within operating limits. With this interrupter, the charging of each can will be uniform without exceeding 4.2 V, the lower voltage is 2.7 V. A built-in balancer is used here.

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

A step-by-step instruction for converting a Makita screwdriver to lithium batteries looks like this.

1. You can disassemble the battery with glue if you tap the junction with a soft-headed hammer while hanging. The direction of impact is down, in the joint along the lower part of the body.
2. Take only the contact plates from the old assembly, carefully disconnecting them from the battery. The sensor and circuit breaker must be left.
3. Solder 3 elements in series using TAGS flux and jumpers with insulation. The cross section of the wire must be greater than 0.75 mm2.
4. Assemble the circuit with the controller, and connect the power supply to the connectors with 1.5 square wires.
5. Check the operation of the circuit and assemble the case by putting 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 supplies. 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 12V, the charger will flash red and green. But the necessary charging is already there. The screwdriver is ready to go.

Converting a Hitachi 12V screwdriver to 18640 lithium batteries

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

You need to get flux, a flat metal connecting tape, hot melt adhesive. It is necessary to install lithium batteries in a screwdriver when reworking through a protective controller. It should serve 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 in one direction, connected with solder to the leads from thick wires and filled with hot melt adhesive.

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

Alteration of the Interskol screwdriver to 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 LH "Interskol" on lithium batteries serve much better. The conversion of a screwdriver to 18 volt lithium batteries has been mastered by craftsmen.

You need 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 18650 lithium batteries, you can leave them with factory thermistors by extending the wires. During installation, create a contact pad, insert the assembly, check the operation, and fix it. The assembly features of the wizard's advice are given in detail in the video. Here's the full info on rebuilding the 18V Lithium Screwdriver

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Cordless tools are more mobile and easier to use than their corded counterparts. But we should not forget about a significant drawback of a cordless tool, this is how you yourself understand the fragility of batteries. Buying new batteries separately is comparable in price to purchasing a new tool. After four years of service, my first screwdriver, or rather, batteries, began to lose capacity. To begin with, I assembled one from two batteries by choosing working "banks", but this modernization did not last long. I converted my screwdriver to a network one - it turned out to be very inconvenient. I had to buy the same, but a new 12 volt Interskol DA-12ER. The batteries in the new screwdriver lasted even less. As a result, two serviceable screwdrivers and not one working battery. On the Internet, they write a lot about how to solve this problem. It is proposed to convert used Ni-Cd batteries to Li-ion 18650 batteries. At first glance, there is nothing complicated about this. You remove the old Ni-Cd batteries from the case and install new Li-ion ones. But it turned out not to be so simple. The following describes what to pay attention to when upgrading a cordless tool.

For conversion you will need:

Let's start with lithium ion batteries 18650. Purchased from AliExpress.
The nominal voltage of the 18650 elements is 3.7 V. According to the seller, the capacity is 2600 mAh, marking ICR18650 26F, dimensions 18 by 65 mm.

The advantages of Li-ion batteries over Ni-Cd are smaller dimensions and weight, with a larger capacity, as well as the absence of the so-called "memory effect". But lithium-ion batteries have serious disadvantages, namely:

1. Negative temperatures drastically reduce capacity, which cannot be said about nickel-cadmium batteries. Hence the conclusion - if the tool is often used at low temperatures, then replacing with Li-ion will not solve the problem.2. A discharge below 2.9 - 2.5V and overcharging above 4.2V can be critical, complete failure is possible. Therefore, you need a BMS board to control charge and discharge, if you do not install it, then new batteries will quickly fail. The Internet mainly describes how to convert a 14 volt screwdriver - it is ideal for upgrading. With a series connection of four 18650 cells and a nominal voltage of 3.7V. we get 14.8V. - just what you need, even when fully charged, plus another 2V, this is not scary for the electric motor. And what about the 12V tool. There are two options, install 3 or 4 18650 elements, if three then it seems to be not enough, especially with partial discharge, and if four - a bit too much. I chose four and in my opinion made the right choice.

And now about the BMS board, it is also from AliExpress.

This is the so-called charge control board, battery discharge, specifically in my case CF-4S30A-A. As can be seen from the marking, it is calculated for a battery of four "cans" of 18650 and a discharge current of up to 30A. It also has a so-called “balancer” built into it, which controls the charge of each element separately and eliminates uneven charging. For the board to work properly, the batteries for assembly are taken in the same capacity and preferably from the same batch. In general, there are a great many BMS boards with different characteristics on sale. I don’t advise you to take a current below 30A - the board will constantly go into protection and in order to restore work, you need to briefly apply charging current to some boards, and for this you need to remove the battery and connect it to the charger. There is no such drawback on the board that we are considering, just release the trigger of the screwdriver and in the absence of short circuit currents, the board will turn on by itself.
To charge the converted battery, the native universal charger was perfect. In recent years, Interskol began to equip its tools with universal chargers. The photo shows to what voltage the BMS board charges my battery together with a standard charger. The voltage on the battery after charging 14.95V is slightly higher than what is needed for a 12 volt screwdriver, but it is rather even better. My old screwdriver became faster and more powerful, and fears that it would burn out after four months of use gradually dissipated. That seems to be all the main nuances, you can start reworking.
We disassemble the old battery.
We solder the old cans and leave the terminals together with the temperature sensor. If you remove the sensor as well, then when using a standard charger, it will not turn on.
According to the diagram in the photo, we solder 18650 cells into one battery. Jumpers between the "banks" must be made with a thick wire of at least 2.5 kv. mm, since the currents during the operation of the screwdriver are large, and with a small section, the power of the tool will drop sharply. The network writes that it is impossible to solder Li-ion batteries because they are afraid of overheating, and they recommend connecting using spot welding. You can only solder a soldering iron with a power of at least 60 watts. The most important thing is to solder quickly so as not to overheat the element itself.
It should look like it fits into the battery case.
From the board to the terminal, the wires must be flexible, as short as possible and with a cross section of at least 2.5 square meters. mm.
We carefully place the entire circuit in the case and fix it with any sealant to prevent damage to parts.
To fix the terminal, I simply placed it in place and wedged it with wooden wedges. It remains only to assemble the body.
The weight of a standard Ni-Cd battery is 558 grams.

The weight of the converted battery is 376 grams, therefore, the tool has become 182 grams lighter. In conclusion, I want to say that this alteration is worth it. The screwdriver has become more powerful and the charge lasts much longer than with the native battery. Change it, you won't regret it!

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Converting a screwdriver battery to Li-Ion

Converting a screwdriver battery to Li-Ion I am going to duplicate this note (source: stumpof.blogspot.ru) on https://mysku.ru, so I need a product that will be reviewed. And this product will be the usual DB9F computer connector. You can buy on Ali, for example, here. But I did not buy this connector, but found it in my historically developed bins. I think that most readers will be able to find it by rummaging through old computer hardware. "Dad" is also needed, it is on old modem and other COM-port laces. Why is this note written? Every time I meet articles on Musk (and other forums) (and especially subsequent discussions) about converting screwdriver batteries to Li-Ion batteries, I think that there are still significantly more screwdrivers in the households of our vast country than radio amateurs with with straight hands and just people who know how to use the soldering iron for its intended purpose.

Well, it's sad to read all these multi-screen discussions (review 1, review 2, review 3, review 4, review 5 ... etc.), in which it is proposed to buy some kind of charging controllers at a price of a little less than 2 thousand rubles (for high currents ). It is enough to look at the dimensions of these boards and the dimensions of the powerful field workers on the boards to intuitively understand that something is wrong here.

In one of the discussions, a person was even going to buy an Imax B6. The idea is good, but not because of the battery for a screwdriver. Naturally, everything can be done much easier and cheaper and without compromising the quality of charging. Next, I skip all the paragraphs about why converting a screwdriver to lithium at all, about the choice of high-current batteries. Actually, the text of what I want to say, I have already stated in the discussion on Musk in next review on this topic. stump August 03, 2016, 22:01 A universal recipe for converting screwdrivers, vacuum cleaners and everything else, and with any voltage from 12 to ... We buy an extension cord with N sockets for 220 V, we buy N network adapters (plugs) for 0.5 ... 1.0A with Usb output, you can buy the very best Chinese ones for 50 rubles (now somewhere around 70 rubles). buy N usb connectors on Ali and in the same place N scarf TP4056 (15 rubles). We get N galvanically isolated "charges" for one Li-ION with an output of 0.5 .... 1.0 A. Next, without any unnecessary equalization boards and extra powerful transistors, we solder a serial Li-ION battery and all its points (extreme and intermediate) are output to the connector DB-9 (enough for 4 or 5 consecutive cans, there is a subtlety here, it is better to avoid joint sections of the charging wires). Soldering the cable: Outputs TP4056 -> DB-9. All!!! Current limit - determined by the type of battery. Each acc. always fully charged up to 4.2V. Cheaper you can't imagine. Charging complete - all LEDs on TP4056 are green (option - blue). You can not buy a network "multiplier", but simply put the TP4056 adapter scarves (N-pairs) into some big old adapter case and put the same DB-9 into the same case.

A screwdriver cannot be recharged in any way, due to the peculiarities of its application (a vacuum cleaner, apparently, is possible). He just stops pulling. Therefore, no indicators and overdischarge protection are required. Even if you turn on the screwdriver with completely discharged batteries - well, the voltage on the battery will drop under load to (below) 2 volts. It's OK. When the load is removed (namely, short-term), the voltage on the bank will be restored to 2.5 ... 3.0 volts. You can't help but feel this moment.

And then, just in the photos, I'll show you how it's done. I have 4 screwdrivers. Two in the country (18V), at home (18V) and at work (12V). If you do with protection boards / charge controllers, then there will be complete financial ruin, especially considering that 18V screwdrivers require boards for 5 series-connected batteries (they are less common and more expensive). Comments, I think, are practically not required here. Option shown for 4 lithium batteries for a 12V screwdriver.

This is my screwdriver. The battery has a DB9F connector.

This is a charger with 4 galvanically isolated channels. At the output, all four channels are “combined” in the DB9M connector.

Four LI-Ion memory boards with Ali on the TP4056 chip. I found 12 rubles (20 pieces). Lost the link.

Naturally, all this can be put into a single box, the output of which will be only a DB9M connector, but it is very convenient to have 4 galvanically isolated separate charging channels. For example, I have converted the power supply of the tester from Krona to two lithium batteries connected in series from disposable electronic cigarettes. I charge with the same charger, two channels. Such a design can be repeated by any, far from electronics, home craftsman. A small note/clarification. We connect the batteries in the screwdriver battery case in series. Four pieces for 12, 14, 16V screwdrivers and 5 pieces for 18V batteries. An 18-volt screwdriver works perfectly well on four Li-Ion batteries, but only on freshly charged batteries. You will have to recharge it much more often. The + and - of the first battery are connected to the DB9.1 and DB9.2 connectors with separate wires that are soldered directly to the battery poles. On DB9.3 it is brought out with a separate wire + a second battery, etc. ... By wiring diagram pin 2 and 3 of DB9 is the same point. However, this is not entirely true in terms of the charge board on the TP4056. Joint sections of conductors should be avoided in the charge circuit, because at different currents from two charge boards at a particular point in time, an error of tens / hundreds of millivolts may appear. It is desirable to install wires in the charging circuit with a larger diameter (well, in the main discharge circuit, of course, too). For a screwdriver with an 18V battery, 10 pins are required with this connection. I have as the 10th contact involved metal case DB9 connector. Another picture. Option for 18 Volt battery, 5 channels.

How to buy small cheap (40 ... 70 rubles) network adapters on Ali so that they actually give out one ampere is a separate issue. I bought adapters in lots of 5 and 10 pieces. I can’t give a link, because the pages on which the adapters shown in the photos were purchased, unfortunately, no longer exist. I remember that the seller on the page had a picture with load resistors and a USB doctor, on which 0.98 A was written. I didn’t deceive, such a current was really present at the output, although it was accompanied by ripples with a swing of one and a half volts. I had to solder tantalum capacitors inside. One capacitance of 220 uF, 6.3 ... 10V at the output of such adapters is enough for the adapter to approach Apple's proprietary charging in terms of characteristics (50 ... 150 mV ripples are obtained). instead of a cat.

Here is such a good USB-doctor can be made from a voltmeter-ammeter (100 V, 10 A) purchased on Aliexpress. It is slightly better than most first-generation "doctors" in terms of voltage drop across the current-measuring shunt. I didn’t measure exactly, but the figure is about 70 millivolts / 1A. This voltage drop is comparable to a "doctor" with an OLED display. The rest (and the "standard" white "doctor" with a lace) have a shunt drop of more than 100 mV. Accurate numbers are actually not as easy to get as you would like, because each extra USB pin in the circuit "eats" about 30 mV / 1.0 A of the flowing current. At high charging currents, the old versions of the "doctors" included in the circuit can by themselves reduce the charging current of a smartphone / tablet, even with short and high-quality USB laces.

Source: stumpof.blogspot.ru

Update as of October 7, 2017

When I wrote this note a year ago and duplicated it on the mysku.ru website, I was “scolded” there for the “collective farm” implementation of my version of the charger. I didn't take the criticism too seriously, because I still don't see much point in making a lot of unnecessary gestures to make an assistive device that is used quite infrequently. On the other hand, this year I bought a few more memory cards on the TP4056 and found in my “bins” a suitable case from a network adapter. Well, I made an option, such as it was planned from the very beginning. Maybe someone will like it more. It is clearer that this is the easiest option for converting a screwdriver to lithium, and in size such a charge is smaller than the standard one. Everything is shown in the pictures, and a bit of explanation.

Used the cheapest network white USB adapters with Ali, or rather their insides. The USB connector is soldered, and electrolyte 1500uF * 6.3V Low ESR is added to the output of each charge (can be found on old motherboards, if the boards are newer, then you can also find tantalum electrolytes 100 ... 200 uF there, this option is even better). Improvement is needed so that you can use the very best Chinese network adapters, regardless of the initial value of their ripples. The fact that these adapters do not always draw a load current of 1A does not affect the performance of the design. Even if the output is only 0.5A, it will work. And the resistor on the TP4056 charger board 1.2 kOhm (charging current 1A) does not need to be replaced by 2.4 kOhm (charging current 0.5A). It will take a little longer to charge and nothing more. The memory case is some kind of typical transformer network adapter bought a very, very long time ago in the Chip @ Dip store.

Increased attention is paid to isolation of channels among themselves. It's about the pictures below. You can’t just get by with a glue gun and stuff a bundle of wires and boards into the case, because the mains voltage is on and it all heats up decently. And we don’t need a short circuit, given that it’s somehow not customary to monitor the charging process.

A small clarification about the fact that the main article dealt with five Li-Ion batteries for screwdrivers with 18 V power supply, and in addition a 4-channel option is presented. The experience of operating converted batteries has shown that lithium batteries are still more powerful than the original nickel-cadmium ones. Yes, and there are 5 of them in series (30 amperes), and not 15 pieces. Everything that used to “fall” and “dissipate” at the source now heats the electric motor. As a result, even without a special load, but with a long turn on (example: I drilled a “slippery” stainless steel with a thickness of 5 millimeters with a 4 ... 5 mm drill), the motor begins to smell of burnt insulation. Therefore, in order to avoid, I removed all the “fifth” batteries from three 18-volt screwdrivers. Result:

It is not very visible, but two red LEDs and two blue ones are lit here (they are white because the plexiglass is yellow). That's how all the red ones go out, so you can start working with Shurik. "Equalization" occurs "automatically" at 4.2 volts.

I forgot to write, but this is important. If anyone is interested, please note that the adapter case from Chip @ Dip initially has ventilation slots, and I myself drilled additional holes from the bottom and sides. IN closed case this whole structure can "give up" due to overheating.

mysku.ru

3S-4S BMS boards or one of the options for converting a screwdriver to lithium

Greetings to all who looked at the light. The review will focus, as you probably already guessed, on two simple scarves designed to control the assembly of Li-Ion batteries, called BMS. The review will include testing, as well as several options for converting a screwdriver to lithium based on these boards or similar ones. Who cares, you are welcome under the cat. Update 1, Added a test of the operating current of the boards and a short video on the red board Update 2, Since the topic aroused little interest, so I will try to supplement the review with several more ways to remake the Shurik to get some simple FAQ General form:
Brief performance characteristics of the boards:
Note: I want to warn you right away - there is only a blue board with a balancer, a red one without a balancer, i.e. This is purely an overcharge/overdischarge/short/high load current protection board. And also, contrary to some beliefs, none of them has a charge controller (CC / CV), so they need a special scarf with a fixed voltage and current limit to work.

Board dimensions:

The dimensions of the boards are quite small, only 56mm * 21mm for the blue one and 50mm * 22mm for the red one:

Here is a comparison with AA and 18650 batteries:

Appearance:

Let's start with the blue protection board:

On closer inspection, you can see the protection controller - S8254AA and balancing components for the 3S assembly:

Unfortunately, according to the seller, the operating current is only 8A, but judging by the datasheets, one AO4407A mosfet is rated for 12A (peak 60A), and we have two of them:

I also note that the balancing current is quite small (about 40mA) and balancing is activated as soon as all cells / banks switch to CV mode (second charge phase). Connection:

The red board is simpler, because it does not have a balancer:
It is also based on the protection controller - S8254AA, but is designed for a higher operating current of 15A (again, according to the manufacturer):

According to the datasheets for the power mosfets used, the operating current is declared 70A, and the peak current is 200A, even one mosfet is enough, and we have two of them:

Connection is similar:

In total, as we can see, on both boards there is a protection controller with the necessary decoupling, power mosfets and shunts to control the passing current, but the blue one also has a built-in balancer. I haven't looked into the circuit too much, but it looks like the power mosfets are in parallel, so the operating currents can be multiplied by two. Important note - maximum operating currents are limited by current shunts! These scarves do not know about the charge algorithm (CC / CV). In confirmation that these are protection boards, one can judge by the datasheet for the S8254AA controller, in which there is not a word about the charging module:

The controller itself is designed for a 4S connection, so with some refinement (judging by the datasheet) - soldering the conder and the resistor, the red scarf may work:

It is not so easy to modify the blue scarf to 4S, you will have to solder the elements of the balancer.

Board testing:

So, let's move on to the most important thing, namely, how suitable they are for real use. For testing, the following devices will help us:

A prefabricated module (three three/four register voltmeters and a holder for three 18650 batteries), which flashed in my review of the iCharger 208B charger, however, already without a balancing tail:

- two-register ampervoltmeter for current control (lower instrument readings):

Current Limiting DC/DC Buck Converter with Lithium Charge Capability:

iCharger 208B charging and balancing device for discharging the entire assembly. The stand is simple - the converter board supplies a fixed constant pressure 12.6V and limits the charging current. Using voltmeters, we look at what voltage the boards work and how the banks are balanced. To begin with, let's look at the main feature of the blue board, namely balancing. In the photo there are 3 cans charged at 4.15V / 4.18V / 4.08V. As you can see, imbalance. We apply voltage, the charging current gradually drops (lower device):

Since the handkerchief does not have any indicators, the end of balancing can only be assessed by eye. The ammeter for more than an hour before the end was already showing zeros. For those who are interested, here is a short video about how the balancer works in this board:

As a result, the banks are balanced at the level of 4.210V/4.212V/4.206V, which is quite good:

When a voltage of a little more than 12.6V is applied, as I understand it, the balancer is inactive and as soon as the voltage on one of the cans reaches 4.25V, the S8254AA protection controller turns off the charge:

The situation is the same with the red board, the S8254AA protection controller also cuts off the charge at the level of 4.25V: Now let's go through the cutoff at load. I will discharge, as I mentioned above, with the iCharger 208B charging and balancing device in 3S mode with a current of 0.5A (for more accurate measurements). Since I don’t really want to wait for the discharge of the entire battery, so I took one discharged battery (pictured is a green Samson INR18650-25R). The blue board disconnects the load as soon as the voltage on one of the cans reaches 2.7V. In the photo (no load->before shutdown->end): As you can see, the board disconnects the load exactly at 2.7V (the seller stated 2.8V). It seems to me that it is a bit high, especially considering the fact that in the same screwdrivers the loads are huge, therefore, the voltage drop is also large. Nevertheless, it is desirable in such devices to have a cut-off under 2.4-2.5V. The red board, on the contrary, turns off the load as soon as the voltage on one of the cans reaches 2.5V. In the photo (no load->before shutdown->end): Everything is fine here, but there is no balancer.

Update 1: Load test:

The following stand will help us with the output current: - the same holder / holder for three 18650 batteries - 4-register voltmeter (total voltage control) - car incandescent lamps as a load (unfortunately, I have only 4 incandescent lamps of 65W, I don't have any more) - HoldPeak HP-890CN multimeter for measuring currents (max 20A) - high-quality copper stranded acoustic wires of large cross section as if one after another, to reduce the length of the connecting wires, and therefore the voltage drop across them under load will be minimal:

Connection of cans on the holder ("valtom"):

High-quality wires with crocodiles from the iCharger 208B charging and balancing device acted as probes for the multimeter, because HoldPeak's ones do not inspire confidence, and extra connections will introduce additional distortion. First, let's test the red protection board, as the most interesting in terms of current load. Solder the power and side wires:

It turns out something like this (load connections turned out to be of a minimum length):

I already mentioned in the section on Shurik's alteration that such holders are not very suitable for such currents, but they will do for tests. So, a stand based on a red scarf (according to measurements, no more than 15A):

Briefly I will explain: the board holds 15A, but I do not have a suitable load to fit into this current, since the fourth lamp adds about 4.5-5A more, and this is already outside the handkerchief. At 12.6A, the power mosfets are warm, but not hot, just right for continuous operation. At currents over 15A, the board goes into protection. I measured with resistors, they added a couple of amps, but the stand has already been dismantled. A huge plus of the red board is that there is no protection blocking. Those. when the protection is triggered, it does not need to be activated by applying voltage to the output contacts. Here is a short video:

I'll explain a little. Since cold incandescent lamps have low resistance, and besides, they are also connected in parallel, the scarf thinks that a short circuit has occurred and the protection is triggered. But due to the fact that the board has no blocking, you can warm up the coils a little, making a “softer” start. The blue scarf holds more current, but at currents of more than 10A, the power mosfets get very hot. At 15A, the handkerchief can withstand no more than a minute, because after 10-15 seconds the finger no longer holds the temperature. Fortunately, they cool down quickly, so for a short-term load they are quite suitable. Everything would be fine, but when the protection is triggered, the board is blocked and to unlock it is necessary to apply voltage to the output contacts. This option is clearly not for a screwdriver. In total, it holds a current of 16A, but the mosfets get very hot:

Conclusion: my personal opinion is that it is excellent for a power tool the usual one will do protection board without balancer (red). It has high operating currents, an optimal cutoff voltage of 2.5V, and can be easily upgraded to a 4S configuration (14.4V / 16.8V). I think this is the best choice for converting a budget shura to lithium. Now for the blue scarf. Of the pluses - the presence of balancing, but the operating currents are still small, 12A (24A) is somewhat not enough for a Shurik with a torque of 15-25Nm, especially when the cartridge almost stops when the screw is tightened. And the cut-off voltage is only 2.7V, which means that under heavy load, part of the battery capacity will remain unclaimed, since at high currents the voltage drop on the banks is decent, and they are also designed for 2.5V. And the biggest disadvantage is that the board is blocked when the protection is triggered, so it is undesirable to use it in a screwdriver. It is better to use a blue scarf in some homemade products, but again, this is my personal opinion.

Possible application schemes or how to convert Shurik's power to lithium:

So, how can you change the power of your favorite Shurik from NiCd to Li-Ion / Li-Pol? This topic is already quite hackneyed and solutions, in principle, have been found, but I will briefly repeat myself. To begin with, I’ll just say one thing - in budget shuriks there is only an overcharge / overdischarge / short circuit / high load current protection board (similar to the monitored red board). There is no balance there. Moreover, even in some branded power tools there is no balancing. The same applies to all tools where there are proud inscriptions “Charging in 30 minutes”. Yes, they charge in half an hour, but the shutdown occurs as soon as the voltage on one of the cans reaches the nominal value or the protection board trips. It is not difficult to guess that the banks will not be fully charged, but the difference is only 5-10%, so it is not so important. The main thing to remember is that the charge with balancing takes at least several hours. So the question is, do you need it?

So, the most common option looks like this:

Mains charger with a stabilized 12.6V output and current limit (1-2A) -> protection board -> 3 batteries connected in series As a result: cheap, fast, acceptable, reliable. Balancing walks depending on the state of the cans (capacity and internal resistance). Quite a working option, but after a while the imbalance will make itself felt by the time of work.

More correct option:

Network charger with stabilized output 12.6V, current limiting (1-2A) -> protection board with balancing -> 3 batteries connected in series As a result: expensive, fast/slow, high quality, reliable. Balancing is normal, battery capacity is maximum Total, we will try to make it like the second option, here's how to do it: 1) Li-Ion / Li-Pol batteries, protection boards and a specialized charging and balancing device (iCharger, iMax). Additionally, you will have to remove the balancing connector. There are only two minuses - model chargers are not cheap, and it’s not very convenient to maintain. Pros – high charge current, high cell balancing current 2) Li-Ion/Li-Pol batteries, protection board with balancing, current-limiting DC converter, PSU 3) Li-Ion/Li-Pol batteries, protection board without balancing (red) , DC converter with current limitation, PSU. Of the minuses, only that over time, an imbalance of cans will appear. To minimize imbalance, before altering the Shurik, it is necessary to adjust the voltage to the same level and it is advisable to take cans from the same batch. The first option will only work for those who have a model memory, but it seems to me that if they needed it, they have already redone their Shurik a long time ago. The second and third options are almost the same and have the right to life. You just need to choose what is more important - speed or capacity. I think the most best option- the last, but only once every few months you need to balance the banks.

So, enough chatter, let's move on to the alteration. Since I do not have a Shurik on NiCd batteries, therefore, about the alteration only in words. We will need:

1) Power supply:

First option. Power supply unit (PSU), at least 14V or more. The recoil current is desirable at least 1A (ideally about 2-3A). We can use a power supply from laptops / netbooks, from chargers (output more than 14V), power supplies LED strips, video recording equipment (DIY PSU), for example this one or this one:

- DC/DC buck converter with current limiting and lithium charging capability, like this one or this one:
- The second option. Ready-made power supplies for shurikov with current limiting and 12.6V output. They are not cheap, as an example from my review of the MNT screwdriver -tyts:
- The third option. Ready PSU with stabilization:
2) Protection board with or without a balancer. It is advisable to take the current with a margin:

If the option without a balancer is used, then it is necessary to solder the balancing connector. This is necessary to control the voltage on the banks, i.e. to assess imbalance. And as you understand, it will be necessary to periodically recharge the battery by the cell with a simple TP4056 charging module if an imbalance has begun. Those. once every few months, we take a TP4056 scarf and charge all the banks in turn, which, at the end of the charge, have a voltage below 4.18V. This module correctly cuts off the charge at a fixed voltage of 4.2V. This procedure will take an hour and a half, but the banks will be more or less balanced. It is written a little chaotically, but for those who are in the tank: After a couple of months, we put the battery of the screwdriver on charge. At the end of the charge, we take out the balancing tail and measure the voltage on the banks. If it turns out something like this - 4.20V / 4.18V / 4.19V, then balancing is, in principle, not needed. But if the picture is as follows - 4.20V / 4.06V / 4.14V, then we take the TP4056 module and recharge two banks in turn to 4.2V. I don’t see any other option, except for specialized balancer chargers. 3) High current batteries:

I have previously written a couple of small reviews about some of them - tyts and tyts. Here are the main models of high current 18650 Li-Ion batteries: - Sanyo UR18650W2 1500mah (20A max.) - Sanyo UR18650RX 2000mah (20A max.) - Sanyo UR18650NSX 2500mah (20A max.) - Samsung INR18650-15L 1500mah (18 A max.) - Samsung INR18650-20R 2000mah (22A max) - Samsung INR18650-25R 2500mah (20A max) - Samsung INR18650-30Q 3000mah (15A max) - LG INR18650HB6 1500mah (30A max) - LG INR18650HD2 2 000mah (25A max.) - LG INR18650HD2C 2100mah (20A max) - LG INR18650HE2 2500mah (20A max) - LG INR18650HE4 2500mah (20A max) - LG INR18650HG2 3000mah (20A max) - SONY US18650VTC3 1600 mah (30A max.) - SONY US18650VTC4 2100mah (30A max.) - SONY US18650VTC5 2600mah (30A max.) I recommend the time-tested cheap Samsung INR18650-25R 2500mah (20A max.), Samsung INR18650-30Q 3000mah (15A max.) or LG INR18650HG2 3000mah (20A max.). I didn’t particularly come across other jars, but my personal choice is Samsung INR18650-30Q 3000mah. Skis had a small technological defect and fakes with low current output began to appear. I can throw off an article on how to distinguish a fake from the original, but a little later, you need to look for it.

How to connect all this economy:

Well, a few words about the connection. We use high-quality copper stranded wires of a decent section. These are high-quality acoustic or conventional ShVVP / PVA with a section of 0.5 or 0.75 mm2 from a household store (we rip open the insulation and get high-quality wires different color). The length of the connecting conductors must be kept to a minimum. Batteries, preferably from the same batch. Before connecting them, it is advisable to charge them to one voltage so that there is no imbalance for as long as possible. Soldering batteries is not difficult. The main thing is to have a powerful soldering iron (60-80W) and an active flux (soldering acid, for example). Soldered with a bang. The main thing then is to wipe the place of soldering with alcohol or acetone. The batteries themselves are placed in the battery compartment from old NiCd cans. It is better to have a triangle, minus to plus, or, as the people say, “valt”, by analogy with this (one battery will be located the other way around), or a little higher a good explanation (in the testing section):

So, the wires connecting the batteries will turn out to be short, therefore, the drop in the precious voltage in them under load will be minimal. I do not recommend using holders for 3-4 batteries, they are not intended for such currents. Side and balance conductors are not so important and can be of a smaller cross section. Ideally, it is better to stuff the batteries and the protection board into the battery compartment, and the DC-down converter separately into the docking station. Charge / charged LED indicators can be replaced with your own and displayed on the docking station case. If desired, you can add a minivoltmeter to the battery module, but this is extra money, because the total voltage on the battery will only indirectly tell about the residual capacity. But if there is a desire, why not. Here is the one:
Now let's estimate the prices: 1) PSU - from 5 to 7 dollars 2) DC / DC converter - from 2 to 4 dollars 3) Protection boards - from 5 to 6 dollars 4) Batteries - from 9 to 12 dollars (3-4$ little thing) Total, an average of $15-20 per alteration (with discounts / coupons), or $25 without them.

Update 2, a few more ways to remake Shurik:

Next option(suggested by comments, thanks to I_R_O and cartmannn):

Use inexpensive 2S-3S chargers like SkyRC e3 (this is the manufacturer of the same iMax B6) or all kinds of copies of B3 / B3 AC / imax RC B3 (tyts) or (tyts) The original SkyRC e3 has a charging current for each bank of 1.2A against 0 ,8A for copies must be accurate and reliable, but twice as expensive as copies. Quite inexpensively you can buy on the same Banggood. As I understood from the description, it has 3 independent charging modules, something akin to 3 TP4056 modules. Those. SkyRC e3 and its copies do not have balancing as such, but simply charge banks to one voltage value (4.2V) at the same time, since they do not have power connectors. In the SkyRC assortment there are really charging and balancing devices, for example, SkyRC e4, but the balancing current is only 200mA and already costs around $ 15-20, but it can charge life-cycles (LiFeP04) and charge currents up to 3A. Those who are interested can take a look at model range SkyRC. In total, for this option, you need any of the above 2S-3S chargers, a red or similar (without balancing) protection board and high-current batteries:

As for me, a very good and economical option, I would probably stop at it.

Another option suggested by comrade Volosaty:

Use the so-called "Czech balancer":

Where it is for sale is better to ask him, I heard about him for the first time :-). I won’t tell you anything about the currents, but judging by the description, it needs a power source, so the option is not so budgetary, but it seems to be interesting in terms of charging current. Here is a link to the article. In total, this option requires: a power source, a red or similar (without balancing) protection board, a “Czech balancer” and high-current batteries.

Advantages:

I have previously mentioned the advantages of lithium power supplies (Li-Ion / Li-Pol) over nickel (NiCd). In our case, a face-to-face comparison is a typical NiCd versus lithium battery: + high energy density. A typical 12S 14.4V 1300mah nickel battery has a stored energy of 14.4*1.3=18.72Wh, while lithium battery 4S 18650 14.4V 3000mah - 14.4*3=43.2Wh + no memory effect, i.e. you can charge them at any time without waiting for a full discharge + smaller dimensions and weight with the same parameters with NiCd + fast time charge (they are not afraid of high charge currents) and a clear indication + low self-discharge Of the minuses of Li-Ion, one can only note: - low frost resistance of batteries (they are afraid of negative temperatures) - balancing of cans during charging and overdischarge protection are required As you can see, the advantages of lithium are obvious, therefore, it often makes sense to alter the power supply ...

Conclusion: the reviewed scarves are not bad, they should be suitable for any task. If I had a Shurik on NiCd cans, I would choose a red scarf for rework, :-) ...

The product was provided for writing a review by the store. The review is published in accordance with clause 18 of the Site Rules.

The advantages of cordless power tools are obvious, it makes no sense to discuss this issue. Negative factors include some inconvenience associated with the need to charge the batteries, as well as high cost batteries (we are talking about high-quality power assemblies).

If you have to put up with charging, then the second problem is solved by manufacturers not in the best way for the consumer. Most screwdrivers in the affordable price range are equipped with nickel-cadmium (Ni-Ca) batteries, the performance of which leaves much to be desired.

In the battery case there are 10-12 interconnected finger-type Ni-Ca batteries (typical voltage - 14 volts). Such elements have a limited service life, and a rather low capacity, which is gradually lost during operation. As a result, after 2-3 years, the charge retention time can be reduced by 3-5 times. You have to regularly change damaged "kegs", or even buy new block battery.

The best option in terms of price and quality is lithium batteries of the 18650 series. Structurally, they look like ordinary finger batteries, the size is 25% larger than the AA format.

Parameters of a typical Li-ion battery:

• voltage 3.6-3.7V
• capacity from 800 to 4500 mAh
• recoil current - about 35A

The optimal capacity is 2500 mAh, too high values ​​do not correspond to reality, and entail an unjustified increase in cost. A 2500 mAh battery from a more or less decent manufacturer (for example, LG) can be bought for 300-600 rubles.

How to calculate the parameters of a new battery

1. The current consumption of a screwdriver usually does not exceed 10-15 amperes. Accordingly, the typical recoil (discharge) current of a Li-ion battery (30-35A) is enough with a margin.
2. The supply voltage is calculated from an old Ni-Ca battery. Typically, a block consists of 12 batteries of 1.2 volts, that is, a total of 14.4 V. Lithium batteries must not be discharged to a voltage below 2.74 volts. The operating voltage is 3.0-3.5 V, that is, for replacement, it is necessary to connect 4 18650 batteries in series.

The resulting operating voltage of 12V to 14V is more than enough. Even relatively fresh regular Ni-Ca batteries rarely give out more than 12 volts.

If volume allows, you can connect 2 consecutive assemblies of 4 batteries in parallel, doubling the battery capacity. At the same time, the relative position can be anything - according to the shape of the body. The main thing is to ensure a reliable connection of wires.

1. In addition, it is desirable to place a charger in a common case. Then you do not have to remove the batteries from the case every time.

Charger - manufacturing options

Optimal design - "all in one". That is, both batteries and a charger with a 220 volt input are placed in the battery case. You simply connect the network cable and charge.

There is another option - the charger is placed in a separate case to save space (this allows you to put more batteries in the battery case).

Most chargers (we are talking about factory boards that can be purchased at radio stores, or on the same Aliexpress) are designed for a certain number of Li-ion batteries in the assembly. You just choose the right option.

You can assemble such a circuit yourself if you have the skills of a radio amateur. In this case, the cost of alteration will decrease.

In any case, a charge (discharge) control device must be installed. It can be indicator LEDs, or a digital display.

Built-in lithium battery monitoring

Cells of this type are sensitive to overdischarge. If the battery voltage drops below 2.75 V, degradation begins and the module loses capacity. Therefore, it is necessary to monitor the parameters during operation.

Some 18650 cells are equipped with built-in discharge control boards, and simply turn off the battery when a critical voltage is reached. When buying items, you need to clarify this point. If your batteries do not have protection, it can be installed additionally. Such ready-made boards also available for sale.

The circuit is installed in a common battery case, and does not interfere with charging the batteries at all.

Option with a ready-made kit for vapers

18650 batteries are popular with the so-called. vapers - lovers of electronic cigarettes. Ready-made kits are available for sale, consisting of a charger and Li-ion batteries. To use such a set in a screwdriver, you will have to install a container with contacts in the battery case, and each time remove the modules for charging.

If the dimensions of the screwdriver body allow, and there is no desire to mess around with diagrams, this is an option for you. Of course, the costs will rise slightly.

Conclusion - the advantages and disadvantages of converting a screwdriver battery to lithium cells

Any modification must be economically justified. If we spend money and time, we need to understand what benefits will come from it.

Advantages of Li-ion batteries

• The energy intensity of lithium batteries is much higher. Therefore, with the same dimensions and weight, the duration of battery use between recharges will be higher.
• The charging process is faster. This means that downtime during recharging is reduced.
• Unlike nickel batteries, lithium batteries do not have the so-called memory effect. They can be charged without waiting for full discharge.

Disadvantages of replacing batteries from Ni-Ca to Li-ion:

• First of all, the cost part. The total cost of rework can reach 2-3 thousand rubles.
• Dependence on external temperature: lithium batteries lose their performance at low temperatures. Therefore, in winter, on the street, it is impossible to use such tools.
• The non-standard voltage of Li-ion batteries (3.6-3.7 V) leads to inaccuracies in the selection of the final value.
• 18650 batteries differ in size from standard Ni-Ca “cans”. To place them in the standard case of a screwdriver, it is necessary to solve a number of design problems.

The standard screwdriver device is not suitable for charging lithium batteries. We have to make a new scheme.