Alteration of the charger of the electric screwdriver for lithium batteries

Conversion of screwdrivers to lithium still does not lose its relevance, since it does not require significant investment and is easily carried out even by an unprepared person. At the same time, you get your favorite and time-tested tool with a much longer operating time without the disadvantages that are inherent in Ni-Cd batteries.

alteration, charger, electric, screwdriver, lithium

High current 18650 batteries

The second main element when reworking an electric screwdriver. Good batteries with a current output of at least 15A are required. LG HE4 2500mah, Samsung 25R 2500mah, Samsung 30Q 3000mah and LG HG4 3000mah (“chocolates”) are ideal in terms of price / quality ratio. You can use medium-current banks of 10A, but only in the 2P scheme (two in parallel).

Nickel tape

Designed to connect batteries to a battery. It can be used for both resistance welding and soldering. It has a low resistance and does not heat up at serious currents, moreover, it has a flat profile, which does not add much in size and allows the assembly to fit in compact cases.

High-current accumulators 21700

The most promising battery format, gaining popularity at a frantic pace. It has a higher energy consumption, but at the same time it is slightly larger in size. The only drawback is that they may not fit in the case, so check this point before buying. When using them, you will get a very impressive autonomy.

Quality wires

High-quality copper stranded wires in heat-resistant silicone insulation. Alternative to nickel tape. They are easy to tin, bend well, the insulation melts only at high temperatures. A good option for a budget rework. In critical projects I use the same.


Designed for correct and full charging of the lithium battery. It is necessary to select for the required assembly voltage. The chargers are equipped with indicators for the charging process. A charge current of 1-2 amperes is enough for any assembly. The lithium battery cannot be charged with a native charger.

BMS boards

One of the main elements when converting a battery to lithium power. The BMS board is required to protect the batteries against over-discharge, over-discharge, over-current and short-circuit (short-circuit). For 12-volt screwdrivers we purchase 3S BMS, for 14-volt. 4S BMS. For a more complete use of the batteries, the 4S BMS is perfect.

What board is needed and what elements are needed to convert a screwdriver to lithium-ion

So, here is my 9.6 V 1.3 Ah battery. At the maximum charge level, it has a voltage of 10.8 volts. Lithium-ion cells have a nominal voltage of 3.6 volts, with a maximum voltage of 4.2. Therefore, to replace the old nickel-cadmium cells with lithium-ion cells, I need 3 cells, their operating voltage will be 10.8 volts, the maximum is 12.6 volts. Exceeding the rated voltage will not damage the motor in any way, it will not burn out, and with a larger difference, there is no need to worry.

Lithium-ion cells, as everyone has known for a long time, categorically do not like overcharging (voltage above 4.2 V) and excessive discharge (below 2.5 V). When the operating range is exceeded, the element degrades very quickly. Therefore, lithium-ion cells always work in tandem with an electronic board (BMS. Battery Management System), which controls the cell and monitors both the upper and lower voltage limits. This is a protection board that simply disconnects the can from the electrical circuit when the voltage goes out of the operating range. Therefore, in addition to the elements themselves, such a BMS board is required.

Battery conversion of Black & Decker Cordless Screwdriver

Now there are two important points that I experimented with unsuccessfully several times until I came to the right choice. This is the maximum permissible operating current of the Li-Ion cells themselves and the maximum operating current of the BMS board.

In a screwdriver, operating currents at high load reach 10-20 A. Therefore, you need to buy elements that are capable of delivering high currents. Personally, I have successfully used Sony VTC4 30-amp 18650 cells (2100 mAh capacity) and 20-amp Sanyo UR18650NSX (2600 mAh capacity). They work fine in my electric screwdrivers. But, for example, Chinese TrustFire 2500 mAh and Japanese light green Panasonic NCR18650B 3400 mAh are not suitable, they are not designed for such currents. Therefore, there is no need to chase the capacity of the elements. even 2100 mAh is more than enough; the main thing when choosing is not to miscalculate with the maximum permissible discharge current.

Likewise, the BMS board must be rated for high operating currents. I saw on YouTube how people collect batteries on 5 or 10-ampere boards. I don’t know, personally, when I turned on the screwdriver, such boards immediately went into defense. In my opinion, this is a waste of money. I will say that the Makita company itself puts 30-ampere boards in its batteries. Therefore, I use 25 Amp BMS bought from Aliexpress. They cost about 6-7 and are searched for “BMS 25A”. Since you need a board for an assembly of 3 elements, you need to look for such a board, in the name of which there will be “3S”.

Another important point: some boards have different contacts for charging (designation “C”) and load (designation “P”). For example, the board can have three pins: “P-“, “P” and “C-“, as on the native Makitov lithium-ion board. Such a fee will not work for us. Charging and discharging (charge / discharge) must be done through one contact! That is, there should be 2 working contacts on the board: just “plus” and just “minus”. Because our old charger also only has two pins.

In general, as you might have guessed, with my experiments I threw out a lot of money both on the wrong elements and on the wrong boards, having made all the mistakes that could be made. But I got invaluable experience.

Conversion of an electric screwdriver 18v ​​to lithium

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 desired voltage. Replacing nickel-cadmium batteries with lithium batteries extends battery life by making the design lighter. Mandatory BMS board installation adds reliability. Therefore, the conversion of an electric screwdriver to lithium batteries, mainly to the 18650 form factor, is justified.

Conversion of an electric 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 battery of an electric screwdriver should be carried out taking into account the characteristics of lithium batteries for 18650.

READ  What Is An Impact Screwdriver For?

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 an electric screwdriver with a voltage of 14.4 V lies in the creation of 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 electric screwdriver is high, you must select the appropriate BMS for the required number of cans and at least 30 A. jumpers.

  • 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 an electric 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.

Conversion of the “Hitachi” 12 V electric screwdriver to 18640 lithium batteries

Features of alteration of the 12 V Hitachi electric 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 an electric screwdriver during rework 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-on 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.

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.

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 separated. In this case, the case is not damaged in any way, I have already disassembled 4 pieces this way.

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 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.

Conversion of the Makita electric screwdriver to a lithium battery

There is a “Makita” electric 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. charge, will add power as the operating voltage rises to 10.8 V.

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 4.2 V, the lower voltage is 2.7 V. 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 electric 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 downwards, butt-joint along the lower part of the body.
  • Take only the contact plates from the old assembly, carefully disconnecting them from the battery. Leave the sensor and breaker.
  • 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 an electric screwdriver with an old DC9710 charger, once the 18650 lithium battery has finished charging, 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. electric screwdriver ready to work.

READ  What is an indicator screwdriver for?

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. Control system and charge balancing in individual components is not provided.

  • Each Ni-Cd bank provides 1.2V and Li-ion 18650 3.6V.
  • The capacity of a lithium battery is 2 times that of a nickel-cadmium battery, similar in size.
  • An overheated li-ion battery threatens an explosion and fire, therefore, the installation of control of 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.
  • an electric screwdriver becomes much easier after converting the battery to li-ion, using 18650 cells.

There are only two obstacles to converting an electric 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 an electric 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 convert a 12 V electric screwdriver using Ni-Cd cans to 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 slightly increase, capacity. solid pluses. But when dismantling, it is necessary to leave the terminals and the native thermal sensor.

Communities Electronic Crafts Blog Budget Battery Charger for Electric Screwdriver Li-ion Battery

How to charge a battery of an electric screwdriver converted to Li-Ion. Not all “charges” are suitable for this. For the correct charging algorithm of Li-Ion batteries and to increase their service life, the standard charger of the electric screwdriver needs to be modified.

Now we will solve the issue with charging. Charging board with voltage stabilization and current limitation.

Just like using the inexpensive #CCCV board on the XL4015E1 or LM2596, you can turn any power supply into a Li-Ion battery charger for your electric screwdriver. An alteration of the adapter from 12volt to 16.8volt is considered. in this way you can get an inexpensive budgetary power supply adjustable from 5 to 24 volts from the adapter. It is necessary to solder the variable resistor to the adjustable Zener diode TL431 according to the diagram.

Next, we connect the voltage stabilization and current limiting board. Using the example of an adapter or standard charging of an electric screwdriver, you can make a charger for a Li-Ion battery of an electric screwdriver.

Tags: charging lithium, batteries for an electric screwdriver, converting a screwdriver to lithium, electronic crafts

Комментарии и мнения владельцев 31

Balancing board for the required number of cans and charging from a laptop and that’s it.

There is the same garbage, only in a homemade laboratory block. Only the current and voltage adjustments in the picture are rearranged

what is described below can also be implemented on light pulse power supplies, if the portability of the charger is important:

but even more, in my experience, the most competent was the charging according to the ideology “we charge each can separately”.

6.3v, each winding was added: its own rectifier, its own 4.2v stabilizer with current limiting

How to make Crappy Ni-Cad cordless tools useful again by converting them to Li-ion Power!!

It works like this: I connect the charger to the battery with a cord. Each of the 3 charger stabilizers charges its own bank in the battery (more precisely, 2 banks in parallel).

This is the only way to overcome the breakdown of the cans in the battery. The balancers didn’t help much.

The whole trouble with these simple charges is that they measure the total voltage of the batteries connected in series. This is good only for batteries that are ideally identical in properties. And this is almost unreal. I also thought about several galvanically isolated charging modules for each element.

the balancer, of course, allows you to equalize the voltage side by side and prevent runaway. But still, separate charging is better.

if we were to get into the OOS on the TL431 of the primary power supply unit, then it was necessary to introduce the OOS on the current there as well. Then the primary power supply would implement the algorithm “limiting the current or voltage, depending on what comes first,” and the scarf on the LM2596 would not be needed.

here is an example of the implementation of such an upgrade of a 12v power supply

only the balancers described there were unsuccessful. The balancers made according to the TL431 scheme with a high-resistance divider p-n-p transistor “on top” turned out to be more successful.


Everything is! You need to be able to search, set target requests!

Tech blog

If you have (or have been lying around with friends) an old Ni-Cd screwdriver and all the batteries have sat down, and even the charger has broken down (burned out), order an MT3608 board on Ali for 40r, look for an old charger from a cell phone (all in bulk) and old laptop batteries (of which we need Li-Ion 18650 batteries).

Today we will convert an old screwdriver from nickel-cadmium batteries to lithium-ion batteries, and modify its charger accordingly.

Everything is easily redone. Let’s start with batteries.

If the screwdriver was at 12V, we will need 4 18650 batteries (16.8V maximum), if at 14.4V. 5 pcs (21V maximum), if at 18V. then 6 pcs (25.2V maximum). The safety margin of the electric motor and other mechanisms in the screwdriver is large, and we will not be in the way of increasing the power.

First, 18650 Li-Ion batteries are tested, if there is anything to choose from, they are selected with the same capacity. Expensively and accurately, this can be done using a BT-C3100 V2.2 device or similar. The factory capacity of 18650 batteries from laptops is 2000-2200 mAh, written on them, if not, then you can divide by 2 the capacity written on the nameplate of the battery. The run will be better if you give 3 charge / discharge cycles. If the measured capacity is 5-10% lower than the written one, then it is permissible, but if the capacity is much lower, then the batteries have lost their capacity. We also measure the internal resistance of the batteries in the device and it should also be the same.

Without precision instruments, it is enough to charge Li-Ion 18650 batteries up to 4.2V in any voltage-limited charging suitable for them, give the same load and after the same time measure the voltage on them. If it fell to the same values, then it is normal. For example, we load a fully charged 18650 into a load of 3-5 Ohms (current from 1.5 to 0.8 A), and after the same time (for example, three minutes) we measure how much remains of 4.2V under load and without load. If the final voltage under load and no load are the same, the batteries are suitable. This indicates the same load capacity and the same internal resistance.

READ  How to Cut Polycarbonate at Home

We throw out the old dead / closed Ni-Cd batteries from the body of the replaceable battery, and instead of them we solder Li-Ion to the voltage we need. For the Li-Ion batteries themselves, it is better to leave flat connectors from the laptop, but if you still solder wires to Li-Ion, cool the soldering place with a blower, solder quickly with flux or acid to reduce the heating time of the battery surfaces, in order to avoid damage Take wires for soldering from an old computer PSU, or thicker.

It will be better if the batteries are soldered through the charging balancer board: “4S or 6S balance protection board”, it will not allow the batteries to recharge above 4.2V. Also, through such a board, multi-capacity batteries will be better charged, but in the case of different batteries, less capacious ones will degrade much faster, because they will discharge below the minimum voltage of 2.8V, while more capacious ones will still have a voltage reserve. The screwdriver is still twisting, but weaker batteries are already degrading.

Then we check how the screwdriver turns on Li-Ion batteries, usually this is an increase in power by 20-40% and a decrease in the weight of a replaceable battery.

Now we move on to reworking the charging, especially if it burned out or not. They are different for different companies, Bosch, Shturm, Hitachi, everything is different. From the charging case, you can get all the stuffing, except for the terminal block. By and large, we only need a terminal block to connect a removable battery. Of course, everything will be better in the case. I had too much current from a heavy transformer, and it was heavy, so I found a better use for it (in a laboratory PSU).

We solder the output of the charger for the cell to the MT3608 board on the VIn contacts, plus, minus. We turn on, tighten the resistor to the output voltage we need, this is 16.8, 21 or 25.2V, respectively, what kind of Li-Ion battery you have.

MT3608 is a Step Up (boost) voltage converter with pulse width modulation, on ordinary boards, the output capacitor must be soldered to the large contact of the VOut output and, accordingly, cleaned the ground next to it to solder the capacitor. This is a deficiency of the Chinese, the board does not work well from the factory.

We limit the charge current, for this we need a 5-15 Ohm resistor and the simplest and smallest diode. Solder the VOut plus wire directly to the battery plus terminal block. And VOut- through a resistor in the negative wire. From the measuring point of the resistor, we solder the diode (anode) (cathode with a strip) to the FB signal of the microcircuit, this is the 3rd contact of MT3608, fine, but it rings out on the potentiometer on the other side of the board, which is much easier to solder.

We connect the battery for charging and check the charge current, it will be from 50 mA (15 ohms) to 200 mA (5 ohms). Accordingly, the current from the cellular charging will be, for example, 50mA (21V / 5V / efficiency) = 300mA, and for 200mA (21V / 5V / efficiency) = 1200mA (it may be too large, not every cellular charging will pull it). We check the charging, if it heats up or the voltage from it sags from 5V to 2.5V, then the current should be reduced to avoid overheating.

You may ask why such a small charging current, because it will take a long time to charge. The first moment, at high charge currents, close to 1.0C (C-capacity of the Li-Ion battery), the charge time is about an hour, the battery will definitely die after 1-2 years of such atrocities. Second, even old Li-Ion batteries tend to recover at low charging currents (unless, of course, chemistry leaks and swells), and charging with a low current will definitely extend the life of the battery. You can look at to study the issue.

Cons: Long full charge time (10-20 hours). It is extremely undesirable to plant Li-Ion batteries below 3V per cell, that is, to do a full discharge (when the screwdriver turns much weaker), Li-Ion batteries lose their capacity much earlier in the cold, already at 0 degrees the screwdriver will work little (You can wear a glove or a scarf or a scarf only for the battery of a screwdriver for short-term work in the cold, or only warm up the battery in a room on a heating battery).

Instead of charging from a cell, you can take 5V or 12V from a computer PSU or a PSU from a router / modem.

Somehow I came across a very weak Chinese cell phone charger. Written 5V, 450mA. Even at 21V 50mA, MT3608 overloaded charging and the output voltage dropped to 2V, charging boiled. What had to be redone:

First, I made a voltage limitation for the beginning of the conversion Uin for the MT3608 (so that the converter does not transfer the charger power supply to the 2V 2A state, when everything starts to get very hot and burn). In a diagram of simple parts, the resistor R2 can be replaced with a 1-10-100kΩ trimmer (10k is optimal and R1 is 10k then). This made it possible to start the StepUp converter only from an increased input voltage, the maximum current for Chinese charging was at a voltage of 4.3 V, if you slightly increase the trimmer, the converter stopped and the voltage jumped to 5V.

I also wanted to raise the charging current, 21V 80 mA was not enough.

The higher the voltage on the secondary winding of the high-frequency transformer of the charging power supply converter, the more power can be removed at the same current (and the maximum current depends on the wire cross-section), but you can reach oversaturation or overheating of the transformer, and the power supply circuit can go into protection or burn out.

At the output of the charging power supply, there is a feedback optocoupler and a 3-4 Volt zener diode or resistors to stabilize 5.2V. I was lucky and came across a charger, including a 7.5V protective zener diode, which I soldered instead of a measuring zener diode, and got 9V at the charger output. Above 10V, it is better not to overclock a charger for a cell phone, usually at 11-12 volts stabilization breaks down.

As a result, I tightened the limitation of input voltage consumption by 8.2 volts, received 21V 140mA at the output of the converter, as a result, 13 hours of charge for my 2000mAh 18650 batteries is normal.

Tags: from scrap parts, can be found everywhere, readily available, easy to alter, simplicity, easier when there is nothing.

Leave Комментарии и мнения владельцев, share your experience, advise who got what, how best to redo it. If you shoot a video of the rework, post a link here.