18 volt battery remake of an electric screwdriver

Power supply for an electric screwdriver 18 V with their own hands

An electric screwdriver is much more practical than a regular screwdriver. It can be used anywhere with little effort on the part of the owner. The advantage is that it saves time. While a person removes one screw with a screwdriver, a power tool can do ten! Tool chargers sometimes break: it happens because of voltage fluctuations, expiration of the shelf life (2 to 5 years), water or household chemicals on them. A new charger costs from 1 to 10 thousand, depending on the model of the tool. Is it possible to make a power supply for an 18v electric screwdriver with your own hands, so that the unit will work from the mains? Yes, you will need a basic knowledge of electronics and practical tips. You can make a power supply for an electric screwdriver from an energy-saving light bulb, a computer battery or a car battery.

Ways to reanimate an electric screwdriver

The main advantage of an electric screwdriver can be called mobility. The battery lasts for a long time and it is possible to buy another battery for this model if the amount of work is great and the deadline is tight. Despite the fact that the battery is used mainly lithium-ion (a very high quality type of battery), there is a possibility of failure of the power supply circuit, as well as the autonomous source.

The electric screwdriver can be powered and recharged from 220V. The battery goes to a voltage of about 14V or 20V (it all depends on the specific model). The battery produces 12 or 18 volts of power respectively.

volt, battery, remake, electric, screwdriver

If the product is not often used, over time the battery becomes worthless, although lithium-ion battery is protected against overcharging and complete discharge, there is no point in hoping for this protection. The main solutions to the issue are:

  • Replace the battery with a serviceable one (will be quite difficult to do, although possible).
  • Buy a new electric screwdriver.
  • Convert a mains-powered electric screwdriver.

It is very easy to convert the cordless model into a network model (electric screwdriver from 220 volts). This option has advantages, such as:

    There is no need to constantly recharge the battery.

  • The operation of the tool without overloads due to the constant torque.
  • You can make a model that will also recharge any type of battery.
  • Build quality (high quality parts will be used for the power supply, because the user is doing it for his own purposes. It makes no sense to be constantly distracted by the repair of the electrical part. it is an unnecessary TIME, and for some. a loss of income).

When converting an electric screwdriver to a cord with your own hands, its mobility disappears. This can be corrected by modifying the tool for any type of battery and any power supply.

Conversion options

There are several options for converting the electric screwdriver, and only the user decides for himself which of them to choose. The main ways:

    Use a laptop battery charger (plug in a laptop adapter).

  • Use a computer switching-mode power supply (hereinafter PSU) from a personal computer.
  • Use a car battery.
  • To improve PSU for halogen lamps.
  • To assemble a PSU by yourself.

Items 1 through 4 require little or no skill and will work for most people. The essence of them lies in the use of readymade devices, because almost all ready-made PSU are protected against short circuits (short-circuits), various kinds of overloads and interference, and car battery is generally the ideal power source.

Laptop charger

A very simple method that requires a minimum of electronic knowledge. To make a power supply for an electric screwdriver 12v with their own hands is suitable for any charger for a laptop. To remodel, find out the power supply voltage of the electric screwdriver and select the appropriate charger. It is necessary to carry out the following actions:

    Disassemble the battery compartment and remove the defective battery.

  • At the laptop charger cut the output plug (not the mains plug. the incoming. This is very important).
  • Strip the wires.
  • Turn on the charger (do not let the leads touch) and test the DC voltage with a meter (any voltmeter with a measurement voltage of over 50V or a regular multimeter will do).
  • After measuring the power supply it is necessary to solder the wires, observing the polarity.
  • Close the battery compartment by placing the battery charger in it and pull out the power cord.
  • Plug it in and check the operation of the tool.

When buying a battery charger, you should pay attention to its dimensions, and it is better to take the electric screwdriver with you, having previously removed the battery and disassembled the battery compartment. During installation, it is necessary to observe safety rules to avoid electric shock and prevent failure of the battery charger for your laptop.

Computer power supply unit

Another good option is to use a power supply from a personal computer and preferably of the AT form factor. Main parameters of the PSU: power 300.350 W, 12 V and a current of at least 16 A. This option is not suitable for an 18 V electric screwdriver. The main advantages are the presence of a button, short circuit and overload protection, as well as a cooling system which is not present in the factory model of the electric screwdriver. To implement this idea, the following steps are necessary:

    Unplug the power supply unit AT.

  • The power-on protection is removed by shorting the green wire to any black wire from this connector (it will not start when the PSU is turned on unless you bypass the protection).
  • Leave the yellow and black wires on the white connectors that go into the hard drive or other mass storage device, and cut and insulate everything else.
  • Extend the yellow and black wires with a cable of the required length (preferably solder, as the twists can oxidize).
  • Solder the yellow and black wire, respecting polarity, to the contacts of the battery compartment and assemble it.
  • A longer wire (power cord) can be used for the PSU. In addition you need to make a cover for the computer power supply in order to observe the safety regulations when working with electrical appliances.

After all the above steps connect the PSU to the mains and start the tool. If everything has been done correctly, it should work. If the rotation is reversed, the battery compartment must be disassembled and the polarity reversed. If there is no power supply, make sure that the input and output voltages are present.

The car battery

Optimal way to source electrical energy, protected from accidental short circuits, the voltage is stabilized and there is no various interference. Significant disadvantages are its size, weight and need for charging. An example of how to use it is very simple. You just need to power the electric screwdriver from the battery terminals, using a cable of the right length, and pre-solder the old battery.

You need to buy a car battery charger or make a homemade transformer battery charger. In addition, you need to protect the battery from rain and debris. For this purpose, a special case with terminals for battery charger and power for an electric screwdriver.

What you can build a power supply with

The power supply for charging an electric screwdriver can be made according to various schemes. It all depends on the skill, availability of tools and materials.

From a computer power supply

A good power supply for an electric screwdriver at 12 volts can be obtained from a PSU for your computer. First you have to check if it fits the parameters.

In this example, the PSU has two 12-volt channels, one for 11 amps and one for 13 amps. Each channel is enough to power the selected 12 volt power tool. On the internet you can find tips on how to connect the channels in parallel until you get the total current (24 A in the above case). It is not recommended to do this, because due to the difference in voltages, one channel can become a consumer for the other. the entire risk is up to the owner’s choice. A loop of wires comes out of the power supply. You have to cut all but:

Sometimes you must leave the red wire as well. some circuits require a base load. To do this, a 12 volt bulb must be connected between the red one and any black one. If the PSU does not turn off in its absence, you can remove it. The green wire should be connected to any black wire. And take 12 volts from the yellow and black (any) conductor.

From the transformer

If there is a suitable transformer, you can build a power supply on it. A general schematic diagram of a non-stabilized power supply is shown in the following figure. Such a device consists of:

If you have a commercially available transformer, you can find its data in a reference book. If you are satisfied with it you can build your PSU with it. If not, it can be rebuilt, having first checked its suitability for the conditions required. The suitability of a transformer is determined by its capacity. If you set the output current of 10 A, voltage 14 V and system efficiency (from transformer to output shaft of electric screwdriver) equal to 0.5, then you need a transformer with power P=10 A14 V/0.5=280 W (we can round up to 300 W).

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To determine the iron power of a transformer you need to find the cross sectional area of its core in centimeters (in most cases you can get the dimensions without disassembly). You should apply the area in square centimeters of the transformer to the formula:

If the result is more than 300 W, the transformer is suitable for making a power supply. Next, all secondary windings must be removed and a new one must be wound. The number of turns can be determined experimentally. To do this, you need to wind any known number of turns with any wire, and measure the output voltage. Let’s say, having wound 10 turns, you get 5 volts at the output. So, for one volt there are two turns, and to get 14 volts you need 28 turns. For 10 amps wire section should be not less than 2.5 kV.The winding thickness is 1.8 millimetres.

Ryobi 14.4V running 18V lithium battery

After making the transformer it is necessary to choose diodes, capable of working at a selected current. They must be placed on the heat sinks. And lastly, install a smoothing capacitor. It must be rated for at least 25 volts and have a capacity of 4000-10000 mcf (you can do more, but the dimensions will increase). For this type of application a transformer power supply is quite bulky and heavy.

It can be supplemented with a voltage regulator, then it will retain torque at any load (but this is not necessary. because in normal mode, the batteries also sag at high current).

You can build the regulator on a 78X series integrated circuit (79X for the negative arm), by recharging it with an external transistor.

Important! Linear regulator works with a certain excess of input voltage before the output voltage, so in this case you will need a transformer with an output voltage of 17.18 volts. The overall power must also be increased. the overall efficiency of the circuit will decrease. This must be taken into account when selecting or making a power supply.

You must enclose the finished power supply in a case. You can make one yourself or get one from a laptop computer.

From a laptop computer

You may get a good result using a laptop power supply. These units are sized for an output voltage of 19 volts and various output currents. You can find source with up to 6 amps, which is enough for most home works. Do not overload such source. triggered protection or self-resetting fuse on the input (self-restoring it is not always restored, and it will have to be replaced).

Universal power supply

Regulated and unregulated DC power supplies, such as those used in laboratories, can be used to power an electric screwdriver. Their advantage is that the output voltage can be adjusted, and set, depending on the model of power tools, either 12V or 18V. The problem is that it is difficult to find a laboratory voltage source with an output current of 10A. So, the unit in the photo for each channel has a current limit of a little over 3A. The voltage is about zero, so you can’t operate an electric screwdriver in this mode. At best, this power supply will provide idle running of the power tool.

Switching power supply

The best choice is a switching power supply. Lightweight, compact, does not contain a powerful and heavy transformer, because the voltage level conversion takes place at a higher frequency. The disadvantage of such a solution. complicated circuitry. To build a pulser with your own hands, you need a certain qualification.

One of the variants of the pulse PSU is shown in Fig. AC voltage rectified by a bridge on VD1-VD4. The generator on VT1 controls the operation of the switches on VT3, VT4. In winding 1 of transformer T2 powerful current pulses of high frequency are created. From winding 3 pulses with reduced amplitude are taken, rectified by the bridge VD7, smoothed by the capacity C5 and fed to the load. The winding data of the transformers are given in the table.

TransformerMagnet wireWinding coilNumber of windingsWire
T1 Ferrite 1000 NM (2000 NM, 3000 NM) 12x8x3 (ring) 1,2,3 20 PEV 0.33
T2 Ferrite 1000 NM (2000 NM, 3000 NM) 40x25x11 (ring) 1 100 PEV 0.54
2 9 PEV 0.33
3 13 PEV 0.96

Preparatory step

Before you start the remodel, you first need to find the right size mains power supply for an electric screwdriver. It is desirable that it can fit into the battery case.

In addition, you should remove all fillings from the case, and measure its interior space, because the dimensions on the outside and inside may be different.

After that the markings or instructions on the case should be studied to find out the voltage of the power supply. Then you will have to independently calculate the current consumption of an electric screwdriver, because this parameter is not specified anywhere by the manufacturers. But you have to know the capacity.

To avoid the calculations you can find the power supply by eye. When buying pay attention not only to the current of the charger, but also to the battery capacity. For example, if the capacity is 1.2 ampere-hours and the charge is 2.5, then the generated current should be approximately between these figures.

In addition, before looking for a suitable power supply, you should first write down the following on paper:

Why convert a cordless screwdriver?

Why convert your screwdriver and when you need it? If you’re reading this article, you’ve probably already appreciated all the convenience of this tool. No extra wires and at any time you can use it even in the most hard-to-reach places until the battery runs out. This is the first disadvantage of the screwdriver. The cheaper the tool, the faster the battery will run out of charge cycles. Here’s the second drawback. And you should understand that the manufacturer is saving just as much as you are, and there’s nothing unusual about it. Buying a new battery is not much different in costs than buying a screwdriver, but there is a way out, and now we will look at options for converting the screwdriver from cordless to mains power.

There are several ways to convert a cordless screwdriver to a corded screwdriver:

  • Using a laptop charger;
  • using a power supply from a PC;
  • using a car battery;
  • using a power supply from halogen lamps;
  • Using a Chinese circuit board for a 24V power supply.

Revitalizing an electric screwdriver. All for converting your electric screwdriver to 18650 lithium-ion battery

The battery of an electric screwdriver sooner or later will “get tired” and you will need to change it. Buy a new battery is justified in a situation where the tool is worth a penny. But if you have something more or less decent, or the battery is old on Ni-CD, then it definitely makes sense to change the dead 18650 batteries for new ones, or completely convert the screwdriver nickel to lithium.

Of course, as in any business, there are nuances, but if your hands are at least minimally straight, it is not difficult to remake the electric screwdriver to lithium. You only need to know what to buy for remodeling and understand the basic nuances of the process. And to buy on aliexpress all to convert the electric screwdriver to lithium. elementary.

Why 18650 Li-ion? The benefits of lithium batteries are obvious:

By the way, if you like to read, it is an excellent option to save money! LITRES book service, the largest in Russia and the CIS gives a fourth book as a gift when you buy three. Personally I’ve been buying books there for about 5 years. The price tag is already affordable, and with this bonus comes out very little. There is a handy app to read and listen to books. The link above is one of my picks that has a bold renewable promo code.

Electric screwdriver battery conversion. What you need to know:

1) An electric screwdriver requires high-current 18650 batteries (ideally Sony/Murata VTC5, VTC5A, VTC6. Acceptable. Samsung 25R), or less high-current batteries connected in parallel (if space allows).

2) Categorically do not use old laptop batteries and just different batteries. All 18650 batteries in the assembly should have minimal variation in capacity and other characteristics. Of course, buying a high-current 18650 battery on aliexpress is the easiest solution. Just be aware beforehand that the model name will not have anything to do with the cell inside. 4 batteries bought in one lot from the same seller may differ significantly in capacity and internal resistance. Although the link below is a good option for those who do not want to solder.

The ideal variant. buy 18650 from a trusted seller on the same avito, or order 18650 on nkon In the latter case, you have to pay 10 euros for shipping, but the batteries will be 100% original and much cheaper than buying locally (which will reduce shipping costs to zero). I buy my rechargeable batteries from this store for many years.

I did an article on how to choose a lithium-ion battery 18650, if interested. read it here

3) Connection of accumulators to BMS board is made strictly in series: at first 0V, then 4,2V, 8,4V, 12,6V, 16,8V. If BMS is broken, it will not work!

4) 18650 batteries in an assembly must be charged equally. It is best to charge each battery separately and then assemble.

5) How to calculate how many 18650 lithium batteries you need instead of nickel batteries? Generally, the calculation is: 2-3 NiCd = 1 lithium, 5-6-7 NiCd = 2 lithium, 8-9-10 NiCd = 3 lithium, 11-12-13 NiCd = 4 lithium

6) Lithium batteries are very afraid of overheating. Spot welding is ideal. Soldering works just as well. How to solder 18650? Most importantly, you need the biggest sting possible. Keep the contact time of the stinger and the 18650 battery to a minimum and do not overheat the latter. Otherwise the process is the same as any other soldering. It is best to get a feel for the old batteries that you will be replacing.

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BMS board

BMS (Battery Management System) is a battery management system. The BMS board is extremely important when converting an electric screwdriver to lithium. Why it is needed and how it works? It controls the charge and discharge, preventing the electric screwdriver battery from overdischarging and overcharging, it has a built-in “balancer” that charges each Li-Ion battery separately in the assembly. The latter is extremely important! There are BMS without a balancer! 3S. 12v, 4s. 14v, 5s. 18v To choose a BMS board, you must consider that the minimum current must be 30A, otherwise it will go into protection.

The BMS board option at the link is 2-3 more expensive than some basic versions, but you get 100A instead of 30A or 40A. In my opinion, in terms of functionality is the best BMS-board from aliexpress and deserves this token overpayment.

Convert your electric screwdriver to a lithium battery

The first screwdrivers were equipped with Ni-CD nickel-cadmium batteries (less often with Ni-MH nickel-metal hydride batteries). They have disadvantages. “memory effect”, fastidiousness in storage, longer recharging time and toxicity. If you charge a battery that is not fully discharged, its power capacity decreases, which causes discomfort when actively working with the tool. To eliminate the defects of work, an electric screwdriver in good condition can be converted to work on a lithium battery. To perform an upgrade of the tool is not difficult without the help of a craftsman. Let’s figure out how to convert an electric screwdriver to lithium batteries to improve its performance.

Conversion of 18 Volt Electric Screwdriver to Lithium Batteries

Many screwdriver owners want to convert lithium batteries. Many articles have been written on this subject and I would like to summarize it in this article. First, we will look at the arguments in favor of turning the screwdriver on and against lithium batteries. Let’s also look at some aspects of the battery replacement process itself.

Pros and cons of recycling a screwdriver from a lithium battery

First I need to think about whether I need this change? In the end, it would be a simple “self-propelled gun,” and in some cases could lead to failure of both the battery and the screwdriver itself. So, let’s look at the pros and cons of this procedure. It is quite possible that after this some of you may decide not to replace the nickel-cadmium battery for a lithium-cell screwdriver.

  • The energy density of lithium-ion cells is much higher than that of nickel-cadmium cells, which is the default in screwdrivers. That is, a lithium can battery will have less weight than a cadmium can with the same capacity and output voltage;
  • Lithium batteries charge much faster than Ni ─ Cd. It will be safe to charge them for about an hour;
  • Lithium-ion batteries have no “memory effect”. This means that they do not need to be completely discharged before charging.

Now for the disadvantages and complexities of lithium batteries.

  • Lithium batteries should not be charged above 4.2 volts and discharged below 2.7 volts. In the real world, this interval is even shorter. Exceeding these limits can damage the battery. Therefore, in addition to the lithium batteries themselves, you will need to connect and install an arrester in the screwdriver;
  • The voltage of a single lithium-ion cell is 3.6-3.7 volts, and for Ni─Cd and Ni─MH it is 1.2 volts. That is, there are problems with the battery assembly for 12-volt screwdrivers. With three lithium cans in series, you can build a battery designed for 11.1 volts. Of the four. 14.8, out of five. 18.5 volts and t. Д. Naturally, the charge-discharge voltage limits will also be different. That is, there may be compatibility issues with the converted battery using a screwdriver;
  • In most cases 18650 cans are used as lithium cells for reconstruction. They are different in size from Ni─Cd and Ni─MH cans. You’ll also need a charging space and a wired controller. All of this is required to fit a standard battery screwdriver case. Otherwise they will be extremely inconvenient to work with;
  • The cadmium battery charger may not be suitable for charging the battery after recycling. You may need to upgrade your charger or use universal chargers;
  • Lithium batteries lose capacity at low temperatures. This is important for anyone using a street screwdriver;
  • Lithium batteries are priced higher than cadmium batteries.

What you need to estimate before you start?

You need to determine the number of cells in the battery, which ultimately determines the voltage value. For three cells, the ceiling will be 12.6 and for four. 16.8 volts. We are talking about the disposal of widespread batteries with a nominal value of 14.4 volts. It is better to choose 4 cells, because during operation, voltage drops quickly to 14.8. The difference of a few volts will not affect the operation of the screwdriver.

Converting an 18 volt electric screwdriver from Ni-Cd to Li-Ion batteries

As promised in the last blog, today I’m converting the 18 into an electric screwdriver.Here is the screwdriver itself:

After reading on the forums, I ordered a BMS board and Li-Ion batteries:

BMS board not much did not fit, trimmed a circular file and stood up as native to the photo at the top see. Next, using a glue stick and a soldering iron (I have not yet got a gun), arranged the batteries on the board:

Next, we connect the terminals, the photo is not very visible, who will do it will understand:

I glued the thermocouple not to much, glued it right on top of the batteries:

Also do not forget to solder the wires for balancing:

Next, installed, in the case of the battery, connector to connect the charger:

Building Alternative Makita Battery 18V 9Ah | BL18XXR1

Next, solder the power wires to the “adapter” for the screwdriver:

By the way, I bought such a charger:

Комментарии и мнения владельцев 8

Hey, how do the batteries on an electric screwdriver work??

And how did the battery behave? I win at 18 volts, new you can tell, but the battery dies instantly, though new! That’s the idea of remaking.

It is worth it or not see for yourself, it may be much more profitable to buy a new screwdriver for 3500 on Ali. Just to remake one battery will cost about 2700. You can certainly save on BMS board, but it is at your own risk. I know a guy who has on ALI bought a screwdriver 12 volt, 2 Acb, charger and case, for all of it paid 3500. Half a year he has a normal flight.

Agreed. I’ll have to think about it, but it’s a shame, too.

From this you can make a stationary if you have a power supply from a computer you do not need, on the internet a lot of circuits.

Hi! Hey, does this charger have an indicator on it to know when the charge is over??

Hi, yes there is an indicator. There LED’s are two color red-green. Red when you connect it to the battery and green when you finish charging it.

Changing the batteries in your screwdriver to lithium batteries

What do you need to know before you begin??

It is necessary to determine the number of cells in the battery, which ultimately decides the voltage value. For three cells the upper limit is 12.6 volts and for four cells 16.8 volts. We are talking about the conversion of widespread batteries with a rating of 14.4 volts. It is better to choose 4 cells, because during operation the voltage will drop to 14.8 rather quickly. A difference of a few volts will not affect the performance of the screwdriver.

In addition, a larger number of lithium cells will give a higher capacity. This means longer battery life for the screwdriver.

Lithium 18650 batteries

The rated voltage of lithium cells is 3.6─3.7 volts, and the capacity in most cases is 2000─3000 mAh. If the battery case allows, you can use 8 cells instead of 4. Two to connect them in 4 parallel assemblies, and then connect them in series. As a result you will be able to increase the capacity of the battery. But not every enclosure can hold 8 18650 cans.

And the last preparatory step is the choice of the controller. In its characteristics it must meet the nominal voltage and discharge current. That is, if you decide to build a 14.4 volt battery, then choose a controller with this voltage. The operating discharge current is usually chosen to be half the current limit.

Above we have established that the short time discharge current for lithium cells is limited to 25─30 amperes. So the charge-discharge controller has to be designed for 12─15 amps. Then the protection will be triggered when the current increases up to 25─30 amperes. Do not forget about the dimensions of the protection board. It and its components must be housed in the battery case of the screwdriver.

I rebuild 18V Battery for Dewalt XRP Drill

Replacing batteries

And then there’s the process of assembling. First you disassemble the battery case. If it is a model for 14.4 volts, then inside there will be 12 nickel-cadmium batteries with a rating of 1.2 volts.

After that you need to solder the purchased cells into an assembly with a series connection. Next, the controller is soldered to it according to its circuit diagram. This connects the balancing points. There is a special connector on the board for them, and often wires with a connector are supplied in the kit.

After the battery assembly the leads for plus and minus are soldered, and the entire construction is placed in the case. Basically, this is the end of the process. Problems may arise only with the charger. But in most cases regular screwdriver chargers charge lithium cells without any problem. At the same time the charge of the cells goes through the controller, so nothing bad will happen to the cells themselves.

Converting the battery of an electric screwdriver to Li-Ion

Rebuilding an electric screwdriver battery to Li-Ion This post (

The electric screwdriver cannot be overdischarged in any way, because of the way it is used (a vacuum cleaner, apparently, can). It just “pulls” stops. So no indicators and overdischarge protection is required. Even if you turn on an electric screwdriver with fully discharged batteries. well, the voltage on the battery under load will drop to ( below) 2 volts. It’s okay. When removing the load (just a short-term) the voltage at the bank will be restored to 2.5. 3.0 volt. There is no way not to feel this moment.

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And next, just in pictures, I will show how it is done. I have 4 electric screwdrivers. Two at the cottage (18V), at home (18V) and at work (12V). If you do with protection boards/charge controllers, it will be a complete financial ruin, especially since 18V screwdrivers require boards for 5 batteries connected in series (they are less common and more expensive). Комментарии и мнения владельцев are almost unnecessary I think. Shows the variant for 4 lithium batteries for a 12V electric screwdriver. This is my electric screwdriver. The battery has a DB9F connector. This is a battery charger with 4 galvanically isolated channels. At the output all four channels “combine” in the DB9M connector. Four LI-Ion charger cards from Ali on a TP4056 chip. I found 12 ( 20 pieces) each. I lost the link. Of course you can put all of them into one box with only DB9M connector but it is very convenient to have four separate galvanically separated charging channels. For example, I converted the power supply of my tester from “Krona” to two lithium batteries in series from disposable electronic cigarettes. Charging with the same charger, two channels. Such a design can be replicated by any household handyman, who is far from electronics. 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. 18. volt electric screwdriver works perfectly well with four Li-Ion batteries, but only with freshly charged batteries. You have to charge it much more often. On the DB9 connector.1 and DB9.2 leads and. of the first battery by separate wires that are soldered directly to the battery terminals. On the DB9.3 is brought out by a separate wire from the second battery and so on.дAccording to the wiring diagram, pin 2 and pin 3 of DB9 are the same point. But this is not exactly true from the point of view of the TP4056 charge board. Joint conductor sections in the charge circuit should be avoided, because with different currents from the two charge boards at a given time, an error of tens/hundreds of millivolts can occur. It is desirable to put wires in the charging circuit with a larger diameter (well, and in the main discharge circuit, of course, too). For an electric screwdriver with an 18 volt battery this connection requires 10 pins. I have the DB9 connector metal housing as the 10th pin. Another picture. The one for an 18 Volt, 5 channel battery. How to buy small cheap (40. 70) Ali AC adapters to really deliver one amp. that’s a separate topic. I bought the adapters in lots of 5 and 10. I can not give you the link because the webpages where the adapters shown in the pictures were bought unfortunately do not exist anymore. I remember that the seller had a picture on the page with load resistors and a USB doctor that said 0.98A. I was not cheated, the current was really present at the output, but it had a ripple of a volt and a half. I had to add tantalum capacitors inside. One 220 uF capacity, 6.3. 10 volt at the output of such adapters is enough to make the adapter similar in its characteristics to the original epple charger (you get a ripple of 50 volts). 150 mV).

Instead of the cat. This is a good USB-doctor you can make from a voltmeter-ampere meter you bought on Aliexpress (100 V, 10 A). It’s slightly better than most first generation “doctors” in terms of voltage drop at the current shunt. I haven’t measured exactly, but the figure is around 70 millivolts/1A. This voltage drop is comparable to a “doctor” with an OLED display. The others ( and the “standard” white “doctor” with a cord) have a shunt drop of more than 100 mV. Exact numbers are actually not as easy to get as one would like, because every extra USB contact in the circuit “eats up” about 30 mV/1.0 A of current flowing. At high charging currents the older versions of “doctors” plugged into the circuit can drop the charging current of a smartphone/tablet by themselves, even with short and good quality USB cords.

When I wrote this post a year ago and duplicated it on mysku.I was “scolded” there for “kolhozny” realization of my variant of the charger. I didn’t really get into the criticism, because I still don’t see much point in making a lot of extra gestures to make an auxiliary device that is used quite infrequently. On the other hand, this year I bought some more TP4056 charger cards and found in my stash a case for the power adapter. And made a variant, the way it was planned from the beginning. Maybe someone would like it better this way. It is easier to see that this is the easiest way to convert an electric screwdriver to lithium, and the size of this charger is smaller than the regular one. All shown in the pictures, and a bit of explanations. We used the cheapest white USB power adapters from Ali, or to be more precise their insides. I unsoldered the USB connector and added a 1500uF6 electrolyte to the output of each charger.3V Low ESR (you can find it on old motherboards, if the board is newer, you can find tantalum electrolits 100. 200 uF, this option is even better). The modification is needed to be able to use the most-very Chinese power adapters, regardless of the initial value of their ripple. The fact that these adapters do not always pull the load current of 1A, the serviceability of design does not affect. Even if the output is only 0.5A. will work. And the resistor on the TP4056 charger board 1.2 kOhm ( charging current 1A) replace with 2.4 kOhm (charging current 0.5A) is not necessary. Takes a little longer to charge, but that’s about it. The case of the charger is some kind of typical transformer power adapter bought a long, long time ago in the store “Chip@Dip.

Isolation of channels between each other increased attention. This is about the pictures below. You can not just use a glue gun and shove the lump of wires and boards into the case because the mains voltage and it all heats up pretty good. And we do not need a short circuit, given that to monitor the charging process is somehow not accepted.

A small clarification of the fact that in the main article it was about five Li-Ion batteries for screwdrivers with 18 V power, and in the addendum a variant for 4 channels is presented. The experience of using these rechargeable batteries showed that lithium batteries are more powerful than the original nickel cadmium ones. And in series there are 5 pieces (30-amp), not 15 pieces. Everything that used to “fall” and “dissipate” on the source, now warms the electric motor. As a result, even without special load, but with long switching on (example: drilling with drill 4. 5mm thick “slippery” stainless steel), the motor starts to smell of burning insulation. Therefore, to avoid this, I removed all “fifth” batteries from three 18 volt screwdrivers. Result:

the light is not very good, but here are two red and two blue LEDs (they are white because the plexiglass is yellow). Now, when all reds go out, you can start working with the screwdriver. “Alignment” occurs “automatically” at level 4.2 volt. Forgot to write, which is important. If anyone is interested, please note that the adapter case from Chip@Dip originally has ventilation slots, and I myself drilled additional holes at the bottom and sides. In a closed case, this entire construction can “give up” due to overheating.

Selecting the batteries

Often 12 V batteries are used for screwdrivers. Factors to consider when choosing a Li-Ion battery for an electric screwdriver:

  • The cells used in such tools have a high discharge current;
  • In many cases, the capacity of the cell is in inverse relation to the discharge current, so you can not choose it only by capacity. The main indicator is the current. The operating current value of an electric screwdriver can be found in the tool’s data sheet. Usually it is from 15 to 30-40 amps;
  • It is not recommended when replacing the battery of an electric screwdriver with a Li-Ion 18650 to use cells with different capacity values;
  • Sometimes you are advised to use a lithium battery from an old laptop computer. This is absolutely unacceptable. They are designed for much lower discharge current and have inappropriate specifications;
  • The number of cells is based on the approximate ratio of 1 Li-Ion for 3 Ni-Cd. For a 12 volt battery, you will need to replace 10 old batteries with 3 new ones. The voltage level will be slightly reduced, but if you install 4 cells, the higher voltage will shorten the life of the electric motor.

Important! Before reassembly, it is necessary to fully charge all cells to equalize.

Repairing the battery of an electric screwdriver with the replacement of the batteries with your own hands

Screwdrivers usually use nickel-cadmium or lithium-ion cells as batteries. Ni-Cd batteries are more unpretentious and if you do a partial replacement of cells in such a unit, it will work for a long time. Partial replacement of lithium batteries can also be done, but it is a bit more difficult. Keep in mind that you will have to solder not only the elements themselves, but also the balancing board. Also in recent years electronics enthusiasts often change the batteries of an electric screwdriver with their own hands, from nicd batteries to lithium batteries. This is a good way out in case the screwdriver has to work often and intensively. The capacity of lithium-ion batteries is much higher and the number of cycles is higher.

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