How To Charge A Screwdriver Battery Without A Charger

Making a charger for a screwdriver with your own hands
Types and types of chargers. How they work. Simple schemes for self-repetition. Methods for charging the battery of a screwdriver without a charger.

Making a charger for a screwdriver with your own hands

When using a screwdriver, users often encounter damage to the charger (charger). First of all, this is due to the instability of the parameters of the electrical network to which the charger is connected, and secondly, with the failure of the battery. This problem is solved in two ways: buying a new charger for a screwdriver or repairing it yourself.

Using a specialized microcircuit

Manufacturers of screwdrivers are trying to reduce prices for their products, often this is achieved by simplifying the memory scheme. But such actions lead to the rapid failure of the battery itself. Using a universal microcircuit designed specifically for the MAXIM MAX713 charger, you can achieve good performance in the charging process. This is what the charger circuit for an 18 volt screwdriver looks like:

The MAX713 microcircuit allows you to charge nickel-cadmium and nickel-metal hydride batteries in a fast charge mode, with a current of up to 4 C. It can monitor the battery parameters and, if necessary, reduce the current automatically. At the end of charging, the microcircuit-based circuit consumes practically no energy from the battery. It can interrupt its work on time or when a temperature sensor is triggered.

HL1 is for power indication and HL2 is for fast charge display. The setup of the scheme is as follows. To begin with, the charging current is selected, usually its value is equal to 0.5 C, where C is the battery capacity in ampere hours. The PGM1 pin is connected to the positive supply voltage (U). The power of the output transistor is calculated by the formula P = (Uin. Ubat) Isar, where:

  • Uin. The highest voltage at the input;
  • Ubat. Battery voltage;
  • Isar. Charging current.

The resistance of R1 and R6 is calculated by the formulas: R1 = (Uin-5) / 5, R6 = 0.25 / Isar. The choice of time after which the charging current will turn off is determined by connecting the PGM2 and PGM3 contacts to different terminals. So, for 22 minutes, PGM2 is left unconnected, and PGM3 is connected to U, for 90 minutes, PGM3 is connected to the 16th leg of the REF chip. When you need to increase the charging time to 180 minutes, the PGM3 is shorted to the 12 leg of the MAX713. The longest time of 264 minutes is achieved by connecting PGM2 with the second leg, and PGM3 with the 12th leg of the microcircuit.

Types of chargers

The popularity of the screwdriver is due to the fact that it simplifies the process of twisting or unscrewing various fastenersand. Characterized by mobility and small size, it is indispensable for assembling furniture structures, disassembling equipment, roofing and other construction work. The tool owes its mobility to the rechargeable batteries included in its design.

The screwdriver battery is charged in two ways: with a built-in or external charger. The built-in charger allows you to charge the battery without removing it from the screwdriver. The capacity recovery circuit is located directly with the battery. While the remote means their extraction and installation in a separate charging device. Distinguish chargers according to the type of recoverable batteries. The batteries used are:

  • Nickel cadmium (NiCd);
  • Nickel metal hydride (NiMH);
  • Lithium ion (LiIon).

The final cost of a screwdriver depends not least on the type of batteries used and the capabilities of the charger. Chargers are available in 12 volts, 14.4 volts and 18 volts. In addition, storage devices are divided according to their capabilities and can have:

  • Indication;
  • Fast charging;
  • Different type of protection.

The most used chargers use a slow charge due to a low current. They do not contain an indication of operation in their design and do not turn off automatically. This is more true for built-in capacity recovery devices. Chargers built on impulse circuits provide the possibility of accelerated charging. They automatically turn off when the required voltage is reached or in the event of an emergency.

Homemade charging devices

It is quite simple to make your own charging for a 12 volt screwdriver with your own hands, by analogy with the one used in the Interskol memory. To do this, you need to take advantage of the ability of the thermal relay to break the contact when a certain temperature is reached.

In the circuit, R1 and VD2 are a charge current flow sensor, R1 is designed to protect the VD2 diode. When voltage is applied, the transistor VT1 opens, a current passes through it and the LH1 LED starts to glow. The voltage value drops on the R1, D1 chain and is applied to the battery. The charge current flows through the thermal relay. As soon as the temperature of the battery to which the thermal relay is connected exceeds the permissible value, it is triggered. The relay contacts switch, and the charge current begins to flow through the resistance R4, the LH2 LED lights up, indicating the end of the charge.

Two-transistor circuit

Another simple device can be performed on available elements. This circuit operates on two transistors KT829 and KT361.

The magnitude of the charge current is controlled by the KT361 transistor to the collector, to which the LED is connected. This transistor also controls the state of the KT829 component. As soon as the capacity of the battery starts to increase, the charge current decreases and the LED goes out smoothly. Resistance R1 sets the maximum current.

The moment the battery is fully charged is determined by the required voltage on it. The required value is set with a variable resistor of 10 kOhm. To check it, you need to put a voltmeter on the battery connection terminals without connecting it itself. Any rectifier unit designed for a current of at least one ampere is used as a constant voltage source.

The principle of operation of the memory

If the charger fails, it makes sense to first try to restore it. For repairs, it is advisable to have a charge device circuit and a multimeter. The circuitry of many charging devices is based on the HCF4060BE microcircuit. Its switching circuit forms the delay of the charging time interval. It includes a crystal oscillator circuit and a 14-bit binary counter, making it easy to implement a timer.

The principle of operation of the charger circuit is easier to disassemble with a real example. This is how it looks in the Interskol screwdriver:

This circuit is designed to charge 14.4 volt batteries. It has an LED indication showing the connection to the network, LED2 is on, and the charging process is on, LED1 is on. The U1 HCF4060BE microcircuit or its analogs: TC4060, CD4060 is used as a counter. The rectifier is assembled on VD1-VD4 power diodes of the 1N5408 type. The Q1 PNP transistor operates in the key mode, the control contacts of the S3-12A relay are connected to its terminals. The key operation is controlled by the U1 controller.

When the charger is turned on, an alternating voltage of 220 volts is fed through a fuse to a step-down transformer, at the output of which its value is 18 volts. Further, passing through the diode bridge, it is straightened and goes to the smoothing capacitor C1 with a capacity of 330 μF. The voltage across it is 24 volts. When the battery is connected, the relay contact block is in the open position. Microcircuit U1 is powered through a Zener diode VD6 with a constant signal equal to 12 volts.

The used SK1 button works momentarily. When it is released, all power is supplied through the VD7, VD6 chain and the limiting resistance R6. And also power is supplied to LED1 through resistor R1. The LED lights up, signaling that the charging process has started. The operating time of the U1 microcircuit is set for one hour of operation, after which the power is removed from the Q1 transistor and, accordingly, from the relay. Its contact group breaks and the charge current disappears. LED1 goes out.

This charger is equipped with an overheating protection circuit. Such protection is implemented using a temperature sensor. Thermocouple SA1. If during the process the temperature reaches more than 45 degrees Celsius, then the thermocouple will work, the microcircuit will receive a signal and the charge circuit will break. After the end of the process, the voltage at the battery terminals reaches 16.8 volts.

This charging method is not considered smart, The charger cannot determine the state of the battery. Because of this, the battery life of the screwdriver will decrease due to the development of the memory effect. That is, the capacity of the battery decreases every time it is charged.

Application of a universal memory

For purchase, there are universal charging units, the output parameters of which are regulated according to the needs of the user, the individual characteristics of the type of device that needs to be charged. Their complete set includes an adapter for the most popular connectors, crocodile clips, such gadgets are suitable for many types of devices and instruments.

Equipping the battery with a USB connector

To be able to replenish the battery of the screwdriver through the YUSB-charging unit, it is equipped with such a connector, using a fuse. The contact points are soldered, the fuse is fixed with glue, the assembled body is fixed with adhesive insulating tape.

Using the car battery charger

Such a device can damage the battery of a screwdriver, because its output characteristics are different, so the charging process can be carried out only after they have been leveled. It is safest to use a car charger equipped with a voltage level control system. If there is one, it is recommended to set the following parameters: with a battery power of 1.3 ampere / hour, the current value is set at 650.130 mA, that is, the current value is 0.5. 0.1 part of the total battery power.

How to charge a screwdriver battery without a charger: methods

The absence or complete breakdown of the screwdriver memory stops all planned work. But, using ingenuity, some available tools, the question that has arisen about how to charge a screwdriver battery without a charger can be successfully solved. There are several ways to resolve this problem.

How to charge a screwdriver battery without a charger: safety

Before using any other charging method, except for the native charger, you should remember that:

  1. The process must be continuously monitored; at the end of filling the battery, it is recommended to stop the procedure, because from overflow, the electrolytic cells of the battery can boil, the temperature will rise sharply, the appearance of the slightest spark will explode the entire structure;
  2. Non-native, homemade chargers threaten to completely ruin the battery, excluding the possibility of its subsequent restoration;
  3. It is necessary to ensure the correct inclusion of all elements of the circuit, strict consideration of the technical parameters of the battery when installing the circuit, the safety of the procedure, the observance of polarity;
  4. If the characteristics of the modules differ slightly (for example, 10 and 13 volts), then you cannot charge the battery for a long time.

Making a homemade charging block

It is possible to fabricate a homemade unit to charge the drive. To do this, the terminals of a failed battery are soldered, respectively, the polarity through the expanded holes are soldered wires. The location of the wires is sealed with some kind of filler, for example, a roll of thick paper / cardboard. The cover is fixed with glue on the charging glass. The assembled unit is placed into the battery through an adapter.

Universal chargers

Universal equipment for battery charging supports step or stepless regulation of voltage and current in the output circuit. The unit is equipped with instruments and indicators to control the charging progress.

Safety and Precautions

Basic safety requirements when charging power supplies to the instrument from non-standard charging blocks:

  1. The tool uses direct current to charge the batteries.
  2. The connection is made with cables with a protective insulator, it is necessary to provide for a reliable fixation of the electrical wiring on the battery contact plugs.
  3. When the capacity of the elements is replenished, heating occurs, accompanied by the release of gases. The battery cells are equipped with emergency valves, but the leaked component is not suitable for further operation.
  4. It is recommended to work in a ventilated area, eyes and hands are protected with personal protective equipment. If the body overheats, smoke or electrolyte marks on the body of the can, charging stops immediately. Reconnection is performed after finding out the causes of the malfunction.
  5. Connecting power adapters that are not designed to charge the screwdriver battery is a last resort. Due to the inconsistency of the current parameters, the circuit components operate with overload, which causes increased heating and fire. Continuous use of non-original charging blocks is not recommended.

Ways to charge a screwdriver without a charger

The cordless electric tool is equipped with a factory charger to replenish the battery capacity. If the unit is lost and broken, the owner has a question about how to charge the screwdriver without a charger. In addition to purchasing the original unit, there are several methods for recharging the power source from household or automotive equipment.

How To Charge A Screwdriver Battery Without A Charger

How to charge a screwdriver battery without a charger

There are 3 types of power sources used in the construction of an electric tool:

  1. Nickel-cadmium elements, characterized by their ability to withstand high loads and operate at negative air temperatures.
  2. The batteries are distinguished by a pronounced memory effect and accelerated self-discharge. Before connecting the battery to the charging station, the jar must be completely discharged.
  3. A short-term connection of the battery bank to a non-original charger is allowed.
  4. Nickel-metal hydride cells have a reduced memory effect and increased capacity. It is not recommended to connect batteries to non-original chargers.
  5. Lithium-ion power supplies that prevent deep discharge and overheating. For charging, special blocks with microprocessor control are used, which control the state of the elements. Do not use battery chargers from car batteries or other power sources.

Before connecting the external unit, you need to find out the type, capacity and charging current of the power supply. The information is indicated on the manufacturer’s label located on the battery can case. If the sticker is lost, then you will need to open the casing and find out the operating parameters by marking on the elements.


To replenish the capacity, it is possible to connect an external charger via a self-installed USB port. It is recommended to use adapters designed for a current of 5-7 A. It is not recommended to use computers or laptops to supply current, since the increased current in the circuit overheats the controller and destroys the unit.

Algorithm for equipping a screwdriver battery with a USB connector:

  1. Dismantle the battery can, and then separate the sections of the case (the elements are held by screws and additional plastic clamps).
  2. Cut a hole in the housing section to accommodate the USB connector. The port installation location should not interfere with the placement of the power source in the tool handle or in the standard charging station. The channel configuration depends on the appearance of the prepared plug. The block is installed in the resulting socket and fixed with a special hot melt glue.
  3. Place a 10 A fuse in the circuit connecting the standard charging controller and the USB connector. Hot glue is used to secure the protective element and wiring. The cables are connected by soldering with lead-tin solder, the fixing points are protected with insulating materials.
  4. Connect the body sections using the standard screws. If a one-piece structure was cut, then the line of the joint is covered with a strip of cloth or masking tape coated with liquid epoxy. After the material has solidified, the surface is sanded and painted in the color of the battery can case.
  5. Conduct a test charge of the DC power supply. Since the voltage in the charging circuit is 5 V, it takes up to 6-8 hours for batteries with a capacity of 1-2 Ah to replenish the capacity.

Using a car charger

Using a charger designed to service a 12-volt car battery can permanently damage the power source for your power tool.

Before connecting the devices, it is necessary to bring the charging operating parameters to the required requirements.

If the equipment is equipped with stepless voltage and current regulators, then it is required to set the parameters identical to the standard unit. To reduce the current load, a ballast resistor is used (for example, a car side light bulb).

If the information on the operating parameters of the standard charging is unknown, then for a 1.3 Ah nickel-cadmium battery, the charging current is set within 50-100% of the nominal capacity. The voltage is set to the minimum level. Then the polarity of the battery bank is determined (according to the factory marking), the location of the minus and plus, if necessary, is specified by the test device.

For measurements, it is necessary to drill the plastic cover of the can and install a sensor inside (for example, from a household test device). Depending on the current parameters, charging lasts from 30 minutes to 2 hours, when the threshold temperature is reached, the external unit turns off.

Methods for charging a screwdriver without a charger

To carry out quick repairs, disassemble and collect removable structures, a non-stationary device is used, which is discharged in a short period of time with continuous use. There is not always a native charger at hand, so you need to know how to charge a screwdriver without a charger.

  1. Safety and Precautions
  2. How to charge a screwdriver battery without a charger
  3. Via USB
  4. Using a car charger
  5. Universal chargers
  6. Using an external current source


To equip the device with a USB connector, you must prepare:

  • Scotch;
  • Fuse for 10 A;
  • Paint;
  • Socket 220 V;
  • USB charger;
  • Electrical tape;
  • Soldering iron;
  • Connectors.

First, disassemble the screwdriver. The working part of the handle is removed from above using a knife. The fuse is installed in a hole that is made in the case. The wire is soldered to the fuse and the resulting structure is inserted into the handle. You can use a heat gun to fix the parts.

Universal chargers

To charge the screwdriver, a special universal device is purchased with which you can also charge other equipment powered by batteries. This can be a mobile device or a laboratory source. This type of device has the advantages. Versatility and a large number of adjustments designed to select a suitable charging mode. The battery recovers in 1 hour. The package includes crocodile clips and adapters for common connectors.

Using a car charger

The main disadvantage of charging with a car charger is battery overflow. The battery in the power tool differs from the lead car battery in its characteristics.

To restore the charge, a device with an electronic voltage and current regulator is used. With a battery capacity of 1.3 Ah, 150-650 mA are set.

The device for a car battery is used to work with high rates of charging current, and the required indicator for charging a screwdriver may be outside the scope of its operation. To limit the current, a ballast resistance is needed. A 12 V lamp, which is included in the circuit along with the battery. Without this part, it is not recommended to use this method of restoring the battery charge.

Then the device is connected to the network and the process of restoring the battery capacity is monitored. It will take 15-20 minutes to get started. When heat dissipation occurs in a charged screwdriver battery, the charger is turned off.

Safety and Precautions

When using any method of charging the device, you must be careful and observe the following precautions:

  1. Observe the process. When the battery is full of energy, the procedure is stopped. Otherwise, overfilling the battery can lead to boiling of its electrical components. When the temperature rises sharply, a small spark will cause the entire structure to explode.
  2. All parts must be correctly connected to the circuit. During assembly, the technical parameters of the device are strictly taken into account, ensuring the safety of the procedure and observing the polarity. Do-it-yourself chargers can completely damage the battery, excluding the possibility of its recovery in the future.
  3. The battery is charged in a short period of time with small differences in the characteristics of the modules (10-12 Volts)

How to charge a screwdriver battery without a charger

They do without memory when:

  • Mounting the USB connector;
  • Using a car charger;
  • Using a universal charger;
  • The use of third-party electrical equipment.