How to turn a cordless electric screwdriver into a cordless power tool
Cordless power tools have supplanted the conventional corded tool even from niches where it seemed impossible just a few years ago. Handy, light, mobile, but powerful and productive drills, circular saws, electric grinders, and, of course, screwdrivers with the development of technology and the appearance of new batteries have taken their place in the toolbox of home masters and in industry. But in some cases it is necessary to reverse. Conversion of battery-powered devices for power supply from 220 volt household voltage. How to make an electric screwdriver powered from the mains and what you need to buy for this. about all this below.
The main reason for converting a portable cordless electric screwdriver into a corded one is that the resource of the mechanical part of the power tool is much higher than that of the battery. When the battery (or a set of batteries) finally fail, the electric screwdriver can work for a long time, but it is difficult to buy new batteries for various reasons. For example, such a model is no longer in production, and to pick up a battery of the same form factor is impossible. there is no unified installation standard for different manufacturers. Batteries can also get lost, fail prematurely because of careless handling, etc.д.
If the batteries are still functional, but have poor charge capacity, the work turns into a torment. And sometimes in stationary conditions it is more convenient to connect the tool to the mains than to spend time charging the battery. In all of these cases, the life of an electric screwdriver can be extended by converting it to 220v power. You can do it with your own hands.
What you can build a power supply with
The power supply for charging an electric screwdriver can be made according to different schemes. It all depends on qualification, availability of tools and materials.
From a computer power supply
A good power supply for an electric screwdriver with 12 volts can be obtained from a PSU for a computer. First you need to check that it has the right rating.
In this example, the power supply has two 12-volt channels, one for 11A and one for 13A. 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 the total current (24A in this case). It is not recommended to do this, because of the voltage difference one channel can become a consumer for the other. all the risk is up to the owner’s choice. There is a trail of wires coming out of the power supply. You have to cut everything but:
Sometimes you have to leave the red wire as well. some circuits require a base load. To do this, connect a 12 volt bulb between the red one and any black one. If the PSU does not turn off in its absence, it can be removed. 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 illustration. Such a device consists of:
If there is a commercially available transformer, you need to find its data in the reference book. If they are good, you can build a PSU with it. If not, it can be rewound, having first checked its suitability for the required conditions. The suitability of the transformer is determined by its power. If you have an output current of 10A, a voltage of 14V and a system efficiency (from the transformer to the output shaft of the electric screwdriver) of 0.5, you need a transformer with a power of P=10A14V/0.5=280W (we can round up to 300W).
To determine the iron power of your transformer, you need to find the cross sectional area of its core in centimeters (in most cases you can get the dimensions without disassembly). The resulting area in square centimeters Sc should be put into the formula:
If the result is more than 300 W, the transformer is suitable for making a power supply. Then remove all secondary windings and wind a new one. The number of windings can be determined experimentally. For this you have 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 have to wind 28 turns. For 10 amps the wire cross section should be at least 2.5 kV.mm, this corresponds to a thickness of 1.8 mm.
After making the transformer you have to choose diodes, which are able to work with the selected current. They should 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 μF (more is possible, but the dimensions will increase). For such applications, a transformer power supply turns out to be quite bulky and heavy.
It can be supplemented with a voltage regulator, then it will maintain torque at any load (but this is not necessary. because in normal mode, the batteries also sag at high current).
It is possible to assemble the stabilizer on the integrated circuit of 78ХХ series (79ХХ for the negative arm), recharging it with an external transistor.
Important! A linear regulator works with a certain excess of input voltage before the output voltage, so in this case you need a transformer with an output voltage of 17.18 volts. The overall capacity should also be increased, because the overall efficiency of the circuit will be lower. This must be considered when selecting or making one.
The finished source must be placed in an enclosure. You can make one yourself or find a ready-made one.
From a laptop computer
You can get a good result using a laptop power supply. Such devices are designed for an output voltage of 19 volts and different load currents. You can choose the source with output current up to 6 amps, this is enough for most household chores. Do not overload such source. will trigger protection or self-resetting fuse on the input (it does not always regenerate on its own, and will have to be replaced).
Universal power supply
Adjustable 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 tool, either 12V or 18V. The problem is that it’s hard to find a lab voltage source rated for 10A output current. So, the unit shown in the photo for each channel has a current limit of just over 3A. The voltage at this is about zero, so the electric screwdriver can’t operate in this mode. This power supply will provide idle running of the power tool at best.
Switching power supply
The best option is a switching power supply. Lightweight, compact, does not contain a powerful heavy transformer due to the fact that the voltage level conversion occurs at a higher frequency. The disadvantage of such a solution. complicated circuitry. To make a pulser with your own hands, you need a certain skill.
How long the screwdriver has existed, it is never used in the same conditions. in one case the battery is enough for all work, in another. it is necessary to constantly recharge it. That’s why all modern models are divided according to the original battery capacity, and therefore cost. into household and professional.
Screwdrivers are equipped with 3 types of batteries:
- Nickel-cadmium. The most common type of battery. Characterized by small size, high capacity and reasonable cost. The number of charging cycles under good operating conditions can exceed 1,000. The main disadvantages are the memory effect, which reduces the capacity, and the harmful production, for which reason many manufacturers no longer produce it.
- Nickel metal hydride. The newest battery generation. Characterized by less memory effect and harmless production, but require constant maintenance of the charge, otherwise a full recharge will be required. In addition, they have a high self-discharge current.
- Lithium-ion. Batteries that have no memory effect at all. Are characterized by fast charging and maximum capacity. However, they are also not without disadvantage. the inadaptability to work at low temperatures and quite high cost.
Important! Lithium-ion batteries must not be allowed to run out completely as this would cause the safety system. As a result, the device will overheat while charging and can simply burn out.
Power supply for an electric screwdriver with your own hands
In order to perform the conversion of a cordless electric screwdriver into a network screwdriver, you must first make a step-down transformer. It is made on the basis of the one that was used in TVs of older models. When the electric screwdriver is powered by an electronic transformer, the transformer must be rated at 160 W. In order to prepare one that is needed for a screwdriver, you need to do the following:
- The prepared transformer should be dismantled.
- The secondary winding must be completely removed.
- You need to wind ten turns.
- Now the transformer is ready, all that’s left is to assemble it.
- Next you need to measure. Now connect it to the network and measure the voltage obtained on the secondary winding. Now the number of turns, which in this case is ten, divide by the voltage now measured. Multiply the obtained value by the required voltage for the instrument, and obtain the number of required turns.
- Now disconnect the transformer from the mains and reassemble it and wind the required number of turns. It must then be assembled.
For the winding take a wire with a cross section of 1 sq. mm.
After the current has passed through the transformer the output will be alternating voltage. The circuit diagram of the power supply for an electric screwdriver provides that in order to get the DC from it, you will need to make a diode bridge. It is made with diodes on heat sinks rated at 20V and 10A.
The converter made in this way is placed in the housing. At its output will be obtained the voltage that is necessary for the operation of the screwdriver. The input will be the mains voltage of 220 V.
Wires coming from the PSU are connected to the pins that power the tool.
Such a power supply for an electric screwdriver from the mains is usually installed in the housing, where previously was a battery cell.
Converting an electric screwdriver to mains power
A screwdriver is a tool designed for screwing screws and drilling small diameter holes. There are mains-powered, powered from 220 V and rechargeable, with two removable batteries.
If the battery in such devices fails, there are three options:
- battery replacement is expensive, in a budget-class machine, the price of the kit is close to the cost of a new machine;
- repair is not always possible, and in some cases its cost is comparable to the cost of new batteries;
- electric screwdriver conversion to a cordless screwdriver.
In this article it is told about how to implement the power of an electric screwdriver from the mains 220v, or how to make a cordless screwdriver network.
1997 NiCd Cordless Screwdriver Teardown (It still works after 20 years!)
Electric screwdriver device
This mechanism consists of the following parts:
- DC motor. Cylinder shaped, with permanent magnets in the housing instead of an excitation winding. This simplifies the design and provides sufficient torque at low speeds. On the shaft of the electric motor is attached to the driving (solar) gear of the planetary gearbox;
- Reversible speed controller. Control circuit is built on a PWM controller and a field-effect transistor. Reverse is carried out by switching the polarity of the power connection to the motor brushes;
- Planetary reduction gears. Made in a separate housing. Got its name because of its resemblance to the solar system. Consists of a ring gear, central (solar) pinion, satellites, and a driver. Ring gear transmits power through springloaded balls. Available with two-speed gearboxes. Increased speed is enabled when using the device as a drill;
- Torque limiting mechanism. Designed to limit the torque of screws. Transmits torque through balls pressed by an adjustable spring;
- Removable battery. Consists of separate elements in one housing. Different models have voltages from 9 to 18 volts.
Electric screwdriver battery design
Electric screwdriver conversion to lithium 18650 batteries
Battery design is brand-independent. In all devices, the design of batteries is similar and differs in appearance, housing and contacts.
In the case there are several cells connected in series. Their number depends on the voltage of each cell and the battery as a whole. If you use the most common, nickel-cadmium cells with a voltage of 1.2 volts, to supply the unit rated 12V you need 10 pcs. Battery capacity is specified in ampere hours.
Interesting. When connected in series, the output voltage increases, but the capacity does not change and is equal to the capacity of the individual cells.
Types of rechargeable cells
Power supply for an electric screwdriver 12v with their own hands
In these devices, elements of different types and voltages are used, each of which has its own advantages and disadvantages.
The most common. nickel-cadmium (Ni. Cd) with a voltage of 1.2V.
How to Repair a weak Drill / Screwdriver / Battery runs out quickly
progressive nickel-metal hydride (Ni-MH) with the voltage of 1.2V.
The most advanced lithium-ion (Li-Ion) 3.6V.
- The lack of memory effect;
- Very low self-discharge current;
- high specific capacity, allowing to reduce the weight and dimensions of the device;
- many times more charge/discharge cycles than other types of batteries.
Converting an electric screwdriver for 220 V mains power
If the battery fails and it is impossible to repair it, the only way out is to convert a cordless electric screwdriver to a mains one.
In this case, the power of the power supply unit must exceed the power of the motor, taking into account possible overloads at the moment of completion of twisting.
it is not specified in the passport of the device, but this parameter is written on the case of the electric motor, or it can be calculated by connecting the device to a constant voltage source through an ammeter.
A 120 watt power supply is sufficient for a 70 watt motor.
Important! The charger capacity is insufficient for its operation. When converting a cordless screwdriver to a 220 volt mains screwdriver, you must use a different power supply.
Using an external power supply
External power supply has larger dimensions than the built-in, but in any case, if you power the electric screwdriver from the mains, the tool will be “tied” with a wire to the socket.
The current from the power supply reaches 10-15A, so the cross section of the cable must be at least 1mm².
Interesting. You can power a screwdriver from an old car battery or from a car, through the cigarette lighter socket.
Computer power supply
The easiest and cheapest option is to use the power supply from an old computer with at least 300W and a current of 15A.
The old units had a switch, the modern ones have to be switched by shorting the wires to the appliance in order to turn it on. The color of these wires depends on the model. You can find this out on the internet or by fitting.
The 12V output is in the four-pin connector: black “-“, yellow “”.
Such devices have a built-in fan, so when you make a case for it, you need to make holes or install the fan outward. It is best to simply hide the extra wires inside the enclosure.
Important! A 14.4 or 18 volt screwdriver will operate on reduced power.
Charger for car battery
The requirements for this device are the same as when using a computer power supply.
If available, a device with a built-in voltmeter and voltage regulation is desirable. Some models have a current-limiting resistor inside. It must be shorted.
How to make a homemade power supply
In addition to the purchased power supply you can make your own. For this you need a 160W transformer, such as used in tube televisions.
Work with hand tools can be performed in the building where there is no electricity. In such cases, the device is connected to the car battery or any other power device that is suitable in terms of parameters for the work of the screwdriver.
To connect the car battery, you need to take the wires with clips “crocodile”, bare one end and solder directly to the contacts of the electric motor of the tool. The other end is clamped to the battery terminals, observing polarity.
The portable battery is connected in the same way as a car battery. Only the ends of the wires are fitted with copper clamp terminals that are suitable for attachment.
Electric tools last much longer than cordless tools. That’s why you shouldn’t throw the screwdriver away when the batteries have run out. The handy man can convert his power tool to mains power, thereby prolonging its life.
An electric screwdriver is useful because of its omnipresence. independence from limiting wires makes it possible to get into hard-to-reach places. Set of two power modules allows you to power one while working with the other. However, each battery pack has a finite number of charge/discharge periods, failing once they are used up. In low-cost tools, units break faster, and the user receives a gadget with a functioning motor, but without power. This is when the dilemma arises of “can an electric screwdriver be plugged in directly to a charger?”.
To feed such an electric screwdriver can be connected to the mains through the power hub, because its motor runs at 220 volts.
After converting the device to mains power, it is necessary to observe the rules of safety and operation:
- Observe device breaks every 30 minutes to extend the life of the device and avoid malfunctions.
- It is not recommended to work higher than two meters.
- It is important to periodically clean the unit’s power supply of dust.
- Check the condition of the power cable. It shouldn’t be overstretched or exposed to moisture and other negative factors. Ignoring this rule may cause the device to short circuit.
If these simple guidelines are followed, the old screwdriver will last longer than the new one, while maintaining its power and ease of use.
Battery cell types
In these devices, cells of different types and voltages are used, each of which has its own advantages and disadvantages.
The most common are Ni-cadmium (Ni. Cd) 1.2V.
advanced 1.2V nickel-metal hydride (Ni-MH) batteries.
The most advanced lithium-ion (Li-Ion) 3.6V.
- no memory effect;
- very low self-discharge current;
- high specific capacity, allowing you to reduce the weight and size of the device;
- Many times more charge/discharge cycles than other types of batteries.
Комментарии и мнения владельцев 154
Hello. I have a very cheap cordless screwdriver with a dead battery that my son used to play with. I want to reanimate for the house to put the electric screwdriver in the case in the garage. Please tell me who knows how to correctly replace the battery in a cordless screwdriver Bort. www.494911.ru/products_pictures/big/5560002_2.jpgFor the sake of trying I ordered the battery from ru.aliexpress.com/item/32269518.104.22.168f37eaOhkzBY and the charge module TP4056 ru.aliexpress.com/item/32269522.214.171.124ce7574qIOcS0 Can you tell me if the components are good enough to replace a dead battery? Maybe something is missing?
5200 divide by two, it will be more or less true. Don’t even get me started on ultras and other phasers, check out the reviews, good LG or Soni will cost a lot more. Do I have to take the batteries out to charge them every time?? if so, it’s a total shkvkar however.
I agree with the opinion that you can not do that. But I did something similar five years ago, but I didn’t buy batteries, I soldered three of them from my laptop. All control-digital volt meter, charging gives 12.2 volts, no BMC, but it takes a long time to charge.Since I use this gamble rarely batteries are still alive, but I keep them in a bucket with sand, as you are advised.
And now count the difference in price between the kolhoz and the purchase of a new Diold 12 volt screwdriver. Or similar.And buying a new one is also no problem and does not require study of the parts!
There is a nuance. and where to dispose of old screwdrivers?After I began to see that the third screwdriver to buy cheaper than the battery to one, the spouse said we need to decide something.
By the service of a shaft of computer b / p. so do not even bother, switched to a cable.
Now come the talkers. but I like the option. For desktop work is great, and repairs of the ceilings are not expected 🙂
Used screwdrivers to be scrapped or sent to workshops for spare parts.As for the power supply from the computer good solution, this is fully supported. Even if you buy a new power supply it would be cost effective.In this case, the cost of the batteries, plus charging them, plus the hassle of charging them, etc.д. It’s not worth it.I had a 20.5V 97NT screwdriver from 2003. In 2013, the charger died, on sale is simply not available, assembled me the technicians for cheap. In 2015, finally died last battery, on sale there are no such. And that’s when I also thought about changing the cans inside. But weighed all the pros and cons, as well as analyzing the need for such power, came to the conclusion that the hell it is not necessary. As a result, in the spring of 2015 bought a screwdriver to 220V Zubr for 1900r. Five meters of cord is enough to work anywhere, and 35 Newtons for most jobs more than enough! The old screwdriver turned in a nearby shop for free.
Almost everything is wrong, but we do live in a free country? So why not?(About the country. just kidding) Комментарии и мнения владельцев have not read, and so I guess what they say, without bms bad, but will do. I don’t feel sorry for other people’s batteries, especially for 9800? Give or take a zero on the label, doesn’t matter.But as far as I know, now a maximum of this form factor can be removed 3500, and they do not cost 200rub. Well and it is clear that this is not ultra fire)))) To take out and charge you can of course, especially when charging all sorts of lights blinking. Fascinating.Accumulators are not high-current, but the two circuits are paralleled. whatever, the chance that pythnut small, and pythnut not sorry.But the springs on the boxes can quickly become a cause of trouble. the springs are shabby, under some load will be heated, will be released and there will be very bad contact. Well only the plastic will melt, but will catch fire? It is necessary to check constantly. And do not let pets and children under 3 years old use it.You don’t have to worry about thin wires against the background of box springs. when they melt, the boxes will already be burnt out.Bottom line. Come on, if you want to, but the load to give accurately, x.з. when and what happens.I would double the budget and do it reliably and not have to come back to this issue for several years.