How many amperes does a 12 volt screwdriver consume?

The charge voltage should be monitored with a multimeter or a circuit with a voltage comparator tuned exactly to the battery being used. But for “entry-level electronics engineers”, you can really only offer a simple and reliable scheme, described in the next section.

Battery types

Batteries are not of the same type and may have different charge modes. Nickel-cadmium (Ni-Cd) batteries are a very good source of energy, capable of delivering high power. However, for environmental reasons, their production has been discontinued and they will be encountered less and less frequently. Now, lithium-ion batteries have replaced them everywhere.

Sulfuric acid (Pb) lead gel batteries have good characteristics, but they make the instrument heavier and therefore are not very popular, despite the relative cheapness. Since they are gelatinous (a solution of sulfuric acid is thickened with sodium silicate), there are no plugs in them, the electrolyte does not flow out of them and they can be used in any position. (By the way, nickel-cadmium batteries for screwdrivers also belong to the gel class.)

Lithium-ion batteries (Li-ion) are now the most promising and advanced in technology and on the market. Their feature is the complete tightness of the cell. They have a very high power density, are safe to use (thanks to the built-in charge controller!), Are beneficially disposed of, are the most environmentally friendly, and have low weight. In screwdrivers, they are currently used very often.


The charger below provides the correct charging current for any of the listed batteries. Screwdrivers are powered by batteries with different voltages of 12 volts or 18 volts. It doesn’t matter, the main parameter of the battery charger is the charge current. The voltage of the charger when the load is disconnected is always higher than the rated voltage, it drops to normal when the battery is connected while charging. During the charging process, it corresponds to the current state of the battery and is usually slightly higher than the nominal at the end of charging.

The charger is a current generator based on a powerful composite transistor VT2, which is powered by a rectifier bridge connected to a step-down transformer with sufficient output voltage (see table in the previous section).

This transformer must also have sufficient power to provide the required current for continuous operation without overheating the windings. Otherwise, it may burn out. The charge current is set by adjusting the resistor R1 when the battery is connected. It remains constant during the charging process (the more constant, the higher the voltage from the transformer. Note: the voltage from the transformer should not exceed 27 V).

Resistor R3 (at least 2 W 1 Ohm) limits the maximum current, and the VD6 LED is on while the charge is in progress. By the end of the charge, the LED light decreases and it goes out. However, do not forget to accurately monitor the voltage of lithium-ion batteries and their temperature.!

All details in the described scheme are mounted on a printed circuit board made of foil-coated PCB. Instead of the diodes indicated in the diagram, you can take the Russian diodes KD202 or D242, they are quite available in the old electronic scrap. It is necessary to arrange the parts so that there are as few intersections as possible on the board, ideally none. You should not get carried away with the high density of installation, because you are not assembling a smartphone. It will be much easier for you to unsolder the parts if 3-5 mm remain between them.

The transistor must be installed on a heat sink of sufficient area (20-50 cm2). All parts of the charger are best mounted in a handy homemade case. This will be the most practical solution, nothing will interfere with your work. But here great difficulties can arise with the terminals and connection to the battery. Therefore, it is better to do this: take an old or faulty charger from friends, suitable for your battery model, and rework it.

  • Open the case of the old charger.
  • Remove all the former stuffing from it.
  • Pick up the following radioelements:
Pos. Description
VD1-VD4 1N4001 rectifier diode
VD5 diode
VD6 VD6 LED, red or green, any type
C1 C1 K50-35 or similar 220-1000 mF from 50 V
C2 C1 K50-35 or similar 220-1000 mF from 50 V
R1 variable resistor 10 kohm, preferably wirewound
R2 resistor MLT-0.25 330 Ohm
R3 resistor MLT-2, 1 Ohm
VT1 transistor KT361V, G
VT2 transistor KT829V (installed on a radiator square 20. 50 sq. cm
T1 Power transformer 220 V / 24 V, power 100 W
  • Choose a suitable size for a printed circuit board that fits into the case along with the details from the given diagram, draw with nitro paint its tracks according to the schematic diagram, etch in copper sulfate and unsolder all the parts. The radiator for the transistor must be installed on an aluminum plate so that it does not touch any part of the circuit. The transistor itself is tightly screwed to it with a screw and an M3 nut.
  • Assemble the board in the case and solder the terminals according to the scheme, strictly observing the polarity. Lead out the wire for the transformer.
  • Install the transformer with a 0.5 A fuse in a small suitable housing and provide a separate connector for connecting the converted charging unit. It is best to take connectors from computer power supplies, install dad in a case with a transformer, and connect mom to the bridge diodes in the charger.
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The assembled device will work reliably if you have carefully and carefully performed

Watt to ampere converter

Electrical systems often require complex design analysis as many different quantities need to be handled, watts, volts, amperes, etc. In this case, it is precisely necessary to calculate their ratio at a certain load on the mechanism. In some systems, the voltage is fixed, for example, in a home network, but power and current mean different concepts, although they are interchangeable quantities.

Online calculator for calculating watts to amperes

To obtain the result, it is imperative to indicate the voltage and power consumption.

In such cases, it is very important to have an assistant in order to accurately convert cotton wool to amperes at a constant voltage value.

An online calculator will help us convert amperes to watts. Before using the online program for calculating quantities, you need to have an idea of ​​the meaning of the required data.

  • Power is the rate at which energy is consumed. For example, a 100 watt light bulb uses energy. 100 joules per second.
  • Ampere. the value of measuring the strength of the electric current, is determined in coulombs and shows the number of electrons that have passed through a certain cross-section of the conductor for a specified time.
  • In volts, the voltage of the flow of electric current is measured.

To convert watts to amperes, the calculator is very simple to use, the user must enter the voltage indicator (V) in the indicated columns, then the power consumption of the unit (W) and press the calculate button. After a few seconds, the program will show the exact current reading in amperes. Formula how many watts in ampere

Attention: if an indicator of a quantity has a fractional number, then it must be entered into the system through a period, not a comma. Thus, the power calculator can convert watts to amperes in a matter of time, you do not need to write complex formulas and think about their re

sheniya. Everything is simple and affordable!

Values ​​table Ampere and load calculation table in Watt

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How many amperes in a 12 volt screwdriver

A friend asked me to assemble an external power supply for a screwdriver. Together with a screwdriver (Fig. 1) I brought a power transformer from the old Soviet burner-engraver “Ornament-1” (Fig. 2). see if it can be used?

First, of course, we dismantled the battery compartment, looked at the “banks” (Fig. 3 and Fig. 4). We checked each “jar” for performance with a charger with several charge-discharge cycles. out of 10 pieces, only 1 was good and 3 were more or less normal, and the rest were completely “dead”. So, you will definitely have to make an external power supply.

How to test an alternator the right way!

To assemble a power supply, you need to know what current the screwdriver consumes during operation. By connecting it to a laboratory source, we find out that the motor starts to rotate at 3.5 V, and at 5-6 V a decent power appears on the shaft. If you press the start button when 12 V is supplied to it, the protection at the power supply is triggered, which means that the current consumption exceeds 4 A (the protection is set to this value). If you start the screwdriver at a low voltage, and then increase it to 12 V, it works fine, the current consumption is about 2 A, but at the moment when the screw to be screwed in half enters the board, the protection at the power supply is triggered again.

To see the complete picture of the consumed currents, the screwdriver was connected to a car battery by placing a 0.1 Ohm resistor in the positive wire break (Fig. 5). The voltage drop from it was applied to a computer sound card with an open input; the SpectraPLUS program was used for viewing. The resulting graph is shown in Figure 6.

The first impulse on the left is the starting impulse when turned on. It can be seen that the maximum value reaches 1.8 V and this indicates a flowing current of 18 A (I = U / R). Then, as the engine revs, the current drops to 2 A. In the middle of the second second, the screwdriver head is clamped by hand until the “ratchet” is triggered. the current at this time increases to about 17 A, then drops to 10-11 A. At the end of 3- her seconds the start button is released. It turns out that for the screwdriver to work, a power supply is required with the ability to deliver power of 200 W and a current of up to 20 A. But, given that it is written on the battery compartment that it is 1.3 A / h (Fig. 7), then, most likely. everything is not as bad as it seems at first glance.

We open the burner power supply unit, measure the output voltages. The maximum is about 8.2 V. Not enough, of course. Taking into account the voltage drop across the rectifier diodes, the output voltage across the filtering capacitor will be about 10-11 V. But there is nowhere to go, we are trying to assemble the circuit according to Figure 8. The diodes are of the KD2998V brand (Imax = 30 A, Umax = 25 V). The fastening of the VD1-VD4 diodes is carried out by hinged mounting on the petals of the burner contact sockets (Fig. 9 and Fig. 10). Parallel connection of 19 pieces of smaller capacity was used as a large-capacity capacitor. The entire “battery” is wrapped in masking tape and the capacitors are sized so that the entire bundle can be easily inserted into the battery compartment of the screwdriver (Fig. 11 and Fig. 12).

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The safety block is very inconvenient in the burner, so it was removed, and the fuse was soldered “directly” between one of the 220 V wires and the output of the interference suppression capacitor C1 (Fig. 13). When closing the case, the power cable is tightly crimped with a rubber ring and this does not allow the wire to dangle inside when bending it from the outside.

Checking the performance of the screwdriver showed that everything is working fine, the transformer, after half an hour of drilling and screwing the screws, heats up to about 50 degrees Celsius, the diodes heat up to the same temperature and do not need radiators. A screwdriver with such a power supply unit has less power compared to powering it from a car battery, but this is understandable. the voltage across the capacitors does not exceed 10.1 V, and as the load on the shaft increases, it further decreases. By the way, it is decently “lost” on a supply wire with a length of about 2 meters, even using its section of 1.77 sq. Mm. To check the drop on the wire, a circuit was assembled according to Figure 14, in which the voltage across the capacitors and the drop voltage on one conductor of the supply wire were monitored. The results in the form of graphs at different loads are shown in Figure 15. Here, in the left channel. the voltage across the capacitors, in the right. the drop on the “minus” wire going from the rectifier bridge to the capacitors. It can be seen that when the screwdriver head is stopped by hand, the supply voltage sinks to levels below 5 V. At the same time, about 2.5 V (2 times 1.25 V) drops on the power cord, the current is of a pulsed nature and is associated with the operation of the rectifier bridge (fig. 16). Replacing the power cord with another one with a cross section of about 3 sq. Mm led to an increase in the heating of the diodes and the transformer, so they returned the old wire back.

We looked at the current in the circuit between the capacitors and the screwdriver itself, having assembled the circuit according to Figure 17. The resulting graph is in Figure 18, “shaggy” is a ripple of 100 Hz (the same as in the previous two figures). It can be seen that the starting pulse exceeds 20 A. most likely, this is due to the lower internal resistance of the power supply due to the use of parallel connection of capacitors.

At the end of the measurements, we looked at the current through the diode bridge, connecting a 0.1 Ohm resistor between it and one of the terminals of the secondary winding. The graph in Fig. 19 shows that when the motor is braking, the current reaches a value of 20 A. In Fig. 20. a section with maximum currents stretched over time.

As a result, while we decided to work with a screwdriver with the described power supply, if there is “not enough power”, then you will have to look for a more powerful transformer and put diodes on radiators or change to others.

And, of course, you should not take this text as a dogma. there are absolutely no obstacles to making a power supply unit according to any other scheme. For example, the transformer can be replaced with TC-180, TCA-270, or you can try to power the screwdriver from a computer pulsed power supply, but most likely you will need to check the possibility of returning a 12 V circuit with a current of 25-30 A.

The topic of powering a cordless screwdriver from a 220 V network has already been partially discussed on this site. It was told about how to choose a power supply for a specific model of a cordless screwdriver, and tests for tightening screws were shown. Measurements of the current consumed by the screwdriver in various operating modes were not presented. This will be discussed further.

We will test the same screwdriver:

It will be powered by the same power supply:

First, we measure the no-load current at slow speed:

On the left, the current values ​​in Amperes, on the right, the voltage in Volts.

Then the no-load current at fast speed:

Now we measure the current at maximum load when the ratchet is triggered:

In the photo, the steady-state value, although the short-term throws slightly exceeded 6A. The power supply protection did not work. Affected by the resistance of the wires with which the screwdriver is connected to the power supply (about 2m).

When you turn the torque regulator to the maximum and maximum load, when the ratchet no longer works, the motor stops, the current reaches almost 10 A and the power supply is turned off. This is an invalid mode of operation.

A 220 volt homemade generator. DIY Bike Generator

But, a stopped motor for a power supply is practically a short circuit. As you know, the short-circuit current of a stopped motor is determined by the purely ohmic resistance of the winding and can reach very high values ​​until the protection of the power supply is triggered. If the power supply is powerful and its protection is triggered at currents of 20-30 A, then the motor winding wire will burn out. As indicated in the previous article, the maximum motor current of this model of a screwdriver is 4 A, the diameter of the wire of its winding is about 0.5 mm.

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A current of 10 A is already more than twice the permissible, not to mention currents of 20-30 A.

The conclusion is the same, there is no point in 20-30 A power supplies for powering screwdrivers whose motor is designed for a maximum current of 4A. Do not operate the screwdriver by loading it until the engine stops by turning off the ratchet.

If the motor of the screwdriver is of a different, higher power, for high currents, then you need to select a power supply for it.

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consumption in amperes.

how scary to live.

I just encoded a video on a Core i7: the difference under / without load. 80 watts (CUDA is not involved, everything counts as a percentage).

10-14 nm probably will not warm at all and the current is minimal

It will be under load, I think. There the maximum temperatures are lower, there will be throttling.

Who’s minus something?

The non-gaming laptop Thinkpad i7-2640M has a 4.5A / 20V adapter. And more modern ones. generally 2.3A (for Core M 5, but there is also cooling.passive).

Not the most voracious stone, there is a 9 series.

What’s the difference between them?

9 are essentially the same as 83 only with high factory overclocking

about 6-10 is usually supplied from the motherboard for most processes, regardless of the manufacturer, but why do you need to know the amperages? It is more useful to know all the same heat transfer in cotton wool

The maximum heat dissipation is divided by the maximum voltage on the core. you get the maximum current consumed by the processor.

Great idea, but no

Did you enclose a museum there? The bugs didn’t fuck you up, that you put up a roof for them and put wires into the hut?

FX8300. ask the tractor driver about overclocking!

Wow, on a 12 Volt mowing line, as it should be, 12 Volts! What is the meaning of this video? The current consumption is important, not the current strength, the current strength can be whatever you want, reduce the resistance or increase the power.

How many amperes does the processor consume!

About amperes, volts (thoughts)

I will not go into the jungle of physics and explain in simple language

The effect of the current on the body is complex and it makes no sense to take into account only one of its parameters. The classic version of the lethal current is an alternating current with a frequency of 50-60 Hertz, a voltage above 36 Volts and a current strength of 0.1 Ampere. With a decrease in voltage, the current may simply not flow through the body, which, as is known, has its own resistance, with an increase in voltage, but with a small current strength, an electric shock can also do without consequences. Direct current is less dangerous than alternating current, but with an increase in the frequency of alternating current, its dangerous effect decreases and high-frequency currents are used even in medicine. It is believed that Ampere is killing, but the rest of the physicists do not remain on the sidelines.

The impact of electric current on each person is individual. But it is generally accepted that the current strength, expressed in amperes, can be lethal. For the onset of death, 0.1 Ampere is enough, at a voltage of 36 Volts.

And for individuals, as in this comment:

There are various ways of calculating, and for the lazy, they even reduced it to tables

and at least once you were interested to know why stun guns do not kill?

I found a lot of interesting things on the net:

Company “Taser” declares that for some models of produced shockers they have the following parameters:
-pulse current,
-each pulse with a total length of about 120 microseconds,
-pulse repetition rate. 20 times per second,
-the frequency of the current inside the pulse. 10 kilohertz,
-current strength in the first period of the pulse. up to 3 Amperes, then. fades out very quickly.

To make it mean?

-the impulses are too short to cause fatal changes,
-frequency. too high to create a high current density through the internal organs (obviously selected to affect only the motor muscles on the surface of the body),
-impulses are inconstant, and decaying

Plus, shocker electrodes are never applied to different ends of the body. Therefore, if you do not try to specifically interfere with the structure, kill them. quite difficult.

Have you ever wondered why the police do not use shockers when it rains?

If it is interesting, I will try to write in more detail.