How to check the battery capacity of an electric screwdriver with a multimeter

Let’s check the indicators under load

This means that we will check how long the battery of an electric screwdriver will be fully discharged if you connect an additional load to it. for example, a light bulb.

The load level should be selected according to the capacity of the battery. If it is not listed in the instruction manual, you must calculate it yourself. It is half the current absorbed by the battery while working, multiplied by the U of the power supply. Usually it is between 35 and 40 watts, which means that a 35-watt car headlight or a 12-volt light bulb can be a load.

To read the battery you need to connect to the lamp through the ammeter, and the readings themselves take a voltmeter. Connection time is two to three minutes, then we measure the U. If it is less than 12.4 volts, some kind of “bank” is definitely out of order. Also about the malfunction of the battery can also indicate a significant decrease in the brightness of the light bulb. If it quickly goes out in two to three minutes, the battery is clearly not in order, and its capacity is very low.

Types of rechargeable batteries

Depending on the design of the materials used in the manufacture, the most common types of rechargeable batteries are:

  • Lead-acid. used in cars, motorcycles, mopeds, scooters. They are also used in UPSs (uninterruptible power supplies), used to store energy generated by wind turbines, solar panels.
  • Lithium-ion batteries are small, durable and reliable, and are used in cell phones, photo and video equipment, construction tools and electric cars.
  • Nickel-cadmium and nickel-metal hydride batteries are reliable, durable, such rechargeable batteries are gradually replaced lithium-ion analogues, which are more compact and less sensitive to environmental conditions.

Measuring your phone’s battery

It often happens that the phone quickly runs out of juice. Thus it is necessary to check the parameters of its battery for the reduction of capacity. Knowing how to check the battery capacity of the phone with a multimeter is necessary not only for specialists in repair shops of portable equipment, but also for ordinary users who are thinking about replacing the battery of their smartphone.

To check the battery, you must determine the voltage delivered and the battery capacity, determined by the check-discharge method. On the phone battery or in the instruction manual these parameters should be specified. If the values obtained in the experiment differ by more than 20% to the lower side. it may be worth replacing the battery.

Knowing how to check the battery phone multimeter, you can quickly identify the fault of this element, to know its condition, if it is no longer new, and to determine the approximate service life.

Knowing how to check the capacity of the battery with the battery tester is useful in many situations: from the question of replacing the batteries of the camera to test the capacity of the car battery.

Testing a Battery Pack

To find out which of the batteries is faulty, you need to unsolder each battery and measure the voltage on the poles.

To connect to the device use the styli, one of which (red) is connected to the positive terminal and the other (black) is connected to the negative terminal of the drive. The multimeter display will read in volts.

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Makita brand screwdrivers with Li-lon should display a voltage of 3.6V to 3.8V. This corresponds to the characteristics of lithium-ion batteries. In simple Chinese models, the Russian Interskol with Ni-cd value should be 1.4V, the minimum value is 1.2V.

It happens that checking this way doesn’t show any malfunctions, although the battery will run down quickly. Then check each battery with a light bulb (25 Watt and 12V). Also use a resistor to measure the resistance level, for example, 10 ohms.

If you connect them together for a couple of minutes, the brightness should not change. If it goes out or flickers, then the drive has insufficient capacity.

Also compare the resistance values of all the batteries by first disconnecting them from the temperature sensor.

The resistance level in the battery is calculated using the formula:

where N is voltage, A is current, S is resistor resistance.

Let’s assume the value of the first battery is 0.60 Ohm and the second battery is 5 Ohm. This means that the second battery is unusable.

A nickel cadmium battery can be restored by trying to replenish the lack of electrolyte. For this purpose it is necessary to make a hole in the case of the battery from the minus side with an awl. Using a syringe, pour in 1 cc of distilled water. Seal the hole with epoxy glue and reassemble the battery.

All other types of batteries (Li-lon, Ni-mh) cannot be restored. In this case you will need to buy a similar battery and make a replacement.

Checking the battery helps to identify the cause of battery failure and fix it. This saves the cost of buying a new device.

Many home handymen have to deal with the need to check the battery serviceability of a drill or an electric screwdriver. Over time, the battery runs down, and in order to assess the possibility of its continued ability to work, you need to know about how to test the battery electric screwdriver with a multimeter or tester. A multimeter is a meter that can read as a voltmeter and an ammeter.

Testing the battery with a multimeter

First you need to test the electric screwdriver battery with a prepared multimeter while charging. This will help determine the overall performance and the need for a more detailed check. The voltage should be measured every hour until it reaches a maximum of 17V. After half an hour of charging the reading should be 13 Volts. At an average of 0.5 volts per hour, this indicates the battery is healthy. Towards the end the rate of voltage increase decreases, this is normal. To test, the multimeter should be set to DC (voltage) and 20V (voltage will not exceed 20V). At the same time, measure the current with the same regularity (once an hour). For a functioning unit the sensor will show a steady increase in current. Ideally it should be over 1Amp.

Battery Multimeter Test

Next you need to check the battery by installing it in an electric screwdriver or by connecting a light bulb with a resistor to it. “Banks” of each type have a standard voltage:

To determine the working voltage of the battery, multiply this figure by the number of batteries. When a battery is simply inserted into a tool, it is in “idle” mode. In this case the voltage should be higher than the working voltage.

check, battery, capacity, electric

For example, lithium ion batteries should show 3.7Vx6=22.2V and in idle mode, respectively, at least 25V. This test should be done after the cell is fully charged. Connect the light bulb to the battery and measure the voltage and current with a multimeter. If the value is lower than the value obtained by the formula, there is a malfunction. Any discrepancy in one of the initial tests indicates a fault in one of the banks or an incorrectly performed procedure.

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Multimeter settings for the test

How to check the battery capacity of an electric screwdriver?

When we know the voltage, we can check the battery capacity of any electric screwdriver. This is the amount of energy given off by the battery over a period of time at a certain voltage. It is measured in Amps (miles Ampere) per hour. Amh.

You will need a fully charged and disconnected battery from the electric screwdriver, a resistor, and a light bulb for the test. We need to connect the light bulb to the battery so that it glows. Then we measure the output voltage with a multimeter and note the time after which the light bulb goes out.

M is the wattage of the bulb in watts, as printed on the package.

N. measured voltage (must be the same as the value from the previous test).

t is the burning time of the light bulb that we measured.

The result is compared with the indicators from the manual of the screwdriver. If the working capacity is much lower than indicated in the description, you need to repair.

How to check the “banks” of the battery

If tests show a faulty battery in a good electric screwdriver, find the dead batteries and replace them. It is possible that one or more of them are faulty, so to restart the circuit it is enough to replace the dead cells. You can also notice problems by the self-discharge rate of batteries stored idle for a month:

To monitor the self-discharge, measure the voltage every day for a month.

First you need to disassemble the case, depending on the brand the process may vary. Then visually check the connections for continuity. It is quite possible that the batteries themselves work, you just need to solder the contacts.

If everything is okay, you need to unsolder each of the “batteries” in sequence and check one by one. To check this the red probe should be connected to the positive pole and the black probe to the negative pole. The multimeter will show the voltage in Volts. It should be compared with the standard voltage for this type of battery. A deviation of 0.1-0.2V is considered to be within the normal range.

Checking a Battery Battery

If the general checks showed the presence of problems, and no faults are found in each of the banks, then you need to check in another way. with a light bulb and a resistor. If the brightness varies (blinks, smoothly decreases or increases), then the problem is here.

Battery Battery Structure

A resistor is needed to check resistance. Battery resistance is calculated according to the formula:

S. resistance of the resistor. Internal battery resistance should be as low as possible. For example, if you check the nickel-cadmium battery of any electric screwdriver, it will be 0.60 ohms. The fact that the internal resistance of the battery depends on the capacity of the battery, and decreases in inverse proportion. Keep in mind that during the year of operation the internal resistance grows by about 6-7%, but once the index exceeds 1 Ohm, the “bank” is no longer usable.

Battery in the process of disassembly

Change of the cans

Battery replacement is conducted in a usual way. new battery is soldered in place of the old one, repeating soldering steps in the reverse order. Some rules must be followed in the process:

  • Solder quickly to prevent overheating.
  • The plates should be native or copper ones of the same size.
  • Connect in series.
  • The minus of the previous “bank” goes to the plus of the next.

Before the final voltage check it is necessary to conduct the discharge-discharge cycle.

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In the nickel-cadmium batteries you can try to replenish the lack of electrolyte by pouring 1 ml of distilled water inside with a syringe. For this purpose it is necessary to make a hole with an awl in the minus area and then seal it with epoxy resin. The other types are not repairable.

How to check the battery capacity of an electric screwdriver with a multimeter

The main property of a battery is its capacity. This value indicates the stored energy, that is, the current intensity in 1 hour. Measured in A/h.

How to check the battery capacity with a multimeter?

  • Disconnect the battery from the electric screwdriver.
  • Charge the battery to 100%.
  • Using a multimeter, a resistor and a light bulb, measure the time it takes the bulb to go out, the voltage at the battery’s output.
  • Calculate the capacity of the device using the formula/
  • Compare the results with those indicated in the instruction manual of the electric screwdriver.

How to Use Multimeter and Measure the Voltage of Power Tool Lithium Batteries

Let’s assume that the battery voltage reaches 18V. At 10 Watt incandescent lamp power the battery discharge time should reach at least 2.3 hours.

If the connected light bulb goes out after 30 minutes, the calculated capacity of the battery is:

This value is much lower than, for example, the nickel-cadmium battery of an electric screwdriver at 1.3 Ah.

Some tips before testing the battery

Before you start checking the battery, you need to determine the type of battery in advance. The fact is that it largely determines how the test will be carried out.

Also, before you check the battery with the tester, it must be fully charged. This will help verify the performance of the drive. It has been repeatedly proved that it is possible to find out the most accurate indicators only under load.

Before checking it is necessary to get rid of the “memory effect”, which over time appears in most batteries. To remove it, you must fully charge and discharge the battery at least three times.

Checking the battery of an electric screwdriver with a multimeter. an algorithm of actions

It is necessary to check the battery of an electric screwdriver with a multimeter to detect its defect in time.

Check the battery with a multimeter

First, check the parameters several times during charging:

The current variation mode is uniform. It rises for the first hour after switching on. If the reading is higher than 1 A after one hour, the device is good and there is no need to take it apart. Otherwise you have to do it by soldering the connections with a soldering iron.

To quickly test the battery with a tester, perform the following steps:

  • By multiplying the number of cells and 1.2 V, obtain the value for the idle stroke;
  • Check the battery of the electric screwdriver with the probes on the terminals;
  • Compare the data obtained with the idle speed value.

You can compare the measurement result with the data in the manual. For nickel-cadmium storage batteries, the corresponding value is 1.2-1.4 volts, for lithium ones it is 3.6-3.8. Inconsistencies in the results obtained indicate a malfunction of some components of the unit. They are removed from the case to test the battery. Carefully examine the power sources for rust, signs of electrolyte leakage, and bump marks.

Battery characteristics for electric screwdrivers