How to check the battery of a screwdriver with a multimeter

Testing electrical batteries with a multimeter under load

The remaining elements are retested. Now let’s figure out how to check the battery capacity under load. To do this, proceed as follows:

  • Connect the test leads of the multimeter to the contacts of the battery under test.
  • Connect the load element in parallel and wait 30-40 seconds.
  • Remove the received result.

Depending on the readings of the device, the measured elements must be sorted. Batteries with a remainder of 1.1V or less can be safely disposed of. Products, when checking which the device showed up to 1.3V, can be used in remote controls. If the element under load shows 1.35V or more, it is completely serviceable.

Useful Tips

Here are some guidelines for battery use and disposal:

  • Do not delay checking and sorting accumulated batteries at home. If new batteries are missing or insufficient, you can temporarily use a tested battery if necessary.
  • Batteries that have sat down in a household appliance do not need to be completely replaced. Usually, their discharge does not occur simultaneously, and the check will reveal batteries that can be operated further.
  • Do not store unusable batteries at home and, moreover, do not keep them in the equipment case. Often, electrolyte leaks from them, and this leads to damage to nearby things.

check, battery, screwdriver, multimeter

  • Do not try to damage the battery case in any way. the liquid (acid or alkali) in it may come into contact with the skin, causing a chemical burn.

In addition, used batteries should not be thrown into trash cans. The electrolyte contained in them is harmful to the environment, therefore the batteries must be disposed of in places that are specially designed for this purpose.

Testing batteries by measuring current strength

This method is applied to new batteries and allows you to evaluate their power immediately upon purchase. The position of the multimeter must correspond to DC current. To measure the amount of charge on a new battery, proceed as follows:

  • Set the battery tester to the maximum measurement limit.
  • Take a new element and attach the test leads of the device to its contacts.
  • After 1-2 seconds, after the growth of the current value on the indicator stops, the probes must be removed.

The normal current for a new battery should be 4-6 Amps. If it is 3-3.9 Amperes, this means that the operating life of the battery is reduced, but the cell is suitable for use in portable equipment.

Multimeter readings in the range of 1.3-2.9 Amperes indicate that it is better not to use a battery in ordinary household appliances, but it can be installed in devices that consume a small amount of current (for example, television or other remote controls).

If the value of the current shown by the tester is 0.7-1.1 Amperes, then such an element is capable of working exclusively in devices with low power consumption, while the quality of the equipment will decrease. It can be used in remote control systems, but only if there are no better elements at hand.

Visually, the process of checking batteries with a multimeter for

How to measure the battery charge with a multimeter

Finger-type batteries are used in many modern devices as batteries. Although outwardly these products are indistinguishable from each other, their technical parameters, as well as cost, can vary significantly. In order not to get into a mess by purchasing a product with a small resource, or even completely inoperative, you should know how to check these elements, and be able to do it in practice. This skill will come in handy when checking the batteries accumulated at home. if one of them is in a landfill, then others can still serve in devices that do not differ in power. In this article we will figure out how to check the battery with a multimeter, and at what amount of residual charge it can be used in electrical appliances.

No load charge test

To identify completely faulty elements, it is enough to carry out a simple check:

  • Select the multimeter mode corresponding to DC voltage measurement.
  • Set the measurement limit equal to 20V.
  • Apply the test leads of the device to the contacts of the tested battery and measure the voltage.
  • Take readings of the tester.

If the voltage shown when checking the battery with a multimeter is more than 1.35V, the battery is good and will work in any electrical appliance. If the cell charge is less than this level, but not lower than 1.2V, it can be used in undemanding devices. If the charge level is lower, the battery cannot be used and must be disposed of.

For completeness, such a check is not enough, since it shows the magnitude of the no-load voltage (EMF).

As a loading element, you can use an ordinary light bulb designed for use in a flashlight. LEDs are not suitable for this due to too little resistance. The load volume should be between 100 and 200 mA. this is the most common indicator for most modern medium power electrical products.

However, to reject clearly unusable batteries, a no-load test with a tester is sufficient. If the device shows less than 1.2V. checking under load is meaningless.

In this material, we figured out how to correctly check the battery with a multimeter, as well as in which devices the tested batteries can be used, based on the measurement results. As you can see, in order to measure the remaining battery charge, it is enough to have a home tester on hand and have a few minutes of free time.

Checking by resistance value

Multimeter device diagram.

The performance of each battery can is more likely to be assessed by comparing the cans by their internal electrical resistance. This parameter clearly indicates the reliability of the battery. The resistance value is determined by calculation as a result of dividing the operating voltage by the operating current strength minus the load resistance.

The operating voltage is necessarily measured under load, and a resistor with a precisely defined value of its own electrical resistance should be used as the load. It is possible to recommend a resistor with a resistance of 10 ohms and a power of 25 watts to create a load. The check is carried out for each bank separately. The operating voltage and current are measured.

For example, consider the averaged check. For a new battery bank, the internal resistance is 0.1 ohm. In general, the lower the internal resistance of the bank, the better it is. In real conditions, the operating voltage was obtained under a load of 1.19 V and a current strength of 112 mA for one can and 1.18 V and 70 mA for the second can. The resistance will be 0.63 ohms and 5.71 ohms, respectively.

A significant excess of resistance indicates the unsuitability of such a battery.

Checking under load

Battery test circuit with an ammeter.

Kompletong paggamit ng Analog Multitester, Multimeter or VOM (Tagalog) [Part 1)with English subtitle

The preliminary check does not allow us to estimate the capacity of the battery, i.e. the time during which it will be discharged. To estimate the parameter, it is necessary to test the battery under load. If the power is indicated on the drive, then the load power is selected according to this value. If the power of the battery is unknown, the load can be approximately selected on the basis that its power is half the product of the current given by the battery during operation and the voltage of the battery. Usually it is sufficient to use a 35-40 W load. As such a load, you can use a 35 W car headlight lamp or a 12 V spot lamp of the same power.

A circuit is being assembled, where the battery, as source of electricity, is discharged to the load through an ammeter. The voltage is measured with a voltmeter. The battery turns on for 2-3 minutes. If during this time the brightness of the loading lamp has not decreased, then the battery capacity can be preliminary estimated as normal. This conclusion should be supported by measuring the voltage (it must be more than 12.4 V). At voltages between 12 and 12.4 V, look for a possible damaged element. Voltage below 23 V indicates insufficient battery capacity.

If the brightness decreases noticeably, then this indicates the presence of non-working elements. And it’s really bad if the lamp goes out. This means the battery is discharging very quickly and its capacity is very low.

How to quickly check the battery of a screwdriver?

Recently, the screwdriver has become a fairly popular tool. For convenience, many tend to purchase a screwdriver powered by a charging battery. Over time, of course, the question arises: how can you check the battery of a screwdriver?

Diagram of a nickel-cadmium battery for a screwdriver.

The first stage of verification

Checking the battery only makes sense when it is fully charged. The first stage of verification is carried out at the stage of battery charging. At this stage, the voltage and current are measured, as well as the rate of their recovery. In other words, these parameters are measured periodically after a certain period of time.

Battery voltage test circuit.

Voltage control is performed as follows. After 0.5 hours of charging, the battery voltage is measured. For example, it reached 13 V, which is normal. The increase in voltage gradually decreases and after another 0.5 hours of charging reaches 13.5 V. The last measurement after 2 hours of charging shows a voltage of 14 V, and for the last 0.5 hours its growth is not noted. Charging has reached the maximum possible. The drives in fully working condition have a voltage value of 17 V. The conclusion of such a check is that there are non-working cells in the battery. In the given example, there are most likely two such elements.

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The quality of the battery can also be assessed by measuring the current during the charging process. A normal battery is characterized by a stable increase in the accumulated current in the first hour of charging. If the current reaches a strength above 1 A, then we can talk about the performance of the battery.

If the battery is already installed in the screwdriver in a charged state (for example, a new one), then the first voltage measurement on it is made without disassembling the tool. Using a simple tester or voltmeter, the voltage between the poles is measured. It should be remembered that the measured no-load voltage corresponds to an open-circuit voltage that is slightly higher than the rated operating voltage. For example, with 12 cells at 1.2 V, each operating voltage will be 14.4 V, and the open circuit voltage is set to 17 V. If the measurement shows a voltage value lower than the required one, then this means that there are non-working cells or the battery is not fully charged.

Thus, the first conclusions about the health of the battery can be made already at the first stage of testing, by using a simple tester. Based on the results of such a check, it is established that it is necessary to disassemble the screwdriver and the battery.

The main types of batteries

The most common type of drive used in screwdrivers is the nickel-cadmium battery. The main advantages of such elements are recognized as high capacity with small dimensions and weight, as well as a fairly long service life (up to 3500 cycles). The electromotive force of the cell reaches 1.37 V, and the specific electrical energy. up to 65 Wh / kg. Limits the use of such elements (especially in imported tools) harmful production.

Nickel-metal hydride batteries for the screwdriver are becoming the main competitor to nickel-cadmium copies. The main advantage of such elements is safety and environmental friendliness. It is recommended to store the cells in a charged state, since if they are not used for a month, they may be discharged to such a state that they cannot be charged.

In the latest models of screwdrivers, modern promising types of batteries are used: lithium-ion and lithium-polymer. They have a very high capacity with small dimensions, but their cost is still quite high.

General information about the battery

Battery type table.

In the general case, an electric storage device is source of constant electric current by converting a chemical reaction into electrical energy. During operation, it transfers the accumulated electricity into the electrical circuit. When charging the battery of a screwdriver, the current is passed in the opposite direction and the process of energy storage takes place.

The main parameter of any battery is the capacity of stored energy, which indicates how much current the battery can deliver in one hour. Therefore, the capacity of the battery is usually measured in ampere-hours.

The principle of operation of any battery is based on electrolysis. Consequently, the battery consists of two electrodes. the anode and the cathode, which are in the electrolyte. A chemical reaction creates an electrical charge on the electrodes (poles). The potential difference between the electrodes determines the battery voltage, which is considered one of the most important characteristics of the battery. Serial connection of individual batteries leads to the addition of their electrical voltages.

The main parameters of the storage devices depend on the materials of the electrodes and the composition of the electrolyte. In nickel-cadmium batteries, the anode is made from a mixture of nickel hydroxide and graphite, and the cathode is cadmium hydroxide or metallic cadmium. Potassium hydroxide with the addition of lithium hydroxide was used as an electrolyte. The nickel metal hydride battery uses a similar anode, but the cathode is made of a rare earth nickel alloy. In lithium-ion batteries, the cathode is made of carbon and the anode is made of lithium dioxide and cobalt. The electrolyte is a saline solution with lithium ions. The difference between the lithium-polymer version is only a change in the composition of the electrolyte. it is a gel-like polymer substance.

Checking other parameters

All batteries have a certain self-discharge value, i.e. discharge no load in storage conditions. So, self-discharge of nickel-cadmium batteries can reach 20% within a month of storage, nickel-metal hydride. up to 30%, lithium-ion. up to 8%. Self-discharge is recommended to be checked by measuring the voltage every day for a month.

Checking for the presence of a “memory effect” is advisable, as it helps to eliminate its harmful effects. It is carried out by carrying out several (3-4 times) cycles: full discharge. full charge of the battery. The battery can be discharged through a load, which is a 12-volt light bulb. The residual operating voltage and the open circuit voltage are measured. With repeated such training, the “memory effect” should disappear.

Battery Cell Test

After a preliminary check has established the presence of faults in the drive, it is necessary to open the screwdriver and remove the battery, i.e. battery cells connected in series with each other. The battery includes from 10 to 12 cells (cans), each has an operating voltage of 1.2 V. Usually, a battery of 10 such cans is installed in screwdrivers.

Checking the elements begins with a visual inspection of the attachment points. Failure in fastening (soldering, welding) can lead to underestimated parameters. Then the voltage on each bank is measured. The voltage should not be less than 1.2 V. It should be borne in mind that thermal sensors are placed in modern screwdriver designs to monitor battery charging. When measuring, they should be disconnected, and the device should be connected to the main terminals (poles of the jar). Identified banks with an underestimated value of the operating voltage are disconnected from the battery and must be replaced. If a simple voltage measurement did not reveal the presence of non-working elements, then measurements should be made under load using a method similar to the preliminary check of the drive.

How to check the battery of a screwdriver with a multimeter?

During intensive use of the screwdriver, there is a possibility of its breakage. And one of the most vulnerable parts is the battery. Consider how to check the battery of a screwdriver for performance by different methods.


The malfunction may lie not only in the battery, but also in the charger itself. Therefore, you first need to check the charger for the screwdriver with a multimeter.

On it, the mode of measuring direct current is turned on and, using probes, it is connected to the charger. The value of the current on the meter should be as close as possible to what is indicated on the case. If this is not the case, then it is better to replace the device with a new one.


To check the power supply of the screwdriver for performance, you just need to take the current and voltage readings at the time of charging. over, it is necessary to repeat the procedure several times in order to obtain the most accurate values.

Stages of voltage rise U:

  • after 30 minutes of charging. 13 V;
  • after 60 minutes of charging. 13.5 V;
  • after 2 hours. 14 V;
  • at the end of charging. 17 V.

Such observations indicate that the battery is completely intact and functional. In most cases, no further analysis is required.

At the same time, for a working battery, the current strength will also steadily increase within an hour after the start of charging. If after an hour the indicator has reached a value of 1 A, then this indicates the serviceability of the device.

There is also a method of accelerated testing of the battery, which consists in measuring the voltage at no load (no load). This voltage must reach the required value, which is directly related to the operating voltage of the battery cells (cells). If the indicator is lower, then there is a high probability of failure of one or more elements.

Testing under load can be considered a separate type of battery capacity test with a multimeter from a screwdriver. Additional equipment is used here, which needs recharging. Incandescent lamps are ideal for this. The power of such a lamp must correspond to the power of the battery. Otherwise, the test results may not be accurate enough. In most cases, the power is equal to half the current that the battery delivers multiplied by the voltage. For standard screwdriver batteries, 12 V lamps are used in the test.

The battery is connected to the load through a multimeter, which then takes readings. After a few minutes, you need to measure the voltage. It should be above 12.4 V. If this value has not been achieved, then there is clearly some kind of malfunction. Additionally, it is recommended to pay attention to the brightness of the light bulb. It must be stable enough.

General recommendations before testing the battery

Immediately before checking the battery, it is necessary to clearly determine what type of battery the battery belongs to. Depending on this type, and the approach may be different. For example, the most common nickel-cadmium batteries are highly sensitive to operating conditions. Infrequent or irregular full recharges will significantly reduce the battery’s capacity and the battery will not fully utilize its resources. In more detail, the types of batteries will be considered below.

It is also recommended to fully charge the battery before checking. This will make it possible to draw more accurate conclusions about the performance of the device. It has been proven that the most accurate readings are taken under load. And the full charge is a very suitable type of load.

Before testing, it is necessary to minimize the influence of the “memory effect” on the device. Since this effect appears with batteries in case of improper use, in order to eliminate it, it is necessary to use the battery several times in accordance with all the rules.

It is enough to carry out the charge / discharge cycles 3 times to significantly reduce the effect of the effect. For an accelerated discharge, it is best to use an incandescent lamp, which, together with a multimeter, will need to be connected to the battery.

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If everything is done correctly, then after a few full cycles, the battery will be able to restore its capacity and can again be used in a screwdriver. If the operation did not help, then the problem was different.

Nickel cadmium battery

The most common type of battery. They charge quickly enough and have a good volume. They are distinguished by their durability and resistance to external influences. The average number of charge / discharge cycles can reach 3500. When using accelerated chargers, the battery does not wear out faster and can last for a long time. Separately, it is worth noting the cheapness of such batteries and the ability to operate at temperatures below zero.

But there are also disadvantages, the main one of which is the so-called “memory effect”. Batteries are quite toxic in the event of a malfunction and have a high self-discharge rate. Due to toxicity, manufacturers are now trying to rapidly reduce the percentage of such devices.

To prolong the life of such a battery, it is recommended to completely discharge it before recharging.

Li-ion battery

A much more expensive analogue, which, however, has a number of undeniable advantages. Such batteries are used in advanced models of screwdrivers from well-known brands.

These batteries have a large capacity and a much lower percentage of charge loss due to self-discharge. However, such batteries are strictly not recommended to be overheated and left completely discharged for a long time. This can lead to degradation of the crystals and damage to the battery. If overheated, there is a risk of explosion of such a device.

Like the first type, the lithium-ion battery is capable of functioning in cold weather.

Battery can voltage

After the first stage of verification, it will become clear whether the device is working properly or not. If the testing indicated a mismatch in the parameters, then it is logical to proceed with the repair, accompanied by the replacement of faulty cans.

You need to open the battery case and identify the malfunction. For this, a multimeter is also used, which is connected to each element separately. The voltage of each jar must be at least 1.2 V. All discrepancies indicate a breakdown of the element. Defective cans must be removed from the common circuit and replaced with new ones.

If such a check does not reveal a breakdown, then you need to resort to stress testing again. And here the level of resistance is of fundamental importance, which is directly related to voltage and current. Each element is tested separately and resistances are calculated as well. In the event of a malfunction, this indicator will clearly deviate from the norm and quickly identify a broken element.

Replacing the “cans” in the screwdriver battery

The task itself is simple. It is good if you have experience in soldering. In the connection of the elements, the faulty battery is cut off, a good one is put in its place, then soldering is performed. As you can see, nothing complicated.

However, in this case, several important nuances should be taken into account:

  • you need to solder quickly so that the “banks” do not heat up. this may affect their performance;
  • to connect the elements, it is better to use native plates, or copper, but of the same dimensions;
  • when attaching a new element to an old one, do not confuse plus and minus. When connected in series, the minus from the previous battery goes to the plus of the new battery.

After soldering, you should carry out a charge-discharge cycle, and then measure the voltage on the “banks”. It should be around 1.3V.

Checking other parameters

In addition to voltage and current output, the battery can be checked for the duration of the current output. In some cases, at the beginning of connecting the load, the current may be sufficient, but soon it will begin to decrease noticeably. If, without charging the battery of the screwdriver, after a while reconnect the load, then the described phenomenon repeats again.

The higher the current, the shorter are the intervals of normal current output. This is due to polarization of the electrodes, gas evolution, changes in the composition of the electrolyte and indicates the aging of the battery. Perhaps recovery will help here if it is a Ni-Cd battery, but this cannot be guaranteed due to the complexity of the chemical processes inside the cell.

Another parameter is temperature. Its value when charging NiMH batteries has a limiting effect. It should not exceed 60 degrees Celsius. For lithium-ion batteries of a screwdriver, an increased temperature is also undesirable, but this is monitored by charge controllers and current balancing.

Ni-Cd batteries behave best in terms of temperature. Chemical reactions when they are charged go with the absorption of heat, which allows them to be charged with a high current.

Checking the screwdriver battery

To determine the real basic parameters of the battery, a check is carried out.

When carrying out actions aimed at checking battery cells, one should not forget about the influence of such a factor as the “memory effect”. The phenomenon itself is that, due to frequent charging of the storage device, the battery cells can change their capacity. This is due to the charges left over from the previous charge. Nickel-cadmium “banks” are more susceptible to this phenomenon than other batteries.

The screwdriver battery is checked when fully charged. Full verification takes place in several stages.

Screwdriver battery repair work

So, during the checks, non-working batteries were identified. What to do in this case? There are two ways out. an attempt to “reanimate” the elements or a simple replacement of non-working “cans”.

Checking the Drive Batteries

So, let it turn out that with the help of preliminary checks, the presence of faulty elements in the drive was established. Then it is necessary to disassemble the battery and remove the batteries connected in series. “banks”. As mentioned above, the battery consists of 10-12 such cells with a voltage of 1.2 V.

First, a visual inspection of the joints of the elements is carried out for violations. They can degrade the overall battery performance.

After inspection, you should measure the voltage of each of the “cans”. The voltage of one cell should not be less than 1.2 V. During measurements, the battery cells should be disconnected from the connections with any kind of sensors. The measuring device is connected to the battery poles. Reduced voltage “banks” must be replaced. If during a simple measurement no faulty elements were found, you should try on the “banks” under load.

Checking the Drive Batteries

If the check under load shows that the battery capacity of the screwdriver is reduced, or there is a suspicion of a short circuit of the cans, then you will have to open the battery pack for a detailed examination of the elements. To do this, you need a list of tools from the first section of the article, and the procedure will be as follows:

  • Open the block case by unscrewing the screws and releasing the latches;
  • Remove the elements and contacts or bite off the wires if this fails;
  • Remove the tape from the cans and unfold the chain;
  • Carefully examine the banks for defects and smudges;
  • Check each item.

Checking the element is essentially the same as in the previous section. If the can is leaking, has characteristic spots or swelling, it changes without further verification. Also, if the cell shows a voltage close to zero, it must be replaced. It is short-circuited.

As a result of the check, undamaged elements are revealed, the voltage on which is correct. They are further tested for internal resistance.

ATTENTION! Never measure the current of a battery cell with an ammeter if there is no resistance in the circuit. Otherwise, you will simply burn the device. Start measuring current from the maximum limit.

Checking under load

To answer the question for how long the battery will be discharged, you should check the drive under load. The load must be selected based on the capacity of the drive. If it is unknown, then it is considered that the load power is equal to half the product of the current that is given to the battery during operation by the voltage of the drive. As a rule, this value is taken equal to 35-40 watts. Thus, you can use a car headlight (35 W) as a load or use a 12 V spot lamp with the same power.

For battery measurements, the battery is connected to the load through an ammeter. Readings are taken with a voltmeter. “Banks” are connected for 2-3 minutes. The measured voltage must be greater than 12.4 V. If the readings fall within the range of 12 to 12.4 V, this means that the battery has a damaged cell. The presence of faulty batteries can also be indicated by a decrease in the brightness of the lamp used as a load. If the lamp goes out in the allotted time period, it means that the drive is discharging very quickly. it has a very small capacity.

How to check battery banks of a screwdriver with a multimeter

Battery pack malfunctions are the most common problem for owners of hand-held power tools. Mechanics break down less often. As a result of haste and negligence when using the tool, the charging and discharging regime of the batteries is disrupted. The result is a two to threefold reduction in battery life. I have to buy a new one. But before buying, it is worth checking the condition of the battery to make sure that the problem is really in it.


Lithium drives are considered the highest quality and most durable

Another common type of battery is lithium ion. Their voltage is 3.7 V. These storage elements have a huge number of advantages:

  • complete absence of self-discharge;
  • large capacity;
  • many charge and discharge cycles;
  • compactness and light weight;
  • no “memory effect”.

Lithium batteries have a serious drawback. high cost. It is almost three times higher than the price of other types of drives.

Inspection tools

The multimeter is an indispensable tool that is often used during battery testing

Each person who is going to check the performance of the battery should familiarize himself with the list of required documents. To carry out the work, you will need the following:

  • voltmeter with a constant voltage of 15 V;
  • tester;
  • multimeter;
  • ammeter.

In some cases, you may need the following tools:

  • soldering iron;
  • knife;
  • Straight or Phillips screwdriver
  • pliers.
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It is better to prepare all this in advance, so that everything you need is at hand.

How to ring a screwdriver batteries using a tester

A screwdriver is a tool that is found in almost every home. The most important and expensive part is the battery. He, like any other part of the device, can fail. To independently determine the breakdown, you need to figure out how to check the screwdriver battery with a multimeter at home and what you need to do for this.

The battery is the element responsible for the performance of the screwdriver

Checking by resistance value

You can check the battery performance by comparing the internal resistance of the “cans”. To find out this value, you will have to divide the voltage by the current and subtract the load resistance.

A 10 ohm resistor is recommended for the load. If the received value is less than 1 ohm, then the battery is functioning normally.

A Few Tips Before Checking Your Battery

Before you start checking the battery, you need to determine its type in advance. The fact is that how the check will be carried out largely depends on him.

Also, before checking the battery with the tester, it must be fully charged. This will help you check the drive is working properly. It has been repeatedly proven that the most accurate indicators can be found only under load.

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


Some types of batteries use lead-acid batteries. They have the following advantages:

  • slow self-discharge;
  • many cycles;
  • environmentally friendly production.

The main disadvantage of such batteries is their high cost. They cost several times more than nickel drives. Also, the disadvantages include the fact that with prolonged storage, some of their characteristics are lost.

Checking under load

The car headlight bulb is used to load the battery

When taking measurements, the battery is connected to the load source using an ammeter. To measure the readings, you need to use a voltmeter. The battery turns on for 3-4 minutes. During its operation, the voltage should not fall below 12.4 V.

Important! If the reading fluctuates, the battery is partially damaged and will drain quickly.

How to test the battery and alternator with a digital multimeter

Battery resuscitation screwdriver

Most cordless screwdrivers are equipped with a standard set of batteries. If there are no complaints about a sufficiently reliable and durable tool, then you should take a closer look at its battery cells, since this is a rather weak point of the device. It is no secret that without proper maintenance of batteries, you can simply go broke buying new batteries, the cost of which can reach up to 50% of the nominal price of the instrument itself.

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  • Dismantling the screwdriver
  • How to properly charge the battery of a screwdriver

It is reasonable to assume that if there is some option for restoring batteries for a screwdriver, then they need to be used, while saving a significant part of their material budget. Let’s figure out which methods allow you to reanimate batteries with minimal labor costs in order to check them for performance.

The “memory effect” and what to do with it?

If we are talking about ni cd batteries, then for them there is such a thing as “memory effect”. This “painful symptom” is defined quite simply. When the battery, after going through a full charge cycle, quickly discharges, and after a short pause continues to function again, then this is a correct diagnosis, which, with proper skill, can be cured.

What needs to be done to heal the “memory effect”?

First, the battery is fully charged (preferably at low currents). Then a small load is applied to it in order to achieve a complete discharge. This simple trick allows the inner plates of the battery to be fully activated. As an example of a successful load, you can use a conventional 220 V incandescent lamp with a power of 60W. The slow charging and discharging process should be repeated at least 4-5 times. The result of these measures will be the return of the original battery capacity by 80%.

By the way, if you carry out work on a disassembled battery, where “weakened” batteries are already known, then a shock effect with a large current can return them to operation. If the electrolyte is present in the battery, then you can always restore the battery using this method.

Quick battery test with a multimeter

Since the batteries are connected in series, it is important to know that when the batteries are in a charged state, the voltage tested by the multimeter must be identical. To correctly identify the faulty link, switch the tester to the constant current change mode, and measure each battery (bank) in the system.

If in your case ni cd batteries are used, then the nominal voltage of each of the blocks should be approximately 1.2 V. In the situation of using Li Ion batteries, the voltage indicator should be around 3.6 V.

In general, to properly initialize a fault, the entire battery pack is first charged to a maximum charge of 6 hours. Then an appropriate measurement is made with a multimeter, based on the above indications for different types of batteries. If no distortion is detected at this stage, then the battery is connected to the load in order to completely discharge it.

After making sure that the battery pack is discharged, it is necessary to re-measure each supply battery in the system with a multimeter. This will make it possible to find unusable “banks” with a high degree of probability. The readings of the multimeter in such blocks will be below 0.5-0.7 V. If you have battery blocks available for replacement, then the reanimation of the entire circuit is eliminated by banal soldering, removing the worn-out elements and replacing them with new ones.

Load testing

This method involves the use of several bulbs or small electric motors that are connected to each power supply in the screwdriver’s battery system.

First, the entire battery is fully charged. Then, one 3-4 V light bulb or a low-power “motor” is connected to each “bank”. The method makes it possible, without measuring devices, to identify inoperative elements in the system, which will lose their charge before all under load. Blocks that have lost their capacity will certainly reveal themselves.

Method for determining the malfunction of the screwdriver battery

If you disassemble the battery case of the screwdriver, then inside you can find the series-connected power supply elements. In most situations, the operating voltage of the electric motor is 18 volts, which is made up of 15 cans in the battery case. As a rule, no external signs of breakage are found. Therefore, the master is faced with the task of correctly determining the link in the existing chain, which has lost its energy intensity.

The performance of the entire battery will lose its effectiveness even if there is at least one element in the system that has lost its capacity. However, all the feeding elements cannot fail. Consequently, having correctly identified ineffective cells, they can either be replaced or the used batteries can be returned to their working capacity. In other words, there are methods to revive the batteries.

As a rule, in order to accurately determine the malfunction of the battery, two main methods have found practical application:

  • Identification of faulty units when using a tester (multimeter);
  • Identification of faulty power supply elements in the system using the load

Let’s see how these methods work in practice.

What additional methods of battery recovery for screwdrivers exist?

It should be noted right away that not all batteries are subject to the ability to restore performance. In particular, with the best success, it is possible to reanimate “banks” with the typical insignia ni cd. Most typical screwdriver models are now equipped with such batteries. Of course, on the tool market you can find Makita or hitachi or bosch screwdrivers, the battery of which is built on a lithium base, but there are not so many of these models yet.

In general, if we talk about the health of the battery pack and methods for its recovery, in any case, you need to pay attention not only to the batteries themselves inside the case, but also to make sure that the charger is working properly. It is likely that the functionality of the power supply has lost the ability to provide the required current when charging.

Many craftsmen, faced in practice with the repair of nickel-cadmium power cells, restore them by adding an electrolyte. The battery begins to lose electrolyte during operation as it evaporates.

The physical impact on the battery “bank” with a drill helps to correct the situation. It is necessary to make a small hole in the body of the battery (diameter 0.8-1mm). Armed with a medical syringe with a needle, a couple of drops of distilled water should be injected into the battery. The hole is then securely sealed with epoxy. This cycle of events will allow to extend the operation of the feeding element for several more charge / discharge operations.

Of course, the simplest and most obvious way to reanimate the battery pack for a screwdriver is to physically replace the faulty unit with a workable one. Here, even the help of a specialist may be inappropriate, since the operation can be easily performed even by the person who at least once used a soldering iron and held a screwdriver in his hands. The main thing here is to show a little dexterity in order to prevent overheating of the cans at the time of their soldering / desoldering.

Of course, there are quite a few ways to reanimate rechargeable batteries, but not all of them are available to the common user. If you cannot extend the life of your screwdriver with a standard battery on your own, then seek help from qualified specialists. They will make error-free diagnostics and “figure out” how to restore the tool battery with minimal labor costs.