How to test a battery: using a tester to check the capacity, resistance and voltage of a battery

When there are problems with turning on any mobile device, be it a smartphone or remote control, first of all change its battery - a battery or battery. But you can make sure that the energy source is working without replacing it. To do this, you just need to know how to check the battery for compliance with its characteristics using a multimeter, and then decide to replace it.

Battery and its parameters

A battery is a battery with stored internal electrical energy. Structurally, it is a container in which a substance (electrolyte) is located, providing the movement of charge carriers from one pole of the product to another, thereby creating electricity. Perhaps this is due to chemical processes that take place with the release of energy. Gradually, these processes slow down, and the battery loses its ability to generate current, that is, "sits down".

Batteries are classified into the following two main types:

1. Non-rechargeable. Depending on the electrolyte used, they are saline, alkaline, lithium. Their supply voltage is one and a half volts, and the ongoing chemical reaction does not have a recovery process.
2. Rechargeable (batteries). They are characterized by the reversibility of the processes taking place inside them. Nickel-cadmium (NiCd), nickel-metal hydride (NiMh), lithium-ion (LiIon), lead-acid (Pb) types of batteries are used as batteries.

Any battery consists of three elements: two electrodes (anode and cathode) and an aggressive environment - an electrolyte. The latter is a liquid, therefore, to prevent it from flowing out of the shell, a polymer thickener is added. The anode is made in powder form. When it reacts with the electrolyte, it gradually dissolves, as a result, free charges are formed, which are immediately absorbed, and an equilibrium state occurs.

If you connect a power source to an electrical circuit, redox reactions begin in it. An excess of electrons appears at the anode, which are attracted by the cathode. The redistribution of charges leads to the appearance of a potential difference on the electrodes.

Over time, the initial composition of the anode and cathode changes, and the amount of electrolyte decreases. When the reaction proceeds, substances appear that impede the movement of charges. All this leads to the fact that the current delivered by the battery decreases, and with it the potential difference decreases.

Rechargeable batteries work in a similar way to batteries. In them, too, when the anode is depleted, electrons are no longer formed, and the battery loses its current and voltage. But due to the type of material used, the anode is recoverable. For this, an electric current is passed through it, leading to its enrichment and replenishment of the charge.

Battery characteristics

All battery parameters are divided into two main types: electrical and physical. The first include the product size and its geometric shape. But no matter how the battery looks, constructively it always has two conclusions: positive and negative. They are designated on the body respectively by signs «+ "and" - ".

The main characteristics of batteries are:

1. Working voltage. This parameter shows the value of the potential difference between the anode and cathode of the battery. To date, batteries are available in 5 and 9 volts. But the batteries can be produced with voltage: 1.2; 2,4; 6; 12 volts. At the same time, it is quite often possible to find a sequential combination of several batteries of the same type in one case, as a result, the working potential difference will be a multiple of the given values.
2. Capacity. It is considered the main parameter characterizing the battery life. It shows the amount of energy that the element can give up. This parameter depends on many factors, the main of which are the geometric dimensions and used in the manufacture of the substance. That is, if the capacity of the battery is 10 ampere-hours, then this means that it can supply a load with a current of 1 ampere for 10 hours or with a current of 5 amperes for 2 hours.
3. Discharge current. This is the highest current that the battery can deliver in a short time in short-circuit mode. Determined to a greater extent by the capacity of the element. In fact, this is the rate of discharge, that is, the amount of current that the power supply can give for 1 amp of its capacity.
4. Self-discharge. This parameter applies more to batteries than batteries, although it is inherent in both. For batteries, it is so negligible that it is almost never considered. It consists in the loss of the capacity of the feeder without connecting it to the load. Usually this value is indicated as a percentage.

Measurement methods

When examining batteries, two parameters are most often measured - capacity and voltage. To measure characteristics, both laboratory stands with specialized electronic devices and household-level testers can be used.

Specialized devices include testers that measure only a certain parameter. For example, a voltmeter or a capacitance meter. Such devices basically use microcontrollers and special analyzers, and their work is fully automated. Moreover, they can be both fully finished devices and devices designed for connection to a personal computer.

And there are also universal meters that, when a battery is connected to them, display the results of measurements of several parameters at once. But usually they are inferior in accuracy to specialized equipment.

In addition, LEDs or piezo speakers can be used to obtain general information about the health of the power supply. With the help of segments of wires, voltage is supplied to them from the battery, and the suitability of the element is assessed visually or by sound. But it will not be possible to get reliable indicators without checking with a tester. It doesn't matter if it is digital or analog.

Using a multimeter

A multimeter is a device designed to measure various electrical parameters. According to their principle of operation, testers can be digital or analog. Regardless, their important characteristics are accuracy and measuring range. The higher these characteristics are, the less the error of the obtained result will be.

Before you check the battery with the tester, you need to set it up correctly and make sure that its power source is working. With insufficient voltage supplied to the meter circuit, the obtained indicators will be distorted.

In order for the user to know exactly when to replace the feeding element, an indication is provided in the digital device. For this, the built-in analyzer monitors the voltage level of the battery supplying it and, in case of problems with it, signals it with a blinking icon on the device screen. And for an analog tester, the reason for replacing the supply elements will be the impossibility of setting the arrow of the device to the zero position.

To obtain the correct result, it is worth not only using a prepared device, but also taking measurements at a temperature of about 20 degrees Celsius. This is due to the fact that the parameters of the battery change with temperature changes, especially when it comes to heating.

Measurement of voltage value

Checking the voltage level with a tester is a snap. To do this, you need to connect the red plug of the wire to the socket of the device, designated VΩ or just V, and the black one to the COM socket. And then set the rocker switch in the DCV zone to a value higher than the nominal voltage level of the battery.

The next step is to connect the ends of the wires to the measured battery. To do this, the red probe of the multimeter is connected to its positive terminal, and the black one to the negative terminal. After that, the device turns on, and a number appears on the display indicating the voltage in volts.

Thus, can be checked with a multimeter as a phone battery, car or any other device, or a simple battery. But at the same time, you should know that even if the voltage level is normal, this does not mean at all that the power source will be fully operational.

Capacity check

Directly checking the battery capacity with a multimeter, despite the versatility of the device, will not work, since it simply does not have such a function. But it is quite possible to measure the discharge time, and then calculate the capacity. To do this, you will need to perform a number of actions:

1. The multimeter switches to current measurement mode. To do this, the red wire is moved to the socket - 10 A, and the black wire to the COM.
2. The range selector is set to the highest number in the DC range. This range can be referred to as DCA or A-.
3. With a quick touch of the probes (no more than a second), touch the battery terminals, while observing the polarity: red - plus, black - minus.
4. At the moment of touching the battery, the screen is visually monitored and the number that appears there is memorized.
5. If the current value is less than 0.4 ampere, then the battery can be considered unusable, and there is no point in taking measurements further.

When the task is to find out exactly the capacity of the battery, the measurements continue. For this, the rule is used that the capacitance is found by multiplying the current passing through the resistance by the time spent for this. Therefore, in addition to the multimeter, you will need a variable resistance of the order of 100 ohms, included in the gap of the red probe.

This method is suitable for measuring a fully charged battery, but not a simple battery. After all, if you check its capacity, then at the end of the measurement it will simply lose its resource.

So, when the circuit is assembled, you need to touch the anode and cathode of the battery with the probes and use a resistor to set the discharge current of about 500 mA. Then you need to turn on the stopwatch and monitor the voltage on the batteries using another tester. As soon as it drops below 30% of the rated voltage, the stopwatch is stopped. Then, by multiplying the resulting time in hours by the current, the desired capacity value is obtained.

Finding resistance

Another measurement that allows you to establish the state of the battery is to find its internal resistance. But besides the meter itself, you will need a powerful 12 volt light bulb like the one that is installed in cars.

The measurement method consists in performing the following sequence of actions:

1. A light bulb is connected in parallel to the object under test, and the voltage is measured with a tester.
2. The voltage at the battery terminals is measured again, but with the light bulb disconnected.
3. The strength of the current passing through the light bulb is measured. For this, the tester switches to the DC current measurement mode, and the light bulb is connected in series with the battery.

Based on the data obtained, using Ohm's law for a section of the circuit, the internal resistance of the battery is calculated, and a conclusion is made. For example, when the light bulb was connected, the voltage U1 was 4 volts, and without it U2 was 4.1 volts. And the measured current strength was I = 1.45 A. Substituting these values ​​in the formula, you need to find the internal resistance. For the considered example, it will be equal to:

R = (U2-U1) / I = (4.1-4) / 1.45 = 0.07 Ohm.

Thus, having carried out a set of measurements, it will be possible to assert with confidence about the state of the accumulator or battery. At the same time, a large internal resistance of the battery will mean a significant deterioration in its condition and rapid degradation.