How to check a car battery when purchasing

How to check your car battery for performance

One of the important elements of a car that requires checking is the battery, or battery. The serviceability of the battery and its performance are very important, since it is thanks to the battery that the car starts, and all systems of the car are powered by it: low and high beam headlights, media system and much more.

Content

If you have already met with the seller and want to be sure that if you buy a car, the first thing you will have to do is run headlong to the store for a new battery, which usually costs more than 10 thousand rubles, then you have several ways to check the battery by car:

Inspect the battery externally;
Measure the voltage on the battery with a multimeter;
Check the battery with a load fork;
Check the electrolyte level in the battery.

We will consider each question in detail, but we immediately note that the fourth option, with checking the electrolyte level, is only available for serviceable batteries. But one way or another, there are a number of methods for checking a car battery for performance, and in this article we will look at them.

External inspection of the battery

You met the seller and have already walked around the car, seeing how clean and beautiful it is. It's time to look under the hood, you lift the lid and see the usual contents of the engine compartment, the engine and numerous systems that keep the car running.

In most cases, here, in the engine compartment, there is also a battery - a rectangular box with electrolyte inside, to which two wires are connected - positive and negative. These wires go to the distribution block, and from this massive electrolytic “battery” the entire machine and all its systems are powered with electricity.

Even if you don’t understand anything about cars and went for an independent inspection rather as part of a formality, you can still determine by the appearance of the battery what condition it is in.

During an external inspection, attention should be paid mostly to the integrity of the elements, and whether the battery itself and contacts are clean. There are a number of external factors, the presence of which immediately indicates the need to replace or at least clean the battery.

Dirt on contacts. In order for the battery to work, both contacts connected to it by wiring must be clean. If the contacts are dirty, this indicates that the battery is not new, and dirt will interfere with the correct operation of the contacts.
Oxidation of the terminals - foreign deposits can be seen on the battery terminals with the naked eye - this is oxidation, which in most cases is associated with electrolyte leakage. Electrolyte is an acid that is found inside the battery. If it spills and gets on the contacts, it can lead to poor battery performance and a reduction in the contact area.
Cracks on the case - the battery itself should be intact. The plastic box containing the electrolyte must not be damaged. This is also clearly visible without additional equipment and in good lighting.
Dirt, dust, electrolyte leaks - all this is removed with a rag, and the car should not be allowed to drive with a dirty battery, since the conductive deposit will contribute to its rapid discharge and deterioration of performance.

In addition to the external inspection, you can start the car engine. A cold start will be especially indicative if the engine has not been started for a long time and it is cold outside. If the car starts easily, the battery is in order, but if it does not start or starts with difficulty, the headlights shine dimly, and the instrument panel is also not brightly lit, then the battery should be changed. Or, at least, check it with instruments, which we will discuss below.

Measuring voltage with a multimeter

If you do not want to check the condition of the battery “by eye”, or simply want to have accurate results in numerical terms, you will need a device such as a multimeter.

So, how to check a car battery with a multimeter: the device itself has two probes, one of which is red and the other black. In order to measure the voltage on the battery, you need to put the multimeter in measurement mode and place the red probe against the “positive” terminal, and the black probe, respectively, against the “negative” terminal.

The procedure is carried out on the battery terminals without load. If the battery is properly charged, the result on the device will be about 12.6-12.9 volts. This is the normal voltage that should be present on a fully charged battery. If you mess up the colors of the probes, the number will be the same, it will just be displayed with a minus sign.

If the engine is running, then you can also check the operation of the battery with a multimeter, but in this case it will be checked whether it is working together with the generator, as well as the serviceability of the voltage regulator. When the motor is running, the readings should be slightly higher - from 13 to 14 volts. If the indicator is lower, this will mean charging problems for the battery, and if the indicator is higher, the process of water electrolysis will begin.

There is a method to determine the degree of battery discharge by voltage. Voltage 12.5 - says that the battery is 90% charged, voltage 12.1 - 50%, and 12 - 10 percent. Although the method is approximate, it is proven.

It is also advisable to measure with the device “cold”, since a car that has recently been running can give higher values and be misleading. The multimeter checks the degree of charge, but does not provide comprehensive information about its performance. To do this, it is better to use a load fork.

Checking the battery with a load fork

The load fork is a very precise tool, but is rarely used in “manual” use, as it is used mainly in service stations. The beauty of this method of verification is that thanks to it an absolutely accurate result will be known.

The load plug works in a similar way to a multimeter: it is also connected to the battery terminals, but produces a short circuit current. As we already said, without load the indicator should approach 13 volts. The load fork imitates the operation of a starter, which is why the voltage “sags” at the moment of use.

The drop should be no more than 9 volts. Otherwise, it will mean that the battery is very discharged. After removing the load, the indicator again “rolls back” to its original value. If under load the voltage “sags” to 5 or even 3 volts, this means that the battery will not be able to start the car engine.

It is recommended to think about changing the battery even if the voltage when using the load plug drops below 9 volts.

An extremely important note: the load plug supplies approximately 200 amps of voltage to the battery and is not recommended for use in low temperatures. The ideal conditions for “field” use of this device is a temperature of +20-25 degrees Celsius.

If you apply voltage to a cold battery, there is a risk of severely discharging it.

Checking the electrolyte level in the battery

Another convenient and reliable method, which, however, is only suitable for checking serviced batteries, is checking the electrolyte level. The method is a little more complicated than the previous ones, but it gives a good idea of the condition of the battery and tells you what’s inside it.

First, remove the battery and completely clean it of dirt. Let us remind you that it is better to do this with a rag; dirt and minor corrosion can also be cleaned off using an ammonia-based glass cleaner.

Next you need to open the two filler plugs. They need to be easily pryed with a screwdriver and unscrewed; six filler holes are hidden under them. The electrolyte level in them is checked by eye and can be seen with a flashlight. If the liquid level is the same everywhere, then everything is in order, if somewhere the liquid does not cover the plate, you need to add distilled water.

In general, this procedure must be carried out regularly, since each time the battery is charged, the electrolyte decomposes in small proportions into hydrogen and oxygen. Without regular maintenance, the battery will simply fail.

The norm is considered to be a level exceeding the height of the plates by about one centimeter, or below the neck of the filler hole by three millimeters. If necessary, it is worth adding distilled water to the battery being serviced, but we remind you once again: if the battery is marked “maintenance free”, or the manufacturers of this particular battery model do not recommend adding distilled water to it, you can only resort to the previous testing methods and, if necessary, replace the battery.

Knowing how to properly check a battery is important when buying a used car. Often, car sellers want to save money on small things, including selling a car with a dead battery, which can lead to negative consequences for the new owner. Always be alert and fact-check what the seller says about the health of your car.

And don't forget to check the car's history before purchasing. This can be done using the Autocode online service using VIN or state registration number. number. The system checks the car in more than 12 official databases: traffic police, EAISTO, RSA, taxi and bank registers, Federal Tax Service, Federal Customs Service and others. From the report you will find out: actual mileage, whether there are traffic police restrictions, compulsory motor liability insurance data, customs history, history of fines, participation in road accidents and much other important information.

If you do not have the opportunity to go for an inspection or you simply doubt your experience, order the Autocode on-site inspection service. An expert will come for an inspection and conduct a comprehensive diagnosis of the car, leaving no doubt about your choice of vehicle.

The battery is a wise purchase. What do we pay attention to and what do we do after purchasing it?

When purchasing a battery for a car, a lot of questions arise that require a qualified answer. An answer that would satisfy not only a person somewhat experienced in the topic, but also someone who is not particularly versed in technology. In order to ask the right questions when purchasing a battery and understand what you should really pay attention to, it is worth outlining the range of specific questions.

Oddly enough, but if we talk about seasonality, then it is the autumn-winter period that turns out to be a time of increased demand for batteries. The reason for this is quite prosaic, because in a warm period of time the oil poured into a car engine does not harden and therefore it is not difficult for the starter to turn the crankshaft. Even a half-charged battery can cope with this task. At the same time, when cold weather sets in, the oil becomes thicker and the starter has to deal with its increased viscosity, making it difficult to turn the shaft. At the same time, the current consumption inevitably increases, and the battery tries to contrive to send its unlucky owner for another expensive purchase.

This is where the real question arises: “How to choose the right battery?”

A confident buyer is the key to a successful purchase. Sufficient preparation will not hurt in any way, so it makes sense to determine a purchase algorithm, which it is highly advisable to adhere to. Below is a list of suggested points of contact for making the right choice.

1. It is important that the dimensions of the battery coincide with the dimensions of the seat where it will be located in the car, be it the engine compartment or the luggage compartment. It will not be very pleasant if the platform on which the battery is installed is a couple of centimeters smaller than its base. To avoid mistakes, the easiest way is to look at the geometric characteristics of the old battery.

2. It is equally important to pay attention to the polarity, that is, to the location of the terminals. The positive and negative terminals may be located on different sides of the battery if it faces the user, and therefore its connection will be difficult or even impossible in principle due to the insufficient length of the supply cable.

3. It is clear that it is necessary to select a battery with an electrical capacity no less than that of the battery being replaced. It is equally important to consider the value of the starting current. This parameter characterizes the ability of the battery to deliver a certain power under short-term load (up to 30 seconds) and at a temperature of -18°C. It is very undesirable for this parameter to be lower than that recommended by the car manufacturer.

4. Many people are concerned about choosing a product brand. There are clear leaders who are determined by numerous tests. For example, the magazine “Behind the Wheel” recommends choosing products from the following brands: Bosch and Medalist, Varta and Tyumen (Tyumen batteries), Topla and a-mega, “Zver” and Mutlu, “Aktech”. You shouldn’t fall for mass advertising, because newcomers, as a rule, are not proven by operating experience, and outsiders, why experiment with them?

Most often, with comparable capacity and declared discharge current, it is the brand that determines the cost of the battery. The estimated cost of a battery of a European configuration with overall dimensions within the range of 242*175*190 mm is in the range of $120-$180 for a conventional battery and $230-$290 for an AGM battery.

5. It is worth especially noting that if an AGM battery was installed by default on the car, then this is the type that you should pay attention to when purchasing/replacing. It is very undesirable to use a so-called “regular” battery instead of the AGM battery recommended by the manufacturer, due to its possible rapid failure.

After purchasing a battery, do not delude yourself that it can be immediately installed in its place of work. It just needs to be charged, because extensive experience with newly purchased batteries testifies: “New, just from the display case, not necessarily fully charged!” Fortunately, a battery charger can now be purchased at almost any auto parts store. After the charging procedure, the old battery can be removed and a newly fully charged one installed in its place. And, let's go!

Those interested in the technical details may want to continue reading as some interesting operational issues will be covered.

Is it necessary to “warm up” the battery by briefly turning on the headlights?

Not so long ago, a recommendation for the use of such a technique could be found even in the literature, but over time everything changes, and studies conducted indicate: “There is no obvious benefit from such a technique, but rather even harm, because the battery in any case is discharged when the consumers are turned on , and the battery is already weak, and after a load... It is clear that having lost part of its capacity “to shine”, the power “to turn” may no longer be enough.”

Eye indicator and its purpose

Inside the vast majority of batteries in use today, the electrolyte is in a liquid state, and the indicator supposedly allows, albeit approximately, to estimate not only its level, but also its density and find out whether the battery needs recharging. However, the peephole is located on only one can out of six, so in essence it is only a marketing ploy. Most manufacturers introduced this constructive “improvement” in pursuit of attracting buyers, who at a certain point in time even began to perceive the absence of an indicator as a significant drawback.

How to assess the condition of a battery without complex manipulations?

In principle, yes, it is possible, but only approximately. A battery disconnected from consumers and fully charged, being at room temperature, should produce a voltage at the terminals within the range of 12.6 - 12.7 V.

And for starters, the most interesting thing is, what is a “calcium” battery?

In fact, when we notice “Ca” or “Ca-Ca” on the marking, we are talking about only a slight addition of calcium metal to the electrode alloy, calculated in fractions of a percent. Such additives began to be added to achieve advertising rather than real effects. Although in reality the benefits are, of course, also present, but not as obvious as those brought by marketers. Such batteries are less prone to boiling, which is very important for maintenance-free models that have flooded the market. During storage, the self-discharge of such batteries is lower than that of conventional ones, the electrodes of which have the previously familiar antimony added to them and which necessarily had plugs. You won’t find such batteries these days, but they also had their own important advantage: they withstood deep discharge much better.

Today, in terms of price-quality ratio, the most popular car batteries are from the manufacturers Bosch (Bosch) and Varta (Varta). The online store AutoStandart33.rf offers a wide range of products from the brands listed above at an affordable price, which you can buy on our website.

Ways to check a new car battery when purchasing

When operating a car, it may be necessary to evaluate the performance of an old battery or test a new battery when purchasing. This will allow you to purchase a serviceable battery and, with proper use, achieve a significant increase in the service life of the device.

Verification Process

To avoid problems in winter and to be sure that the battery is in good condition, you need to check the car battery at several points when purchasing it.

Main stages of the study:

External inspection of the battery.
Checking the electrolyte level and its density for serviced models.
Measuring the voltage on the battery with a multimeter.
Checking with a load fork.

Before purchasing a new battery, you need to inspect it and check for damage to the case, chips or cracks that could have formed during transportation. If there are defects, then the battery cannot be purchased. Vibration during operation can quickly damage a car battery. Then you should evaluate the following parameters :

Date of issue. If the battery was stored for a long time, the plates could crumble: such an installation will not last long. The maximum shelf life is two years.
Terminal voltage. It should be at least 12.6 V. If the voltmeter shows less than 12 V, then the battery is either discharged or faulty.
Fill out the warranty card. Otherwise, the driver will have to pay for the breakdown.

Measuring the voltage at the terminals is not enough. To check the battery upon purchase, you need to use a load fork. It consists of a voltmeter and a load resistance connected to it in parallel. The plug allows you to check the battery when purchasing and when assessing the performance of the device in use.

To check, you need to connect the plug with correct polarity and measure the voltage without load. It should be 12.5−13 V. Then the load is connected for 5 seconds. At the end of this period of time, the voltage with a fully charged battery should not fall below 10.2 V.

If there is a large drawdown of up to 6-7 V, we can talk about a battery malfunction. If the voltage under load drops to 9.6 V and then recovers, then the battery is discharged and should be charged.

Measurements with the engine running

When the engine is running, the multimeter should show from 13.5 to 14.0 V. A voltage greater than 14.2 V indicates a low battery charge, and the generator operating mode is increased. If after 5-10 minutes the situation levels out, then everything is in order with the electrics.

If the voltage does not drop to normal, overcharging and boiling off of the electrolyte may occur. A voltage of 13.0−13.4 V with the engine running and energy consumers (heating, headlights, radio) turned off indicates that the battery is not fully charging.

If the multimeter shows less than 13 V, this means that the generator is not charging the battery. With all consumers turned on, the voltage should not be less than 12.8-13.0 V. If it is less, the battery needs to be changed.

The battery charge level indicates its ability to maintain voltage for some period of time. When the battery is fully charged, even after a week of inactivity, the voltage will not drop much. If the car’s battery is discharged, the charge will not last long.

Battery categories

All batteries are divided into three types: maintenance-free, low-maintenance and maintenance-free.

Before purchasing , you need to figure out what type of battery is needed :

Serviceable - fully repairable devices. It allows you to replace the plates and control the level and density of the electrolyte. This is an outdated model. It becomes unpopular precisely because it quickly breaks down if poorly maintained. Most often this happens due to boiling and evaporation of the electrolyte. Such a battery requires constant monitoring.
Low-maintenance batteries are distinguished by the design of their lids, which allows electrolyte vapor to condense and return to the jar. They rarely have to be serviced, but the need to monitor the electrolyte level remains.
Maintenance-free - this is a sealed design; they do not need to be serviced; it is not possible to add water or check the density of the electrolyte. But if used correctly, it is reliable and will work for a long time.

You need to buy a battery of the capacity specified in the car’s instructions. It is possible to choose a slightly larger container. This will help the car start more easily in winter conditions.

It is better to purchase batteries in specialized stores . They always check the battery upon purchase. The goods in such stores are certified, and if they are defective, they will be replaced. Nowadays, the most common batteries are low-maintenance ones. They have a long service life and a good ratio between price and quality.

Checking a new battery

There are several basic methods used to test a new car battery. Each of them has its own characteristics and operating principle. Before purchasing a battery, in order to avoid further problems, you need to know what to pay attention to, first of all, the following points:

Before purchasing, you should check the release date of the battery. Batteries should be stored in stores for no more than two years, otherwise their service life will be reduced.
The voltage at the battery terminals should be slightly greater than the voltage of the battery itself. If the indicator on the terminals is less, most likely the battery is very discharged.
You should check the battery case for mechanical damage, dents and scratches. If the battery breaks after purchase, you can use the warranty. The warranty period for goods imported into the Russian Federation is from 1 to 2 years. When purchased, a new battery should not have any visible damage.

Today, thanks to constantly improving technologies, there are several devices with which you can test a new battery.

Checking with a multimeter

A multimeter is a special device for measuring battery voltage, which is sold in specialized stores at an average price of 300 rubles. It is one of the easiest to use and does not require large expenses. The multimeter is suitable for working with any electronic devices, so it may be needed not only by motorists. Today there are two main types of multimeter: digital and pointer.

The first option is recommended for purchase, as it most accurately measures the battery voltage. When taking measurements, all information will be displayed on the device display.

Step-by-step instructions for measuring battery voltage using a multimeter include the following steps:

Turning the multimeter into DC voltage measurement mode.
Setting the switch to 20 volts.
Connect the black probe to the negative pole (minus), the red probe to the positive pole (plus).

If the display shows 12.6 volts, the battery is charged. If the voltage is less than 12 volts, the battery is less than 50% charged. A number below 11.6 indicates the battery is completely discharged.

Using a multimeter, you can not only measure voltage, but also determine current leakage. If the current leakage is too great, the battery will discharge faster than usual. The optimal figure is no more than 60 mA, a higher figure indicates severe leakage and loss of energy.

An increased voltage during measurement is observed when the car engine is running. This is not a bad indicator - the figure should be at least 14 volts. But, if the voltage is less than 13.4 volts when the engine is running, this indicates that the car’s battery is completely discharged.

Checking with a load fork

Testing using a load fork is the most effective along with other methods. The voltage measurement time with a load fork should be no more than five seconds.

The device is connected to the battery with correct polarity. At the beginning of the measurement, the voltage should be no more than 14 volts, after five seconds it should drop to 10 volts.

This indicates that the charged battery is operating correctly. But, if the number drops below 9 volts, this indicates that the battery is severely discharged. Experts advise charging the battery in a timely manner to avoid getting into an unpleasant situation.

Checking the voltage when the engine is running

When using a multimeter to measure the voltage on a running engine, you should note the initial number - it should be approximately 13.6 volts. Next, you need to gradually turn on various sources of energy consumption - headlights, air conditioning or stove, music player, and so on. In this case, the battery voltage should drop by 0.1 or 0.2 volts, but no more.

A strong voltage drop indicates a critically low battery charge level, and therefore you need to contact a service center.

The basic relationship between voltage and battery charge in percentage:

12.9 volts – 90% charge
12.5 volts – 50% charge
12.1 volts - less than 10% charge

According to experts, voltage measurements should be taken in the morning, when the engine has not yet been started. It is not recommended to measure the battery voltage after the car is turned off, as the voltage reading may change the next day.

This table shows the main methods for checking the voltage of a new battery, the necessary series of actions for checking, as well as the results and their meanings.

How to check a car battery?

Checking the battery charge level takes little time and does not require high qualifications or expensive equipment. The operation allows you to check the condition of the battery and the need for charging. This is the first thing to do if you have problems with the starter. Also, the ability to check the charge will be useful when buying a new battery or servicing an old battery. In this article we will look at three ways to diagnose a battery: using a multimeter, an indicator and a load plug.

In this article you will learn:

Why check the battery charge?
Ways to check the car battery for performance
Video instruction

Also at the end of the article you can watch an instructive video that gives useful tips for quickly and accurately checking the performance of the battery.

Why check the car battery charge?

Lead-acid batteries, which are used in cars with internal combustion engines, have low internal resistance. This allows them to deliver the hundreds of amperes of current required to operate the starter. However, this type of battery cannot be subjected to deep discharge. Otherwise, the plates become covered with a layer of lead sulfate and the battery suddenly loses capacity.

A fully charged battery produces a voltage above 12.6 V. As the charge level drops, this figure decreases:

Given the tendency to sulfate, it is undesirable to discharge lead-acid batteries to less than half the charge. Therefore, if the voltage at the terminals drops to 12 volts, you need to immediately charge the battery.

When purchasing a new device, you should not buy severely discharged batteries. It is possible that sulfation of the plates has already begun in them. Therefore, if there is no indicator on the battery, it is worth checking it with a multimeter or a load plug.

How to check the battery charge using the indicator?

Many maintenance-free batteries have charge indicators that allow you to visually determine the condition of the battery. This option first appeared on Japanese products and quickly gained popularity due to its convenience and accessibility.

The hydrometer, as the indicator is called, is a transparent window on the battery cover. The color of the window changes depending on the condition of the battery:

Green —full charge.
Gray or white - need to be charged.

For some indicators, the window turns red when capacity is lost.

The principle of operation of the device is based on changes in the density of the electrolyte at different charge levels. It works like this:

A tube with a green float is attached to the window.

When charging the battery, the density of the electrolyte increases and the float rises, approaching the window.
If the battery is discharged, the density drops and the ball sinks in the electrolyte. As a result, the indicator window changes color to gray or black.

Some indicator models have a red ball that floats up when the density of the electrolyte decreases. This provides a red indication of the discharge.

When the electrolyte level drops, not the ball, but the electrolyte itself will be visible through the window. To prevent the destruction of the plates, you need to add distilled water to the jars and charge the battery.

The advantage of the indicator is that the device allows you to determine the condition of the battery without the use of special instruments. This is convenient when purchasing a battery or in road conditions when you need to quickly check the condition of the battery. However, indication using a float does not always allow one to draw accurate conclusions about the performance of the battery. Therefore, when in doubt, you should use a multimeter or a load fork. They are also useful when you need to check a battery that is not equipped with an indicator.

How to check battery charge with a multimeter?

To check the voltage at the battery terminals you need a voltmeter. However, instead of these specialized devices, it is easier to use universal measuring devices - multimeters. In addition to voltage, they measure current and resistance. Depending on the indication method, these devices are divided into two categories - digital and pointer . If you have a choice, it is better to buy a digital multimeter. It is simpler and more convenient to use.

On-board computers of modern cars are also equipped with voltmeters that display the voltage at the battery terminals. However, they are not connected directly to the terminals. Therefore, due to contact and wiring resistance, the on-board computer readings may differ from the battery voltage. With the engine running, the voltmeter on the dashboard shows too much voltage. If the engine is turned off, the device will give low readings.

Readings must be taken with the engine running and switched off. In the first case, you will be able to check the condition of the battery and wiring, in the second - only the battery.

Measurements while the engine is running

Place the car on a level surface, open the hood, put the handbrake on and start it. When the engine is running, the generator and voltage regulator operate, which charge the battery. Therefore, the voltage at the terminals should be within 13.5-14 volts. In some cars, when the battery is discharged and the air temperature is low, the electronics automatically increases the voltage to speed up charging. In this case, it should fall smoothly as it charges. If this does not happen, the electrolysis process is activated in the banks. The electrolyte will begin to boil away rapidly. Overcharging is especially dangerous for modern gel batteries with limited gas emissions.

A voltage of less than 13.4 volts is a sign of undercharging. Operating in such conditions promotes sulfation of the plates and shortens battery life.

When measuring voltage, you need to turn off all powerful consumers: headlights, heater, audio system. Otherwise, the power of the generator when idling will not be enough to maintain the optimal voltage level.

There are several possible reasons for low voltage at the terminals:

Poor contact.
Generator failure.
Voltage regulator malfunction.

You cannot operate a machine whose battery is in undercharge mode. The cause of the failure must be immediately localized and eliminated. If the voltage at the terminals and the output of the generator is very different, you need to clean the contacts on the battery with sandpaper or a file.

After checking without load, you need to turn on the headlights and other powerful energy consumers, add engine speed and repeat the measurements. If at high speeds under load the voltage drops to 13.4 volts or lower, diagnostics of the generator system and control unit is required.