Checking the Car Battery. 10 Ways to Determine Performance

No sooner had winter arrived than something became wrong with the battery, which had been working well for the last couple of years.
You can feel him straining with all his strength, trying to revive the frozen car. And this is at ten to ten degrees below zero, or will it still be at twenty, as they promised this winter? How do you know if it’s time to do something with the battery so as not to be left alone with a cold car in winter? Many people looking under the hood ask the question: How to check if the battery is charged? There is an old grandfather’s method, which almost every issue of the magazine “Behind the Wheel” wrote about. We buy a hydrometer at the store. This is a glass tube with a bulb and a float that needs to be put into the battery and the float should show whether our friend is charged.

Hydrometers are different, the float should indicate the state of charge of the battery

The hydrometer operates on the principle of measuring the density of the electrolyte; we use a bulb to collect the electrolyte from the battery, and the float sinks or floats depending on the density. On the float there is a scale showing the density and the corresponding degree of charge. Somewhere there was also a table that made adjustments to the readings if the temperature at the time of measurement differed from 25 degrees Celsius. The most accurate way to determine capacity, and also the most correct.

We carefully inspect the battery. To get a better look at it, I even brought the battery home. And so, we look and are surprised, and where is there something? By and large, most modern batteries are considered maintenance-free. (Maintenance-free means you don’t need to do anything with it for the first two or three years, and when you need it, it’s easier to throw it away and buy a new one) And there’s even a peephole to visually check the charge. For some reason I can't see anything through it.

With maintenance-free batteries, everything is considered to be sealed and sealed, but you and I understand that at the factory the electrolyte should have been poured into this standard acid battery somewhere. We look carefully and see that there are still holes, just unscrew them with a coin and you can check. But we will not test it with a hydrometer. Firstly, there is acid in the battery, and it will be very unpleasant if it gets, for example, on your finger. And secondly, you can understand the degree of charge of a 12-volt battery simply by measuring the voltage at its terminals and without getting dirty with acid. The method is of course less accurate, but there is no need to get dirty.

There are only two nuances here. The voltage should be measured a few hours after the last trip (charging) so that all chemical processes calm down. If you measure it right away, the battery will always show a very good result. You need to measure it with a digital voltmeter, which shows tenths, or even better, hundredths of a volt. Of course, if you are a big fan of car batteries, you can use the first option, with acid and pears, but I prefer the second. In addition, my alarm key fob shows the voltage on the battery, look in the instructions for your car, maybe you have something similar.

So: table of charged battery voltages

Voltage Volt

State
12.6 or more	100%
12,5	90%
12,42	80%
12,32	70%
12,20	60%
12,06	50%
11,9	40%
11,75	30%
11,58	20%
11,31	10%
10,5	0%

The good thing is that air temperature has virtually no effect on voltage. Those. In cold weather the voltage will be a little less, but not much. However, negative temperatures greatly affect the battery’s ability to deliver its capacity. Let's look at the table.

Approximate dependence of battery capacity on ambient temperature

Air temperature in degrees Celsius

Capacity
25	100%
20	95%
10	90%
85%
-10	70%
-20	50%
-30	40%

If the battery is 100% charged at 25 degrees Celsius, then the lower the temperature, the less it can give up its capacity. But if the battery is discharged, say 50%, then when the temperature drops to -20, you can start the car only by calling a friend for help. And a discharged battery can simply freeze, turning into an ice barrel. Of course, you can thaw it and then try to charge it, but how it will all work later is unknown. It won't work well, if at all. So it’s better not to let this happen.

And at what voltage should the battery be charged? The answer comes from the car manufacturer. In some particularly advanced cars, if the battery voltage drops below 12 volts, for example to 11.9, which according to the first table is 40% of the capacity, then the car displays “Battery low” on the on-board computer. For me, for example, it starts making nasty noises every time I open the door, like, master, quickly charge me, my death will come soon. Of course, the manufacturer is playing it safe and you can still drive on such a discharged battery, but it’s still better to take the battery to a warm room for charging without waiting for a frost of 20 degrees.

We charge the battery using an automatic charger.

And in a warm time, so that the battery takes all the possible capacity, and not how much is indicated in the table. The charger must be fully automatic, so as not to carry around with hydrometers to determine the degree of charge/discharge. I still have it from the old days and it works great, it even charges a 70A battery, although the instructions say that it works for 55-60 amperes.

Is it possible to recharge the battery at idle so as not to carry these 15-19 kilograms? Of course you can give it a little extra charge, the question is how long you need to run the car at idle speed. This time depends on many factors. But besides empirical arguments, let's look at the numbers. A car generator produces up to 80 Amps at a maximum speed of about 5000 rpm. At idle, the generator will produce about 30-40 amps. Is it a lot or a little? It all depends on the consumers. If the ignition circuit takes about 20 amperes, the headlights another 20, the glass heating 15. Of course, a little less, since we look at the size of the fuses.

But we still see that even with consumers turned off, almost all the current generated by the generator will be spent on maintaining the operation of the machine, and there will be nothing left to charge the battery, good if there are 10 amperes. With this current, a discharged 60 ampere battery will be charged in about 6 hours, and even if the battery takes a charge, we remember that in the cold the battery capacity decreases sharply. Here is the answer. And if you remember that the starter immediately takes 150-200 amperes, and maybe up to 500 amperes in a very slow-frozen version, then it’s not worth starting the engine again to “recharge” the battery. It’s better to take the discharged battery to charge somewhere warm and it will be fine.

What to do if the battery charge is not normal?

The answer to this question is simple. If the battery charge is not normal, the battery needs to be charged. The charging process was described in detail in the article “How to properly charge a car battery with a charger.” Here I would like to note some nuances.

accelerated This mode is often called Boost and can be found on many modern chargers (chargers). In this mode, the battery charge is not fully charged, but it is quite enough to start the engine. This type of charging is used when you need to go urgently and the battery is low. This mode is not recommended to be used continuously. Here, the charge is accelerated by increasing the current strength, which increases the battery life;
with constant voltage. This type of charging involves maintaining a constant voltage across the terminals. This mode is used in the automatic charge mode on most chargers. It is recommended to use it when the battery is not very discharged (not lower than 12 volts). Read more about car battery voltage in the article at the link. The advantage of this mode is that you don't have to control it. The charger itself will determine when the charge is normal and stop the process;
with direct current. This charging option involves supplying constant current to the battery. The process is carried out in several stages, in which the current gradually decreases. This mode is recommended when charging a deeply discharged battery. It allows you to charge the battery most fully and evenly. The downside is that you will have to constantly monitor the process, measure the voltage and stop the process when the battery charge is normal.

Battery charging process

In conclusion, I would like to remind you about the safety rules when charging a battery. The process must be carried out in a ventilated area. It is better not to charge in residential areas. There should be no open flames or sparks near the battery being charged. During the charging process, hydrogen is released, which in combination with oxygen forms an explosive mixture!

Signs and causes of battery failure

An experienced driver will quickly guess about problems with the power source. To do this, he only needs a few signs, including:

Sluggish engine cranking, indicating a low charge level. His efforts are not enough to ignite the fuel mixture.
The battery drains quickly. Usually this problem is detected in the cold season, when a seemingly full battery goes out after a couple of cranks.
Energy consumers are unstable.

All these factors should not be ignored, since the final failure of the battery can occur at the most unexpected moment. To avoid consequences, it is necessary to diagnose the unit.

There are several reasons for the battery to malfunction. Among the main ones the following are considered:

The absent-mindedness of the owner, when electrical appliances are left on when leaving the car, which leads to the rapid landing of the container.
Low quality of equipment maintenance.
Increasing service life beyond established standards.
Technical problems in the electrical wiring system, which can result in oxidation and destruction of contact connections.
Incorrect connection of consumers leads to increased electricity consumption and reduced battery life.
The generator does not work well, disrupting the battery recharging cycle while driving.

The root causes of battery failure can be diagnosed and prevented. It is important that this be done by properly qualified specialists and using high-quality and reliable tools.

Lighting a cigarette from a charged battery

The most popular way to “reanimate” a battery. When connecting batteries to each other, remember the diagram:

We connect the wire for lighting one end to the positive on the operating unit;
with the other end we also connect it to the positive on the non-working battery;
with the second wire we do the opposite (first we connect the wire to the negative of the failed battery, and then we connect to the negative of the charged battery).

Problems with the generator

The battery does not charge from the generator due to a number of reasons. In order to quickly identify these problems, you need to know their characteristics.

Belt problems

If the generator does not charge, then the problem may lie in the integrity of the belt. Even an inexperienced car owner will detect serious damage. It is more difficult to determine its weakening. Indeed, in this case, the generators either provide charging or not.

To identify problems with the belt, look at the indicators and lights. They glow almost constantly. To eliminate this, tighten the belts or completely replace them.

Faulty diodes, regulators, brushes

The generator does not charge the battery if faulty diodes are included. Such elements are identified using multimeters or testers. It is possible to replace one diode or the entire bridge. Incorrectly functioning elements cause the battery to be poorly charged or recharged.

When the power supply is overcharged, the diodes, which are operating normally, heat up. Voltage surges result from the use of an ineffective regulator. It is replaced immediately.

Poor charge occurs because the brushes that make up the generator wear out. If the replacement is not made, the generator does not charge the power source.

Polarity reversal

If the battery of a laptop or vehicle is completely discharged, perform a polarity reversal. If done correctly, the power supply will charge. Polarity reversal can be performed if changes in the poles can be observed. Otherwise, the charging unit should not be connected.

When determining pole reversals, you should focus on the capacity of the cans that are included in lead-acid batteries, but not other sources. For recharging, use only those chargers that are equipped with protective elements.

Polarity reversal is not performed if:

The electrolytic composition has become cloudy and the charged car battery is quickly discharged.
The lead plates were destroyed.
KZ banks, which is included in the composition.
Low composition density.

Overload

Why does the battery receive a charge, but the voltage does not increase? The main reason is generator overload. This is caused by the connection of standard and non-standard electrical equipment, various gadgets and installations. In this case, the generator operates at the limit.

Such difficulties arise for new car enthusiasts. After all, they use a variety of units and devices, acoustic systems, and lighting equipment for tuning. Sometimes car batteries are upgraded by increasing the power level of the power sources. Therefore, the output voltage does not “cover” all costs.

Other reasons

Why won't the generator charge? This occurs due to rapid wear of the rotor, which does not perform rotational movements and gets stuck in the stator. The rotor stop frequency varies. The only way to cope with this problem is to dismantle the old installation and install a new unit that works normally.

A breakdown in the circuit is an equally common problem due to which the car battery does not take charge from the electric generator. It is problematic to independently identify why the generator stopped functioning. Car mechanics and workshop workers are involved in this event.

The generator does not produce rated voltage

When determining why the battery is not charging, specialists constantly disassemble the generator. These steps allow you to identify the following faults:

The damaged pulley is replaced. To identify such a defect, this element is periodically inspected. Abrasion of current collecting brushes. During active use of vehicles and car batteries, current collection brushes are periodically replaced. When selecting elements, they are guided by the manufacturers’ recommendations. Wear of slip rings. Copper components lose integrity and properties. This results in a reduction in the rated voltage. As a result, the generator does not produce a charge. Violation of the integrity of the diode bridge. Damaged diodes are soldered or pressed in

It is very important to carry out all processes correctly. Soldering irons and other tools are used for these purposes.

The car battery does not charge for various reasons. If the problems are related to current leakage, then elimination of them must be started immediately. After all, a malfunction of the electrical system leads to short circuits, fires, etc. You need to check not only the car battery, but also the generator. After all, it is not difficult to disable it. For example, such consequences result from the installation of non-standard equipment, untested units and installations.

Can I charge at home?

If there is no garage, it is possible to recharge the battery in the apartment. But it’s better to do this on the balcony. During this process, the electrolyte releases sulfur dioxide and oxygen chloride, which are harmful to humans. Inhaling it may cause dizziness and nausea. Therefore, we charge in the most remote and well-ventilated area. Also monitor the electrolyte condition.

Do not allow the battery to boil. This reduces its resource. On average, a 60-amp passenger battery charges in 7-8 hours. In this case, the charger must be set to the minimum current strength. Stress loads are harmful to the battery. If the battery takes a long time to charge, or one of the cans boils after half an hour, it means it has become unusable.

Internal battery failures

Reasons for discharging the VAZ 2110 battery
The main problem that spoils the battery from the inside is the coating of the plates with reaction salts of acid and lead. They prevent the movement of charged particles from one electrode to another. At the same time, the resistance increases, which leads to a decrease in the overall battery capacity. The early stages of such a process are reversible, but if the reaction has significantly damaged the plates, then restoring the operation of the unit is impossible.

Device for measuring electrolyte density

Sometimes particles may fall off the plates, leading to a short circuit. If this happened not so long ago, then washing the inside with distilled water will help. To avoid swelling of the case from severe long-term frosts, you should not leave the battery in the car. The electrolyte expanded due to this process will destroy the structure of the battery, which after such “stress” cannot be restored.

How to determine whether a battery is charged or discharged

This can be determined by the voltage at the contacts and the density of the electrolyte.

In a fully charged battery (100% charge), the voltage at the terminals should be 12.7V. When discharged, 11.7V (0% charge). Therefore, every 0.1V is 10% charge. These values are relevant for a battery temperature of 20-25 degrees.

For example, the voltage at the contacts is 12.2V, therefore the charge is 50%.

Table - dependence of the battery charge level on voltage.

The second, more accurate way to determine the degree of charge is by determining the density of the electrolyte. This method is only suitable for serviceable batteries in which it is possible to unscrew the plugs and get to the electrolyte.

A sulfuric acid solution is used as an electrolyte in batteries, the density of which is measured in g/cm3. During discharge, the density of the electrolyte decreases. Knowing this property, you can determine the degree of battery discharge. Density is determined using a special device - a hydrometer.

The density of a fully charged battery (100%) at 25 °C is 1.27-1.28 g/cm3.

The density of a completely discharged battery (0%) at 25 °C is approximately 1.1 g/cm3.

Knowing these data, it can be calculated that approximately every hundredth unit of density is equal to 6% charge (0.01 g/cm3 = 6% charge).

For example, the density is 1.24 g/cm3, therefore the degree of charge is 76%.

Graph showing the dependence of electrolyte density on temperature.

Table - dependence of electrolyte density on temperature.

Before checking the electrolyte density, be sure to turn off the charger and wait a few minutes. Density is more accurately determined when no gas is released from the electrolyte.

Why does a discharged, undercharged battery not boil?

Everyone knows that a normal battery placed on charge does not boil.
And why? Because the current supplied from the charger to the battery is initially spent on the electrochemical reaction of sulfate decomposition. When a battery discharges, lead sulfate forms on the positive and negative plates as a natural result of the discharge process. Such sulfate, when charged, turns into active substances without any difficulty. The fault term “plate sulfation” is used when discharged (i.e. coated with a layer of lead sulfate) plates do not charge when normally charged.

Lead sulfate, formed under normal discharge conditions, consists of small crystals evenly distributed in a porous and highly conductive active mass. With a subsequent charge, such sulfate again easily turns into lead dioxide and lead.

With unacceptably deep discharges, the active mass of the plates almost completely turns into sulfate, and in some cases the sulfate goes from a fine-crystalline state to a coarse-crystalline state.

Moreover, if there are surface-active organic substances in the battery, then adsorption of these substances occurs on the lead sulfate crystals of the negative plates, as a result of which the rate of dissolution of the crystals decreases.

In this case, the internal electrical resistance of the active mass increases sharply. The sulfate completely covers the particles of the conductive active mass, and the passage of current through the plates stops. In addition, the potential at which gas evolution begins during charging changes.

The transition of the adsorbed sulfate formed in the plates into lead dioxide and lead becomes impossible under these conditions, and the battery loses part of its capacity, and with very deep sulfation, almost all of its capacity, as we wrote about in the previous article.

The reasons for the formation of large lead sulfate crystals may be:

systematic, excessively deep discharge of batteries;
regular undercharging;
leaving batteries in a half-discharged or discharged state for a long time;
low electrolyte level.

When the battery is almost fully charged and there is little soluble sulfate left on the plates, then some of the current supplied to the terminals turns out to be excessive.

Where does the excess current go?

That's right, the process of electrolysis begins in the battery, i.e. decomposition of water into hydrogen and oxygen. Therefore, the battery begins to “boil”.

For this reason, an uncharged battery does not boil during charging, but an already charged battery “boils.” This is a sign that the battery has been charged and has stopped accepting a charge.

How to check if the battery is alive in a car without instruments?

It is quite easy to determine the condition of the battery in a car without special instruments. There are several ways to do this.

Modern batteries have a special charging indicator, usually in the form of a round window. You can determine the charge by the color of this indicator. Next to such an indicator on the battery there is always a decoding indicating which color corresponds to a particular charge level. Green - full charge; gray - half charge; red or black - full discharge.

In the absence of such an indicator, you can use two methods. The first is using headlights. The cooled engine is started and the low beam is turned on. If the light does not dim during 5 minutes of operation, then everything is normal.

The second (also when cold) is to turn on the ignition, wait a minute, and then press the signal several times. With a “live” battery, the beep sound will be loud and continuous.

Built-in indicator

Most imported batteries have a built-in indicator that can be used to check the charge. For the first time such batteries appeared in Japan. Then European manufacturers began to practice a similar trick.

What is its essence? There is a transparent window on the battery cover (a kind of peephole). If you look at it, you can see that it is colored green. But this doesn't always happen. The green tint in the window will only appear if the battery is fully charged. If the window is transparent or white, it means the battery has lost part of its charge. The worst case is a black window. In this case, the battery has run down and needs to be charged urgently.

For your information, this is one of the easiest ways to check the charge of a car battery without a voltmeter and other devices. After all, all you need to do is open the hood and look through that very window. But it is worth noting that not all batteries have such a peephole (especially when it comes to domestic ones). Therefore, to determine the charge level, you need to know other methods.

How to check the car battery charge using the indicator

Currently, many batteries are equipped with a built-in indicator indicating its current condition. Japan was the first to use it in battery production.

There is a special window on the battery cover. This is the car battery charge indicator. It is also called a hydrometer. Usually has a green color , indicating that it is completely infected. As the discharge progresses, the color changes. If the color is white or gray, this is a signal that part of the capacity has been lost. This means it needs to be charged. If the color is black , this means that it is completely discharged and needs to be replaced .

Electrolyte condition

You can understand how stable the serviceability of the power source is by looking at the state of the electrolyte. It should also be checked in cases where voltage and current readings cannot be measured.

To check, you will need a Phillips screwdriver - you will need to unscrew the caps on the jars in which the electrolyte is poured.

Some batteries have a charge indicator that helps determine the condition of the electrolyte - level, density, charge - and give a general idea of the health of the battery in this regard.

In other cases, you can simply check the electrolyte level with a flashlight; you just need to direct the beam into each of the cans. A signal that the battery will soon lose serviceability is exposed plates.

The liquid must always be above the critical level, since otherwise it will lead to the destruction of the grating filler, which, in turn, can cause a short circuit.

If the electrolyte is at an acceptable level, the next step is to measure its density. For this you will need a hydrometer. If the battery is 100% charged, the density will be ≥ 1.27 g/cm³.

The type of electrolyte also matters. A brown tint may be a sign of destruction of the plates. In this situation, you must carefully use a bulb to remove all the liquid that you can, and then replace it with the same volume of new electrolyte.

We use a multimeter

This is an indispensable device that every motorist should have. Allows you not only to check the battery voltage level, but also the resistance of the sensors, the load of the on-board network in real time and many other important parameters. You can purchase this device for 300-700 rubles, which is 2-3 times cheaper than a load fork. This device is very easy to use.

How to check the charge of a car battery with a multimeter? First you need to assemble it. We perform the following actions:

We connect two wires with positive and negative polarity to the corresponding connectors.
There will be probes at the ends of the wires. We apply them to the battery terminals.
First, set the device to voltage measurement mode and set the rotary switch to 20 Volts.
We connect the multimeter leads to the battery and look at the result. In this case, the car ignition must be turned off.

Reinstalling the battery

After cleaning the case, terminals and tray, reinstall the battery.

Carefully place it on the tray.
Attach to tray using clamping mechanism.
Connect the terminals. This time, start with the positive terminal and connect the negative or ground terminal last.
After connecting the terminals, spread a thin layer of Vaseline around the top of the terminals and terminal posts. This prevents corrosion from accumulating around the terminals.

How to check battery electrolyte density

To measure the electrolyte density level, you will need a car hydrometer. You need to lower it into the battery filler hole and use a bulb to draw in such an amount of electrolyte so that the float dangles freely. Then look at the level on the hydrometer scale.

The peculiarity of this measurement is that the density of the electrolyte in the battery in winter and summer in some regions will be different depending on the season and the average daily temperature outside. The table presents the data that you should focus on.

Season	Average monthly air temperature in January (depending on climatic region)	Fully charged battery	Battery is low
by 25%	by 50%
-50°С…-30°С	Winter	1,30	1,26	1,22
Summer	1,28	1,24	1,20
-30°С…-15°С	All year round	1,28	1,24	1,20
-15°С…+8°С	All year round	1,28	1,24	1,20
0°С…+4°С	All year round	1,23	1,19	1,15
-15°С…+4°С	All year round	1,23	1,19	1,15

DC current regulation

How to store a batteryHow to store a battery. Let's say in winter, charged or discharged. Correct instructions

The essence of this method is to control the current value by adjusting it depending on the current battery charge. For novice motorists it is difficult, since changes in the indicator depend on the actual condition of the battery. It is recommended to use if it is possible to constantly monitor the process.

It is best to consider the essence of this method using the example of a battery, the capacity of which is 60A*h. Recommended course of action.

Set the current value to 6A, from a ratio of 0.1 to the rated capacity.
After the release of electrolyte gases begins, it is necessary to reduce the indicator by half. If the battery charge is 14.4 V, the current should be 3 A.
As soon as the charge indicator reaches 15 V, the current decreases to 1.5 A.

In this way, you can charge the battery to a level from 70% to 100%. In the latter case, it is necessary to monitor the battery charge level and current strength. If the first remains unchanged for two hours, this is a sign of full charge.

How long does it take to charge the battery?

There is no exact definition of the time required for a full charge, as there are several factors that influence this. Therefore, the charging time can be from a couple of hours to several days.

There are 4 main factors affecting battery charging time.

Battery discharge percentage. A completely discharged battery will take much longer to charge than one that is 50% discharged.
Degree of battery wear. Over time, the battery plates crumble and its capacity decreases. Let’s take as an example a worn-out battery with a capacity of 60A*hour. But its capacity in fact will not be equal to 60A*hour, but will be less, for example, 50-45A*hour. Consequently, a worn-out battery will charge faster than a similar, but new one.
Charging current and voltage . The lower the current, the slower charging occurs.
Charge acceptance rate. For example, a cold battery charges less well. This is due to the fact that the rate of chemical reaction (electrolysis) depends on temperature. Therefore, before charging, it must be warmed up at room temperature if it is brought in from the street in winter.

If an automatic charger is used for charging, it will automatically determine when the battery is charged, turn off and indicate full charge with some kind of indication. When charging, as the battery charges, the difference between the battery's emf and the charging voltage decreases, resulting in a decrease in current. When the current reaches approximately 0.5A, the charger stops charging.

If the charge is not carried out automatically, then you need to wait until the current drops to its minimum value (approximately 1-0.5A) and remains at this level for about three hours without changing. After this, you can turn off the charger and measure the density of the electrolyte.

You can understand that the battery is fully charged by two signs. This results in the electrolyte achieving a density of 1.27 g/cm3 and a voltage at the battery terminals of 12.7V. Density and voltage measurements should be made after the charger is turned off and some time has passed after charging. It is necessary for the electrolyte to settle and stop releasing gas bubbles.

Articles

How to charge and check the battery charge

The main purpose of the starter battery is indicated in its name: it is a source of energy for the starter to operate. That is, the battery plays its main role at the engine starting stage, and then energy is supplied to the on-board electrical network from the generator.

At the moment the engine starts, the battery loses a significant part of its stored energy and needs to be charged - this is performed by a generator, which, in theory, should restore the battery in a relatively short time. However, this does not always happen, or rather, it rarely happens; in general, the batteries are either constantly undercharged (mainly in the city) or overcharged. In the first case, it is necessary to bring the charge to a normal level, and in the second, you should think about contacting a car service: overcharging may indicate a malfunction of the relay regulator. With constant recharging, the battery simply fails, and this, among other things, is not a warranty case; it will be impossible to replace the battery for free.

Battery diagnostics

How to check the battery? Based on what parameters can we conclude that the battery really needs to be charged and restored?

There are only two such parameters - voltage and electrolyte density. But if everything is simple with checking the first, then problems may arise with the second - now maintenance-free batteries are widespread, it is simply impossible to find out the density of the electrolyte in them. However, let’s not get upset in advance, but let’s see what can be done about it.

First you need to measure the voltage: at 100% charge there should be 12.7 V at the terminals, and the density of the electrolyte should be 1.265 g/cc. If the voltage is lower, then the battery is discharged: 12.4 V corresponds to a 75% charge, 12.2 V indicates a 50% charge, and a voltage of 12.1 V indicates that the charge is only 25%.

Checking the battery showed that it needs charging, what should I do next?

How to charge a classic car battery

It is easiest to charge a battery with a classic design - the presence of plugs and the ability to see the electrolyte allows you to control the charging process and achieve better results.

Before connecting the charger to the battery, you need to unscrew the plugs to open access to the electrolyte. Then you can proceed directly to charging, choosing one of several methods.

It is easiest to charge a battery of a classic design with a constant current. To do this, a current equal to 10% of the battery capacity is selected on the charger: if the capacity is 60 Ah, then the current will be 6 A. There is no need to set the voltage in this case - it will be automatically adjusted by the charger.

Now you need to show a little patience - a new battery can be charged in this way for up to 8 hours, a battery with “experience” gains a full charge in a longer time. And all this time (every one and a half to two hours) you need to check the voltage and density of the electrolyte.

Don’t be surprised that the voltage will be higher than the usual 12.7 V - that’s why the battery is charging. When the voltage reaches 14.4 V, it is worth halving the current. The electrolyte density should also constantly increase, but not too quickly.

In this regard, remember about safety!

Charge the battery in a well-ventilated area, and do not bring open fire to it - hydrogen mixed with air will ignite even from a spark, and can lead to a fire and even an explosion of the battery!

You can turn off the charger 15 - 20 minutes after the electrolyte “boils”, after another 20 minutes you can tighten the plugs - you need to let the gas escape completely.

But bubbling electrolyte is not the only sign of a full charge. The battery can be considered charged if the current, voltage and electrolyte density do not change within one to two hours. Then you can safely turn off the charger and put the battery back in place.

How to properly charge a maintenance-free car battery

It is best to charge a maintenance-free battery using another method (which, however, is suitable for any type of battery) - constant voltage charging.

In this case, a certain voltage is set on the charger, and the current will be adjusted automatically. More precisely, the current will change due to the laws of electrical engineering - as the voltage on the battery increases, the current will drop, and when the voltages on the battery and the charger reach equality, the current will become zero.

The latter circumstance determines the popularity of this charging method - it occurs automatically, since once a full charge is reached, no further charging is performed, which means there is no need to monitor the process.

However, this method has a drawback: it requires a lot of time - at least 20 - 24 hours. But even this time will not be enough if the charging voltage is set too low. So, at a voltage of 14.4 V, the battery will be charged 80% per day, at 15 V - 90%, and at 16 V - 95 - 97%. Full charging can be achieved at a voltage of 16.3 - 16.4 V.

This method is good because it allows you to easily maintain the battery in working condition, especially if the car is constantly operating in “taxi” mode. However, it is better to bring the battery to a full charge using the first method.

How to charge a car battery in winter

In winter, the battery operates under the most difficult conditions, since when starting the engine it is required to produce almost twice the starting current. But this is not so bad, because frost reduces the battery capacity, which means the starter can work normally for less time than in summer. So, at a temperature near zero, the battery capacity decreases by about a third, and at a temperature of minus 18 degrees, the capacity drops by half. Now it’s clear why the battery discharges in severe frosts.

But the battery charge level affects not only the car’s ability to start in cold weather, but also the physical condition of the battery itself. The fact is that the lower the charge, the higher the freezing point of the electrolyte. If the battery is fully charged, it will not freeze even at minus 60, but if completely discharged, freezing can occur even at zero degrees.

In this case, the electrolyte turns into ice and, due to the known properties of water, increases in volume. This leads to “inflation” of the battery, and sometimes the battery walls are completely destroyed. It must be said that this case is not guaranteed, so in winter it is necessary to monitor the condition of the car and use special winter oil - this will prevent the battery from being discharged by a long start-up due to thickened oil.

If the battery is not damaged by freezing, it must be warmed until the electrolyte is completely thawed and charged.

Fast battery charging

Sometimes you need to charge the battery very quickly, literally in two or three hours - is this possible? Yes, it is possible, as many car enthusiasts prove every day. Reducing charging time is achieved by simply increasing the charging current - in practice, the current is selected within 10 - 20 A.

It must be said that this method is not the best - too high a current contributes to rapid wear of the battery. But sometimes there is simply no other choice, and you have to risk the battery to save time.

First battery charge

In most cases, it is not advisable to immediately install a new battery in a car - it needs to be charged. But if you have a little time, but do not want to carry the battery home, then you can charge it from a car generator - just drive for at least an hour in moderate mode.

It is not allowed to immediately park a car with a newly installed battery in a garage or parking lot for several days - such idleness, especially in winter, will most likely lead to a discharge of the battery.

If you purchased a dry-charged battery, then in any case you will have to spend some time getting it into working condition.

How long does it take to charge a battery just bought in a store? As practice shows, from three to eight hours. You can charge it using any of the methods described above.

A dry-charged battery is another matter. First, you need to pour electrolyte into it, wait until the plates are saturated (this lasts from 15 minutes to an hour), then add electrolyte to the desired level, and wait - after about an hour and a half, the battery will charge, this can be seen by the “boiling” electrolyte.

When gas evolution stops, you need to check the battery voltage, and if it is lower than required, carry out normal charging using a charger. If the battery is new, then all this will take 3-4 hours, but if the battery has been in the store for over a year, then charging may take 6-10 hours.

Proper charging of the battery is a guarantee of its long and stable operation, and great attention must be paid to this matter. Moreover, with some skill this will not cause problems or inconvenience.

Source

Checking the battery charge when measuring electrolyte density

This method of checking is quite useful before the onset of winter. A decrease in ambient temperature reduces the density of the electrolyte. Thus the charge also drops. Low density increases the risk that the car engine will not be able to start.

To check the charge of a car battery, you need a special device - a hydrometer. The sequence of actions is as follows:

6 caps of battery cans are unscrewed.
The hydrometer is placed inside the jar. And you need to wait until it is completely filled with electrolyte.
It is pulled out and over time the float will indicate the current readings.

If the car battery is in good condition, then during the cycle from full discharge to full charge, the range of changes in electrolyte density will be from 0.15-0.16 g/cm3.

Using a car at low negative temperatures with a discharged battery will lead to freezing and disintegration of the lead plates.

In the table you can see at what sub-zero temperature, depending on the density of the electrolyte, ice appears in the battery.

g/cm3	1,10	1,11	1,12	1,13	1,14	1,15	1,16	1,17	1,18	1,19	1,20	1,21	1,22	1,23	1,24	1,25	1,28
°C	-8	-9	-10	-12	-14	-16	-18	-20	-22	-25	-28	-34	-40	-45	-50	-54	-74

As you have already noticed, even a fully charged car battery will freeze at a temperature of -74 degrees, and with a capacity of 40% it will freeze at -25 degrees. And with a low charge, up to 10%, it will not be possible to start the engine even in mild frost.

If the loss of current is more than 45-50% in winter, and more than 25% in summer, it must be charged.

Measurement of AC current values

Any household electrical appliance is a load that consumes alternating current. But when considering issues of household use of electricity, power remains an important concept, because they pay for kilowatts (kW). What is an ammeter in this case? Indirect measurement device. Using it, they find out the current and using the formula:

P=IU (Ohm’s law), where I – current (A), U – voltage (V),

calculate power (P) (W).

For example, the device has lost information about its parameters; in this case, measurements cannot be avoided. Or you need to calculate the power consumption of a building, where it is simply impossible to take into account all the devices. Then a powerful ammeter is connected to the input from the power panel and measurements are taken. But in the latter case, you need a permit, which only professional electricians have!

Source: net-gadget.ru

How to check the battery condition with a load fork

This charge current test is a more professional method. This method is used in technical car repair centers. Because It gives fairly accurate readings and is also capable of working under load.

A load fork is a device that allows you to accurately check the health of the battery. It consists of a multimeter and a load resistor. There are also more complex versions of the device, in which there is an additional ammeter.

How to check the condition of a car battery using a load fork? The verification principle is as follows:

The load plug is connected to the terminals of the battery, which produces the short circuit current. Thus, the operation of the starter is simulated.
The readings on the device are read, which show how much the battery charge has decreased when you start the car.

It is worth remembering that the battery voltage must be checked when its temperature is in the range of 20 to 25 degrees. It’s not worth checking a cold one, as you can overdischarge it, losing a significant part of the capacity.

Indications, V	Charge level, %
More than 10.2	100
9,6	75
9	50
8,4	25
Less than 7.8

How much should the battery read under the load plug? Controlling the charge with a load plug is the most accurate method at the moment. Because it simulates the operation of a car starter. If, as a result of the test, the device shows a drop in battery voltage to 9 Volts, it means it is weak and needs to be charged. It is considered normal when at least 10 Volts.

Remember! It will quickly discharge in winter if the voltage is less than 9 Volts. We also draw your attention to the fact that frequent use of a load plug can damage the battery, significantly reducing its capacity.

Watch the video on how to check the battery with a load fork:

Checking the remaining battery capacity

If you notice some deterioration in parameters, you can check the remaining battery capacity. Such measurements can be made with the Lancol Micro-200 device. It calculates an estimate of battery wear and displays the main indicators on the screen. In the photo below:

Lancol Micro-200 battery performance tester

SOH - battery performance as a percentage of maximum capacity.
SOC - battery charge.
R is the internal resistance of the battery.

You can calculate the residual capacity yourself using the formulas.

The internal resistance of the battery indicated in the passport

Let's say there is a battery with a cold cranking current of 420 amperes, a capacity of 60 ampere/hour and an internal resistance of 4.2 mOhm (0.0042 Ohm). Resistance data can be found in the battery data sheet.

First you need to calculate the actual resistance. Before starting, we measure the voltage on the battery, for example it was 12.69 volts. We take a 50 W light bulb from a headlight and connect it to the battery via an ammeter. The current was 3.65 amperes. The voltage when the light bulb is connected is 12.5 V.

We substitute the values into the formula: R (actual) = (12.69 (for example, without load) – 12.5 (under load))/3.65 A (bulb current). We get R (actual) = 0.052 Ohm.

Since the resistance also depends on the external temperature. At 25 degrees it is 100%, and at minus 20, for example, 40% of the norm. It is necessary to calculate the reference resistance: Ret = 0.0042*100 = 0.042 Ohm.

From here we get C residual = 60*0.042/0.052 = 48.46 A/h. Now let's calculate as a percentage: 48.46/60*100%= 80%. The remaining battery capacity is 80 percent, which is still not bad.

Checking the electrolyte in the battery

The electrolyte level in the battery plays an important role when operating the device. Its testing can be carried out in different ways depending on the design of a particular battery. Traditionally, motorists assess the electrolyte level visually through the holes under the lids of the battery cans. Some models are equipped with a scale to determine how full the battery is, indicating the maximum and minimum allowed for safe operation of the device. At best, manufacturers make part of the plastic box transparent. To determine the level even more accurately, glass measuring tubes are used, lowered to the bottom of each jar. If you decide to take measurements in this way, do not forget about safety measures, because the electrolyte contains sulfuric acid.

When assessing the condition of the electrolyte in a battery, it is important to measure its density. To study this indicator, you will need a special device, a hydrometer, or densimeter. The complex design consists of a double glass flask, a bulb and a test tube filled with mercury or shot. A hydrometer allows you to establish the exact ratio of the parts of water and sulfuric acid contained in the electrolyte.

The density assessment procedure is carried out no less than 2 hours after the battery is fully charged by taking samples from each jar. The measurement result is considered reliable if a sufficient amount of electrolyte has been collected (before the float rises). The optimal density indicator is 1.27-1.29 g/cm3. If the norm is exceeded, the electrolyte can be diluted with distilled water, and if it is too low, a similar solution with a normal density must be added.

Car charger

Device diagram

All motorists have found themselves in such an unpleasant situation. There are two options: start the car with a charged battery from a neighbor’s car (if the neighbor doesn’t mind), in the jargon of car enthusiasts this sounds like “lighting a cigarette.” Well, the second way out is to charge the battery.

When I found myself in this situation for the first time, I realized that I urgently needed a charger. But I didn’t have an extra thousand rubles to buy a charger. I found a very simple circuit on the Internet and decided to assemble the charger on my own.

I simplified the transformer circuit. Windings from the second column are indicated with a stroke.

F1 and F2 are fuses. F2 is needed to protect against short circuits at the output of the circuit, and F1 – against excess voltage in the network.

Description of the assembled device

Here's what I got. It looks so-so, but most importantly it works.

Transformer

Now let's talk about everything in order. A power transformer of the TS-160 or TS-180 brand can be obtained from old black-and-white Record TVs, but I didn’t find one and went to a radio store. Let's take a closer look.

Checking a car battery using a multimeter

A special device can measure the charge and warn of current leakage. You can buy it at any large automotive store, or in the “everything for electricians” section of a construction supermarket. How this is done - step by step:

Make sure the car's ignition is turned off.
Switch the multimeter to voltmeter mode and set the switch to 20 Volts.
Connect the wires to the appropriate connectors of the device.
Attach metal probes at the ends of the wires to the battery terminals: red corresponds to the “plus” terminal, black to the “minus”.
Record the instrument readings.

Voltmeter readings (no load), V	Battery charge level, %
12.6 Volts or more	100%
12.5 - 12.3 Volts	75% — 50%
12.1-11.7 Volts or less	25% — 0%

The table data shows that if the voltage at the terminals is less than 12.7 V, then the battery is not fully charged, and if the multimeter produces less than 11.7 V, these are signs of a malfunction or deep discharge.

Interesting measurements

If there are leaks of electrolyte on the car battery, then the following interesting experiment will demonstrate the current leakage. It is necessary to put the multimeter in voltage measurement mode: place one probe against the car terminal, and the other against the surface of the electrolyte spot. The performance of the device will surprise you.

Electrolyte stains, as well as other liquids, are removed from the surface of the battery with an alkaline 6% soda solution (about a tablespoon per glass of water). Use a rag soaked in this solution. Avoid flooding the entire battery case, terminals, and car wires with water.

Ultimately, using an ordinary multimeter, you can study a large number of characteristics of a standard battery and more. That is why even the simplest such device is an extremely important thing in the household.

Moreover, such simple home diagnostics will allow you to avoid many unpleasant situations, and will also help you carry out timely maintenance and repair of your car.

How to prepare a battery for charging

Charging the battery is a simple process, but you need to take it responsibly and seriously. The battery contains a solution of sulfuric acid, which is very dangerous for humans. In addition, during charging, gases are released from the electrolyte, including explosive hydrogen.

Safety precautions are not just a formality. The health or lives of many people around us may depend on this knowledge. Therefore, it is extremely important to follow safety rules when charging a car battery:

First you need to put on overalls or ordinary things that will cover your body as much as possible. Cotton clothing is not suitable because the acid easily eats it away. The main thing is to protect your eyes with glass or plastic glasses, and your hands with rubber gloves.
Then you need to check the battery cover in the car for damage and electrolyte leaks. But if acid is detected, there is no need to try to remove it mechanically - wipe it off with something or rinse with water. For these purposes, use soda. If the device is in order, it can be removed from the car.
The battery should not be charged in a poorly ventilated area or in an apartment where there are children. It is best to do this in the garage. The reason lies in the dangerous gases that are released during charging.
Do not smoke in the area where the battery is being charged. One spark can be enough to cause an explosion.
If the battery has been left in the cold for a long time, it must first be allowed to warm up to room temperature.
Before connecting the charger, you must clean the battery case from dirt. You also need to remove oxidation from the battery contacts.
The battery must be charged away from other electrical devices. It is better to remove metal accessories from your hands, and put electronic gadgets away.
If the battery has a fill hole, do not shake it or turn it over. Care must be taken when working with such batteries, otherwise the acid solution may spill.
Remove the caps from the battery containers, if any. For maintenance-free batteries, remove the plug from the gas outlet. This is necessary so that the evaporation of substances does not accumulate inside the container.

When working with a battery, you should keep a solution of soda (10%) with you - it can neutralize the acid. If battery fluid gets on your skin and you don’t have soda on hand, you can rinse the burn area under running tap water. After charging, you should wash your hands with warm water and soap.

Why won't the car start? 10 main reasons and methods for eliminating them

Don’t rush to change components ahead of time

Try the methods given in our article to restore functionality and diagnose the cause of the malfunction. A battery, especially a new one, rarely fails suddenly. Much more common are software problems or failures in the operation of the power supply or its connectors. Check all the options, and only then decide to buy a new device.

Hello everyone, today I want to tell you why the battery on a Lada Kalina car does not charge. If the red battery indicator lights up, then this is already a reason to sound the alarm, since most likely the car is running only on the battery and is not receiving a charge.

Now a little joke: “Do you know why the battery can’t go down? Yes, because he can only sit down.” So, let’s go.

The first reason is the battery itself; if it is old enough, it may no longer take a charge, this is due to sulfation of the plates. You can borrow a working battery from someone and install it to check for sure, and then you can buy a new one. By the way, I noticed such a strange thing, for some reason the batteries that come from the factory with the car last much longer, I don’t know why. The second reason is oxidation of the wires and poor contact on the battery terminals; if they are oxidized, then you need to clean and tighten the contacts. Next, we check the minus of the body and engine and all other connections. Also, the wires that go to the generator also need to be checked. If necessary, tighten and clean. After all, sometimes it happens that due to poor mass the battery is not recharged. There was a case when everything was changed, both the battery and the generator, it was on a VAZ 2114 car, and in the end it turned out to be a ground wire going to the engine. The replacement did not help, I had to run an additional wire from the engine to the body.

The third reason for a poor battery charge lies, of course, in the alternator belt. If it doesn’t reach enough or something gets on it, say oil, then it will slip. The belt must be dry and taut. Well, if necessary, you need to replace it with a new one. In my case, the generator does not have a tensioner, so the only solution is replacement.

The fourth reason is the generator, but there is no need to rush and immediately run for a new generator for your Lada Kalina, perhaps your voltage regulator has failed or the brushes have worn out, if this is the case, then you need to replace it.

It is also possible that your diode bridge has failed and also needs to be replaced. There are also copper rings in the generator, they are also erasable. Well, then the rotor wears out and the circuit breaks, and in this case, you will probably have to buy a new generator. I looked at the most common reasons for the lack of battery charge on a Lada Kalina car, if you had other reasons, then write in the comments. Well, that's all for now everyone.

How to care for your battery

To avoid unnecessary troubles, you should regularly check the battery and give it the necessary care. To do this, the battery and its terminals must be kept clean and discharged/charged during prolonged inactivity. In severe frosts, it is better to take the battery from under the hood to a warmer place. Some manufacturers recommend charging the battery once every 1-2 weeks, arguing that sometimes the consumption exceeds the self-charging of the battery. Thus, checking the battery is a completely feasible task and necessary for the proper operation of the car.

Life time

Typically, the battery life with proper care is 4-5 years. If maintenance is carried out in a timely manner, it will serve faithfully for these years. But sometimes, with proper maintenance, it can work for 6–7 years.

This period can be influenced by many factors:

Workmanship. As you know, expensive brands still work longer even with less care.
Temperature operating conditions. Both low and high temperatures have a negative impact on battery life. Summer high temperatures under the hood further provoke sulfation.
Generator operation. Proper operation of the voltage relay will extend its service life.
Terms of Use. Short trips are detrimental to the battery.
Regular maintenance.

Batteries work better in cold weather if they are in good condition and fully charged.

Methods for connecting an ammeter in a car

There are only three main ways to connect an ammeter in a car. These schemes have variations that can be studied separately if desired. The choice of the three described methods depends on what goals you are pursuing and what device you managed to find for reasonable money.

Ammeter in the generator-battery circuit

For such a connection, an ammeter is suitable, which can measure current only in one direction, and also designed for connection to the positive section of the circuit. With this connection, it will be possible to control the current supplied by the generator to charge the battery and power electrical equipment. The discharge current (with the engine off) cannot be determined, even if the ammeter is double-sided.

The connection is made according to the following algorithm:

The wire going to the positive terminal of the battery is disconnected from the generator.
A current shunt is installed into the resulting gap, observing the polarity (according to the instructions and markings).
Wires going to the ammeter itself are connected to the low-current terminals of the shunt.
The ammeter is supplied with 12 V power from the on-board network.
The desired gap for installing a shunt can also be created directly near the battery.

Since the plus of the on-board network will pass through the shunt, in order to avoid a short circuit, it is highly recommended to carefully insulate the created node.

Ammeter in the battery-consumer circuit

This connection method is not much more complicated than the previous one, but the functionality expands significantly. Especially if you purchase an ammeter that can measure current in two directions. Such a device will allow you to see not only the current from the generator, but also the discharge current and the exact current consumed by the vehicle's electrical equipment. Accordingly, the ammeter shunt for this connection method should be designed to be installed on the positive line.

Algorithm for connecting an ammeter to a car:

At the positive terminal of the battery, all wires are disconnected, except for the one that goes to the starter (this is extremely important).
A current shunt is installed into the resulting gap, observing the polarity according to the diagram and markings.
Low-current wires are connected to the shunt to the ammeter according to the instructions.
The ammeter itself is supplied with power from the on-board network.
The created node is carefully isolated.

If you use a one-way ammeter with this connection method, it will only display the current consumed by the vehicle's electrical equipment. Double-sided devices will allow you to see both the charge current and the discharge current.

This method is the most common, as it most fully reveals the capabilities of the installed ammeter.

Other ways to connect an ammeter (to “minus”)

There are also situations when an ammeter designed for connection to the positive line cannot be found for reasonable money. In such cases, you can purchase a “negative” device, but connecting it involves two difficulties at once. Firstly, the negative from the battery can be connected to the ground of the car with several wires, but only one is needed, through which all the current flows. Secondly, when the engine starts, a starting current flows through this very negative wire, which can burn out the ammeter. Thirdly, such an ammeter requires a separate power supply.

Therefore, to connect such ammeters, the following method is used:

Disconnect the negative terminal from the battery.
Install an ammeter current shunt into the resulting gap.
Install a breaker parallel to the shunt, which will allow the shunt to be unloaded while the engine is starting.
Connect the measuring leads to the ammeter to the low-current terminals of the shunt according to the instructions.
To power the shunt, use a DC-DC voltage converter 12 V -12 V with galvanic isolation.
Carefully insulate the created nodes.

As a breaker in point No. 3, you can use a classic power switch with a separate button, which is located in the car interior. The voltage converter from point No. 5 is sold in abundance from the Chinese. When choosing it, it is important to pay attention to the voltage characteristics, as well as the presence of galvanic isolation (if you supply power to such an ammeter directly, it will instantly fail).

LET THE TIME OF YOUR CHANGE WORK FOR YOU!

Each of us, motorists, at least once in our lives has found ourselves (or will find ourselves) in a situation where a dead battery does not allow us to start the engine.
This phenomenon is especially common in winter, since at low temperatures the battery does not hold a charge well. And if the car has been standing in severe frost for more than a week, problems with the battery are almost guaranteed, up to complete discharge. What to do in such a situation? Of course, you can “light” the battery of another car, and this will help if you have a long trip ahead, but it will be completely useless if you only have to drive a couple of kilometers. The battery simply won't have time to charge. In this case, it is best to charge the battery with an external device. InfoCar.ua knows how to do this correctly and safely.

Preparatory work and precautions

Many car enthusiasts ask the following question: “Is it necessary to remove the battery for charging, or can you leave it in the car?” In principle, both options are applicable. The choice of charging method depends on the conditions of the room where it will take place, as well as on how long you plan to charge the battery.

If you remove the battery and disconnect it from the car’s on-board power supply, you must be prepared for the fact that the settings of the connected electronics, for example, air conditioning, climate control, and sound system, may be lost. This also erases data from the engine control unit memory system (diagnostic results and other information). Therefore, this method is used extremely rarely, only when it is necessary to properly charge a completely dead battery. This process typically takes a long time (10 to 30 hours), so it is usually done at home. After all, few people are willing to sit in the garage for so long, and leaving a working charger unattended is unsafe.

It is important to know! If you plan to charge your car battery at home, try to place it in a place where there are no people, for example, on a balcony. This way you will protect your loved ones from the harmful effects of released toxic substances (hydrogen chloride, sulfur dioxide, etc.). The first signs of poisoning are headache, metallic taste in the mouth, and cough. But if you make sure that the air from the balcony does not get inside the room, but goes outside, you can avoid these consequences.

If you charge the battery in a car , then you need to do this in a dry place (preferably in a heated garage). If the car was parked in the cold, you need to wait several hours until the battery warms up at room temperature. Charging the battery should be done with the engine off, and you should also turn off the ignition and other electrical systems of the car or put them into sleep mode, if possible. This method is usually used when you need to recharge the battery to start the engine.

Regardless of where you charge, you need to comply with several general requirements. There should be no open fire near the location of the battery, since hydrogen released along with gases mixed with oxygen can cause an explosion from a spark. The wires from the starter-charger must be positioned in such a way that nothing pinches them and there is no possibility of accidental contact.

The following steps will help you understand the reason:

Check that the charger is connected to the power supply correctly and that the polarity of the device and battery terminals is correct.

Checking the memory

To check the voltage produced by charging, connect it to the battery and turn it on. Then, connect a voltmeter in parallel (a multimeter in DC measurement mode). You should get stable (not jumping) readings of 13-14.5 Volts. Readings that fluctuate or differ from the norm are considered a faulty memory. If the charger readings are adjustable, then adjust them to the normal value.

To check the current strength of the charger, connect an ammeter (multimeter in ammeter mode) in series with the charging circuit. One probe is connected to the charging terminal, the second to the battery terminal, the battery is connected to the charger through an ammeter. The readings obtained are compared with the readings of the ammeter of the device. A discrepancy between the readings of the charger and the tester means a breakdown of the charger.

We are looking for a memory failure

To make sure that the memory is faulty, check it this way:

Disconnect the device from the power supply.
Disassemble the housing using a screwdriver.
Visually inspect all parts, blackened ones need to be replaced
The soldered contact can be simply soldered back with a soldering iron.

The cables are checked by simply “ringing”, connecting the tester with one probe to the plug of the device, the second to the end of the wire inside the device body. Infinite resistance means a break. The second wire and the wires going from the charging to the battery are connected in the same way.

fuse is checked visually; if it is blown, it will be noticeable. Replace the blown fuse.

The transformer is checked when the charger is connected to the network and running. Readings are taken from the charging terminals; they should be 13-14.4 Volts.

The diode bridge is tested by connecting the tester in the desired output mode. Absence of readings or incorrect readings is a sign of bridge failure. The monolithic bridge is being replaced entirely. Otherwise, you can ring each diode. The tester is switched to resistance mode and the probes are applied to the diode outputs. Swap the probes. A diode allows current to pass in one direction, so one measurement will show no resistance and the second will show infinite resistance. If the readings are different, the diode should be re-soldered. This is done with all diodes in the bridge.

It is not worth replacing the fuse with a wire “Bug”. This threatens to break other components and is dangerous for your life. Disassemble the device only without power, the plug is removed from the socket. Tested when switched on, only in assembled form. Don't forget about the danger of electric shock.

Battery check

When the battery is charging, the ammeter needle does not drop, you have already checked the device, all that remains is to check the battery itself.

Use a tester to check the voltage at the battery terminals. It is better to use a load fork, then the voltage under load is immediately detected. A working and fully charged battery should show 12.6 -13.2 volts. Under load for 3-5 seconds, the voltage should not fall below 9 volts.

A voltage below 12.6 indicates a low battery charge, but a low voltage under load means that the battery is “dying” or requires increasing the density of the electrolyte.

Try charging a battery that is not in service again with a higher current to the required voltage; if this does not work, you need to buy a new one. A severely discharged battery requires a higher charging current, perhaps a more powerful charger will solve the problem.

When being serviced, you should check the electrolyte level inside each jar and its density.

The low level is increased by adding distilled water. By adding tap water, you reduce the density of the electrolyte. The salts contained in such water decompose the acid. By adding acid, you will ruin the battery plates, because you will greatly increase the density of the acid and corrode them.

When the battery is discharged, the acid density drops. When recharging, the process proceeds in the opposite direction. For a working battery, the density in the charged state is 1.27 g/cm3. Check the battery is in a charged state.

The density is checked with a hydrometer.

Work with electrolyte wearing rubber gloves and safety glasses. If acid gets into your eyes, rinse it immediately with water.

Why is there an ammeter in a car?

Those who are older remember that some kind of ammeter was installed on domestic cars. That device worked “in both directions”, and primitively showed where the current was flowing relative to the battery - from it, or to it. In fact, the ammeter served only to monitor whether the battery was charging or, conversely, discharging.

Modern ammeters allow you to learn much more information about currents in automobile circuits. This is possible due to the fact that the devices are now digital and can show not only the direction of the current. Based on their readings, you can find out the load accurate to tenths of an ampere. And this significantly expands the capabilities of the device.

This article is not about those devices that are an analogue of Soviet pointer “ammeters”. Today they are sold in the form of a plastic box with several LEDs of different colors. Such devices do not measure current. They are only suitable for roughly understanding whether the battery is charging or discharging.

Using a digital ammeter in the car, you can constantly monitor the following parameters of the on-board network:

Battery charge current . Gives a clear picture of how the battery charges at different states of charge, depending on the temperature outside, at idle, and so on.
Battery discharge current . When the motor (and generator, respectively) is not turned off, the actual current consumption from the battery makes it possible to calculate the battery life.
Generator performance . Does it charge the battery or power the on-board network while driving?
Adequacy of generator power . Is the generator capable of powering a powerful load, for example, heating something, emergency acoustics, a 220 V inverter, etc.
Current consumption of electrical equipment . The ammeter always shows how much current is consumed by the consumers.
Relationship between current consumption and switched on load . For example, you can find out how the current consumption changes when you turn on particularly “gluttonous” equipment, whether the battery is “deprived” in this case, and so on.
The real power of this or that equipment . Using an accurate ammeter, you can easily calculate how much current any particular powerful appliance consumes. Then, knowing the voltage of the on-board network at the current moment, you can calculate the real power in watts.

This is not the entire list of capabilities of the ammeter built into the on-board network. For example, if an accurate device is installed, then even leakage currents can be assessed when the car is parked.