Voltage at the battery terminals when the engine is running. Learn more about charging and discharging your car battery. Normal battery voltage

Battery voltage is a physical quantity in an electrical circuit that is determined by the potentials between the positive terminal and the negative terminal. Voltage in the theory of physics is closely related to EMF and many motorists confuse them, so first you need to distinguish between these two concepts. In simple terms, EMF is the maximum value of Volts that a power source can give. But the devices that it supplies are connected to any power source, and then the number of volts in the circuit becomes less - this is the voltage.

Voltage and EMF will match if no energy absorbers are connected to the battery. If expressed in the language of physics, then the EMF will be equal to the sum of the voltage at the battery terminals and the product of the current in the circuit and the internal resistance. [EMF] = [voltage] + [current] * [resistance]

In a car battery without load, the EMF is measured, and under load, the voltage is measured. EMF is formed in such a battery due to the occurrence of electrochemical reactions in it, as a result of which energy is released.

How to measure voltage

To measure the battery voltage, devices are used, which are based on a voltmeter. Such devices measure the voltage at the battery terminals and show the value through an analog or digital display. The analog screen displays a scale of voltage values, in the interval of which an arrow moves, indicating the measured value. In digital devices there is a liquid crystal display, which displays the value in numbers. It is believed that digital screens are optimal because the least susceptible to scale errors, more resistant to vibrations and more accessible to human perception.

Among the devices themselves, there are 3 main types:

1. Voltmeter (as a separate device)
2. Multimeter (with voltmeter function)
3. Load fork (we have already written about them in more detail).

How to measure voltage on a car

The process of measuring the voltage of a battery that is on a car has its own characteristics. The check takes place on a muffled engine, otherwise you will measure the voltage from the generator. Before measuring the voltage, at least 8 hours must pass from the moment the engine is stopped, otherwise the measurements will be overestimated due to surface voltage. The surface tension can be relieved with a load plug for 5 seconds.

No matter how the car changes, the design of the car battery remains unchanged, and the requirements for it are growing. Despite the ultra-modern technologies for the production of plates and electrolytes, batteries, as before, require attention and care. And charging first. Today we will talk about the battery charging time, we will only remember how to properly charge it and how it needs to be charged. By the way, time also depends on this.

When to charge the battery

Not every store-bought battery is dry-charged. This means that it is enough to add electrolyte to it and you can safely put it on the car. The batteries are also sold completely ready for use. But this needs to be clarified in the instructions for a specific battery. We're not talking about new devices at all. A battery that is operated under normal conditions, without overloading and on fully functional electrical equipment, may need to be charged extremely rarely. The battery loses its charge quickly:

The fact that the battery needs to be charged is eloquently indicated by the fact that the car simply does not start. The battery does not have enough voltage to crank the engine with the starter, therefore starting is not possible. To make sure that the battery is discharged, you can simply check the voltage at the terminals. The normal indicator is 12-13 volts, if the tester shows 11 V, the battery is 75% discharged, half the battery will show 10 volts, and if the voltage at the terminals is less, the battery is completely discharged.

How to properly charge the battery

It is very important to know how much to charge. car battery, because correct charging it allows for a longer service life, and the battery warranty is typically 4-5 years. This is if you do not violate the charging technology and properly operate the device. The principle of charging the battery is quite simple, but you need to strictly adhere to the technology. A charging current of about 14 volts is supplied to the battery terminals, while the resistance of the battery increases and becomes less. The moment the battery reaches its nominal charge, the resistance is highest and the current tends to zero.

If you overexpose the battery in this position, then the electrolyte may boil, which does not shine with anything good. As a result, sulfation can begin, the plates crumble and the battery is short-circuited. This is no longer cured. Therefore, for charging, they try to use special chargers that automatically control the charging process. Let's talk about them.

What are the chargers

Depending on the design, chargers can be of two types:

1. Transformer.
2. Pulse.

Transformer devices do their job better, from the point of view of physics, but they are very cumbersome, expensive and require constant control over the process. The fact is that the highest quality battery charge is achieved with several charge / discharge cycles. The battery capacity is then maintained at a stable level throughout its life. But in order to constantly monitor the transformer charger, time and inspiration are needed, which, unfortunately, many do not have enough. Therefore, transformer devices have been replaced by more technologically advanced pulse chargers.

Impulse chargers

Impulse devices are incredibly compact and high level automation in comparison with transformer devices. The charger, among other things, must also rectify and stabilize the current in the network, because we charge the battery direct current, and the household network gives a break. In addition, the quality of battery charging is highly dependent on the voltage. The impulse device is precisely designed to control these indicators, and much more accurately than transformer devices.

But this is not the most important thing in pulse chargers. The most valuable thing in them is the complete automation of the process. We only need to check the electrolyte level, polarity, set the desired charging time, and the device begins a series of cyclic charging / discharging until the battery reaches the required charge value of 12 volts. After charging, the device automatically turns off, which is indicated by the LED indicator.

Consequently, the battery charging time is influenced not so much by the degree of its discharge as by the charging method. Therefore, with experience and transformer device, the best option of course there will be such a way. But on the other hand, the impulse memory will allow you to clearly and quickly charge the battery at the proper level, without requiring special knowledge and skills from the user. Watch your battery, do not run out, and good luck to everyone!

One of the main components of cars is the battery. It can be used to start the engine and enjoy various benefits in the cabin, including lighting, playing music, watching TV and more.

For this reason, every driver should know what the ideal battery voltage is, how to use it correctly, and under what conditions to charge. The following will tell you what the normal voltage of the car's battery is, depending on the operating conditions and the season.

In many cars, there is no way to view the current voltage, so it is worth getting a multimeter. It is advisable to control the voltage once a month, and in winter at least once a week, especially if the car is parked on the street.

The reasons for the loss of voltage in the battery.

Before considering methods of analyzing and charging a battery, you should analyze the main reasons why a battery is discharging:

• The battery has completely used up its own resource;
• the generator is out of order;
• there is a leakage current;

Many of these reasons can be corrected, after which the battery restores normal voltage, even if the unit itself has been in operation for many years. It is equally important to evaluate the battery before using an additional recharge or overhaul with the purchase of a new cell:

• visual inspection;
• measurement;
• preliminary voltage measurement.

Just measuring the current is not the correct factor in assessing the quality of the battery. Several indicators are taken into account simultaneously, including the analysis of the unit under load, forming complete picture component work.

Norms and indicators of the battery in normal condition.

The ideal normal voltage for a car battery is in the order of 12.6-12.7 volts. This is provided that the unit is fully charged and ready for operation. But, from certain characteristics, properties and factors, the indicators may be different, up to 13-13.2 volts. Many battery companies claim that the values ​​in their products are slightly different and this factor should also be taken into account.

Do not measure when the battery has just been removed from charge. It is not right. Only after an hour can a measurement be taken when the voltage drops from 13 volts to a normal value.

With readings below 12 volts, we can say that the battery is almost half discharged. An urgent restoration of normal parameters will be required. Operation under these conditions will lead to sulfation of the lead plates, after which the unit can only be thrown away.

When the engine is not demanding on resources, this voltage is enough to start. If the battery is in good condition and the generator does not require repair, natural processes are sufficient to restore normal operation of the battery.

A drop to 11.6 volts signals the complete discharge of the unit. Its use in such a situation is not possible. Here you need a professional recharging, which allows you to restore the factory standards and parameters.

A small conclusion can be made that the normal voltage of the car battery is always kept in the range from 12.6 to 12.7 volts. It is extremely rare, depending on the battery model, the indicator can be 13.2 volts.

Ideal indicators are exclusively on paper, because in real life it's hard to meet them. The average battery voltage in an ordinary car is 12.2-12.49 volts, and this is the first signal that insufficient charging appears. Don't worry about this. The final death for the battery starts at 11.9 volts and below.

Video (checking the battery with a multimeter).

Analysis of stress under load.

Consider the state battery it is necessary from several sides in order to determine its condition as accurately as possible. For this reason, stress includes several factors:

• nominal indicators;
• actual properties;
• stress under load.

The main indicator for analysis and study is considered to be the nominal indicator, which is actively used to study the principles of battery operation in the literature. According to all calculations, the normal voltage of the car battery should be 12 volts, but in fact this is not correct.

After applying the load, the indicators change. it important parameter analysis of the condition of the unit, because it is possible to withstand the nominal indicators, but the load is the only correct way to conduct a quality analysis.

For work it is used " load fork"Is a device that generates a load in terms of capacity. It is twice as large actual capacity on the battery.

If there is a unit with an indicator of 60 Am / h, the load indicator should be 120 Amperes. Within a few seconds, a load is formed, while the voltage should be at the level of 9 volts. When the indicator is in the region of 5-6 volts, then the battery is not suitable for further use. A few seconds after the load is removed, the nominal voltage returns.

When there were voltage problems, you need to recharge and repeat the experiment. When the voltage is kept at 9 volts, then the battery is still usable and an elementary recharge was needed.

Video (checking the battery voltage under load).

The electrolyte is the main parameter of the analysis.

The electrolyte can be used to determine the voltage level. If discharging occurs, the acid level decreases. Its total indicator in working fluid is about 35% (more details). Charging recovery allows you to compensate for the acid consumption through its recovery, but at this time water is consumed, which needs to be refilled. As a result, the density increases and the factory settings are restored.

In the usual position at 12.7 volts, the density will be 1.27 g / cm3. All components are mutual with each other, therefore, a decrease in one will lead to the same decrease in the other.

Battery electrolyte density table.

Winter is a bad enemy for any battery.

During cold weather, many note that the battery performance is significantly reduced and preventive measures are to take the unit home and put it in a warm place. The bottom line is that cold affects the density of the electrolyte, and a decrease in this indicator forms a decrease in voltage.

When there is enough charge, frost affects the battery by increasing the density. For this reason, if the unit is properly charged, there will be no negative effects. A discharged battery undergoes a depletion of electrolyte, making the engine more difficult to start.

In winter low temperatures slow down some processes, so you need to constantly monitor the indicators and, if possible, adjust them using the available methods.

By the voltage of the battery, one can judge the degree of charge of the battery, therefore, you should learn how to correctly determine this value at the terminals of the power source. This article will describe the basic methods of measuring this parameter using a multimeter, and also provide reference voltage values ​​for batteries of various designs.

Curbing

Battery voltage under load

The battery voltage under load will be lower than at rest. This indicator can also be used to judge the health of the battery. If, after connecting the load plug, the control device shows less than 9 V, then the battery is discharged and must be charged. If after repeating the procedure the situation does not change, then the battery will need to be replaced with a new one in the near future.

If it is not possible to use a load plug to test the battery under load, then you can use a digital multimeter, and turn on the engine starter as a load.

If the voltage in the on-board network drops below 9 V when the starter is turned on, then in this case it will also be necessary to charge the battery using a charger. It is also worth checking the wiring elements and electricity consumers for serviceability. If there is no electricity leak in the system, and with a fully charged battery, an excessive voltage drop will be observed again, then the battery should be replaced.

If powerful consumers of electricity are not connected to the battery, then the voltage under low load will not change too much.

No-load battery voltage

The voltage of the battery, to which the consumers of electricity are not connected, is 12.6 - 12.8 V. If the voltage at rest is less than this indicator, then this will indicate that the battery is discharged or there is a short circuit in some banks. Operating the battery with a reduced charge level will certainly lead to the formation of lead sulfate on the plates, which will cause a significant drop in the capacity of the device.

To make accurate battery voltage measurements without load, be sure to remove the battery terminals immediately before connecting the meter.

Charged battery voltage

If the battery is fully charged, the voltage value will depend on the battery model. If a conventional antimony battery is used, then the minimum value of this indicator should be 12.6 V.

For a calcium battery, this indicator may be slightly higher, and on the terminals of a gel battery, this parameter should not fall below 13 V. If this indicator deviates from the norm, the battery must be charged with a current equal to 10% of the battery capacity.

If the battery voltage is measured with the engine running, the meter reading will be much higher. With a working battery and a relay-regulator, the voltage at the terminals can reach a maximum value of 14 V.

Battery normal voltage

Normal voltage Battery is an indicator that is displayed in the documentation for the power source. If upon purchase new battery, it cannot be charged to the value specified in the instructions, then such a malfunction will be considered a warranty case.

If the relay-regulator and the generator are working properly on the car, then the battery, during the operation of the car, will be automatically charged to the normal level. It is advisable throughout the entire service life to strive to use the battery only when there is normal voltage at the terminals. With significant deviations of this parameter downward in winter time years, the electrolyte in a discharged battery can freeze completely, and in the summer lead plates will be destroyed more intensively.

Discharged battery voltage

If the battery voltage is less than 11.6 V, then the battery is considered to be completely discharged. In this case, the operation of the power source is impossible and to restore its operability, you will need to use Charger operating from a 220 V network.

Almost all lead batteries sensitive to full discharge. Calcium acid batteries can lose a significant part of their capacity even after a single deep discharge. Antimony device has great tolerance. The most resistant to full discharge are gel and AGM batteries.

Battery voltage in winter

In winter, constant undercharging of the battery can lead to a significant decrease in the density of the electrolyte, as a result of which the liquid inside the cans can freeze. Freezing of the electrolyte, in many cases, leads to the complete inoperability of the power source. To prevent this from happening in winter period the terminals must be at least 12.5 V.

If a serviceable battery model is in use, the battery charge level can be monitored without using a voltmeter. It is enough to make regular measurements of the electrolyte density, which for a fully charged battery should be about 1.28 g / cm3.

Modern vehicles can have different kinds backlights, music players, televisions and other items that put a load on the power supply. Insufficient voltage of the car battery will not allow the full functioning of all devices and devices. In this case, it will simply not be possible to achieve comfortable operation of the machine.

The main reasons for voltage drop

A car battery works by converting chemicals directly into electrical energy. When charging, the opposite happens. During the operation of the device, a current is generated due to the deposition of sulfates on the plates. The concentration of the electrolyte decreases, and the internal resistance increases at the same time.

Most often, the voltage of a car battery is lost for the following reasons:

• the battery life has completely expired;
• the generator has broken;
• there is a current leakage through the wiring;
• the chain was not rated for a specific load.

The situation can be corrected in almost all cases, if we are not talking about wear and tear of the device. Normal voltage can be restored even if the unit has been used for several years. Current measurement alone cannot be the basis for an assessment quality characteristics batteries.

Indicators in the normal state

Ideally, the normal voltage of a car battery should not be less than 12.4-12.8 volts. With a decrease in indicators, it is not able to ensure the full operation of the engine, but it can be started with a working generator. However, it is not recommended to continue using such a device, since coarse-crystalline lead sulfate may appear on the plates, which leads to a decrease in the battery capacity.

A drop in readings to 11.6 volts indicates a complete discharge of the device. Its use in this state is not possible. This will require a special recharging that can restore factory standards and get the normal voltage of the car's battery at the output.

Auxiliary table

Knowing how many volts the measuring device shows, it is impossible to know the degree of wear of the power source. However, it is quite possible to determine the approximate percentage of charging. To do this, use the table below.

Parameters under load

The above is the typical no-load voltage of the vehicle battery. However, it turned out that it is impossible to determine the health of the battery in this way. To do this, the device must be loaded twice with a special plug.

The duration of the working phase should be 4-5 seconds. The voltage should not drop below 9 volts. In the event of a severe drawdown, first of all, charge the battery and re-check. The situation will not change if the battery resource is completely depleted.

Normal voltage on the vehicle battery with the engine running

The number of volts is measured even with the motor running. Under normal conditions, the operating voltage of the car's battery should fluctuate between 13.5 and 14 V. At low battery charge, the indicator exceeds the maximum value, since the generator is forced to operate in an increased mode.

In most cases, overvoltage does not pose any danger. If everything is normal with the electrical equipment, then it returns to its normal state 5-10 minutes after starting the engine. A constant increase in performance can lead to overcharging of the power source, which will cause the electrolyte to boil off.

During measurements, there is also an undervoltage of the car battery. This indicates that the battery does not have time to fully charge. For testing, it is necessary to gradually turn on electrical consumers (lights, music, air conditioning and other devices), making measurements. With a faulty generator, the readings will drop by more than 0.2 V.

The influence of the winter season

Often vehicle owners complain that battery parameters deteriorate at subzero temperatures. However, this is not quite true. During frost, the density of the electrolyte changes, which affects the generation of current. However, with sufficient charge, the battery is safe. Therefore, it is not at all necessary to remove it in the cold season and bring it into the warmth.

Taking indicators using special devices

The above is theoretical information to familiarize yourself with the basic rules. However, you also need to know how to measure the voltage of a car's battery. To take readings, special devices must be used that are connected directly to the battery terminals. The test is recommended to be carried out at an electrolyte temperature of 25 degrees.

When taking measurements without load, a tester is usually used. A certain operating mode is selected on it. The red contact is connected to the positive pole, and the black one to the negative pole. The display should show the current value.

The reading in a closed circuit allows the load plug to be fixed. It simulates a starting situation by measuring the operating voltage under these conditions. The measuring device is connected to the outlets in the same way. The battery is loaded for 5 seconds.

additional information

It is even worth checking the voltage of a new car battery after prolonged use. With a poorly working generator, it can gradually discharge, which means that the voltmeter readings can be much lower than normal. Recharging will be required to restore acceptable values.

It is not recommended to make measurements using the on-board PC, since final result will have a significant error, which is explained by the specifics of connecting the device to the network. Rough data should not be used to identify problems.

A comprehensive battery check must be carried out regularly. If the vehicle has not been used for several days and the meter shows a significant decrease in voltage, then the life of the power supply will expire.

Features of battery operation

In order for the voltage of the car's battery to be normal for a long time, certain rules must be followed.

1. Disconnect electrical consumers immediately before starting the engine. The load at one attempt should not exceed the time interval of 5-10 seconds. If the engine does not start from the fourth or fifth time, then the ignition and fuel supply systems should be diagnosed.
2. Periodically it is required to check the integrity of the vehicle wiring. The existing leakage current in the circuits leads to a rapid discharge of the battery, and hence the loss of operating voltage. Measurement of energy loss should be carried out at service stations.
3. When driving in the city in winter, when the engine is running at low revs, and there are a lot of switched on consumers, it is advisable to recharge the battery using stationary chargers. In this case, the power supply device will last longer, producing the required current.
4. The battery must be kept clean, especially around the terminals. It is recommended to wipe it with a cloth soaked in a solution of soda ash. You can also use an ammonia mixture.

Battery recharging rules

The battery must be charged in a timely manner so that the voltage during operation vehicle was optimal. When implementing this event, you must adhere to a number of rules.

1. Charging should be carried out at a temperature of more than 0 degrees.
2. Before connecting to the electrical network, the filler plugs are unscrewed and left in the mounting holes.
3. An instrument capable of supplying 16 volts must be used.
4. Do not tighten the plugs within 20 minutes after charging is complete so that accumulated gases can escape freely.
5. The room must have supply and exhaust ventilation.
6. The criterion for the completion of the charge will be the achievement of the optimal voltage or density of 1.27 g / cc. cm.
7. The electrolyte temperature inside the device connected to the network should not exceed 45 degrees.
8. It is recommended to measure the current 8 hours after charging.
9. If there is an indicator, then the time of disconnection of the device from the network is determined by it.

Final part

It will not hurt every driver to study the information about what should be the voltage on the car's battery. With its help, he will be able to accurately determine the charge level and operational capabilities of the battery. Measurements should be carried out both in static and dynamic mode using the above-mentioned devices. If necessary, the power supply must be charged in accordance with the basic rules.