Normal battery voltage of the vehicle. The voltage of a charged car battery


2019-12-02 16:20:26




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Rechargeable battery (battery) – this is one of the most important parts of the vehicle. It provides electricity to the starter when starting the motor, and is also responsible for the operation of the other devices with the engine off: backlight the instrument panel and interior, radio, signal, fuel pump, etc. the Normal operation of all systems is only possible with a charged battery. That is why it needs to be timely serviced and charged.

But what often happens is quite the opposite. You come to the garage or to the Parking lot, trying to start the engine, but the starter issues you or sounds unbelievable his effort a little bit to rotate the flywheel, or simply clicks the retractor relay. In addition, the dashboard warning lamp indicating the battery drainage.the battery voltage of the car

Not to get into such a situation, it is necessary to systematically diagnose the battery, but first let's understand why it is discharged.

Causes battery

The Reasons, for which there is a discharge of the battery, there may be several. Here are some of them:

  • The battery is completely used up its resources;
  • Malfunction of the generator;
  • Leakage current
  • Increased load on the electrical grid;
  • Unauthorized operation of electrical appliances with the engine off.

Why it happens

Any battery has a certain resource, even with timely service. Modern batteries, depending on operating conditions, can last between 3 to 7 years. After this period, the battery voltage of the vehicle gradually begins to decrease. This is due to the destruction of the lead plates, which, unfortunately, over time, can not be avoided. Of course, you can try to restore the battery, but work as new, it will be gone.


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The failure of the generator the charging voltage of the vehicle battery jumps, falls or is absent. In this case, the battery works in emergency mode, which can lead not only to defuse, but also to its failure.the Voltage of a charging battery of the car

Drain – one of the main causes of battery drain. She is easily determined with an ammeter or multimeter on its mode. Measurements of current taken between the ground terminal and the negative terminal of the battery determined by the amount of leakage. If it is above 80 mA, you should immediately contact the service to find the leak and correct the problem.

Often the owners of the machines independently installs additional electrical devices (speakers, subwoofers, lighting elements, various electronic devices), not even knowing that significantly exceed the value of the network load, provided the passport data of the car. This inevitably leads to the fact that the generator ceases to cope with this load, and part of it is covered by the battery.

It Happens that the hapless drivers, sometimes leaving the car, simply forget to turn off the dimensions, the radio, interior lights or other devices consuming electricity. Such carelessness is also the cause of rapid discharge of the battery.the Voltage of a charged car battery

Time has not serviced the battery also will never work for long. Even if in your car installed maintenance-free battery, he would need to constantly supervise and periodically charge it.

How to check the status of the battery

To Determine the status of the battery one way is impossible. Not worth listening to “experts”, claiming that by measuring the vehicle battery voltage or current, can be concluded about its performance. This is a complex process, involving the following activities:

  • Visual inspection;
  • Determination of the electrolyte level;
  • Determination of the density of the electrolyte;
  • Measuring the battery voltage.

Visual inspection of the battery

The First thing you can do for the establishment of battery performance – to look at her. Appearance can tell a lot.

The Mud mixed with moisture and automotive fluids terminal – an unacceptable phenomenon. It leads to oxidation of metal parts and loss of electrical contact. As a result, in the best case unable to self-discharging in the worst – short circuit. If soiled, do not be lazy to check the current of self-discharge, to determine the necessity of maintaining cleanliness under the hood. To do this, take the ammeter, disconnect the battery leads, touch the probe to one of the terminals, and the other just slide the battery case. Indicated on the screen of the ammeter value will be the current self-discharge.

Next look at the battery housing. The presence on it of cracks and water stains evidence of mechanical damage, which caused leakage of the electrolyte. If this happens, use this battery next inappropriate. When there are drips from under the tubes, it is necessary to check the amount of the electrolyte in each of the cans and to eliminate the cause of the outpouring.

How to install the electrolyte level

To Check the level is possible only in the accepted battery. Highly not recommendedto violate the integrity of the hull, maintenance-free battery for the conduct of unintended “service”.Normal battery voltage of the vehicle

If the battery is serviceable, it need to be removed to clean the dirt and remove the tube. The measurement level is performed using a special tube with a millimeter scale. It falls into the jar until it comes into contact with the upper separator plate, the opening in the top is clamped finger. When removing you can easily determine the electrolyte level. It should not be less than 10 mm. If the electrolyte level is less than the specified value, you must determine why it is lower. Usually it crashes due to conventional boiling and evaporation. In this case, you just need to fill in the jars with distilled water.

If the level has decreased as a result of spilling of the electrolyte, top up you need to prepare an electrolyte. After topping up battery need to be recharged.

How to determine the density of the electrolyte

The Main factor affecting the operating voltage of the vehicle battery is the electrolyte density. To measure it only by using a special device – the hydrometer. It is a large pipette with a rubber bulb at the top of the scale and float inside. Density measurement naturally also can be produced only in the serviced batteries. But what should be its value?

The electrolyte Density for fully charged battery at a temperature of 20 0C is 1.27 g/cm3. If the battery is low, the figure is reduced.

Measuring battery voltage

What is the battery voltage of the vehicle should be to be able to start the engine? A definite answer here there can not be.

It is Known that the voltage of a charged car battery should be about 12.6 to 12.7 V. depending on various conditions, this figure may change slightly, but if the charge dropped below 12 V, the battery can be considered discharged at 50 %. She needs to charge as deep discharge will inevitably lead to sulfation of the lead plates. But in this indicator, engine start is possible. Provided that the battery is not in need of repair, and the generator is charging, it is safe to drive. But if the voltage does not exceed 11.6 V, the battery is considered fully discharged, and its further operation without diagnostics and charging impossible.the Voltage of the car battery in winter

Measure the voltage of the battery snap. This will need to disconnect from it wires and to the terminals of the voltmeter or multimeter in his routine, putting the restriction in the range of 20 V.

What determines the battery voltage of the vehicle. The degree of discharge of the battery

Now let's try to understand how interrelated the main parameters of the battery. The battery voltage of the vehicle directly depends on the density of the electrolyte. When the battery is discharged, the expenditure of acid, which is part (36 %) of the electrolyte. As a consequence, decreases its density. The reverse process occurs when charging battery: consumption of water leads to the formation of acid, with the result that the electrolyte density increases.

The Voltage of a charged car battery (12.7 In) corresponds to a density of 1.27 g/cm3. If you reduce one of the indicators is reduced and the other.

Table based on the battery voltage from the density of the electrolyte

The Density of the electrolyte, g/cm3

Voltage of the vehicle battery,

The Degree of discharge of the battery %






13.5 cm













How does the density of the electrolyte and the battery voltage the temperature of the environment

From car owners often hear that the battery voltage of the vehicle in winter can be significantly reduced. Leave, say, a car for a few days in the cold and all, then will not start. That is why some of them off and take the battery home.

What is happening inside the batteries at a low temperature and where it may lead? In fact, the battery voltage of the vehicle falls in the winter. Yes, the density of the electrolyte varies, but a charged battery, it grows, and is discharged – falls. In other words, if the battery is discharged, it must either charge up or to carry. Otherwise, it will not only be able to start the engine in the cold, it can freeze the electrolyte, which will lead to hull failure.What is the battery voltage of the vehicle

Charged battery nothing of the kind is not threatened. Yes, there are sometimes problems with the engine start, but only due to the fact that at low temperatures the chemical processes are much slower, so the battery may fail to deliver required to run power. Butenough to make it into heat, and a little to survive, and she will again be ready to work as before. Therefore, a normal battery voltage of the vehicle for the winter period does not differ from the indicators for the summer.

How to charge battery

There are four ways to charge the battery. Each of them has its advantages and disadvantages. Let's look at them.

  1. Charging Method with constant current. the Only drawback – permanent control over the process. Its essence lies in the fact that the charger sets the current equal to one tenth of the nominal battery capacity. Charging is carried out for 20 hours. Due to the fact that the battery, charging will gain a current value of the charging current will decrease, therefore need to adjust every 1.5-2 hours.
  2. Charging Method at a constant voltage. This method also involves charging process during the day. It should be noted here that the charging voltage of the car battery will depend on the magnitude of the applied voltage. For example, when continuous charge at 14.5 volts for 24 hours the battery will only charge to 75-80 %, with 15 – about 90 %, and only with the figure 16.3-16.5 V battery will have charged fully. This method is considered the most safe and effective.the voltage of the battery of the car
  3. Combined method. To charge with this method you will need a special charger. The process is fully automated and requires no monitoring or presence. Just connect the terminals and turn on the machine. When the charging process is reached the normal voltage of the vehicle battery, the device will turn off automatically.
  4. Fast charging. This method is not recommended for use in normal conditions. It is used in extreme cases when you need to charge the battery in the shortest time possible. For this purpose, the device sets the maximum current the battery should be charged no more than 20 minutes. Of course, on a full charge is out of the question, but to start the engine this will be enough.

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