How do I charge the car battery?

Where does a car start? Oddly enough, not from the wheels, engine or transmission. Until the engine is started, it is just a piece of iron. And only with the engine running, the car is capable of something. But to start it, you need a battery, without which such a procedure is impossible. Therefore, the technical condition of the battery should be given constant attention. Even with good electrical equipment on board, it is sometimes worth considering how to charge the car's battery using external devices.

Necessary information about the battery

To understand the processes occurring during battery charging, it is advisable to know its device and understand what is going on in it at any time. Here you should immediately make an explanation - the speech will concern ordinary lead-acid batteries. Structurally, the battery consists of a set of galvanic cells.

It is believed that one such cell, or, as it is also called, a bank, gives a voltage of 2.1 V. Six such capacitors, when connected, form a battery capable of showing voltage 12.6 V. To ensure the flow of current-generating reactions in the battery design are used:

• at the anode (positive electrode) - PbO2 (lead dioxide, which has a dark brown color);
• at the cathode (negative electrode) - Pb (spongy lead, gray color);
• electrolyte - H2SO4 (in the form of an aqueous solution).

The operation of such a battery is based on the principle of double sulfation, known since 1858 and expressed by the equation:

the interaction of the active mass at plus and minus with an acid, during the reaction, water and lead sulfate are formed, the density of the electrolyte decreases. Lead sulfate settles on the surface and in the depth of the electrodes, blocking its access to the interior of the active mass. When charging (arrow to the left), the opposite process occurs, under the action of an external source, the original state is restored. This increases the density of the electrolyte.

On the methods of charging the battery. General considerations

The battery can be charged:

• at constant current;
• Woodbridge (ampere-hours);
• at constant voltage;
• control-training cycle;
• pulsed current charging, including:
• pulsed current;
• asymmetrical current.

Each of these methods has its own characteristics, and each of them allows you to achieve the goal. Nevertheless, in practice, in order to charge a car battery, a technique based on the use of direct current or voltage is most often used. One point should be noted here. Battery manufacturers recommend charging up to a voltage of 16-16.6 V on a rechargeable battery, while on a car the generator outputs a voltage not exceeding 14.5 V.

It turns out that the battery is not fully charged during operation on the car... However, if the charging voltage is raised, then when it exceeds the value of 14.5 V, the battery begins to boil, water decomposes and hydrogen is rapidly released. When mixed with air, detonating gas is formed, this requires additional safety measures. And a sign of electrolyte boiling is a signal about the end of charging.

Another signal that the battery is charged is the constancy of the voltage at its contacts for 2 hours. External devices used for these purposes, called chargers (chargers), are direct current sources (rectified). They can be any, allowing adjustment of the output parameters.

Charging the battery with direct current

Its value with this method should not exceed 1/10 of the battery capacity. If, for example, it is 60 Ah, then the value of the charging current should be 6 A. This value should be maintained quite accurately, acid batteries are sensitive to exceeding its value. It is supported by a special regulating device. During charging, it is necessary to control the current value of the current and, if necessary, perform its correction.

To reduce gassing, when the voltage becomes equal to 14.4 V, the current value can be reduced to 3 A (for a battery with a capacity of 60 Ah), and when reaching 15 V - to 1.5 A. keeping the charger parameters unchanged for an hour, while, according to the recommendations of the battery manufacturers, the voltage at its contacts should be 16.4 V.

Charging the battery with constant voltage

The state of charge of the battery will depend on the value set voltage. So, with a 24-hour exposure to a voltage of 14.4 V, it will charge by 75-85%, when using 15 V - up to 85-90%, and at 16 V - by 95-97%.

At the first moment when the charger is turned on, a large current may flow, therefore, certain protective measures must be provided against this phenomenon. In the future, as the battery is charged, the voltage at its terminals will approach the applied external one, and the current value will decrease.

The convenience of this technique is the automatic execution of the entire process, since it does not require monitoring the current value. However, this procedure does not fully charge the battery when the set value of 14.4 V is reached. Therefore, DC charging must be applied periodically.

Control and Training Cycle (CTC)

Use a similar technique when you need to assess the current state of an old battery. In addition, several discharge / charge cycles can be improved.

For this, the following technique is used - a charged battery is discharged in a 10-hour cycle to 10.2 V, and then charged. However, you should not use KTC often enough, each battery has a certain resource (i.e., it can withstand a certain number of discharge / charge cycles), and such a technique reduces it.

Charging the battery with a pulse current

This is the name of a current that periodically changes its value. For charging use:

1. Pulsing. Its shape is shown in the figure. It can be seen that the current and voltage supplied to the battery periodically change their value from zero to the maximum value.

   

2. Asymmetrical or reversible. With this approach, the battery is charged and discharged in one cycle. The charging current is greater than that supplied by the battery. The usual ratio between them is 10: 1, i.e. the battery is receiving more charge than it is losing.

   

The use of such currents promotes the restoration of the active mass in the entire volume, and, in addition, reduces the sulfation of the plates. This allows you to slightly increase the capacity of the battery and extend its service life.

Woodbridge Charging

According to this law, the value of the charging current (in amperes) should not exceed the value of the missing capacity (measured in ampere-hours). For example, if the battery capacity is 60 Ah, and it is half discharged, then the charging current is set to 3 A (30 Ah x 0.1) and charging will take approximately 10 hours (30 Ah / 3 A).

Practical recommendations for charging the battery

A large number of ways to restore the battery allows you to choose the most suitable for a variety of situations. But usually, as already noted, only a few of them are used in everyday practice. The rest are most often used in special cases. Usually the charging method is determined by the available charger.

It is not uncommon for the battery to be discharged. Either an accidental short circuit, or a light bulb that is not turned off, left overnight - and now the problem arises of how to charge a completely discharged car battery. To solve it, it is enough to have any charger. What happens when the battery is restored is described above, and instructions for using a specific product are given in the manual for it.

For more information on the charging process and the use of dedicated devices, please refer to the video.

There are several different ways to charge the battery. You can use any of them, they all provide normal battery charging, allowing it to operate for 5-7 years. A similar procedure should be carried out at least once a year, and always with the onset of winter. Usually, on a car, especially if it is operated in an urban cycle and not very intensively, the battery is undercharged, which can affect it negatively in the winter. Therefore, before the onset of cold weather, it is best to charge the battery using an external charger.