What is a Maintenance-free Car Battery

For a long time, modern cars are equipped with unattended car batteries. Under the word "unattended" many car enthusiasts understand that there is no need to perform any actions with the battery during the whole period of service. This opinion is correct only partly, it is correct that such batteries do not require absolutely any actions during the whole service life, but with a reservation as to the battery life time. In other words speaking - AKB you can not serve its entire service life, but this period will be shorter than it could be.

In the absence of a need for maintenance, battery manufacturers mean no water consumption from the electrolyte, and as a consequence - no need to add water and control the electrolyte level. At the same time, such an action as a charge requires any battery - the most modern, most maintenance-free.

It is assumed that a constant charge of the battery is carried out by an automobile generator. This is correct, but again, with the reservation.

In order to deal with this, you need to consider the process of charging the battery. With the apparent simplicity of the device, which has not changed radically for several decades, the car battery accumulates rather complicated chemical and electrochemical processes. From the theoretical point of view, up to 60 different reactions occur in the lead-acid accumulator . At the same time, it is enough for a car enthusiast to know the main principle of battery operation: when discharged, sulfuric acid restores lead dioxide at the anode and oxidizes lead at the cathode, and when charging, reverse processes occur. At the same time, simplistically speaking, when discharged, the amount of acid in the electrolyte decreases (the density of the electrolyte and the voltage of the battery fall), and when the charge is reversed.

Here there is one important point in terms of practical application of the battery. The discharge of the battery is flexible enough, that is, if for example the battery constantly feeds a light bulb with a power of 5 W, then the battery can feed it constantly up to full discharge, giving out the current of the required characteristic with a small drop before a full discharge. Or, with several unsuccessful winter starts, the battery will each time give the starter a current of 300 A, again with a certain current drawdown before discharge.

As for the battery charge, from the practical point of view it can not be carried out by a current of constant characteristics. For a full and safe charge, the characteristic of the charge current must vary in its course. For example, the classical IU charge scheme implies a battery charge at the beginning of a current with a constant force (equal to, for example, 1/10 capacitance) before the electrolysis of water in the electrolyte begins, and then with a constant voltage current (about 13.8 V). The procedure is simplified - in the course of the charge the current also requires a smooth adjustment. In this case, the charge time in each of the modes is not fixed, and depends on a number of factors - the degree of discharge, the need to remove sulfation, etc. This is how the full charge of the battery is ensured, ensuring maximum durability and stability of the characteristics.

Such a charge is only possible if you use a charger - with manual current regulation and a hydrometer, or an automatic, but not a regular generator of the car. It is the ratio of the above-described requirements of the battery to the charging current and the capabilities of automobile generators that explains the reservation to the word "unattended" when we talk about the battery.

A car generator, for example 100 A, respectively, gives a charging current of 100 A, which the battery receives until the charging current controller stops charging the battery. Given the above, as you understand, this current does not provide a full charge of the battery, it is rather a recharge - similar to the accelerated charge mode, which can be used on chargers, if the battery has sat down, and you need to drive urgently. In this mode, figuratively speaking, only the surface layers of the plates of the battery operate. There is nothing to worry about if after 1-2 unsuccessful starts the engine starts for the third time, the generator will recharge your unattended battery to 80% of the charge, which is considered the norm. But if the engine was started after numerous unsuccessful attempts, the battery will not be charged sufficiently by the generator, and as we all know well, the battery life is significantly reduced when the discharge is deep, or if they are in a semi-discharged state for a long time.

Thus, there are several quite common situations at which the battery needs to be charged by a charger, in other words speaking - to service.

However, modern high-tech cars are equipped with various systems that prevent or signal problems related to the battery. Such cars, as a rule, do not allow an accidental discharge, for example from a light switched on. Such a car is likely to inform the master at the next maintenance order about the need to replace the battery. In application to such cars it is quite possible to talk about the maintenance-free batteries. Moreover, on some modern cars, the battery is installed in hard-to-reach places, which causes the laboriousness of its replacement, and, even, the disadvantage of dismantling for a charge.

In conclusion, it remains to add that if your car is deprived of the above described systems - watch for the battery charge, the belt tension of the generator and the electrical safety of the car - and then your battery will become completely unattended.