Maintenance-free battery: what it means, lifespan, recovery

The development of electrical energy storage systems using chemical processes helps to create truly useful maintenance-free devices, thereby greatly simplifying the life of motorists. On the other hand, even the slightest innovation in battery design is immediately used by car battery companies to effectively portray the undeniable benefits of their products.

From the presentation of advertising slogans, the new battery designs looked like they did not require human intervention for normal operation. More than an attractive offer, especially if a person already has a negative experience of servicing and charging batteries.

What does maintenance-free battery mean?

The main task in the maintenance of batteries of classical design was to maintain the given density and electrolyte level. The high temperature and overcharging forced to periodically replenish the loss of water in the battery banks. The first maintenance-free batteries appeared in the United States in the early 1980s. Thanks to the use of electrodes and bridges for the armature instead of lead, an alloy with a calcium content of up to 0.1%, tin up to 0.12%, it was possible to significantly, almost six to seven times, reduce the intensity of gas evolution and self-discharge. Water losses were small and did not require replenishment for over two years. The market dubbed these structures "maintenance-free".

Modern designs of maintenance-free batteries appeared in the US and Western European markets in the late 90's. After numerous experiments, a multicomponent alloy of high purity was developed, in which additives of silver, aluminum, calcium, tin, antimony were already present.

Such batteries began to be positioned in sales as maintenance-free. They acquired:

• sealed enclosures,
• special separators and traps for lead sludge,
• holes for electrolyte control and water filling have been removed from the structure.

For some time, even the formulation of the problem disappeared - how to add water to an unattended battery, its losses were reduced to almost zero.

Despite some optimism, the question of how to maintain a maintenance-free battery became more complex and required higher quality chargers. The battery presented new but feasible operating conditions. The main condition is a constant voltage of high stabilization, the deviation from the optimal parameters is not more than 0.1 V. Only in this way is the guaranteed service life of the maintenance-free car battery and its reliability ensured. The stability of the charging system of a generator or stationary device is created by electronic control systems.

On machines of old designs with a high degree of wear of engine components and assemblies, the use of a maintenance-free battery will require the installation of modern generators with microprocessor-controlled charging voltage and current. In this case, it is worth thinking about which battery is better to use - maintained or unattended.

Disadvantages of using maintenance-free batteries

One of the world's leading manufacturers of maintenance-free batteries corporations "VARTA Geraetebatterie GmbH" and "Robert Bosch GmbH" position their products as an improved product with a 30% increased discharge current, a guaranteed pre-sale storage period of up to 18 months. It must be admitted that German and European factories really produce the highest quality maintenance-free batteries.

Interesting! According to Sandia National Labs statistics, the critical parameter for battery longevity is the purity of the materials used in the manufacture, not the perfection of the instrument design.

High discharge parameters make it possible to use lighter and more compact batteries for cars than standard 45 and 55 Ah for gasoline engines of B and C class cars. The possibility of completing batches of vehicles for export to third countries with maintenance-free batteries makes it easier to supply vehicles located in the warehouse.

In real operating conditions, the high sensitivity to incomplete charging and deep discharge, especially at negative temperatures, makes maintenance-free batteries vulnerable. Two or three short-distance runs with an undercharged battery in frosty winter weather, long-term parking in the open, and, perhaps, there will not be enough charge for the subsequent start of a frozen engine. And for the battery itself, such a load will be fatal; you will have to look for a way to restore the maintenance-free car battery.

At low temperatures, the viscosity of the electrolyte increases, and the rate of diffusion of ions in the active mass decreases. With a starter discharge, local local heating areas appear on the surface of the electrodes, from which the main part of the energy is removed. In the process of temperature recovery, such spots sulfate faster and more intensely than other areas of the electrode.

For objective reasons, the concentration of acid in the electrolyte cannot be higher than 1.3 g / cm3. With an increase in the amount of sulfuric acid, the potential capacity of the positive electrode increases, and the potential capacity of the negative electrode decreases due to a drop in the rate of reactions on lead. The optimum level of electrolyte density is determined taking into account the operating conditions and the load of the battery. For serviced batteries of the old design, there were instructions according to which the concentration of H2SO4 in the electrolyte was adjusted by adding water or acid from 1.22 to 1.28 g / cm3, depending on the operating temperature. Acid correction tables should be used to optimize the electrolyte density in a maintenance-free battery.

How to check the electrolyte level in a maintenance-free battery? For these purposes, the manufacturer uses a transparent plastic window-insert, which allows an objective assessment of the electrolyte level, or the battery case is made of a translucent material through which the levels in all banks are clearly visible.

Sooner or later, the characteristics of the battery will no longer satisfy the owner, and the question will arise about the advisability of buying a new one or repairing a maintenance-free battery.

The diagnosis of the battery is made after several reference control-training cycles: The last charge is carried out with a current of 7-8A, not allowing the recommended voltage to be exceeded. Immediately after charging, check the voltage at the battery terminals using a special load plug or record the exact reading of the multimeter.

Important! The repeated measurement of the voltage of the maintenance-free battery is carried out after 6-8 hours, according to which the degree of loss of charge by the battery is estimated.

The load plug detects the voltage drop across the terminals under the reference load and can be used to check the charge of the maintenance-free vehicle battery.

If intense gas evolution starts during charging, it may be necessary to correct the electrolyte composition by adding water. How to add water to a maintenance-free battery - you can use a syringe, as in the video:

Repair of maintenance-free batteries is largely available only if you have the skills and equipment, but in 90 cases out of 100, repairs are limited to:

• desulfation of battery plates, including the use of Trilon-B or other special chemicals;
• repeated charging and discharging with very small currents on an electrolyte of low density;
• gluing or sealing cracks in the battery case;
• repair of terminals.

The more difficult level of repair is limited by the need to decide how to open the maintenance-free battery. Typically, the top polypropylene battery face cover is hot pressed onto the base. Any heating of the case to remove the cover causes deformation, and subsequent attempts to replace it will not be successful. There are options when the cover snaps into the battery case lock on rubber gaskets.