Accumulator battery: 1 - body; 2 - cover; 3 - positive conclusion; 4 - interelement connection; 5 - negative conclusion; 6 - cork; 7 - filler neck; 8 - separator; 9 - positive plate; 10 - negative plate
Automotive (starter) the battery is designed to start the engine and power consumers of electricity when the engine is off. When the engine is running, the battery is charged by the alternator.
Comment. With the simultaneous inclusion of a large number of consumers and a low frequency of rotation of the engine crankshaft (idling) generator power may not be enough. In this case, the consumers will be powered from the battery. This must be taken into account in order to avoid its complete discharge.
Batteries from different manufacturers have their own design and technological features.
The car battery consists of six series-connected batteries with a nominal voltage of 2 V, placed in isolated compartments of the case (monoblock). The housing compartments are filled with electrolyte, in which the negative and positive electrodes of the batteries are located, having the form of plates. The filling holes of the compartments are closed with plugs. The plugs can be made both separate and fixed on a common cover. The negative electrodes of batteries are made of lead, the positive electrodes are made of lead dioxide, the electrolyte is an aqueous solution of sulfuric acid.
To connect the wire terminals on the battery cover, positive and negative terminals are made.
Comment. To eliminate the possibility of accidentally connecting the vehicle's negative wire terminal to the positive battery terminal, the positive battery terminal is made with a larger diameter than the negative one.
Distinguish between serviced and maintenance-free batteries.
The serviceable battery is an open type battery. The electrolyte of such a battery is in a liquid state. During operation, the battery requires periodic monitoring of the electrolyte level and the addition of distilled water, since when the battery is recharged, it evaporates. To exit from the battery of gaseous substances, the battery cover has one or more ventilation holes. The frequency of adding distilled water is determined by the design features of the battery. Open batteries are divided into batteries with normal, low and very low water flow.
Comment. For batteries with very low water consumption, the reduction of the electrolyte level to the minimum allowable level usually exceeds the life of the battery. Such batteries can be considered maintenance-free.
The maintenance-free battery has a cap without vents or filling holes. During the service life, distilled water is not added to the battery. The battery has a regulating valve, which is closed under normal operating conditions. When the internal pressure in the battery rises to a certain level, the valve opens and the gas escapes.
Comment. Maintenance-free batteries have a long service life, but are more demanding on the health of the car's electrical equipment and do not allow improper operation. If the electrolyte level falls below the permissible value, such a battery must be replaced.
A variety of maintenance-free batteries are gel batteries, where the electrolyte is a special composition that is in a gel state (jelly). If the case is damaged, the electrolyte almost does not leak from the battery.
The electrolyte density of fully charged, serviceable batteries should be within the range of 1.27-1.30 g/cm3 at 25°C; electrolyte density is not measured in maintenance-free batteries.
The battery may be equipped with a charge level indicator. The indicator of the state of charge is installed in one of the middle batteries and is fixed on the battery cover.
The indicator consists of a tubular body with an eye for observation, inside the body there is a ball, the buoyancy of which varies depending on the density of the electrolyte. When the density or electrolyte level drops, the color of the indicator changes.
Battery indicator
Batteries are characterized by the following main parameters:
1. Nominal battery voltage, V. Vehicles use rechargeable batteries with a nominal voltage of 12 V.
2. Cold cranking current, A. The discharge current specified by the manufacturer, which the battery is capable of providing to start the engine.
3. Nominal discharge current, A. The current that the battery must give to the external circuit for 20 hours until the voltage at the terminals drops to 10.5 V.
4. Battery capacity, which is indicated as nominal (or actual) twenty-hour capacity, Ah, and nominal (or actual) reserve capacity, min. Rated (or actual) twenty-hour capacity is the estimated amount of electricity that a fully charged battery can deliver during 20 hours of discharge at its rated current under certain conditions (actual capacity determined by testing). Rated (or actual) reserve capacity is the estimated discharge time in minutes during which the battery can have a discharge current of 25 A before the voltage at the terminals drops to 10.5 V (actual capacity determined by testing).
5. Charge acceptance is the ability of a battery to accept a charge.
6. Charge retention is the ability of an electrolyte-filled and charged battery to retain its charge when the circuit is open.
7. Water consumption is the rate of water decomposition when the battery is recharged (for serviced batteries).
8. Overall dimensions of the battery, mm.
9. Execution of the bottom bar. A design feature of a battery, determined by the way it is attached.
10. Battery weight, kg.
11. Polarity, direct or reverse. A design feature of a battery, determined by the location of its terminals. The battery has a direct polarity if, when viewed from the side of the terminals, the negative terminal is located on the right, reverse - if on the left.
Location of battery terminals: 1 - battery with direct polarity; 2 - battery with reverse polarity
Average battery life is 4 to 5 years. In order for the battery to work properly and not become unusable before this time, a number of simple rules must be observed:
- avoid deep discharge of the battery;
- do not overcharge the battery (what could be caused by a faulty alternator voltage regulator);
- prevent short circuit of the battery terminals;
- once every six months, check the reliability of the fastening of the wire terminals on the battery terminals (see below, «Battery - removal and installation»);
- once every six months, clean the battery cover from dirt with a solution of baking soda or ammonia (to reduce its self-discharge);
- once a year, clean the wire terminals and battery terminals from oxides formed on the contact surfaces (see below, «Battery - Maintenance»).
Do not leave an uncharged battery for a long period of storage. Even with an open external circuit, the battery self-discharges. A weakly charged battery can be completely discharged, causing the battery plates to peel off and fail.
Comment. A serviceable battery filled with electrolyte can be stored without operation for no more than one year. The battery must be fully charged beforehand (see below, «Battery - service»), Periodically (once a month) Check battery charge and recharge if necessary.
Before and after a long period of parking, check the density and electrolyte level and, if necessary, charge the battery using a charger.
Comment. The density of the electrolyte is used to estimate the state of charge of the battery. As the battery discharges, the density of the electrolyte decreases.
Battery needs to be checked and recharged regularly (see below, «Battery - Maintenance») in the event that the car is operated in the mode of short trips with frequent stops and starts of the engine (especially in winter). During short trips, the battery does not have time to charge, which can gradually lead to its deep discharge.
With a decrease in the density of the electrolyte, its freezing point increases. Thus, an electrolyte with a density of 1.20 g/cm3 (battery discharge rate 50%) freezes at about -33°C, and with a density of 1.15 g/cm3 (battery discharge rate 75%) - about -20°C. Freezing of the electrolyte in the battery will damage the battery case.
Comment. If the battery has been in operation for more than a year, then in the fall, check the density and electrolyte level to monitor its condition (see below), top up with distilled water if necessary, and charge the battery.
Batteries are supplied for sale, as a rule, in a ready-to-use form (filled with electrolyte and charged).
Comment. To increase the shelf life before the start of operation, batteries can be supplied without electrolyte, the electrodes of such batteries are in a dry-charged state. In such batteries, the electrolyte is poured immediately before installation on the car.
Before replacing the battery, it is necessary to clarify its overall and electrical parameters.
The battery must correspond in size to the dimensions of the installation place on the vehicle and be securely fastened to it. Location of terminals on the battery case (battery polarity) and their shape must match the terminals on the previously installed battery. If you install a battery of a different polarity, the length of the wires may not be enough, and it is possible to mix up the wires when connecting, which will cause damage to the vehicle's electrical equipment. Battery terminal polarity designation (plus «+» or minus «—») printed on the battery case next to the terminal.
The battery parameters are indicated on the information plate attached to it.
The electric capacity and value of the starting current of the purchased battery must correspond to the characteristics of the previous battery or the values given in the vehicle's operating instructions.
To facilitate starting in cold weather, you can choose a battery with a large starting current. The battery capacity should not differ significantly from that recommended by the car manufacturer. If the battery capacity is exceeded, the generator power will not be sufficient to charge it, and the battery will always be in a discharged state.