Fig. 15.1. Varta battery (12 V): 1 – set of positive plates; 2 - positive lattice; 3 – positive plate; 4 – separator; 5 - negative grid; 6 – negative plate; 7 – set of negative plates; 8 – element
The storage battery (Fig. 15.1) is designed to start the engine and supply power to consumers when the engine is not running, when the generator does not generate electricity. Six series-connected elements (cans) form a car storage battery. Each element consists of alternately located positive and negative plates, which, as a result of a chemical reaction, generate a voltage of approximately 2 V. The plates are made in the form of a grid filled with a porous active mass. The positive plate contains lead dioxide, the negative plate contains pure lead. Plates of the same polarity are assembled into half-blocks and welded to common plates. Microporous separators are located between the plates in the blocks. And although they separate the plates, the electrolyte can penetrate through the microscopic pores of the separator. The small thickness and high porosity of the separators reduce the internal resistance of the battery and allow for a higher discharge current. The electrolyte in the battery is a solution of sulfuric acid in distilled water (37% sulfuric acid and 63% distilled water). When the battery is discharged, the sulfuric acid of the electrolyte interacts with the active mass of the plates and converts it into lead sulfate, while the amount of acid in the electrolyte decreases and its density decreases.
TECHNICAL DICTIONARY
Battery
Designation.
Located on the battery case, contains its technical characteristics. For example: 12V 40Ah 200A (12V is the nominal voltage (12 V); 40Ah — nominal capacity (40 Ah); 200A — control discharge current in cold state.
Nominal voltage.
All Fiesta models are equipped with 12V batteries. The voltage depends primarily on the battery's state of charge and may be higher or lower than the nominal voltage.
Nominal capacity.
The ability of a battery to store electrical energy. Capacity determines the current strength that a fully charged battery can deliver at a 20-hour discharge rate, an electrolyte temperature of 27°C and a voltage of at least 10.5 V (discharge voltage). For example, the power of the parking lights of your Fiesta is 25 W. At a voltage of 12 V, the battery delivers an electric current of 2.08 A - current (A) = power (W) / voltage (V). Theoretically, the energy of a fully charged battery is enough for 19.2 hours of parking lights. The emphasis is on the word "theoretically", since in practice the battery will be completely discharged after about 15 hours.
Capacity.
The amount of current drawn in ampere-hours. It primarily depends on the discharge current, temperature, charge level and general condition (age) of the battery.
Cold state discharge control current (starter discharge current).
Indicates the ability of the battery to start the engine at a negative temperature (unit of measurement A). This is the discharge current that can be obtained from a 12-volt battery at an electrolyte temperature of -18°C, and the voltage should not decrease below 9 V for 30 s, and below 6 V for 150 s.
Self-discharge of the battery.
Chemical processes in the battery cells lead to discharge, even if no consumers of electrical energy are connected. Every day, a new charged battery loses approximately 0.5% of its charge. High temperatures, damage and contamination of the battery cover accelerate self-discharge.
Accumulation of electrical energy by a battery
Chemical processes of consumption and accumulation of electric energy take place inside the battery. The most important task of the battery is to supply the starter with the necessary energy during engine start-up: depending on the engine and starter types, up to 2000 W is consumed in a short time. Most of the power when starting a cold engine is used to overcome internal friction. When starting a warm engine, the starter already operates with a consumption of approximately 1/5 of this power, since all the gaps in the moving and rotating units correspond to the optimal ones, and hot oil is more fluid than cold oil, which circulates with difficulty in the lubrication system.
TECHNICAL DICTIONARY
Starter
Fig. 15.2. Starter: 1 – starter assembly; 2 – traction relay; 3 – drive lever; 4 – starter cover on the drive side; 5 – freewheel clutch with drive gear; 6 – anchor with collector; 7 – brush holder; 8 – covers on the collector side with parts of the bearing axial adjustment mechanism
The Fiesta car is equipped with a starter, which is a DC electric motor with mixed excitation and an electromagnetic two-winding traction relay (Fig. 15.2).
Turn the ignition key to the "Start" position - voltage is supplied from contact "50" of the ignition switch (lock) to the traction relay, which is located on top of the starter.
At the same time, the relay anchor moves the freewheel clutch with the gear through the lever. The freewheel clutch hub rotates on the helical splines of the starter anchor shaft and the gear, which facilitates its engagement with the flywheel ring gear.
The relay anchor is pulled in and the relay contacts are closed. Current flows through the closed contacts of the traction relay, feeding the stator and anchor windings, the starter anchor begins to rotate together with the hub and freewheel clutch and turns the engine crankshaft.
After the engine starts, the rotation speed of the pinion exceeds the rotation speed of the starter anchor. In this case, the freewheel clutch rotates freely and the torque is not transmitted from the engine flywheel to the starter anchor shaft. After the ignition key is released, the power supply circuit of the traction relay windings through the ignition switch is opened, the anchor of the traction relay is pressed by the spring to its original position, the relay contacts are opened and the drive pinion disengages from the toothed ring of the flywheel.
(The material was copied from an information website: «www.fordbook.ru»)