Contents: Battery ↡ Battery - energy storage ↡
Fig. 9.1. Battery location under the rear seat on the right side in the T-model (station wagon) similar to the arrangement in the sedan: 1 – battery; 2 – negative terminal, "ground" (–); 3 – ventilation tube; 4 – battery mount; 5 – fuse box
On all E-class cars, the battery is located under the rear seat on the right side. To access the battery, remove the rear seat cushion (sedan) or fold the right rear seat (T-model), the battery itself is covered by an additional cover. In the engine compartment, there is a control contact for checking the battery. It is marked with the "+" symbol (Fig. 9.1).
Fig. 9.2. Battery structure: 1 – positive electrode grid; 2 – positive electrode; 3 – separator; 4 – negative electrode grid; 5 – negative electrode; 6 – negative electrode block; 7 – battery section; 8 – positive electrode block
Six batteries connected in series form a battery (12 V) (Fig. 9.2). One battery consists of a block of positive and negative plates, which together create a voltage of 12 V. The plates consist of lead grids, which are filled with an active electrolyte. The positive plates are made of lead dioxide, the negative ones are made of pure lead. A separator is installed between them. It separates the plates, preventing a short circuit, but the electrolyte can pass through its tiny pores. The electrolyte is a conductive liquid, which consists of approximately 37% concentrated sulfuric acid and 63% distilled water.
Battery
Marking. It is located on the battery case and indicates its characteristics. For example, marking "12 V 74Ah 350 A" means the following: 12 V is the nominal voltage; 74 A h — nominal capacity; 350 A is the control discharge current.
The nominal voltage of the battery is 12 V. The actual voltage depends on the state of charge of the battery, it can be higher or lower than the nominal voltage.
Nominal capacity is the current that a fully charged battery can deliver for 20 hours at a temperature of +27°C without a voltage drop at the terminals of at least 10.5 V.
The cold discharge current reflects the capacity output by the current of the battery in a cold state. The discharge current of 12 V, which the battery can output at a temperature of -18°C without the voltage falling below 9 V for 30 s and 6 V for 150 s.
Self-discharge is a chemical process that occurs in a battery and leads to its discharge when no consumers are connected to it. A charged new car battery loses approximately 0.5% of its charge daily. High temperatures, damage or contamination of the battery caps accelerate the self-discharge process.
Battery - energy storage
Chemical processes occur inside the battery, thanks to which it produces and accumulates energy. During current output, the energy of the chemical reaction is converted into electrical energy. The most important function of the battery is to provide the starter with energy to start the engine. Depending on the engine and starter model, the power consumption at the moment of starting can be 5000 W. This is also due to losses in overcoming friction forces to turn the crankshaft of a hot engine - the starter needs only a fifth of this power, consumption increases at low temperatures, since then the lubricants harden.