How is energy stored in a lead acid battery?
This chapter details the storage methods of lead-acid batteries
From the charging and discharging process of the lead-acid battery, it can be known that the fully charged positive plate is not positively charged, but is in activated PbO2. State; the fully charged negative plate is not negatively charged, but is in the activated PbO2 state. If it is considered that the positive and negative plates of the charged battery are respectively positive and negative, then in the sulfuric acid electrolyte with good conductivity, won’t all the electrical energy be discharged immediately? This misunderstanding is caused by understanding the battery of a chemical power source as a capacitor of a physical power source. The principle of a battery is completely different from that of a capacitor: the former converts electrical energy into chemical energy and stores it, while the latter converts electrical energy into electric field energy for storage. The external characteristics of the two in the circuit are completely different, as shown in Figure 1-1
Figure 1-1 Comparison of lead-acid batteries and capacitors
It can be seen from Figure 1-3 that the general capacitor is charged in “seconds”
On the order of magnitude, the terminal voltage can rise to hundreds of volts; when discharging, it is also on the order of “seconds”, and the terminal voltage drops to zero. The terminal voltage of the lead-acid battery after several hours of charging, the voltage rises from “1” to “2” in Figure 1-3 (b), and it can only be kept slightly higher than 2V. Know more, such as Jun
2.7V; the discharge process is reversed. After several hours of discharging, the terminal voltage drops to 1.5V. After stopping the discharge, it quickly rises to about 2V.
This “memory” characteristic of the lead-acid battery terminal voltage is often used as a filter and voltage regulator component. If the battery is removed from the telephone communication power supply and the charger is used to power the telephone equipment directly, the noise in the headset is very strong due to the interference of the current clutter, and normal calls cannot be made. If the battery is incorporated into the power supply loop, the noise disappears immediately.
In the process of battery charging and discharging, it is essentially the conversion of electrical energy and chemical energy. This conversion requires many conditions. For example, the temperature, the proper concentration of electrolyte, the effective surface area of the plate, the connection state, etc., once these conditions are not met, the battery will show “failure”. When the conditions are restored, the performance of the battery will be restored. Therefore, when the battery cannot work normally, first confirm whether the conversion conditions are met, otherwise, false scrap will occur.
Figure 1-2 Understanding of battery symbol
From an electrical point of view, the battery symbol (1) shown in Figure 1-2 should be understood as (2). The battery has a zener tube function in the circuit. From an electrochemical point of view, the symbol (1) should be understood as (3) The two electrodes of the battery have a similar volume capacity concept.