Common battery charging methods
The charging mode of the battery will affect the performance and life of the battery. When the charging current is too large, the chemical reaction of the battery is not enough, so that the internal resistance of the battery increases, causing the battery temperature to rise sharply. If used improperly, the internal material will be damaged; On the other hand, if the charging current is too small, a long charging time is required, which is very inconvenient to use. Therefore, in order to exert the great performance of the battery and does not require too long time to charge the battery, the charging method of the battery is very important.
The charging method of the battery includes a constant voltage (CV) charging method, a constant current (CC) charging method, a mixed constant current/constant voltage (CC/CV) charging method, and a pulse charging method (CP). Generally, most of the charging methods commonly used in the market are constant voltage charging method and constant current charging method. The main reason is that the circuit structure of the charger is simple and the design is easy, but there are two main methods for the two methods. The problem is that the constant voltage charging method has a large current at the initial stage of charging. In addition to causing the temperature of the battery to rise, the battery plate is also easily damaged, and the constant current charging method is too long when charging. The pulse charging method can provide a charging rest time during the charging process, so that the battery electrolyte can be depressed for a long time, so a larger current can be used for charging to shorten the charging time of the battery. The charging rule mentioned above will be respectively introduced below.
(1) Constant voltage charging method: As shown in the following figure, the principle of the constant voltage charging method is to charge the battery with a constant voltage source, which has the advantages of simple circuit structure and easy control circuit design. In the constant voltage charging mode, the charging current will decrease as the battery is fully charged. When the battery is fully charged, the charger automatically enters the Float charging mode to keep the battery fully charged. In the initial stage of charging, the initial charging current is too large due to the low voltage at the battery end, so that the electrode plate of the battery is easily damaged and the temperature of the battery itself is increased, so that the life of the battery is shortened. In order to improve this disadvantage, a multi-stage voltage charging method can be used, that is, charging is performed with a lower charging voltage at the beginning of charging, and the charging voltage is raised after the voltage at the battery terminal rises.
(2) Constant current charging method: As shown in the figure below, the constant current charging method charges the battery with a fixed current. This method is the same as the constant voltage charging method. When the battery is fully charged, the charger must be converted into a trickle. Charging mode to avoid damage caused by overcharging of the battery. Compared with the constant voltage charging method, this method can fully charge the battery in a short time, but must pay attention to the charging degree of the battery, because the charger will always provide a constant current to charge the battery, so when the battery is full, if not Stop charging immediately or switch to trickle charge mode, which will cause the battery to overcharge, damage the battery's plates, and reduce battery life.
(3) Mixed constant current / constant voltage charging method: It is known from the above that the constant voltage and constant current charging methods have their own advantages and disadvantages. In order to improve the shortcomings of the two methods, a constant current / constant voltage charging method is proposed. This charging method can significantly reduce the charging time, and also has the function of self-regulating current with a constant voltage charging method, and does not cause the battery to overcharge. As shown in the figure below, the constant current mode is used at the beginning of charging. Since the battery accepts higher current when the battery is low, most of the energy released can be quickly replenished. When this mode continues until the battery voltage reaches. When the voltage is set, the charger will switch to the constant voltage mode to continue charging. At this time, it is called the equalization mode. After the battery is fully charged, the charger will automatically switch to the floating mode to keep the battery fully charged.
(4) Pulse charging method: The pulse charging method charges the battery with periodic pulse current. As shown in the figure below, this method can make the electrolyte in the battery more uniform during this period because there is a period of time to stop charging. Diffusion, so the energy of charging can be fully converted into electrical energy by chemical energy, so the charging efficiency is higher than the above method.
Since the closed lead-acid battery only adds just enough electrolyte, any loss of electrolyte will cause the battery capacity to drop. Therefore, it is not advisable to charge the battery with excessive current during the charging process to avoid excessively high. The current causes the vaporization rate of the electrolyte to exceed the rate of gas absorption. Therefore, in the experimental design, the charging current and frequency need to be standardized to ensure that the battery can be fully charged without harming the battery.