What are the methods for charging a battery?

[PaisleyLee]

There are five methods for charging a battery: constant current charging, constant voltage charging, constant voltage charging with a fixed resistor, step constant current charging, and floating charging. Constant current charging method: During the charging process, the charging current remains unchanged, which is called the constant current charging method, abbreviated as CC charging or constant current charging. As the battery voltage gradually increases during charging, the charging current gradually decreases. To prevent the charging current from decreasing due to the rising battery voltage, the power supply voltage must be gradually increased to maintain a constant charging current. This requires a high level of automation in the charging equipment, and generally, simple charging devices cannot meet the requirements of constant current charging. Constant voltage charging method: During the charging process, the charging voltage remains unchanged, which is called the constant voltage charging method, abbreviated as CV charging or constant voltage charging. Since the power supply voltage remains constant from the beginning to the end of charging, the charging current is quite large at the start, significantly exceeding the normal charging current. However, as charging progresses, the battery voltage gradually rises, and the charging current gradually decreases. When the battery voltage equals the charging voltage, the charging current drops to a minimum or even zero. The advantage of the constant voltage charging method is that it can prevent excessive charging current in the later stages, which could cause active material shedding from the plates and energy loss. The required power supply voltage is approximately 2.4–2.8V per cell for acid batteries and 1.6–2.0V per cell for alkaline batteries. Constant voltage charging with a fixed resistor: This is a method used to compensate for the shortcomings of constant voltage charging. A resistor is connected in series between the power supply and the battery, allowing the initial charging current to be adjusted. However, the maximum charging current is sometimes limited, so as the battery voltage rises during charging, the current decreases almost linearly. Sometimes two resistor values are used, switching from a low to a high resistor at around 2.4V to reduce gas generation. Step constant current charging method: This method combines the characteristics of constant current and constant voltage charging. The battery is charged with a larger current in the early stages, then switched to a smaller current after a period, and finally to an even smaller current in the later stages. This method, which uses different currents in different stages for constant current charging, is called step constant current charging. Most step constant current charging processes can be divided into two or more stages. This method requires less charging time and achieves good results. Since a smaller current is used in the later stages, it reduces the washing effect of gas bubbles on the active material of the plates and minimizes material shedding. This method extends the battery's service life, saves energy, and ensures thorough charging, making it a commonly used charging method. Most batteries are charged at the first stage with a current rate of 10h, and at the second stage with a current rate of 20h. The duration of each stage varies depending on the specific requirements and standards of different batteries. Floating charging method: Intermittently used batteries or those only used during AC power outages are charged using the floating charging method. Most stationary batteries used in special applications are charged using this method. The key advantage of floating charging is that it reduces the battery's gas generation rate and prevents overcharging. At the same time, since the battery is connected in parallel with the DC power supply, it can instantly deliver a large current when high-power devices are in use, helping to stabilize the voltage of the power system and ensuring normal operation of electrical equipment. The disadvantage of floating charging is that some batteries may not be charged evenly or sufficiently, so periodic equalization charging is required. Functions of the battery: Provides a strong starting current to the starter when starting the engine; assists the generator in supplying power to electrical devices when the generator is overloaded; supplies power to electrical devices when the engine is idling. Battery maintenance: Start the car regularly to charge the battery; add distilled water or a special replenishing solution when the electrolyte is low; frequently check the small holes on the battery cover for ventilation during daily use; inspect the positive and negative terminals for signs of oxidation.

[McAlexander]

There are several common methods for charging a car battery. When I maintain my car battery at home, the most frequently used method is a smart battery charger. Simply connect the charger's positive and negative terminals to the corresponding battery terminals, then set the charging mode, such as slow charge or fast charge. Slow charging is better for the battery but takes longer, while fast charging is quicker but may shorten battery life. Another option is an automatic charger, which stops charging when the battery is full to prevent overcharging. Also, don’t forget about safety—ensure the area is well-ventilated, the battery isn’t leaking, and the connections are tight to prevent sparks before starting. If the battery is completely dead, use a low current initially to avoid damage. Regular charging can extend battery life, especially in winter or when the car isn’t used for long periods. I usually charge it once a month to maintain battery health.