Analysis of battery charging methods

There are three ways to charge the battery: constant voltage charging, constant current charging and pulse fast charging. 1. Constant-voltage charging Constant-voltage charging refers to a charging method in which the charging power supply voltage remains constant during the charging process. In the car, the battery uses this charging method. The connection method of constant voltage charging is shown in Figure 1-12, and the charging characteristic curve is shown in Figure 1-13. During constant voltage charging, according to Icu003d(U-E)/R, as the battery electromotive force E increases, the charging current Ic gradually decreases. If the charging voltage is adjusted properly, the charging current is zero when fully charged, that is, the charging is completed. During constant voltage charging, the battery to be charged is connected in parallel with the charging power source, the number of cells in each branch should be equal, and the appropriate charging voltage should also be selected. If the charging voltage is too high, it will cause overcharging, the plate will bend, the active material will fall off, and the temperature will be too high; if the charging voltage is too low, the battery will not be fully charged. Generally, the charging voltage of a single cell battery is 2.5V. In the initial stage of constant voltage charging, the charging current is relatively large, 90% to 95% of the rated capacity can be reached within 4 to 5 hours, so the charging time is short, and it is suitable for supplementary charging without taking care of and adjusting the charging current. Since the charging current cannot be adjusted, constant voltage charging is not suitable for initial charging and desulfurization charging. 2. Constant current charging Constant current charging refers to the charging method in which the charging current is kept constant during the charging process. It is widely used for initial charging, supplementary charging and desulfurization charging. The connection method of constant current charging is shown in Figure 1-14, and the charging characteristic curve is shown in Figure 1-15. When charging with constant current, the battery to be charged is connected in series. Each cell battery needs 2.7V when fully charged, so the number of cell batteries in series u003d the rated voltage of the charger/2.7 (pieces). The charging current should be selected according to the small-capacity battery, and after it is sufficient, it should be removed in time, and then continue to charge the large-capacity battery. In order to shorten the charging time, the charging process is usually divided into two stages. The first stage uses a larger charging current to quickly restore the capacity of the battery. When the battery power is basically sufficient, the single cell battery voltage reaches 2.4V, and bubbles appear in the electrolysis of water, turn to the second stage and reduce the charging current by half until the electrolyte density and battery terminal voltage reach the maximum value and within 2～3h The battery no longer rises, and air bubbles emerge violently inside the battery. 3. Pulse fast charging Pulse fast charging must be carried out with a pulse fast charger, and its charging current waveform is shown in Figure 1-16. The process of pulse fast charging is: first use a large current of 80% to 100% of the rated capacity for constant current charging, so that the battery can be charged to 50% to 60% of the rated capacity in a short time. When the single cell battery voltage rises to 2.4V and starts to bubble, it is automatically controlled by the control circuit of the charger to start pulse fast charging, first stop charging for 25ms (called pre-stop charging), and then discharge or reverse charge to make the battery Pass a larger pulse current in the reverse direction (the pulse depth is generally 1.5-3 times the charging current, and the pulse width is 150-1000μs), and then stop charging for 40ms (called post-stop charging), and the subsequent process is positive pulse charging → Stop charging before → negative pulse instantaneous discharge → stop charging after → positive pulse charging. This process is repeated until it is fully charged. The advantage of pulse fast charging is that the charging time can be greatly shortened (new battery charging takes 5h, supplementary charging takes 1h); the disadvantage is that it has a certain impact on the life of the battery, and the pulse fast charger has a complex structure and expensive price, which is suitable for battery concentration , Frequent charging, occasions with emergency requirements. Disclaimer: Some pictures and content of articles published on this site are from the Internet. If there is any infringement, please contact to delete. Previous post: Performance characteristics of ceramic composite diaphragms for lithium batteries and analysis of the advantages of bolmstone for ceramic diaphragms