How to correctly distinguish lead-acid batteries and lithium-ion batteries

When charging batteries, appropriate methods must be selected according to different situations, and charging equipment must be used correctly. This can improve work efficiency and extend the service life of batteries and charging equipment.

Usually, there are two methods for charging batteries: constant current charging and constant voltage charging. In recent years, fast charging (pulse charging) has also been gradually promoted.

(1) Constant current charging

During the charging process, the charging current remains constant, which is called constant current charging, as shown in the figure.

How to charge lead-acid batteries_lead-acid battery charging principle

Constant current charging has greater adaptability and can arbitrarily select and adjust the charging current, so it can charge batteries in various situations.

For example, this method can be used for the initial charging, supplementary charging, and desulfurization charging of new batteries.

However, its disadvantage is that the charging time is long and the charging current needs to be adjusted frequently.

(2) Constant voltage charging

During the charging process, the charging method in which the power supply voltage U remains unchanged is called constant voltage charging, as shown in the figure.

How to charge lead-acid batteries_Lead-acid battery charging principle

When using constant voltage charging, you must choose a good charging voltage: if the voltage is too high, not only will the charging current be too large at the beginning of charging, but overcharging will also occur, causing the plate to bend, a large amount of active material to fall off, and the battery temperature to rise too high; if the charging voltage is too low, the battery will not be able to charge.

Constant voltage charging also requires that the battery being charged must be connected in parallel between the charging power sources. Since the battery is connected in parallel with the generator in the car, the battery is always charged at the constant voltage of the generator (adjusted by the regulator).

The above charging methods are collectively referred to as "conventional charging". It takes 60h to 70h to complete an initial charge, and about 20h for supplementary charging. Because the charging time is too long, it brings great inconvenience to use.

(3) Pulse fast charging

Pulse fast charging can greatly overcome the polarization phenomenon generated during the charging process and effectively improve the charging efficiency.

The charging current waveform is shown in the figure:

How to charge lead-acid batteries_Lead-acid battery charging principle

The advantages of pulse fast charging are:

①The charging time is greatly shortened. Generally, the initial charging is no more than 5h, and the supplementary charging is no more than 1h.

②It can increase the capacity of the battery. Because pulse fast charging can eliminate polarization. Therefore, the chemical reaction is sufficient during charging, which deepens the reaction depth and increases the battery capacity. Therefore, the new battery does not need to be discharged after the initial charging. It can be used. This not only saves energy, but also brings convenience to use.

③It has a significant desulfurization effect. Because pulse fast charging has the above advantages, its advantages are more prominent in departments with concentrated batteries, frequent charging or emergency use. However, the control circuit of the pulse charger is complex, the price is higher than that of ordinary chargers, and it is not ideal in use, and needs further improvement.

④Identification of the positive and negative polarity of the battery during charging

When charging, the positive and negative poles of the battery should be connected to the positive and negative poles of the charger accordingly. Therefore, it is necessary to correctly judge the polarity of the battery.

The poles of the battery are generally marked with "+" and "-"; or the positive pole is painted red. If the marking is unclear, the following methods can be used for identification:

① Observe the color of the poles. The positive pole of the used battery is dark brown and the negative pole is light gray.

② Connect the two poles of the battery with a DC voltmeter and determine the positive and negative poles according to the direction of the pointer deflection.

③ Use electrolyte to identify. Connect the two poles of the battery to the wires and insert them into the electrolyte respectively (do not let the two wires touch each other). The one with more bubbles around the wire is the negative pole.

Conventional charging method

There are two conventional charging methods for lead-acid batteries: floating charge (also known as constant voltage charging) and cyclic charging.

When floating charge, the charging voltage must be strictly controlled. For example, for a battery with a rated voltage of 12V, the charging voltage should be between 13.5 and 13.8V. If the floating charge voltage is too low, the battery will not be fully charged, and if it is too high, it will cause overcharging. The voltage should be set in such a way that the initial charging current does not exceed 0.3C (C is the rated capacity of the battery).

For cyclic charging, the initial charging current should not exceed 0.3C, and the charging ampere hours should be slightly greater than the discharging ampere hours. It is also possible to charge at a constant current of 0.1C for several hours. When the charging ampere hours reach 90% of the discharging ampere hours, switch to floating voltage charging until it is fully charged.

The above are the commonly used lead-acid battery charging methods, but these two methods have some shortcomings. During the charging process, the battery voltage gradually increases and the charging current gradually decreases. Since constant voltage charging does not care about the actual state of the battery voltage, the charging voltage is always constant, and the charging current is relatively large at the beginning, and then decreases exponentially; using fast charging may cause the battery to be overcharged, which may easily cause battery damage. For cyclic charging, using a smaller current charging has a better charging effect. However, for large-capacity batteries, the charging time will be very long, the time efficiency is low, and many inconveniences will be caused.