Do lead-acid batteries charge the same way as lithium batteries?
The charging control methods of lead-acid batteries and lithium battery chargers are different. The difference is that the materials used are different, and the principle of discharge is also different. The quality of charging and discharging of batteries and lithium batteries will directly affect the electrical performance and service life of the batteries. At present, there are two types of lead-acid batteries and lithium batteries on the market. These two types of chargers cannot be mixed, otherwise the batteries will be directly scrapped. Because the charging modes of lithium battery chargers and lead-acid battery chargers are different. Lithium batteries are charged at constant current and constant voltage, and lead-acid is charged in three stages.
Since lead-acid battery chargers are generally set to two-stage or three-stage charging mode, the voltage levels of lithium batteries and lead-acid batteries do not match. There are many kinds of lithium batteries, and the battery performance and battery protection board parameters may be different. Therefore, lithium batteries do not have universal battery chargers like lead-acid batteries. Generally speaking, lithium batteries are equipped with special chargers when they leave the factory. In order to protect the lithium battery, a special charger is required.
The lithium battery charging control is to charge at a constant current first, and then when the battery voltage rises to 4.2V, the voltage will no longer rise, and the charger will detect the current. If the current is less than a certain value, the charging will be terminated. Lithium batteries are sensitive to overcharge, so the protection circuit is complicated. The maximum charging rated voltage for a single-cell nominal 3.6V battery is 4.2V, and the upper limit of the allowable error is not more than 1%.
The ideal charging current of lead-acid batteries is pulsed, and the pulsed charging is best with the 50-60HZ mains power supply we use to directly rectify and unfiltered pulsating DC charging (this is the practice when the circuit is simple and the cost is low). The self-discharge rate of acid batteries is relatively large. When using power frequency charging, constant voltage charging is generally used (also limited current).
Lead-acid battery is a very complex chemical reaction system. External factors such as the size of the charge and discharge current and its operating temperature will affect the performance of the battery. It is a key technology for electric vehicles to calculate the SOC value of the battery and determine the operation mode of the vehicle according to the operation state of the vehicle and other parameters. Lead-acid batteries have the longest application history, and are also the most mature and cheapest batteries, and have achieved mass production. But it has low specific energy, high self-discharge rate and low cycle life.
Charging method:
Pulse charging is simple and economical. This method has a large charging current and fast charging speed. The disadvantage is that when the grid voltage fluctuates, the charging current also fluctuates.
Constant current charging, in order to prevent the lead-acid battery from being too high in temperature and losing too much electrolyte, the charging current is adjusted relatively small, and the charging time is long. On the other hand, if the charging time is too long, it will happen Overcharge, in order to prevent damage to the battery due to overcharge, an overcharge detection or timing circuit is required.
Constant voltage charging, both theory and practice have proved that constant voltage charging is safe when the charging voltage is lower than the upper limit of the charging voltage (for 12V batteries, this value), even if the charging time is very long, there is no danger. If necessary, the battery can also work in a floating state.
Lithium battery power supply needs to be charged with a matching charger. In the industrial supporting market, since each product is also packaged separately, it is not compatible with each other. Therefore, the corresponding charger should be selected according to the lithium battery pack used, and the charging should be strictly in accordance with the requirements. Regardless of whether it is in the industrial or civilian market, since the basic principles of lithium battery charging are the same, the steps and standards for charging lithium batteries can be standardized. is 4.2V.
Lithium battery charging is divided into two stages:
Constant current charging, that is, the current is constant, and the voltage of the lithium battery gradually increases with the charging process. According to the above specifications, it is generally charged with a current of 0.2C (C is a way of expressing the comparison between the nominal capacity of the battery and the current, 0.2C That is, 200mA), when the battery voltage is close to the full voltage of 4.2V, change the constant current charging to constant voltage charging. This process is about five hours.
Constant voltage charging, that is, the voltage is constant, and the current gradually decreases as the saturation of the cell deepens. According to the specification, when the current decreases to 0.01C or 10mA, the charging is considered to be terminated. After this process and the constant current charging time are added together, the total charging time should not exceed eight hours.
Therefore, there are two criteria for judging whether the charging of the lithium battery has reached saturation: one is that the current is 0.01C, and the other is that the total duration does not exceed eight hours. In other words, if the charging process of the lithium battery still cannot reach 0.01C after eight hours, then regarded as non-conforming products.