What is equalization charging? The significance of the equalization charge management system for Li-ion battery packs. Currently, charge equalization is used in most applications, but there are also equalization in discharging situations and equalization in static situations; in practice, equalization in certain situations may be counterproductive. So what is equalization charging? What is the significance of a balanced charging management system for Li-ion battery packs? Let's discuss it below.
What is equalization charging?
Balanced charging, referred to as even charging, is the charging of balanced battery characteristics, refers to the use of the battery, due to individual differences in the battery, temperature differences and other reasons caused by the voltage imbalance at the battery end, in order to avoid the deterioration of this imbalance trend, the need to increase the charging voltage of the battery pack, balanced charging of the battery, in order to achieve a balanced battery pack in the individual characteristics of each battery, to extend the battery life.
The concept of balanced charging is proposed in the use of old lead-acid batteries, most of the current valve-regulated batteries are clearly proposed "voltage balance, into a thorough", while "the battery does not form an acid layer, no need for balanced charging. The definition of charging voltage for a 2.4V single cell battery is accelerated charging.
Equalization charging will cause damage to the valve-controlled battery. The equalization charging voltage is a higher float voltage for most batteries, so most normal batteries are in an overcharge state, and the gas that cannot be compounded forms a certain pressure inside the battery, and when the pressure exceeds the safety control valve threshold, the valve opens and the gas is discharged from the control valve.
The need for balanced charging of lithium battery pack
With the current manufacturing level and process of lithium battery pack, in the lithium power battery cells in the production process, each lithium power battery monomer will have subtle differences, that is, consistency problems, inconsistency is mainly manifested in the lithium power battery monomer capacity, internal resistance, self-discharge rate, charge and discharge efficiency. The inconsistency of lithium power battery cells is transmitted to the lithium battery pack, which inevitably brings about the loss of capacity of the lithium battery pack, and then causes a decline in life.
The meaning of lithium power battery equalization is the use of power electronics technology, so that the lithium-ion lithium power battery monomer voltage or lithium power lithium battery pack voltage deviation is maintained within the expected range, so as to ensure that each single lithium power battery in normal use to maintain the same state, in order to avoid the occurrence of overcharge, overdischarge. Without equalization control, as the charge and discharge cycles increase, the voltage of each single lithium power battery gradually diverges, and the service life will be greatly reduced.
The significance of Li-ion battery pack equalization charging management system
Li-ion battery pack equalization charging management system is mainly divided into passive equalization and active equalization. In a series battery pack, although the current through the single cell is the same, but due to its different capacity, the depth of discharge of the battery will be different, the capacity of the large one will always be shallow charge and shallow discharge, while the capacity of the known one will always be overcharge and overdischarge, which causes the decay of the large capacity to be slow and the life to be extended; the decay of the small capacity to be accelerated and the life to be shortened, and the difference between the two The difference between the two will become bigger and bigger.
The main purpose of Li-ion battery pack equalization is to improve the consistency between battery cells, to achieve the same or close characteristics of power and voltage between each cell, and to reach the safety level of industrial applications. The main function of charge equalization is to prevent overcharging, and the negative impact in discharging use makes the use of such equalization more than worthwhile.
Without charge equalization, small capacity batteries are somewhat overcharged and the battery pack output is slightly above the minimum capacity of the individual cells before any individual cell in the pack is overdischarged. When using charge equalization, the small capacity battery is not overcharged, and its actual charging capacity is smaller than the charging capacity of other batteries, and the power that can be released is less than the power that can be released by mild overcharging without equalizer, which makes the single battery discharge time shorter and the possibility of overcharging greater.
The use of lithium battery equalization technology can solve the mismatch problem and thus improve the performance of the series lithium battery pack. The mismatch problem can be corrected by equalizing the battery during the initial conditioning process, and then simply equalizing it during the charging process. Although the defect rate may be low for a lithium battery manufacturer, further quality assurance is necessary to avoid the problem of short battery life.
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