3.7 volt battery 18650

　　3.7 volt battery 18650 balanced charging management power supply design

　　Multiple 3.7 volt battery 18650 charging and discharging experiments have shown that this balanced charge management circuit can effectively improve the consistency of battery pack charging, improve the battery pack's working performance, and extend its service life.

　　In order to solve the consistency problem in the use of power 3.7 volt battery 18650s, this article proposes an implementation plan for a balanced charging management circuit. First, the characteristics of a single lithium battery are analyzed; then, based on comparing various balanced charging theories, the partial shunt method is selected as the design idea and the specific circuit design is carried out. Multiple 3.7 volt battery 18650 charging and discharging experiments have shown that this balanced charge management circuit can effectively improve the consistency of battery pack charging, improve the battery pack's working performance, and extend its service life.

　　As international crude oil prices soar, research on various new energy sources has become the focus of public attention. Electric energy has been widely used as a power source in various vehicles. Lithium batteries have become the first choice for power electric energy due to their high energy-to-mass ratio and energy-to-volume ratio, no memory effect, many recharges, and long service life.

　　As a new power technology, lithium batteries must be connected in series to meet the voltage requirements. The uneven performance of individual cells is not entirely due to technical problems in battery production. Even if each battery leaves the factory with exactly the same voltage and internal resistance, After being used for a period of time, differences will also occur, which makes solving the technical problem of power battery charging an urgent technical issue that needs to be solved. Based on full consideration of industrial cost control and stability requirements, this design uses an energy-consuming partial shunt method to balance the charging of power lithium batteries, which improves the imbalance of battery pack charging and improves working performance.

　　3.7 volt battery 18650 charging solution selection

　　1. Charging requirements for single-cell lithium battery

　　The charging requirements for single-cell lithium-ion batteries (GB/T18287-2000) are first constant current charging, that is, the current is constant, and the battery voltage gradually increases with the charging process. When the battery terminal voltage reaches 4.2V (4.1V), change Constant current charging is constant voltage charging, that is, the voltage is constant, and the current gradually decreases as the charging process continues according to the saturation degree of the battery. When it decreases to 10mA, the charging is considered to be terminated. The charging curve is shown in Figure 1.

　　2. Charging characteristics of 3.7 volt battery 18650

　　In the power battery pack, there are inconsistencies between individual cells. The differences caused by continuous charge and discharge cycles will accelerate the capacity decay of some single cells. The capacity of the series battery pack is determined by the minimum capacity of the single cell, so these differences will shorten the service life of the battery pack. The main reasons for this imbalance are:

　　●During the battery manufacturing process, due to process and other reasons, there are differences in capacity, internal resistance, etc. of batteries in the same batch;

　　●Differences in battery self-discharge rates, accumulated over a long period of time, result in differences in battery capacity;

　　●During battery use, differences in usage environment such as temperature and circuit boards lead to imbalance in battery capacity.

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