12V 200Ah 26650 32700 Lithium Iron Phosphate Energy Storage Battery Pack

Lithium-ion battery charging circuit design

According to the structural characteristics of lithium-ion batteries, the maximum charging termination voltage should be 4.2V, which cannot be overcharged, otherwise the battery will be scrapped due to too much lithium ion on the positive electrode. It has high charging and discharging requirements, and can be charged with a special constant current and constant voltage charger. Usually, after the constant current is charged to 4.2V/section, it is transferred to constant voltage charging, and the charging should be stopped when the constant voltage charging current drops to less than 100mA. Battery capacity (such as a 1350mAh battery, its charging current can be controlled between 135~2025mA). The conventional charging current can be selected at about 0.5 times the battery capacity, and the charging time is about 2~3 hours.

Due to the internal structure of the lithium-ion battery, the lithium ions cannot all move to the positive electrode during discharge, and a part of the lithium ions must be retained at the negative electrode to ensure that the lithium ions can be smoothly embedded in the channel during the next charge. Otherwise, the battery life is shortened accordingly. In order to ensure that some lithium ions remain after discharge in the graphite layer, the minimum voltage at the end of discharge must be strictly limited, that is, the lithium-ion battery cannot be over-discharged. The discharge termination voltage is usually 3.0V/cell, and the minimum voltage should not be lower than 2.5V/cell. The length of battery discharge time is related to the capacity of the battery and the size of the discharge current.

The principle of the lithium-ion battery charging circuit

Principle: Charge the battery at a constant voltage to ensure that it will not be overcharged. The input DC voltage is 3 volts higher than the voltage of the charged battery. R1, Q1, W1 and TL431 form a precision adjustable voltage regulator circuit, Q2, W2 and R2 form an adjustable constant current circuit, and Q3, R3, R4, R5 and LED are charging indication circuits. As the voltage of the charged lithium-ion battery rises, the charging current will gradually decrease, and the voltage drop on the R4 will decrease when the battery is fully charged, so that Q3 will be cut off, and the LED will be off, in order to ensure that the battery can be sufficient, please continue to charge for 12 hours after the indicator light is off. When using, please install a suitable radiator for Q2 and Q3.

Everwin Tech Co., Limited was established in 2009 and is a professional battery manufacturer specializing in reserach design and producing power solutions for all kinds of market . EWT Battery provide ODM, OEM battery solutions for medical, solar lighting, smart metering  low speed vehicle and solar power storage system for customers all over the world.

Our products are widely used in various fields such as electric bicycles, electric motorcycles, electric scooters, electric forklifts, outdoor and home energy storage, electric tools, wireless vacuum cleaners, smart homes, security, medical and other fields. We provide a full range of intelligent manufacturing and services, including project evaluation, scheme design, battery pack structure design,  battery pack production, as well as product inspection and after-sales service, aiming to efficiently provide customers with the most competitive lithium battery solutions.