What are the classifications of resistance? How to see the resistance value?

　　Lithium batteries are very common products. They are completely different from lead-acid batteries that do not require electronic protection. Even lithium iron phosphate batteries with high safety performance contain BMS or PCM. And these circuit boards must have many electronic components, among which resistance is a very basic but important passive component.

　　Resistor is a passive electronic component that can hinder the flow of electronic current. Have you seen an LED that is lit? With resistance, it can shine brightly instead of being burned. The unit of resistance is Ohm (Ω), which conforms to Ohm's law in the circuit.

　　The international symbol of resistance is a rectangular square, but the standard symbol of the United States is a wavy line.

　　Type of resistance

　　From the structure, there are fixed resistors and variable resistors.

　　The basic parameters of fixed resistance are resistance and tolerance. Tolerance refers to changes caused by changes in factors such as temperature and light.

　　Variable resistors include variable resistors and physical quantity resistance sensors. Variable resistors include adjustable potentiometers and sliding rheostats. Physical quantity resistance sensors include thermal sensors, photosensitive sensors, pressure sensitive sensors and magnetic sensors.

　　From the manufacturing materials, including carbon resistors, carbon film resistors, metal film resistors, thick film resistors, foil resistors, wire-wound resistors.

　　Carbon resistors are relatively old structures. The accuracy is low, and it is usually used where high-energy pulses are generated.

　　Wire wound resistors are the oldest structure. The resistance is accurate and is usually used in high power applications. The small resistance is still very reliable.

　　Nowadays, metal and metal oxide resistors are used more frequently. The resistance value and tolerance are relatively stable, and the temperature coefficient is relatively good.

　　How to use resistors?

　　Usually, resistors are used for voltage division, heat generation, impedance matching, in the circuit as a load, gain control, delay, and even as an energy discharge resistor for an electric controller in a train.

　　Typical applications are:

　　1) Measure circuit current according to Ohm's law;

　　2) Drive LED;

　　3) In the automobile ventilation system, drive the blower motor.

　　Representation of resistance value

　　There are usually two methods, one is the color code method, and the other is the numerical notation (SMD Codes).

　　The color ring resistance usually has 3 to 6 color rings. The four-color circle and the five-color circle are usually used more frequently. The first two color circles represent the resistance value of the resistance value, the third bar usually represents the exponential factor, and the fourth bar represents the resistance tolerance.

　　The above is an example of SMD Codes.

　　Lithium-ion battery (LIB) has become the main energy storage solution in modern social life. Among them, lithium iron phosphate battery is a perfect replacement for lead-acid batteries, and it is the first choice for grid-connected peak shaving, off-grid energy storage, photovoltaic energy storage, UPS, data center and other industries.