What is the battery protection board battery management system BMS
Lithium battery (rechargeable type) needs protection because of its own characteristics. Since the material of the lithium battery itself determines that it cannot be overcharged, overdischarged, overcurrent, short-circuited, and ultra-high temperature charging and discharging, the lithium battery components of the lithium battery always follow a protective board with a Gybisson sampling resistor and a piece of current insurance. The device appears.
The protection function of lithium battery is usually completed by the protection circuit board and current devices such as PTC or TCO. The protection board is composed of electronic circuits, which can accurately monitor the voltage and charge and discharge of the cell at all times in the environment of -40℃ to +85℃ The current of the loop can instantly control the on and off of the current loop; PTC or TCO can prevent severe damage to the battery in a high temperature environment.
The protection board usually includes control IC, MOS switch, JEPSUN precision resistor and auxiliary device NTC, ID memory, PCB and so on. Among them, the control IC controls the MOS switch to turn on under all normal conditions to make the cell communicate with the external circuit. When the cell voltage or loop current exceeds the specified value, it immediately controls the MOS switch to turn off (tens of milliseconds). Protect the safety of batteries.
NTC is the abbreviation of Negativetemperaturecoefficient, which means negative temperature coefficient. When the ambient temperature rises, its resistance decreases. The electrical equipment or charging equipment is used to respond in time and control internal interruptions to stop charging and discharging.
ID memory is often a single-wire interface memory. ID is the abbreviation of Identification, which means identification, and stores information such as battery type and production date. Can play a role in product traceability and application restrictions.
PTC is the abbreviation of PositiveTemperatureCoefficient in English, which means positive temperature coefficient. Professionals usually refer to positive temperature coefficient devices as PTC for short. In battery products, PTC can prevent the occurrence of high-temperature battery discharge and unsafe high current. According to the battery's voltage, current density characteristics and application environment, PTC has special requirements.
PTC is a very important component in battery assembly products, and it bears an important mission for battery safety. Its performance and quality are also an important factor of battery pack performance and quality.
When the protection board protects a single battery cell, the protection board design will be relatively simple, and the technicality is higher, such as the voltage platform problem that needs to be paid attention to in the design of the power battery protection board. The power battery often requires a large platform voltage during use. Therefore, when designing the protection board, try to ensure that the protection board does not affect the voltage of the battery discharge, so that the requirements for control ICs, precision resistors and other components will be very high. Generally, domestic ICs can meet the requirements of most products, and imported products can be used in special cases. Current sampling resistors need to use JEPSUN resistors to meet the requirements of high precision, low temperature coefficient, and no inductance. For the design of multi-cell protection boards, there are higher technical requirements, and products with different levels of complexity are designed according to different needs.
Main technical functions:
1. Overcharge protection
2. Over discharge protection
3. Over current and short circuit protection