What is the principle of the lithium battery module protection circuit board, and how to design the lithium battery pack protection circuit board? When charging a group of lithium batteries in series, ensure that each battery is charged equally, otherwise the performance and life of the entire battery will be affected during use. A single-cell lithium battery protection chip is used to design a battery pack protection board with multiple lithium batteries connected in series. In addition to the necessary over-voltage, under-voltage, over-current and short-circuit protection functions, it can also achieve balanced charging functions.
The reason for the lithium battery pack protection board:
The reason why the lithium battery pack needs protection is determined by 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 charge and discharge, the lithium battery lithium battery components will always appear with a delicate protection board and a current fuse.
The main functions of the lithium battery protection board:
The protection function of the lithium battery pack 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 charging of the cells at all times in the environment of -40°C to +85°C. Discharge the current of the loop, and control the on-off of the current loop in real time; PTC or TCO can prevent the battery from being badly damaged in a high temperature environment.
The lithium battery protection board requires Control (IC) to detect and control the voltage of the battery cells and the working current and voltage of the charging and discharging circuit at -25°C to 85°C. The circuit board is in normal working state, and when the cell voltage or the working current in the loop exceeds the preset value of the comparison circuit in the control IC, within 15-30ms (different control ICs and C-MOS have different response times), the The CMOS is turned off, that is, the discharge or charging circuit of the cell is closed to ensure the safety of the user and the cell.
Lithium battery pack protection board principle:
The lithium battery pack protection board is the charge and discharge protection for the series-connected lithium battery pack; when fully charged, it can ensure that the voltage difference between the individual cells is less than the set value (generally ±20mV), and realizes the equalization of each single cell in the battery pack. It can effectively improve the charging effect in the series charging mode; at the same time, detect the overvoltage, undervoltage, overcurrent, short circuit, and overtemperature status of each single cell in the battery pack to protect and prolong the service life of the lithium battery pack; undervoltage The protection enables each single cell to avoid damage to the battery due to overdischarge when it is discharged.
Ordinary lithium battery pack protection board usually includes control IC, MOS switch, resistor, capacitor and auxiliary devices FUSE, PTC, NTC, ID, memory, etc. Among them, the control IC controls the MOS switch to turn on when everything is normal, so that the battery cell and the external circuit are connected, and when the battery cell voltage or loop current exceeds the specified value, it immediately controls the MOS switch to turn off to protect the battery cell. Safety.
How to design the lithium battery pack protection board?
Most of the protection plates are placed in the battery box and the battery is very close, or even close. Therefore, such a high temperature will heat up the heat conduction battery. The problem is that high temperature is the mortal enemy of the battery. When choosing a lithium battery pack protection board, you must first calculate the continuous discharge current provided by the battery according to the actual power of your own motor. For battery assembly, it is necessary to pay attention to whether the self-discharge of the battery is balanced when connecting in series. In short, the smaller the internal resistance, the better when purchasing a lithium battery pack protection board. The lithium battery pack needs to control the maximum temperature when it is in use. It is best to keep the battery at the plateau voltage.