The principle of lithium battery protection board and the wiring method of lithium battery protection board. Lithium battery protection board, as the name suggests, is used to protect lithium batteries. The function of the lithium battery protection board is to protect the battery from discharge, charge, and current, as well as output short-circuit protection. There are two design methods for lithium battery protection plates, namely positive plate and negative plate. The principle and purpose are the same, but the device does not support modifying the settings of the positive and negative protective plates through software.

　　Introduction to the principle of lithium battery protection board

　　The reason why lithium battery (rechargeable type) 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, or charged and discharged at ultra-high temperatures, lithium battery components always appear with a delicate protective board and a current fuse.

　　The lithium battery protection board is to protect the charge and discharge of the series-connected lithium battery pack; when fully charged, it can ensure that the voltage difference between each single cell is less than the set value (generally ±20mV), achieving even charging of each single cell in the battery pack. , effectively improves the charging effect in series charging mode; simultaneously detects the overvoltage, undervoltage, overcurrent, short circuit, and overtemperature status of each single cell in the battery pack to protect and extend the service life of the battery; undervoltage protection enables each When a single battery is discharged, it can prevent the battery from being damaged due to over-discharge.

　　The protection function of lithium batteries is usually completed by a protection circuit board and current devices such as PTC. The protection board is composed of electronic circuits and can accurately monitor the voltage and charge return circuit of the battery core at all times in an environment of -40°C to +85°C. Current, timely control the on and off of the current loop; PTC prevents severe damage to the battery in high temperature environments.

　　Ordinary lithium battery protection boards usually include control IC, MOS switches, resistors, capacitors 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 core is connected to the external circuit. When the battery core voltage or loop current exceeds the specified value, it immediately controls the MOS switch to turn off to protect the battery core. Safety.

　　When the lithium battery protection board is normal, Vdd is high level, Vss and VM are low level, DO and CO are high level. When any parameter of Vdd, Vss and VM changes, the voltage of DO or CO terminal Ping will change.

　　1. Overcharge detection voltage: Under normal conditions, Vdd gradually increases to the voltage between VDD and VSS when the CO terminal changes from high level to low level.

　　2. Overcharge release voltage: In the charging state, Vdd gradually decreases to the voltage between VDD and VSS when the CO terminal changes from low level to high level.

　　3. Over-discharge detection voltage: Under normal conditions, Vdd gradually decreases to the voltage between VDD-VSS when the DO terminal changes from high level to low level.

　　4. Over-discharge release voltage: In the over-discharge state, Vdd gradually rises to the voltage between VDD-VSS when the DO terminal changes from low level to high level.

　　5. Overcurrent 1 detection voltage: Under normal conditions, VM gradually rises to the voltage between VM and VSS when DO changes from high level to low level.

　　6. Overcurrent 2 detection voltage: Under normal conditions, VM rises from OV at a speed of more than 1ms and less than 4ms to the voltage between VM and VSS when the DO terminal changes from high level to low level.

　　Lithium battery protection board wiring method

　　The connection methods of lithium battery protection boards are generally three types of commonly used protection boards: negative pole same-port plate, negative pole split-port plate, and positive pole same-port plate. The other methods will not be described one by one. During the process, there are many connection methods when testing the lithium battery protection board on non-standard battery equipment. It is also worth getting familiar with the test connection. The simple process is as follows:

　　1. Place the device on a relatively horizontal table and adjust the stability of the device to make it stable;

　　2. Ensure that the humidity of the environment in which the equipment is used is within the range of 30~50%. If the humidity is too high, it is easy to cause leakage of the chassis and electric shock accidents;

　　3. Connect to the appropriate power supply (AC220V/0.1A), turn on the power button of the main device, and turn on the respective power module buttons.

　　4. Check whether the device can display and test normally.

　　In fact, the wiring methods of each lithium battery protection board are different depending on the number of series, and the wiring methods of the same port and separate ports are also different. If you want to be precise about each product, please check the protection board details page, but the overall wiring remains unchanged. Wiring sequence: When assembling the wiring, correctly weld the flex cable to the battery core, connect B- of the PCM to the total negative pole of the battery core, and then insert the flex cable into the pin holder on the PCM.

　　As the country vigorously develops new energy, many companies use lithium batteries to replace the original lead-acid batteries, nickel-metal hydride batteries, etc. Due to the activity of lithium ions, protective plates must be added when using lithium batteries to prevent overcharging of lithium batteries. Let go of the flow.

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