Analysis of the use of lithium battery protection board

The circuit and parameters of the lithium battery protection board are different depending on the IC, voltage, etc., the following is an explanation with DW01 with MOS tube 8205A: 1. The normal working process of the lithium battery protection board is: when the battery cell voltage is between 2.5V and 4.3 When between V, the first pin and the third pin of DW01 both output high level (equal to the supply voltage), and the second pin voltage is 0V. At this time, the voltage of pin 1 and pin 3 of DW01 will be applied to pins 5 and 4 of 8205A respectively. The two electronic switches in 8205A are in the conducting state because their G poles are connected to the voltage from DW01, that is Both electronic switches are in the open state. At this time, the negative pole of the battery and the P- terminal of the protection board are equivalent to a straight connection, and the protection board has a voltage output. 2. Protection board over-discharge protection control principle: When the battery cell is discharged through an external load, the voltage of the battery cell will slowly decrease, and at the same time, the internal DW01 will monitor the cell voltage through the R1 resistance in real time. When the cell voltage drops to about At 2.3V, DW01 will think that the cell voltage is already in the over-discharge voltage state, and immediately disconnect the output voltage of pin 1, so that the voltage of pin 1 becomes 0V, and the switch tube in 8205A is closed because there is no voltage on pin 5. At this time, the B- of the battery cell and the P- of the protection board are in a disconnected state. That is, the discharge circuit of the battery cell is cut off, and the battery cell will stop discharging. The protection board is in an over-discharged state and has been maintained. After the P and P- of the protection board are indirectly charged with the charging voltage, DW01 will immediately stop the over-discharge state after the B- test the charging voltage, and output a high voltage at pin 1 again to turn on the over-discharge control tube in the 8205A. That is, the B- of the battery cell and the P- of the protection board are reconnected, and the battery is charged straight through the charger. 3. Lithium battery protection board overcharge protection control principle: When the battery is normally charged by the charger, as the charging time increases, the voltage of the battery cell will become higher and higher. When the battery cell voltage rises to 4.4V, DW01 will think that the cell voltage is already in the overcharge voltage state, and immediately disconnect the output voltage of pin 3, so that the voltage of pin 3 becomes 0V, and the switch tube in 8205A is closed because there is no voltage on pin 4. At this time, the B- of the battery cell and the P- of the protection board are in a disconnected state. That is, the charging circuit of the battery cell is cut off, and the battery cell will stop charging. The protection board is in an overcharged state and has been maintained. After the P and P- of the protection board discharge the load indirectly, although the overcharge control switch tube is closed, the forward direction of the diode inside is the same as the direction of the discharge circuit, so the discharge circuit can be discharged. When the voltage of the battery cell When it is placed below 4.3V, DW01 stops the overcharge protection state and outputs a high voltage at pin 3 again, so that the overcharge control tube in 8205A is turned on, that is, the B- of the battery and the protection board P- are reconnected , The battery cell can be charged and discharged normally. 4. Short-circuit protection control process: Short-circuit protection is a limit form of over-current protection. Its control process and principle are the same as over-current protection. The short-circuit is only equivalent to adding a small resistance between PP- (approximately 0) Make the load current of the protection board reach more than 10A instantaneously, and the protection board will immediately perform overcurrent protection. The purpose of the lithium battery protection board is to guard against overcharge or overdischarge of the lithium battery for corresponding protection purposes. There is a protection board to protect the battery itself. If not, the lithium battery itself is easily damaged, and the second is a safety hazard. This is no joke. Of course, the protection board is not used, because the internal resistance is small, the use time may be a little longer, and the price is cheaper, but I personally think that safety is the first thing. Disclaimer: Some pictures and content of articles published on this site are from the Internet. If there is any infringement, please contact to delete. Previous: How to extend the service life of UPS maintenance-free batteries?