What are the corresponding protection measures for lithium batteries

1. The normal working process of the lithium battery maintenance board is: when the battery cell voltage is between 2.5V and 4.3V, the first and third pins of DW01 both output high level (equal to the supply voltage), and the second pin voltage It is 0V. At this moment, the voltage of pin 1 and pin 3 of DW01 will be separately applied to pins 5 and 4 of 8205A. The two electronic switches in 8205A are connected to the voltage from DW01 due to their G poles. All electronic switches are in the on state. At this moment, the negative pole of the battery and the P- terminal of the maintenance board are equivalent to a straight connection, and the maintenance board has a voltage output. 2. Over-discharge maintenance operation principle of the maintenance board: When the battery cell is discharged through an external load, the voltage of the battery cell will gradually drop. At the same time, the internal DW01 will monitor the cell voltage through the R1 resistor in real time. When the cell voltage drops to about 2.3 At V, DW01 will think that the cell voltage is already in the over-discharge voltage condition, and will immediately cut off 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 moment, the B- of the battery cell and the P- of the maintenance 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 maintenance board is in an over-discharge condition and always insists on it. After comparing the P and P-indirect charging voltages of the maintenance board, the DW01 will immediately stop the over-discharge condition after the B- test the charging voltage, and output a high voltage at pin 1 from the beginning to turn on the over-discharge control tube in the 8205A , That is, the B- of the battery core and the P- of the maintenance board are connected again, and the battery is charged directly by the charger. 3. Maintenance board overcharge maintenance operation 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, the DW01 will Thinking that the cell voltage is already in the overcharge voltage condition, immediately disconnect the output voltage of pin 3, so that the voltage of pin 3 becomes 0V, and the switch tube in 8205A is turned off because there is no voltage on pin 4. At this moment, the B- of the battery cell and the P- of the maintenance 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 maintenance board is in an overcharged condition and has always insisted on it. Compared with the P and P of the maintenance board, after the load is discharged indirectly, even though the overcharge control switch tube is turned off, the forward direction of the internal diode is the same as the direction of the discharge circuit, so the discharge circuit can discharge. When the voltage is lower than 4.3V, the DW01 stops the overcharge maintenance status and outputs a high voltage at pin 3 from the beginning to turn on the overcharge control tube in the 8205A, that is, the battery core B- and the maintenance board P- are connected again On, the battery cell can perform normal charging and discharging again. 4. Maintenance operation principle of maintenance board short-circuit maintenance: As shown in the figure, in the process of external discharge of the maintenance board, the two electronic switches in 8205A are not completely equivalent to two mechanical switches, but are equivalent to two resistances. The small resistance is called the conduction internal resistance of 8205A. The conduction internal resistance of each switch is about 30m\U03a9 and a total of about 60m\U03a9. The voltage applied to the G pole is actually to directly control each switch tube When the voltage of the G pole is greater than 1V, the internal resistance of the switch tube is very small (tens of milliohms), which is equivalent to the switch closed. When the voltage of the G pole is less than 0.7V, the switch tube is turned on. The internal resistance is very large (several M), which is equivalent to the switch off. The voltage UA is the voltage appearing between the on-resistance of 8205A and the discharge current. When the load current increases, UA will inevitably increase. Because UA0.006L? IUA is also known as the tube voltage drop of 8205A, UA can be simply connected to indicate the discharge current. big and small. When it rises to 0.2V, it is assumed that the load current has reached the limit value, so the output voltage of pin 1 is stopped, the voltage of pin 1 becomes 0V, the discharge control tube in 8205A is closed, and the discharge circuit of the cell is cut off, and it will be turned off. Discharge control tube. In other words, the maximum current that DW01 promises to output is 3.3A, which completes the over-current maintenance. 5. Short-circuit maintenance control process: Short-circuit maintenance is a limit form of over-current maintenance. Its control process and principle are the same as over-current maintenance. The short-circuit is only equivalent to adding a small resistance between PP- (approximately 0) Make the load current of the maintenance board reach more than 10A instantaneously, and the maintenance board will perform over-current maintenance immediately. Disclaimer: Some pictures and content of the articles published on this site are from the Internet. If there is any infringement, please contact to delete.