Analyze the corresponding protection measures for lithium batteries

Lithium battery protection measures The lithium battery maintenance board is different in terms of IC, voltage, etc., but the circuit and parameters are different. The following is the DW01 description of the MOS tube 8205A: 1. The normal working process of the lithium battery maintenance board is as follows: When the battery voltage is between 2.5v and 4.3v, the first and third pins of DW01 both output high level (equal to the power supply). Voltage), the second pin voltage is 0V. At this time, add the first and third pin voltages of DW01 to the fifth and fourth pin voltages of 8205A. Since the G poles of the two electronic switches in the 8205A receive the voltage of DW01, they are in the on-off state, that is, both electronic switches are in the open state. At this time, the negative pole of the battery is directly connected to the p terminal of the repair board, and the repair board has a voltage output. 2. The principle of over-flow control of the maintenance board: the battery discharge voltage of the battery will gradually decrease when passing the external load, and the battery voltage of the DW01 will be monitored in real time through the resistor R1. When the battery voltage drops to 2.3V, DW01 will consider the battery voltage to discharge voltage. Then immediately disconnect pin 1 of the output voltage, and pin 10V. In 8205, one is closed by a 5-foot no-voltage switch tube. At this time, the B- of the unit is disconnected from the P- of the maintenance panel. In other words, the battery's discharge circuit is cut off, and the battery will stop discharging. The maintenance board is in an over-discharged state, and always adhere to. After comparing the charging voltage of P and P-indirect on the maintenance board, DW01 immediately stops the over-discharge state b-detected charging voltage, and outputs the high voltage at the first toe from the beginning, so the over-discharge control tube has been carried out for 8205 years That is to say, the battery's B-cell and P (maintenance board are connected from the beginning, the battery is directly charged by the charger. 3. The maintenance board overload working principle: when the battery charger is normal, the charging time is added, The battery voltage will get higher and higher. When the battery voltage rises to 4.4V, DW01 will consider the battery voltage to charge the voltage, and then immediately disconnect the output voltage of 3 feet to make the voltage of 3 feet 0V. In 8205, a voltage of 4 feet is no voltage. The switch tube is closed. At this time, the B- of the unit is disconnected from the P- of the maintenance panel. That is to say, the charging circuit of the battery is cut off, and the battery will stop charging. The maintenance committee charges too high, always insist. Ratio and P , After the P-indirect maintenance board discharges the load, so although the charge control switch tube is turned off, its internal diode has the same forward direction and the discharge circuit in the same direction, so the discharge circuit discharges. When the battery voltage input is less than 4.3V, DW01 suspends the charging condition from At the beginning, the output voltage of 3 feet high makes the charging control tube 8205 conduct, and the BP- of the battery is connected to the maintenance board again, and the battery can be charged and discharged normally. 4. The working principle of the maintenance board is short-circuited maintenance:, see the external discharge of the maintenance board In the process, the two electronic switches in 8205 are not completely equivalent to mechanical switches, but they are equivalent to two small resistances, and the on-resistance of each switch of 8205 is about 30m\U03a9, a total of about 60m\ U03a9, the voltage added to G and the on-resistance of each switch that is actually directly operated invades V. When the voltage is greater than 1G, the on-resistance of the switch is very small (a few milliohms), which is equivalent to opening and closing, when G is at the voltage Less than 0.7V, the on-resistance of the switch tube is very large (several meters), which is equivalent to a switch. The voltage UA is the voltage that appears from the conductive internal resistance of 8205A and the discharge current. When the load current increases, UA must increase, because ua0 .006l? IUA, also known as 8205A tube voltage drop, can simply indicate the size of the discharge current. When the voltage rises to 0.2v, the load current is considered to have reached the limit value, so the first pin of the output voltage stops, so the first pin A pin becomes 0v voltage and the discharge control tube is closed in 8205, the battery's discharge circuit is cut off, and the discharge control tube is closed. In other words, the maximum allowable output current of DW01 is 3.3a, which completes over-current maintenance. 5. Short-circuit maintenance and control process: short-circuit maintenance is an extreme form of current maintenance, and its control process and principle are the same as over-current maintenance, short-circuit is equivalent to PP-plus a small value between resistance (about 0) to maintain the board load The current reaches more than 10 instantaneously, and the board of directors is maintained immediately. 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