Design of self-repairing circuit for Ni-Cd Ni-MH batteries

This circuit automatically repairs the battery. When in use, connect the power supply VCC to the +12V of the switching power supply, and connect points A and B to the positive and negative poles of the battery respectively (you can use a special battery box, or you can make your own battery box to connect the battery to the circuit). After powering on, let the circuit automatically work intermittently to perform a large current intermittent "impact" on the battery, and gradually activate the "dormant" battery. If the original battery cannot be charged during normal charging, when LED1 flashes, the battery is basically activated; if there is a short circuit inside the original battery, after a suitable period of large current impact, when LED2 flashes, the battery basically returns to normal. Since the large current "impact" time is short (this circuit is designed to be about 200ms) and the intermittent time is long enough (about 10s), the battery will not heat up or be damaged. The circuit consists of an LM555 integrated circuit and R1, R2, D1, and C2 to form a multivibrator. The LM555's pin ③ outputs a periodic pulse signal with a narrow high level (about 200ms) and a wide low level (about 10s). This periodic pulse signal controls the on and off of Q1. When the signal is high, Q1 is turned on and the 12V power supply voltage is added to the battery. Due to the high voltage, the battery is "shocked" with high voltage and high current in a short time; when the signal is low, Q1 is cut off and the circuit does not power the battery. At this time, Q1 and the battery dissipate heat. When C2 is fixed, adjusting R1 can adjust the width T1 of the high level output of the LM555's (3) pin, that is, the time for the large current to "shock" the battery. T1≈0.693xR1xC2; adjusting R2 can control the width T2 of the low level output of the LM555's pin ③ to ensure that Q1 and the battery will not overheat. T2≈0.693xR2xC2. Q1 in the circuit should use a transistor with a high current and high magnification of more than 20A (this circuit uses the disassembled Darlington transistor MJ11032). In this circuit, since the conduction time of Q1 (0.2 seconds) is extremely short compared to the cut-off time (10 seconds), there is no need to add a heat sink for Q1. Vcc is connected to the +12V of the switching power supply of the scrapped computer. The switching power supply has the functions of large current and overcurrent protection, which is suitable for the operation of this circuit. R3 and R6 need to use power resistors. The unit of resistance in the figure is kΩ. The unit of capacitance is μF, and the withstand voltage of the electrolytic capacitor is 35V.