Lead-acid batteries have a history of more than 100 years, and they have generally followed the old ideas and operating procedures around the world: the charging and discharging rate is 0.1C (C is the battery capacity) and the life is longer. In order to solve the problem of fast charging, Mr. Max, an American, announced his research results to the world in 1967, charging the battery with a pulse current greater than 1C, and discharging the battery during intermittent charging. Discharge is beneficial to eliminate polarization, lower the temperature of the electrolyte, and improve the ability of the plate to accept electric charges.
Some scientific and technological workers in my country succeeded in producing fast chargers of various brands according to Mr. Max's three laws around 1969. The charging cycle process is: high current pulse charging→cutting off the charging path→short-term discharge of the battery→stop discharging→connecting the charging path→high current pulse charging...
Around 2000, some people applied this principle to electric vehicle chargers. During the charging process, the charging path was not cut off, and the battery was short-circuited with a small resistor for instantaneous discharge. Since the charging path is not cut off during a short circuit, an inductance is connected in series in the charging path. Generally, it is short-circuited within 1 second for 3-5 milliseconds (1 second=1000 milliseconds). Since the current in the inductor cannot jump, the short-circuit time is short, which can protect the power conversion part of the charger. If the direction of the charging current is called positive, the discharge will naturally become negative, and the term "negative pulse charger" appears in the electric vehicle industry, and it is said that it can extend battery life and so on.