Lead acid batteries have a history of over 100 years and have begun to follow the old beliefs and operating procedures worldwide: a charging and discharging rate of 0.1C (C is the battery capacity) with a longer lifespan. Mr. Max, an American, announced his research results to the world in 1967 to solve the problem of fast charging. He charged the battery with a pulse current greater than 1C, and discharged it intermittently during charging. Discharge is beneficial for eliminating polarization, reducing electrolyte temperature, and improving the ability of the electrode to accept charges.

Some scientific and technological workers in our country successfully produced various brands of fast chargers around 1969 based on Mr. Max's three laws. The charging cycle process is: high current pulse charging → cutting off the charging path → briefly discharging the battery → stopping discharging → connecting the charging path → high current pulse charging

Around 2000, some people applied this principle to electric vehicle chargers. During the charging process, without cutting off the charging path, a small resistor was used to short-circuit the battery and discharge it instantly. Due to not cutting off the charging path during a short circuit, an inductor is connected in series in the charging path. Generally, a short circuit occurs within 1 second for 3-5 milliseconds (1 second=1000 milliseconds). As the current in the inductor cannot jump, the short circuit time can protect the power conversion part of the charger. If the charging current direction is called positive, the discharge naturally becomes negative, and the electric vehicle industry has the term "negative pulse charger", which claims to extend battery life and so on.