The method is as follows: the 6 volt battery is connected to the full bridge < Prevent misconnection reverse polarity damage to the charger > At lm7805, the voltage is stabilized to 5 V < The voltage of the low-voltage output of the ordinary charger switching power supply is 5 V > , at the low voltage input terminal connected to the charger. The high voltage end is empty, only the protection after the low voltage end and the blanking circuit are used. This modification requires a certain amount of hands-on ability, and the use effect of this is similar to the charging effect of the original charger.