Connect the (red) positive pole (+) of the charger to the positive pole (+) of the battery; The negative electrode (black line) (-) is connected with the negative electrode (-) of the battery. After charging the manual charger, adjust the charging voltage to 12V or 24V, and then adjust the charging current to 3 ~ 5. Observe that the charging current is 4 ~ 6 A (24V the current of 24 V battery is 5 ~ 10A), and then the automatic green light is on, and it is fully charged.