The UC3842 starting voltage of the 48V battery car charger is too low, which is to change the resistance value of 100 kilohm. Before charging, lithium batteries do not need special discharge, improper discharge will damage the battery. When charging, try to charge slowly, reduce the fast charging mode; No more than 24 hours. After three to five full charge and discharge cycles, the chemical substances inside the battery will be all \"activated\" to achieve good use results.
Starting low voltage is not necessarily caused by this resistor, if it does not change value do not change. It is most likely caused by 7-pin filter capacitor or diode leakage, or 3842 itself