A lithium ion power battery lossless charger adopts a charging method of overall serial constant-current and monomer parallel constant-voltage to realize lossless charging on lithium ion power batteries. Charging efficiency is close to 100%, and charging and discharging are completely based on the characteristic curve of the battery. All functions of a battery system, a charging system, a discharging system and a maintenance management system are realized only by a simple circuit, and no overcharge, overheating, over discharge, over current or short circuit occurs. The terminal voltages of all monomer batteries are completely equal when charging is finished, and no equalized charging is required.