NOVELTY - Lithium ion battery pack charging system (100) comprises lithium ion battery pack (150) with several lithium ion cells (155) connected in series and in electrical communication with positive and negative terminals (157, 158), and comprising anode (154), cathode (156), and electrolyte composition which comprises redox shuttle and lithium salt at least partially dissolved in solvent; charger (120) being capable of charging battery pack at first and second charge rate; and charger controller capable of monitoring voltage difference between positive and negative terminals.    USE - As lithium ion battery pack charging system (claimed) for lithium ion battery packs in electric vehicle and/or hybrid electric vehicles.    ADVANTAGE - The lithium ion battery pack charging system eliminates the need for supervisory circuitry presently included in lithium ion battery packs to monitor individual cell voltage; and especially useful for charging lithium ion battery packs having unbalanced lithium ion cells.    DETAILED DESCRIPTION - Lithium ion battery pack charging system comprises lithium ion battery pack having positive and negative terminals, with several lithium ion cells connected in series and in electrical communication with positive and negative terminals, each of the lithium ion cells comprising anode, cathode, and electrolyte composition which has redox shuttle and lithium salt at least partially dissolved in solvent; charger in electrical communication with positive and negative terminals, being capable of charging the battery pack at at least first charge rate and second charge rate which is greater than zero and less than first charge rate; and charger controller in electrical communication with charger, and capable of monitoring voltage difference between positive and negative terminals, calculating rate of change of voltage difference, and depending at least in part on at least one of the voltage difference or rate of change of voltage difference, changing first charge rate to second charge rate.    DESCRIPTION OF DRAWING(S) - The figure shows block diagram of lithium ion battery pack charging system.    Lithium ion battery pack charging system (100)    Charger (120)    Lithium ion battery pack (150)    Anode (154)    Lithium ion cell (155)    Cathode (156)    Positive terminal (157)    Negative terminal (158)