NOVELTY - The system has a first battery pack (100) comprising multiple first battery cells being lithium-ion battery cells. The first battery pack and second battery pack (200) are connected in parallel with an alternator (300) for charging and discharging of the first and second battery packs. The negative electrode of each of the lithium-ion battery cells comprises a carbon-based material excluding graphite and has an interlayer spacing along a plane labeled by the miller indices in the range of 0.34 nm to 0.5 nm in X-ray measurements.    USE - Battery system for use in vehicle (all claimed).    ADVANTAGE - The multi battery pack is charged with the power other than the power required for the load, thus the charging speed of the first battery pack is faster than a charging speed of the second battery pack. Since the interlayer spacing satisfies the range, lithium ion is easily inserted and separated with ease. Hence the excellent high-rate charging/discharging characteristic is achieved. Since the soft carbon has disordered crystal compared to the graphite, the soft carbon includes many gates that help entry and exit of ion and ion is easily dispersed. Since the concentration of the lithium salt is included in the range, the electrolyte has a proper conductivity and viscosity so that excellent electrolyte performance is achieved and lithium ion is effectively moved. The soft carbon is that the automatic arrangement easily forms a layered structure, thus the soft carbon is easily changed to a graphite structure according to an increase of a heat treatment temperature. Since the surface area of the carbon material is included such a range, an activation site of the positive electrode active material is increased. Thus high input output is simply achieved, and excellent high-rate cycle-life of the lithium secondary battery is acquired.    DETAILED DESCRIPTION - An INDEPENDENT CLAIM is included for a method for operating a vehicle.    DESCRIPTION OF DRAWING(S) - The drawing shows a block diagram illustrating the vehicle battery system provided with a multi battery pack.    Multi battery pac (10)    First battery pack (100)    Second battery pack (200)    Alternator (300)    Load (400)