▎ 摘　　要

NOVELTY - A battery group comprises at least a type of battery cell (C1) and a type of battery cell (C2) electroconnected in series. The type of cells (C1) comprise N' cells. The type of cells (C2) comprises M' cells, where N' and M' are positive integers. When the discharge battery balance rate of the cell (C1) is CB1, and the discharge battery balance rate of the cell (C2) is CB2, the discharge battery balance rates (CB1) and (CB2) satisfy a relation of: 0.5≤ CB1≤ CB2≤ 1.4. Ehen the charging of the battery pack reaches the range of 95%-100% state of charge, the open-circuit voltage change rate corresponding to the cell (C1) is 0.005V/%SOC or less and the open-circuit voltage change rate corresponding to the second type of battery cell is greater than the open-circuit voltage change rate corresponding to the battery cell (C1). USE - Battery group used in battery pack used as power source of electric device or energy storage unit (all claimed). ADVANTAGE - The charge state of the battery pack is taken at this time as the state of filling electricity, so as to prevent accumulated error of ampere-hour integration method, improve SOC prediction precision of the whole battery pack, and the capacity of the high-end area (namely high SOC area) is not released, so that the working electric core can adopt small discharge battery balance rate (CB value) to design, to realize the service life (capacity) compensation and save the negative electrode of the graphite, can further improve the energy density of battery pack. DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for the following: battery pack; electric device; manufacture of battery group; manufacturing device for battery group; and control method for battery group. DESCRIPTION OF DRAWING(S) - The drawing shows a schematic view of the battery cell. 5Cells