A system comprising: a variety of battery packs having different electrical characteristics, wherein each battery pack includes a battery block and a memory, wherein the battery block includes at least one battery cell, and the memory stores battery information, wherein the battery information includes a battery block lower limit voltage (VLb) and/or a battery cell lower limit voltage (VLc), wherein the battery block lower limit voltage (VLb) is a value set for each model of the battery block, wherein the model of a battery block is set in accordance with a battery characteristics of the battery cells and a quantity of the battery cells, and wherein the battery cell lower limit voltage (VLc) is set in accordance with a model of the battery cells; and a charging device configured to charge each of the variety of different battery packs, wherein the charging device is configured to determine over-discharging of one battery pack of the variety of battery packs when the one battery pack is attached to the charging device by (a) reading the battery block lower limit voltage (VLb) from the memory of the attached battery pack, and by measuring an inter-terminal voltage (Vmb) of the battery block or an inter-terminal voltage (Vmc) of each battery cell, and by determining whether or not the attached battery pack is over-discharged based on the battery block lower limit voltage (VLb) and the measured inter-terminal voltage (Vmb) of the battery block, and/or by (b) reading the battery cell lower limit voltage (VLc) from the memory of the attached battery pack and determining whether or not the attached battery pack is over-discharged based on the battery cell lower limit voltage (VLc) and the measured internal-terminal voltage (Vmc) of each battery cell, wherein the charging device is further configured to prohibit charging of the one battery pack, when the one battery pack attached to the charging device is over-discharged. a variety of battery packs having different electrical characteristics, wherein each battery pack includes a battery block and a memory, wherein the battery block includes at least one battery cell, and the memory stores battery information, wherein the battery information includes a battery block lower limit voltage (VLb) and/or a battery cell lower limit voltage (VLc), wherein the battery block lower limit voltage (VLb) is a value set for each model of the battery block, wherein the model of a battery block is set in accordance with a battery characteristics of the battery cells and a quantity of the battery cells, and wherein the battery cell lower limit voltage (VLc) is set in accordance with a model of the battery cells; and a charging device configured to charge each of the variety of different battery packs, wherein the charging device is configured to determine over-discharging of one battery pack of the variety of battery packs when the one battery pack is attached to the charging device by (a) reading the battery block lower limit voltage (VLb) from the memory of the attached battery pack, and by measuring an inter-terminal voltage (Vmb) of the battery block or an inter-terminal voltage (Vmc) of each battery cell, and by determining whether or not the attached battery pack is over-discharged based on the battery block lower limit voltage (VLb) and the measured inter-terminal voltage (Vmb) of the battery block, and/or by (b) reading the battery cell lower limit voltage (VLc) from the memory of the attached battery pack and determining whether or not the attached battery pack is over-discharged based on the battery cell lower limit voltage (VLc) and the measured internal-terminal voltage (Vmc) of each battery cell, wherein the charging device is further configured to prohibit charging of the one battery pack, when the one battery pack attached to the charging device is over-discharged. (a) reading the battery block lower limit voltage (VLb) from the memory of the attached battery pack, and by measuring an inter-terminal voltage (Vmb) of the battery block or an inter-terminal voltage (Vmc) of each battery cell, and by determining whether or not the attached battery pack is over-discharged based on the battery block lower limit voltage (VLb) and the measured inter-terminal voltage (Vmb) of the battery block, and/or by (b) reading the battery cell lower limit voltage (VLc) from the memory of the attached battery pack and determining whether or not the attached battery pack is over-discharged based on the battery cell lower limit voltage (VLc) and the measured internal-terminal voltage (Vmc) of each battery cell, wherein the charging device is further configured to prohibit charging of the one battery pack, when the one battery pack attached to the charging device is over-discharged.