A method of forcibly charging a high-voltage battery using a motor and a Hybrid Starter Generator, HSG, comprising: a) sensing, by a controller, speeds and temperatures of the motor and the HSG; b) calculating, by the controller, maximum chargeable power using three dimensional, 3D, maximum charging power maps based on speeds, and torque (power) of the motor and the HSG, and torque applying times; c) forcibly charging, by the controller, the high-voltage battery with the maximum chargeable power using the motor and HSG; d) adjusting, by the controller, maximum charging power using energy integration during the forced charging; e) executing, by the controller, a first excessive temperature prevention logic for the motor and the HSG to continuously perform the forced charging by one of the motor and the HSG, during the forced charging of the high-voltage battery using the motor and the HSG simultaneously; and f) executing, by the controller, a second excessive temperature prevention logic for adjusting current temperatures of the motor and the HSG below an operating power limiting temperature after the forced charging of the high voltage battery being completed, g) wherein the execution of the first excessive temperature prevention logic includes: g1) comparing, by the controller, the current temperatures of the motor and the HSG to a charging power limiting temperature; g2) continuing to forcibly charge, by the controller, the high-voltage battery using the HSG in response to the motor being in a motor power limited state in which the temperature of the motor exceeds the charging power limiting temperature to prevent the motor from generating power; and g3) continuing to forcibly charge, by the controller, the high-voltage battery using the motor in response to the HSG being in a HSG power limited state in which the temperature of the HSG exceeds the charging power limiting temperature to prevent the HSG from generating power. a) sensing, by a controller, speeds and temperatures of the motor and the HSG; b) calculating, by the controller, maximum chargeable power using three dimensional, 3D, maximum charging power maps based on speeds, and torque (power) of the motor and the HSG, and torque applying times; c) forcibly charging, by the controller, the high-voltage battery with the maximum chargeable power using the motor and HSG; d) adjusting, by the controller, maximum charging power using energy integration during the forced charging; e) executing, by the controller, a first excessive temperature prevention logic for the motor and the HSG to continuously perform the forced charging by one of the motor and the HSG, during the forced charging of the high-voltage battery using the motor and the HSG simultaneously; and f) executing, by the controller, a second excessive temperature prevention logic for adjusting current temperatures of the motor and the HSG below an operating power limiting temperature after the forced charging of the high voltage battery being completed, g) wherein the execution of the first excessive temperature prevention logic includes: g1) comparing, by the controller, the current temperatures of the motor and the HSG to a charging power limiting temperature; g2) continuing to forcibly charge, by the controller, the high-voltage battery using the HSG in response to the motor being in a motor power limited state in which the temperature of the motor exceeds the charging power limiting temperature to prevent the motor from generating power; and g3) continuing to forcibly charge, by the controller, the high-voltage battery using the motor in response to the HSG being in a HSG power limited state in which the temperature of the HSG exceeds the charging power limiting temperature to prevent the HSG from generating power. g1) comparing, by the controller, the current temperatures of the motor and the HSG to a charging power limiting temperature; g2) continuing to forcibly charge, by the controller, the high-voltage battery using the HSG in response to the motor being in a motor power limited state in which the temperature of the motor exceeds the charging power limiting temperature to prevent the motor from generating power; and g3) continuing to forcibly charge, by the controller, the high-voltage battery using the motor in response to the HSG being in a HSG power limited state in which the temperature of the HSG exceeds the charging power limiting temperature to prevent the HSG from generating power.