A method for detecting a fusion of a relay of a battery, the method comprising, when an ignition of a vehicle has been adjusted to an off position: adjusting, by a controller, a first relay to an off position (S11); determining, by the controller, whether the first relay is fused based on measuring a voltage of a first interval between after the first relay is in the off position and before a second relay is in an off position (S13, S14); and adjusting, by the controller, the second relay to the off position (S15), and the method further comprising, when the ignition is engaged after being in the off position: adjusting, by the controller, the second relay to an on position (S23), if it has been determined that the first relay is fused based on measuring the voltage of the first interval, and determining, by the controller, the fusion of the first relay and adjusting the second relay to the off position (S27, S29) when a measured voltage is greater than 0V by measuring a voltage of a second interval (c) until a precharge relay is turned on, and determining, by the controller, that the first relay is not fused and adjusting the second relay to the off position (S29) when the measured voltage is 0V. the method comprising, when an ignition of a vehicle has been adjusted to an off position: adjusting, by a controller, a first relay to an off position (S11); determining, by the controller, whether the first relay is fused based on measuring a voltage of a first interval between after the first relay is in the off position and before a second relay is in an off position (S13, S14); and adjusting, by the controller, the second relay to the off position (S15), and adjusting, by a controller, a first relay to an off position (S11); determining, by the controller, whether the first relay is fused based on measuring a voltage of a first interval between after the first relay is in the off position and before a second relay is in an off position (S13, S14); and adjusting, by the controller, the second relay to the off position (S15), and the method further comprising, when the ignition is engaged after being in the off position: adjusting, by the controller, the second relay to an on position (S23), if it has been determined that the first relay is fused based on measuring the voltage of the first interval, and determining, by the controller, the fusion of the first relay and adjusting the second relay to the off position (S27, S29) when a measured voltage is greater than 0V by measuring a voltage of a second interval (c) until a precharge relay is turned on, and adjusting, by the controller, the second relay to an on position (S23), if it has been determined that the first relay is fused based on measuring the voltage of the first interval, and determining, by the controller, the fusion of the first relay and adjusting the second relay to the off position (S27, S29) when a measured voltage is greater than 0V by measuring a voltage of a second interval (c) until a precharge relay is turned on, and determining, by the controller, that the first relay is not fused and adjusting the second relay to the off position (S29) when the measured voltage is 0V. <EOS>