i) getting power source signal from positive and negative poles of a main battery and a backup battery of vehicles;

ii) measuring voltage of the main battery at a specific sampling time;

iii) measuring current of the backup battery at a specific sampling time;

iv) measuring voltage of the backup battery at a specific sampling time;

v) measuring voltage noise of a vehicle generator at a specific sampling time;

vi) enter a first power management pattern when detected voltage values of successive sampling signals of the main battery in a certain interval are higher than a third voltage;

vii) enter a second power management pattern when detected voltage values of successive sampling signals of the main battery in a certain interval are lower than a first voltage;

viii) enter a seventh power management pattern when detected current values of successive sampling signals in a certain interval are higher than a limited current, wherein, the successive sampling time in a certain interval ranging from 5 to 8, or equivalent with sampling time;

ix) when the detected battery voltage values of successive sampling signals in a certain interval are lower than the third voltage and higher than a second voltage, and the power source noise variation matches noise pattern that the generator charges the batteries, it is learned that the vehicle is turned on normally and the generator charges the main battery as well as the backup battery so that a third power management pattern is taken; wherein the successive sampling times of the main battery in a certain interval ranging from 4 to 9, or equivalent with sampling time, and the successive sampling times of the noise in a certain interval ranging from 6 to 10, or equivalent with sampling time;

x) when the detected battery voltage values of successive sampling signals in a certain interval are lower than the second voltage and the voltage noise variation doesn't match noise pattern that the generator charges the batteries, it is leaned that the engine is off and stops charging the batteries while other electric appliances still consume power, and a fourth power management pattern is taken; wherein the successive sampling times of the main battery in a certain interval ranging from 4 to 9, or equivalent with sampling time, and the successive sampling times of the noise in a certain interval ranging from 6 to 10, or equivalent with sampling time;

xi) under the fourth power management pattern, when the preset timing of a variable timer is up, take the fifth power management pattern; wherein the time of the variable timer is set from 0 minutes to the defined hours and the switches are turned on at predetermined interval;

xii) when the detected battery voltage values of successive sampling signals in a certain interval are lower than the first voltage and the power source noise variation doesn't match noise pattern that the generator charges the batteries, it is leaned that the engine is off and stops charging the batteries while other electric appliances still consume power so that the main battery power is lowered to safe limit, and a sixth power management pattern is taken; wherein the successive sampling times of the main battery in a certain interval ranging from 4 to 9, or equivalent with sampling time, and the successive sampling times of the noise in a certain interval ranging from 6 to 10, or equivalent with sampling time;

xiii) on the first power management pattern, cut off and stop charging the main battery as well as the backup battery, and display that the batteries are full charged;

xiv) on the second power management pattern, take alarming and display that the battery voltage is low;

xv) on the third power management pattern, connect and charge the main battery as well as the backup battery, and display charging status;

xvi) on the fourth power management pattern, display power exhaustion of the main battery, and supply power from the backup battery;

xvii) on the fifth power management pattern, cut off power supply from the main battery when the preset time is up, display power exhaustion of the main battery, and supply power from the backup battery;

xviii) on the sixth power management pattern, cutoff power supply from the backup battery, display power exhaustion of the main battery as well as the backup battery while the power is enough for restarting the vehicle;

xix) on the seventh power management pattern, cutoff power supply from the main battery as well as the backup battery, display/alarm abnormal status or short circuit of vehicle electric appliances and take measures for protection of the batteries and the vehicle.