Abstract:
A battery pack is constructed with a rechargeable battery, a protection circuit part that protects the battery when the battery is charged and discharged, and a switching unit that turns on or off a power source of the protection circuit part. Also, the battery pack may be constructed with a rechargeable battery, a protection circuit part that protects the battery when the battery is charged and discharged, and electric wiring lines constructed so that the power source of the protection circuit part may be turned on and off. When the battery pack is not connected to a charger or a load by the switching unit or the electric wire lines, the power source of the circuit is blocked to prevent the battery pack from being shorted and to reduce the idle power. When the battery pack is connected to the charger or the load, the power source is applied to the circuit so that the circuit operates.

Description:
CLAIM OF PRIORITY 
     This application makes reference to, incorporates the same herein, and claims all benefits accruing under 35 U.S.C. §119 from an application for BATTERY PACK earlier filed in the Korean Intellectual Property Office on 30 Oct. 2007 and there duly assigned Serial No. 10-2007-0109727. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a battery pack, and more particularly, to a battery pack that is prevented from being shorted and that is capable of reducing idle power. 
     2. Description of the Related Art 
     Recently, compact and light electrical and electronic apparatuses such as mobile telephones, notebook computers, and camcorders have been actively developed and produced. Battery packs are built in the portable electrical and electronic apparatuses so that the portable electrical and electronic apparatuses can operate in a space where an additional power source is not provided. The battery packs recently adopt batteries that may be charged and discharged in consideration of economics. The batteries include a nickel-cadmium (Ni—Cd) battery, a nickel-hydrogen (Ni-MH) battery, a lithium (Li) battery, and a lithium ion (Li-ion) battery. In particular, since the operation voltage of the lithium secondary battery is three times higher than the operation voltages of the Ni—Cd battery and the Ni—H battery that are widely used as the contemporary power sources of the portable electronic apparatuses, and the energy density per unit weigh of the lithium ion secondary battery is high, the use of the lithium ion secondary battery rapidly increases. 
     In the lithium secondary battery, lithium based oxides are used as positive electrode active materials and carbon materials are used as negative electrode active materials. In general, the lithium ion secondary battery is divided into a liquid electrolyte battery and a polymer electrolyte battery in accordance with the kind of an electrolyte. The battery in which the liquid electrolyte is used is referred to as a lithium ion battery and the battery in which the polymer electrolyte is used is referred to as a lithium polymer battery. In addition, the lithium secondary battery is manufactured to have various shapes such as a cylinder type, a square type, and a pouch type. 
     A protection circuit part is attached to the lithium ion battery such that the lithium ion battery may be selectively charged and discharged, or that power is blocked to protect the lithium ion battery when the lithium ion battery is overcharged or when over-current flows. Therefore, the lithium ion battery is integrated with the protection circuit part to form a pack and is connected to a charger to perform charging or is connected to a portable electronic product that is a load to perform discharging. 
     At this time, the protection circuit part includes a positive terminal and a negative terminal connected to the charger or the load. When the positive and negative terminals are shorted by a clip or a conductor, the lithium ion battery deteriorates or causes the protection circuit part to abnormally operate. 
     In addition, the protection circuit part is integrated with the lithium ion battery to form the pack. Although the lithium ion battery is not connected to the charger or the load, the protection circuit part receives power from the lithium ion battery to protect the lithium ion battery so that the power of the lithium ion battery is continuously consumed. 
     SUMMARY OF THE INVENTION 
     It is therefore an object of the present invention to provide an improved battery pack. 
     It is another object of the present invention to provide a battery pack that is capable of preventing positive and negative terminals electrically connected to a charger or a portable electronic product that is a load from being shorted. 
     It is still another object of the present invention to provide a battery pack that is capable of preventing a protection circuit part from consuming the power of a battery when the battery pack is not connected to a charger or a load. 
     It is a further object of the present invention to provide a stable battery pack. 
     According to one aspect of the present invention, a battery pack may be constructed with at least one rechargeable battery, a positive charging and discharging terminal electrically connected to a positive high current path of the battery, a negative charging and discharging terminal electrically connected to a negative high current path of the battery, a charging and discharging switching element electrically connected to a high current path on which the positive charging and discharging terminal or the negative charging and discharging terminal and the battery are electrically connected, a protection circuit part including positive and negative power terminals electrically connected to positive and negative electrodes of the battery to receive power, and electrically connected to the charging and discharging switching element to either turn on or turn off the charging and discharging switching element in accordance with a charging and discharging state of the battery, a switching unit electrically connected in a current path on which the positive and negative power terminals of the protection circuit part are electrically connected to the positive and negative electrodes of the battery, and an auxiliary terminal electrically connected between the switching unit and at least one of a charger and a load when charging or discharging. 
     The switching unit may be constructed with a switching element. The switching element of the switching unit may electrically connecting either one of the positive power terminal and the negative power terminal in accordance with an on or off signal supplied from the at least one of the charger and the load electrically connected to the auxiliary terminal. 
     The switching element may be made from either one of a P-type field effect transistor or an N-type field effect transistor. 
     A first buffer resistor may be electrically coupled between the switching element of the switching unit and the auxiliary terminal. 
     A second buffer resistor may be electrically coupled between the switching element of the switching unit and the positive charging and discharging terminal. 
     A reverse current blocking diode may be electrically coupled in parallel with the switching element. 
     The charging and discharging switching element may include a charging field effect transistor and a discharging field effect transistor. A first parasitism diode for blocking a discharging path may be electrically connected to the source and drain of the charging field effect transistor in parallel. A second parasitism diode for blocking a charging path may be electrically connected between the source and drain of the discharging field effect transistor in parallel. 
     A first condenser may be electrically coupled between the positive power terminal and the negative power terminal. 
     A third condenser may be electrically coupled to a high current path of the charging and discharging switching element to absorb an impulse current generated by on and off operations of the charging and discharging switching element. 
     A second condenser may be electrically coupled between the positive charging and discharging terminal to the negative charging and discharging terminal. 
     According to another aspect of the present invention, a battery pack may be constructed with at least one rechargeable battery, a positive charging and discharging terminal electrically connected to a positive high current path of the battery, a negative charging and discharging terminal electrically connected to a negative high current path of the battery, a charging and discharging switching element electrically connected in a high current path on which the positive charging and discharging terminal or the negative charging and discharging terminal and the battery are electrically connected, a protection circuit part including positive and negative power terminals that receive power from positive and negative electrodes of the battery, with one of the positive and negative power terminals being electrically connected to the battery and to the charging and discharging switching element to turn on and off the charging and discharging switching element in accordance with charging and discharging states of the battery, and an auxiliary terminal electrically connected to at least one of a charger and a load during charging or discharging. The at least one of the charger and the load may be constructed with a positive terminal and a negative terminal. Either one of the positive and negative terminals of the at least one of the charger and the load may be electrically connected to one electrode of the battery, and the other one of the positive and negative terminals of the at least one of the charger and the load may be electrically connected to the other electrode of the battery to apply a power to the battery. 
     The charging and discharging switching element may include a charging field effect transistor and a discharging field effect transistor. A parasitism diode for blocking a discharging path maybe connected to the source and drain of the charging field effect transistor in parallel. And a parasitism diode for blocking a charging path may be connected to the source and drain of the discharging field effect transistor in parallel. 
     A third condenser may be electrically connected to the high current path of the charging and discharging switching element to absorb an impulse current generated by on and off operations of the charging and discharging switching element. 
     A first condenser may be electrically coupled between the positive power terminal and the negative power terminal. 
     A second condenser may be electrically coupled between the negative charging and discharging terminal and the positive charging and discharging terminal. 
     A buffer resistor may be electrically coupled between one of the positive power terminal and the negative power terminal and the auxiliary terminal. 
     According still another aspect of the present invention, a battery pack may be constructed with at least one rechargeable battery, a positive charging and discharging terminal electrically connected to a positive high current path of the battery, a negative charging and discharging terminal electrically connected to a negative high current path of the battery, a charging and discharging switching element electrically connected in a high current path on which either one of the positive charging and discharging terminal and the negative charging and discharging terminal and the battery are electrically connected, a protection circuit part including positive and negative power terminals that receive power from positive and negative electrodes of the battery, and electrically connected to the charging and discharging switching element to turn on and off the charging and discharging switching element in accordance with charging and discharging states of the battery, a first auxiliary terminal electrically connected to at least one of a charger and a load during charging or discharging and electrically connected to the positive power terminal, and a second auxiliary terminal electrically connected to the at least one of the charger and the load during charging or discharging and electrically connected to the negative power terminal. 
     The charging and discharging switching element may include a charging field effect transistor and a discharging field effect transistor. A parasitism diode for blocking a discharging path may be connected to the source and drain of the charging field effect transistor in parallel. A parasitism diode for blocking a charging path may be connected to the source and drain of the discharging field effect transistor in parallel. 
     A third condenser may be electrically coupled to a high current path of the charging and discharging switching element to absorb an impulse current generated by on or off operations of the charging and discharging switching element. 
     A first condenser may be electrically coupled between the positive power terminal and the negative power terminal. 
     A second condenser electrically may be coupled between the negative charging and discharging terminal and the positive charging and discharging terminal. 
     A buffer resistor may be electrically coupled between one of the positive power terminal and the negative power terminal and the auxiliary terminal. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       A more complete appreciation of the invention, and many of the attendant advantages thereof, will be readily apparent as the same becomes better understood by reference to the following detailed description when considered in conjunction with the accompanying drawings in which like reference symbols indicate the same or similar components, wherein: 
         FIG. 1  is a circuit diagram of a battery pack according to a first embodiment of the principles the present invention; 
         FIG. 2  is a circuit diagram of a battery pack according to a second embodiment of the principles of the present invention; 
         FIG. 3  is a circuit diagram of a battery pack according to a third embodiment of the principles of the present invention; and 
         FIG. 4  is a circuit diagram of a battery pack according to a fourth embodiment of the principles of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the entire description of the present invention, the same drawing reference numerals are used for the same elements across various figures. Also, the same elements across various figures are not explained again as possible. In the exemplary embodiments of the present invention, a charger or a load of a portable electronic product that is connected to a battery pack according to the present invention are described. At this time, the charger and the load of the portable electronic product include terminals connected to the battery pack and the terminals may vary in accordance with the structure of the battery pack. 
       FIG. 1  is a circuit diagram of a battery pack according to a first embodiment of the principles of the present invention. 
     Referring to  FIG. 1 , a battery pack  100  according to the present invention includes a battery  110 , a positive charging and discharging terminal  120 , a negative charging and discharging terminal  130 , a charging and discharging switching element  140 , a protection circuit part  150 , a switching unit  160 , and an auxiliary terminal  170 . 
     Battery  110  is rechargeable and may be one or more. And, battery  110  may be a lithium ion battery or a lithium polymer battery. 
     Positive charging and discharging terminal  120  is electrically connected to positive electrode  110   a , i.e., a negative high current path of battery  110 . Positive charging and discharging terminal  120  may be electrically connected to terminal  120   a  of a charger  100   a  or a load  100   b . The high current path is the path that is electrically connected to the positive electrode and the negative electrode of the battery. The charging and discharging current flows through the high current path. 
     Negative charging and discharging terminal  130  is electrically connected to negative electrode  110   b , i.e., a positive high current path of battery  110 . Negative charging and discharging terminal  130  may be electrically connected to terminal  130   a  of charger  100   a  or load  100   b , or may be electrically connected to a ground. 
     Charging and discharging switching element  140  is electrically connected to a high current path to which positive charging and discharging terminal  120  or negative charging and discharging terminal  130  and battery  110  are electrically connected. Charging and discharging switching element  140  may be made from an electronic element that performs a switching function such as a field effect transistor or a transistor. In addition, charging and discharging switching element  140  may be divided into a charging switching element that flows current in a charging direction and a discharging switching element that flows current in a discharging direction. That is, charging and discharging switching element  140  illustrated in  FIG. 1  is for convenience sake and may be one or more. 
     Protection circuit part  150  includes a positive power terminal  151  and a negative power terminal  152  that receive power from positive electrode  110   a  and negative electrode  110   b  of battery  110 . Protection circuit part  150  is electrically connected to positive and negative electrodes  110   a ,  110   b  of battery  110  and charging and discharging switching element  140  to turn on and off charging and discharging switching element  140  in accordance with charging and discharging states of battery  110 . When charger  100   a  or load  100   b  is electrically connected to positive and negative charging and discharging terminals  120  and  130  to perform charging and discharging function, protection circuit part  150  detects over-current by an over-current detecting unit (not shown) of protection circuit part  150 , turns off charging and discharging switching element  140 , and thus preventing battery  110  from being overheated and exploded. At this time, the over-current detecting unit of protection circuit part  150  may be electrically connected to the high current path of battery  110  by a buffer resistor  155  that buffers impulse current. Protection circuit part  150  may further include a functioning unit (not shown) that detects the voltage and current of battery  110 . In the present invention, however, the additional functions of protection circuit part  150  are not limited. 
     Switching unit  160  may be electrically connected between a path on which positive and negative power terminals  151  and  152  of protection circuit part  150  are electrically connected to the positive and negative electrodes of battery  110 . In  FIG. 1 , switching unit  160  is formed between a path on which positive power terminal  151  and positive electrode  110   a  of battery  110  are electrically connected to each other in a state where negative power terminal  152  and negative electrode  110   b  of battery  110  are electrically connected to each other. Alternatively, switching unit  160  may be formed between a path on which negative power terminal  152  of protection circuit part  150  and negative electrode  110   b  of battery  110  are electrically connected to each other in a state where positive power terminal  151  of protection circuit part  150  and positive electrode  110   a  of battery  110  are electrically connected to each other. Switching unit  160  may be made from an electronic element that performs the switching function such as a transistor or a field effect transistor, and may be turned on by a signal input through auxiliary terminal  170 . Therefore, positive power terminal  151  or negative power terminal  152  of protection circuit part  150  may be electrically connected to positive or negative electrode  110   a  or  110   b  of battery  110  to drive protection circuit part  150 . 
     Auxiliary terminal  170  is electrically connected to charger  100   a  or load  100   b  when charging or discharging battery  110 , and is electrically connected switching unit  160 . When auxiliary terminal  170  is electrically connected to the other connection terminals  120   a ,  130   a , and  170   a  of charger  100   a  or load  100   b  together with positive and negative charging and discharging terminals  120  and  130 , a signal output from charger  100   a  or load  100   b  is supplied to switching unit  160  through auxiliary terminal  170 . Switching unit  160  electrically connects positive electrode  110   a  of battery  110  and positive power terminal  151  of protection circuit part  150  to each other to supply power to protection circuit part  150 . 
     The above-described battery pack  100  may supply power to or block power from protection circuit part  150  by switching unit  160  that electrically connects one of positive and negative power terminals  151  and  152  of protection circuit part  150  and one of positive and negative electrodes  110   a  and  110   b  of battery  110  to each other. At this time, switching unit  160  is electrically connected to auxiliary terminal  170 . When auxiliary terminal  170  is electrically connected to the terminal of charger  100   a  or load  100   b , switching unit  160  is operated by a signal input to charger  100   a  or load  100   b  to electrically connect positive electrode  110   a  of battery  110  and positive power terminal  151  of protection circuit part  150  to each other. Therefore, switching unit  160  supplies power from battery  110  to protection circuit part  150  so that protection circuit part  150  starts to operate. In addition, when terminals  120   a ,  170   a , and  130   a  of charger  100   a  or load  100   b  and battery pack  100  are not connected to each other, because protection circuit part  150  does not receive power from battery  110 , it is possible to prevent protection circuit part  150  from consuming the power of battery  110 . In addition, when positive and negative charging and discharging terminals  120  and  130  are shorted, since protection circuit part  150  does not perform the charging and discharging function, charging and discharging switching element  140  is turned off. Therefore, battery  110  is not shorted. 
       FIG. 2  is a circuit diagram of the battery pack according to a second exemplary embodiment of the principles of the present invention. 
     Referring to  FIG. 2 , battery pack  200  according to the second exemplary embodiment of the present invention includes battery  110 , positive charging and discharging terminal  120 , negative charging and discharging terminal  130 , charging and discharging switching element  240 , protection circuit part  250 , a switching element  261 , and auxiliary terminal  170 . According to the second exemplary embodiment, since the structures of and the connection relationship between battery  110 , positive charging and discharging terminal  120 , and negative charging and discharging terminal  130  are the same as those according to the above-described exemplary embodiment, description thereof will be omitted. 
     First, the above-described switching unit may include switching element  261 . Switching element  261  is turned on by an on or off signal output from charger  200   a  or load  200   b  which is electrically connected to auxiliary terminal  170  so that positive power terminal  151  and positive electrode  110   a  of battery  110  may be electrically connected to each other. Switching element  261  may be made from a transistor or a field effect transistor. Since switching element  261  is a semiconductor switching element, switching element  261  is turned on or off by a small signal voltage or current received from auxiliary terminal  170  at high response speed to perform the switching function. 
     Also, switching element  261  may be made from a field effect transistor and a P-type field transistor or an N-type field transistor. When switching element  261  is made from the field effect transistor, a voltage is applied to auxiliary terminal  170  to which a gate electrode of switching element  261  is connected, and then positive charging and discharging terminal  120  to which a source electrode of switching element  261  is electrically connected, is changed to turn on switching element  261  and to thus supply power to protection circuit part  250 . 
     In addition, a first buffer resistor  262  may be formed to electrically connects the gate electrode of switching element  261  to auxiliary terminal  170 . When charger  200   a  or load  200   b  is connected to battery pack  200  so that positive charging and discharging terminal  120  and auxiliary terminal  170  are shorted, first buffer resistor  262  causes a difference in a voltage between the gate and the source so that the field effect transistor, i.e., switching element  261 , may be turned on. 
     In addition, a second buffer resistor  263  may be formed between source electrode  261   s  of switching element  261  formed of the field effect transistor and positive charging and discharging terminal  120 . When charger  200   a  or load  200   b  is connected to battery pack  200  so that positive charging and discharging terminal  120  and auxiliary terminal  170  are shorted, second buffer resistor  263  causes a difference in a voltage between gate electrode  261   g  and source electrode  261   s  so that the field effect transistor is turned on. In addition, second buffer resistor  263  may adjust the operating voltage of protection circuit part  250 . 
     In addition, when switching element  261  is formed of the field effect transistor, a reverse current blocking diode  261   a  may be formed between source electrode  261   s  and drain electrode  261   d  of switching element  261  in parallel to block current received from battery  110 . At this time, in order to block the current received by battery  110 , reverse current blocking diode  261   a  may be connected so that the direction in which the current is received by battery  110  is reversed as illustrated in  FIG. 2 . 
     On the other hand, charging and discharging switching element  240  may be divided into a charging field effect transistor  242  and a discharging field effect transistor  241 . In this case, a parasitism diode  242   a  for blocking a discharging path may be connected to the source and drain of charging field effect transistor  242  in parallel. In addition, a parasitism diode  241   a  for blocking a charging path may be connected to the source and drain of discharging field effect transistor  241  in parallel. In this case, in order to block the current that flows to a discharging path during charging, parasitism diode  242   a  for blocking the discharging path may be connected in the reverse direction of the current that flows to the discharging path. In order to block the current that flows to a charging path during discharging, parasitism diode  241   a  for blocking the charging path may be connected in the reverse direction of the current that flows to the charging path. Since the charging path and the discharging path are in the opposite directions, the charging path and the discharging path may be reversed when the polarity of battery  110  changes. In  FIG. 2 , the discharging path is in a clockwise direction and the charging path is in a counter-clockwise direction. 
     On the other hand, in protection circuit part  250  that controls charging field effect transistor  242  and discharging field effect transistor  241 , positive power terminal  151  and negative power terminal  152  are electrically connected to positive and negative electrodes  110   a  and  110   b  of battery  110  to measure the voltage of battery  110  and to thus control charging field effect transistor  242  and discharging field effect transistor  241 . In this case, when charger  200   a  is electrically connected to positive charging and discharging terminal  120  and negative charging and discharging terminal  130 , protection circuit part  250  senses the initial charging voltage of charger  200   a  to turn on charging switching element  242 , and thus charging battery  110 . When load  200   b  is electrically connected to positive charging and discharging terminal  120  and negative charging and discharging terminal  130 , discharging switching element  241  is turned on to discharge battery  110 . 
     In addition, a first condenser  253  may be formed to electrically connect positive power terminal  151  with negative power terminal  152 . First condenser  253  attenuates static electricity received from the outside or an impulse voltage or current to protect protection circuit part  250 . In addition, first condenser  253  may absorb the impulse voltage and current that are generated when terminals  270   a  and  230   a  of charger  200   a  or load  200   b  are connected to auxiliary terminal  170  and negative charging and discharging terminal  130 . 
     In addition, a condenser  243  may be formed in charging and discharging switching element  240  to absorb instantaneous impulse current generated by the on and off operations of charging and discharging switching element  240 . 
     In addition, a second condenser  211  may be further formed to electrically connect positive charging and discharging terminal  120  and negative charging and discharging terminal  130  to each other. Second condenser  211  may absorb the impulse voltage and current that are generated when terminals  220   a  and  230   a  of charger  200   a  or load  200   b  are electrically connected to positive charging and discharging terminal  120  and negative charging and discharging terminal  130 . Here, in comparison to the high current path that is electrically connected to the positive electrode and the negative electrode of the battery, a low current path is the path through which the control signal passing in or out of the protection circuit part flows, e.g., the path electrically connecting protection circuit part  250  and the charging and discharging switching element  240 . 
       FIG. 3  is a circuit diagram of a battery pack according to a third exemplary embodiment according to the principles of the present invention. 
     Referring to  FIG. 3 , battery pack  300  according to the third exemplary embodiment of the present invention includes battery  110 , positive charging and discharging terminal  120 , negative charging and discharging terminal  130 , protection circuit part  250 , and an auxiliary terminal  170 . Since the structures of and the connection relationship between battery  110 , positive charging and discharging terminal  120 , negative charging and discharging terminal  130 , and charging and discharging switching element  240  are the same as those according to the above-described exemplary embodiment, description thereof will be omitted. 
     The structure and function of protection circuit part  250  may be the same as those according to the above-described exemplary embodiment. When the connection relationship is described, however, one of positive and negative power terminals  151  and  152  that receive power from positive and negative electrodes  110   a  and  110   b  of battery  110  may be electrically connected to battery  110  and the other one of positive and negative power terminals  151  and  152  may be electrically connected to auxiliary terminal  170 . In  FIG. 3 , negative power terminal  152  is electrically connected to negative electrode  110   b  of battery  110 , whereas positive power terminal  151  is electrically connected to auxiliary terminal  170 . Alternatively, although not shown in FIG.  3 , negative power terminal  152  may be electrically connected to auxiliary terminal  170  and positive power terminal  152  may be electrically connected to positive electrode  110   a  of battery  110 . Terminals  320   a  and  370   a  of charger  300   a  or load  300   b  are connected to battery pack  300  having the above-described connection relationship so that auxiliary terminal  170  and positive charging and discharging terminal  120  of battery pack  300  are shorted. Then, a power source is supplied to protection circuit part  250  so that protection circuit part  250  operates to control charging and discharging switching element  240 . Therefore, when terminals  320   a  and  370   a  of charger  300   a  or load  300   b  that short auxiliary terminal  170  and positive charging and discharging terminal  120  are not connected, since protection circuit part  250  does not receive power, charging and discharging switching element  240  is cut off. As a result, although the two terminals of positive and negative charging and discharging terminals  120  and  130  are shorted, battery  110  is not damaged. In addition, since protection circuit part  250  does not receive power from battery  110 , battery  110  does not consume power. Therefore, although battery  110  is left for a long time in a state where battery  110  is not connected to the charger or the load, protection circuit part  250  does not consume power so that it takes long to fully discharge battery  110 . 
     At this time, first condenser  253  may be further provided to electrically connect positive power terminal  151  and negative power terminal  152  to each other. First condenser  253  absorbs the surge voltage or the impulse current that is received between positive power terminal  151  and negative power terminal  152  and removes noise received by positive charging and discharging terminal  151  and auxiliary terminal  170  to stabilize the power supplied to positive power terminal  151  and negative power terminal  152  of protection circuit part  250 . 
     In addition, second condenser  211  may be further provided to electrically connect negative charging and discharging terminal  130  and positive charging and discharging terminal  120  to each other. Second condenser  211  absorbs the surge voltage or the impulse current received between negative charging and discharging terminal  130  and positive charging and discharging terminal  170 . 
     In addition, a buffer resistor  354  may be electrically connected to a path where auxiliary terminal  170  and positive power terminal  151  are electrically connected. Alternatively, unlike in  FIG. 3 , when auxiliary terminal  170  is electrically connected to negative power terminal  152  in a state where positive power terminal  151  is electrically connected to positive electrode of battery  110 , buffer resistor  354  may be connected between auxiliary terminal  170  and negative power terminal  152 . Buffer resistor  354  may reduce the voltage applied to positive power terminal  151  or negative power terminal  152  of protection circuit part  250  or can buffer the impulse current received through auxiliary terminal  170 . 
       FIG. 4  is a circuit diagram of a battery pack according to a fourth exemplary embodiment of the principles of the present invention. 
     Referring to  FIG. 4 , battery pack  400  according to still another exemplary embodiment includes battery  110 , positive charging and discharging terminal  120 , negative charging and discharging terminal  130 , charging and discharging switching element  240 , protection circuit part  250 , a first auxiliary terminal  471 , and a second auxiliary terminal  472 . According to the fourth embodiment, since the structures of and the connection relationship between battery  110 , positive charging and discharging terminal  120 , negative charging and discharging terminal  130 , charging and discharging switching element  240 , first condenser  253 , second condenser  211 , and buffer resistor  354  are the same as those according to the above-described exemplary embodiment, description thereof will be omitted. 
     First, the structure and function of protection circuit part  250  may be the same as those according to the above-described exemplary embodiment. Negative power terminal  152  formed in protection circuit part  250 , however, is electrically connected to first auxiliary terminal  471 , and positive power terminal  151  is electrically connected to second auxiliary terminal  472 . At this time, terminals  430   a  and  471   a  of charger  400   a  or load  400   b  are connected to first auxiliary terminal  471  and negative charging and discharging terminal  130  to short first auxiliary terminal  151  and negative charging and discharging terminal  130 , and the other terminals  420   a  and  472   a  of charger  400   a  or load  400   b  short second auxiliary terminal  472  and positive charging and discharging terminal  120 . Therefore, power is supplied to protection circuit part  250 , and protection circuit part  250  operates charging and discharging switching element  240  to protect battery  110  when battery  110  performs charging and discharging. In addition, when charger  400   a  or load  400   b  is not connected to positive and negative charging and discharging terminal  120  and first and second auxiliary terminals  471  and  472 , a power source is blocked between positive and negative power terminals  151  and  152  of protection circuit part  250  and the positive and negative electrodes of battery  110 . Therefore, when charger  400   a  or load  400   b  and battery pack  400  are not connected to each other, since protection circuit part  250  does not receive the power source from battery  110 , protection circuit part  250  does not consume the power of battery  110 . At this time, battery  110  may be shorted only when positive and negative charging and discharging terminal  130  and first and second auxiliary terminals  471  and  472  are all shorted. That is, when one of positive and negative charging and discharging terminal  130  and first and second auxiliary terminals  471  and  472  is not shorted, it is possible to prevent battery  110  from being shorted. 
     When the battery pack according to the present invention is not electrically connected to the charger or the portable electronic product that is the load, the positive and negative charging and discharging terminals are not shorted. 
     In addition, when the battery pack is not connected to the charger or the load, the protection circuit part does not consume the power of the battery. 
     In addition, the battery pack stably operates at the moment when the above-described effects are achieved. 
     Although a few exemplary embodiments of the present invention have been shown and described, it would be appreciated by those skilled in the art that changes might be made in this exemplary embodiment without departing from the principles and spirit of the invention, the scope of which is defined in the claims and their equivalents.