Patent Publication Number: US-2007120524-A1

Title: Battery charger for charging different types of battery pack

Description:
REFERENCE TO RELATED APPLICATIONS  
      This application claims the benefit of the filing date of the U.S. Provisional Patent Application No. 60/729,686 filed Oct. 24, 2006, the disclosures of which are hereby incorporated herein by reference. 
    
    
     FIELD OF THE INVENTION  
      The present invention relates to battery chargers and more particularly to battery chargers for recharging battery packs.  
     BACKGROUND OF THE INVENTION  
      Batteries are commonly used to supply power to electrical devices. Batteries offer particular convenience by supplying power to portable electric devices including mobile telephones, radios, CD players and toys, including remotely operable toys. A particular drawback of relying on batteries to supply electrical power is that batteries have a limited useful life during which they are able to supply power. Once a battery is depleted of charge, it may be disposed of and replaced with a new battery. However, since disposal of discharged batteries is harmful to the environment and a wasteful use of resources, rechargeable batteries, such as nickel-cadmium batteries for example, are often used in place of single use batteries. Rechargeable batteries may be discharged and repeatedly charged to prolong their useful life.  
      Rechargeable batteries require regular charging to maintain a reliable power supply. Once a rechargeable battery is substantially depleted of charge, it is removed from the device to which it supplies electrical power and inserted into a battery charger. Batteries come in a wide range of sizes and shapes to suit a variety of uses. Typically, the size of the battery is relative to the amount of electrical power that the battery is able to supply to an electrically powered device.  
      Battery packs comprise a plurality of battery cells connected in series with one another. The number of cells within a pack determines the voltage of the battery pack. Battery packs come in a variety of forms including cartridge type battery packs wherein the plurality of battery cells is enclosed within a casing, and shrink-wrapped battery packs wherein the plurality of battery cells is secured together in a desired configuration using shrink wrap film. Such battery packs come in a range of shapes and sizes determined by the number of battery cells included in the battery pack and the manner in which they are connected together. Furthermore, different types of battery packs include different means of contact with the device to which they supply power and a battery charger. Such battery packs are used for supplying electrical power to remote controlled cars and the like.  
       FIG. 1A  is a top view of a shrink-wrapped battery pack  100  comprising in this case, four battery cells  102  secured together by shrink-wrap  104 . Contact between the shrink-wrapped battery pack and the device to which power is supplied or a battery charger is provided in the form of a plug  106  and lead  108  type connector  110 .  FIG. 1B  shows the shrink-wrapped battery pack  100  of FIG,  1 A as seen from one end.  FIG. 2  is a perspective view of a cartridge type battery pack  200  in which the plurality of battery cells is enclosed in a casing  202 . Contact between the cartridge battery pack  200  and the device to which power is supplied or a battery charger is provided in the form of terminals  204  on an outer surface of the casing  202 .  
      Whilst battery packs come in a large range of shapes, sizes and configurations, most battery chargers suitable for charging battery packs are configured to receive only a single type of battery pack. That is, typically only a battery pack of a particular type will slot into a socket in the battery charger having terminals to electrically connect to the battery pack to be charged.  
      Accordingly, there remains a need for a battery charger that solves these and other shortcomings of existing battery chargers.  
     SUMMARY OF THE INVENTION  
      It is an object of the present invention to provide a battery charger which is configured to receive more than one type of battery pack for the purpose of charging the same.  
      An embodiment of the present invention provides a battery charger for charging two different types of rechargeable battery pack. A first type of battery pack comprises two electrical terminals, and a second type of battery pack comprises a plug and lead type electrical connector. The battery charger comprises a housing. A first socket is provided in the housing for receiving the first type of battery pack, the first socket including contact points for electrical connection of the terminals of the first type of battery pack to the battery charger. A second socket in the housing includes contact points for electrical connection of the plug and lead type connector of the second type of battery pack to the battery charger. The battery charger further comprises AC connectors for connecting the battery charger to an AC electrical power supply outlet. The battery charger also comprises a circuit board having first and second DC electrical circuits for providing power to one or more battery packs and a switch for activating one of the circuits. When the first type of battery pack is inserted into the first socket the switch activates the first DC circuit for charging of the first type of battery pack. When no battery pack of the first type is inserted into the first socket, the first DC circuit is open and no current is delivered through the first DC circuit. The second DC circuit, which enables the second type of battery pack to be charged by connection to the second socket remains active at all times. Current is delivered through the second DC circuit when the second type of battery pack is connected to the second socket.  
      In one embodiment of the invention, the second type of battery pack is insertable into the first socket but without causing the switch to activate the first DC circuit.  
      An advantage of an embodiment of the invention is that the battery charger is configured to permit electrical connection to more than one type of battery pack for the purpose of charging the same.  
      Another advantage of an embodiment of the invention is that a socket of the battery charger is configured to receive more than one type of battery pack.  
      Another advantage of an embodiment of the invention is that the contact points within the first socket of the battery charger are not part of the circuit when the second type of battery pack is received therein, thereby preventing the second type of battery pack from being short-circuited.  
      Another advantage of an embodiment of the invention is that both the first type of battery pack and the second type of battery pack may be charged by the battery charger simultaneously.  
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      The present information can be more fully understood by reading the subsequent detailed description and examples with reference made to the accompanying drawings in which:  
       FIG. 1A  is a top view of a shrink-wrapped battery pack.  
       FIG. 1B  is the shrink-wrapped battery pack of  FIG. 1A  as viewed from the side.  
       FIG. 2  is a perspective view of a cartridge type battery pack.  
       FIG. 3A  is a top view of the battery charger.  
       FIG. 3B  is a front view of the battery charger of  FIG. 3A .  
       FIG. 3C  is a side view of the battery charger of  FIG. 3A .  
       FIG. 3D  is a back view of the battery charger of  FIG. 3A .  
       FIG. 3E  is another side view of the battery charger of  FIG. 3A .  
       FIG. 3F  is a bottom view of the battery charger of  FIG. 3A .  
       FIG. 4A  is a perspective top view of the battery charger of  FIG. 3A .  
       FIG. 4B  is a perspective bottom view of the battery charger of  FIG. 3A .  
       FIG. 5A  is a side view of the battery charger of  FIG. 3A  showing a configuration of internal mechanisms of the battery charger when the first type of battery pack is not inserted into the first socket.  
       FIG. 5B  is a side view of the battery charger of  FIG. 3A  showing a configuration of internal mechanisms of the battery charger when the first type of battery pack is inserted into the first socket.  
       FIG. 6  is a perspective side view of the battery charger of  FIG. 3A  with the first type of battery pack inserted.  
       FIG. 7  is perspective side view of the battery charger of  FIG. 3A  with the second type of battery pack inserted.  
       FIG. 8A  is a simple circuit diagram showing the circuit actuated when the second type of battery pack is connected to the battery charger.  
       FIG. 8B  is a simple circuit diagram showing the circuit actuated when the first type of battery pack is connected to the battery charger.  
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS  
       FIG. 3A  is a top view of the battery charger  300  of a preferred form of the present invention. The battery charger  300  is suitable for charging two different types of rechargeable battery pack. A first type of battery pack  200  that may be charged by the battery charger  300  comprises two electrical terminals  204  and a switch actuator  206 . An example of the first type of battery pack is the cartridge type battery pack (as shown in  FIG. 2 ). A second type of battery pack  100  that may be charged by the battery charger  300  comprises a plug and lead type electrical connector  110 . An example of the second type of battery pack  100  is the shrink-wrap type battery pack (as shown in  FIGS. 1A and 1B ).  
      The battery charger  300  has a housing  302  to encase the internal mechanisms. The battery charger  300  further comprises AC connectors  304  for connecting the battery charger  300  to an AC electrical power supply outlet.  
       FIG. 3B  is a front view of the battery charger  300  of  FIG. 3A . A first socket  306  is provided in the housing  302  for receiving the first type of battery pack  200 . The first socket  306  includes contact points  308 , which provide for electrical connection of the terminals  204  of the first type of battery pack  200  to the battery charger  300 . A second socket  310  is provided in the housing  302 , the second socket  310  including contact points  312  for electrical connection of the plug and lead type connector  110  of the second type of battery pack  100  to the battery charger  300 . Also shown is a light emitting diode (LED)  313  which emits a signal in the form of light when the battery charger  300  is providing power to at least one battery pack. The battery charger  300  also includes a switch  314  for activating one of the DC electrical circuits for providing power to the battery pack. The switch  314  is actuated when the first type of battery pack  200  is received in the first socket  306 . A switch actuator  206  provided on the first type of battery pack  200  serves to engage the switch  314  causing it to move and thereby activating a first DC circuit for charging of the first type of battery pack. When the first DC circuit is activated in this manner, a second DC circuit for charging the second type of battery pack  100  is also active. Therefore, in one embodiment, it is possible to charge both the first type of battery pack  100  and the second type of battery pack  200  simultaneously. However, it is also possible to charge only one of the two types of battery packs at a given time.  
      The switch actuator  206  may also assist positioning of the battery pack  200  within the battery charger  300  or the electric device to which power is to be supplied. Removal of the first type of battery pack  200  from the first socket  306  causes the switch  314  to return to a non-actuated position. According to one embodiment, regardless of the position of the switch  314 , the second DC circuit is activated to enable the second type of battery pack  100  to be charged by connection to the second socket  312 .  
       FIG. 3C  is a side view of the battery charger  300  of  FIG. 3A  showing the first and second sockets  306 , 310  and the AC connectors  304  as viewed from the side. In one embodiment, one or more supports  315  may be provided to rest against all wall when the AC connectors  304  are connected to an electrical wall outlet. The supports may be integrated into the housing  302  of the battery charger. However, the supports  315  are not necessary and these or other structures may be included or omitted to suit needs of the use and design of the battery charger  300 .  
       FIG. 3D  is a back view of the battery charger  300  of  FIG. 3A  showing the AC connectors  304  and the supports  315  as viewed from the back.  
       FIG. 3E  is another side view of the battery charger  300  of  FIG. 3A  showing the first socket  306 , the AC connectors  304 , and the supports  315  as viewed from the side.  
       FIG. 3F  is a bottom view of the battery charger  300  of  FIG. 3A  showing the AC connectors  304  as viewed from the bottom.  
       FIG. 4A  is a perspective top view of the battery charger  300  of  FIG. 3A . The first and second sockets  306 ,  310 , which provide a means of connection of the battery packs  100 , 200  to the battery charger  300 , are shown. The LED  313  is also shown.  
       FIG. 4B  is a perspective bottom view of the battery charger  300  of  FIG. 3A . The AC connectors  304 , which provide means of connection to an AC power source, and the supports  315  are shown.  
       FIG. 5A  is a side view of the battery charger  300  of  FIG. 3A  showing a configuration of internal mechanisms of the battery charger  300  when the battery pack  502 , of the first type or the cartridge type, is not inserted into the socket  306 . The battery charger  300  is configured to receive two different types of battery pack for charging. One type of battery pack  502  suitable for use with the battery charger  300  of the present invention comprises two electrical terminals  504 , one on each side of the battery pack  502  (only one of the pair shown in  FIG. 5A ) and a switch actuator  506 . A second type of battery pack  100  (see  FIG. 1A and 1B ) comprises a plug and lead type electrical connector  110 . The battery charger  300  has a housing  302 . The housing  302  comprises a first socket  306  in the housing for receiving the first type of battery pack  502 , the first socket  306  including two contact points  512  (only one shown in  FIG. 5A ) for electrical connection of the terminals  504  of the first type of battery pack  502  to the battery charger  300 . The battery pack  502  is inserted into the first socket  306  in the direction generally indicated by arrow  514 .  
      The battery charger  300  comprises AC connectors  304  for connecting the battery charger  300  to an AC electrical power supply outlet. The AC connectors  304  may take the form of a conventional plug to be received in a socket for connection to an AC power supply.  
      The battery charger  300  further incudes a circuit board  516  having alternative first and second DC electrical circuits for providing power to the battery pack  502 . A switch  518  is provided for activating the first DC circuit. The circuits include two conductive metal plates, first metal plate  524  and second metal plate  526 , arranged on the circuit board  516  such that connections between the first and second metal plates  524 ,  526  can be opened and closed, thereby opening and closing the first DC circuit.  
      The configuration of a circuit board  516  of the battery charger  300  provides that, when the switch  518  is in a non-actuated position, as shown in  FIG. 5A , the first and second metal plates  524 ,  526  are not in contact, and the first DC circuit is opened. In one embodiment, when the switch  518  is in the non-actuated position, the second DC circuit is closed and activated to enable the second type of battery pack  100  to be charged by connection to the second socket  310  of the battery charger  300 .  
      As described previously, the switch  518  is actuated by engagement with the switch actuator  506  provided on the first type of battery pack  502 . In  FIG. 5A  the battery pack  502  having the switch actuator  506  has not yet been inserted into the first socket  306  of the battery charger  300 . Therefore, the first and second metal plates  524 ,  526  arranged on the circuit board  516  are not in contact. Therefore, the first DC circuit for charging the first type of battery pack  502  is not activated and only the second DC circuit for charging the second type of battery pack  100  is activated.  
      Referring to  FIG. 5B , a side view of the same battery charger  300  with the first type of battery pack  502  inserted in the first socket  510  for charging. As in  FIG. 5A , the internal mechanisms are shown. In the illustrated embodiment, the switch actuator  506  provided on the first type of battery pack  502  takes the form of an L-shaped member. However, the switch actuator  506  may take any other suitable form that is configured to actuate the switch  518 .  
       FIG. 5B  shows more clearly how the switch  518  is actuated when the first socket  306  receives the first type of battery pack  502 . The L-shaped member  506  engages the switch  518  causing it to move generally in the direction of the arrow  514  (shown in  FIG. 5A ) to bring conductive metal plates  524  and  526  into contact with one another. This movement causes the first DC circuit for charging of the first type of battery pack  502  to be activated.  
      Conversely, removal of the first type of battery pack  502  from the first socket  306  causes the switch  518  to return to a non-actuated position. In one form of the invention, the switch  518  may be urged to return to the non-actuated position by a biasing means, such as a spring member (not shown). In another embodiment, the first metal plate  524  is acts as a spring such that an end of the first metal plate  524  contacting the switch  518  exerts a force in a direction opposite to the direction of the arrow  514  (shown in  FIG. 5A ). The amount of force exerted by the first metal plate  524  on the switch  518  may be any amount suitable to return the switch  518  to the non-actuated position.  
      The configuration of elements on the circuit board  516  provide that when the switch  518  has been moved to the actuated position by engagement by a switch actuator  506  provided on the first type of battery pack  502 , the first and second metal plates  524 ,  526  are brought into contact with each another. This movement causes the first DC circuit to be activate do provide for charging of the first type of battery pack  502  inserted in the first socket  306  of the battery charger  300 .  
       FIG. 6  is a perspective side view of the battery charger  300  of  FIG. 3A  with the first type of battery pack  502  inserted into the first socket  306 . Also shown is a light emitting diode (LED)  313  which emits light when the battery charger  300  is providing power to the battery pack  502 .  
      When the first type of battery pack  502  is inserted into the first socket  306  and the switch actuator  506  triggers activation of the first DC circuit for charging the first type of battery pack  502 , the first DC circuit forms a closed circuit through the first type of battery pack  502  via the contact points  512  in the first socket  306  and the terminals  504  on the battery pack  502 .  
       FIG. 7  is perspective side view of the battery charger  300  of  FIG. 3A  with the second type of battery pack  100  inserted. This second type of battery pack  100  includes a plug and lead type connector  110  which is inserted into the second socket  310  in the housing  302 . The second socket  310  includes contact points for electrical connection of the plug and lead type connector  110  to the battery charger  300 .  
      Furthermore, in one embodiment of the invention, the second type of battery pack  100  is configured to be received in the first socket  306  without actuating the switch  518  (shown in  FIG. 5A and 5B ). This provides a convenient means of storing the second type of battery pack  100  during the charging operation. In another embodiment, the second type of battery pack  100  may be connected to the battery charger  300  by the plug and lead type connector  110  being connected to the second socket  310  but not located in the first socket  306 . Simultaneously, the first type of battery  502  may be located in the first socket  306 . Accordingly, it is possible to charge both the first type of battery  502  and the second type of battery  100  simultaneously.  
       FIG. 8A  is a simple circuit diagram showing the circuit actuated when the first DC circuit  802  is not actuated; that is, only the second DC circuit  804  is activated. The second type of battery pack  100  may be connected to the battery charger  300  when the switch  518  is in the non-actuated position (see  FIG. 5A ).  
       FIG. 8B  is a simple circuit showing the circuit actuated when the switch  518  (see  FIG. 5A ) is actuated by insertion of the first type of battery pack  502  into the first socket  306  of the battery charger  300 . Accordingly, it can be seen that both the first DC circuit  802  and the second DC circuit  804  are actuated when the first type of battery pack  502  is inserted into the first socket  306  of the battery charger  300 .  
      It is an advantage of the present invention that causing the first DC circuit to be closed will not cause the second DC circuit to be open. Accordingly, two circuits may be closed simultaneously and two different types of battery packs may be charged simultaneously.  
      One particular problem relating to the charging of the shrink wrapped type battery packs  100  described earlier, is that when certain portions of the shrink wrap  104  are damaged, that is, a portion of the shrink wrap  104  that covers an area of a battery cell or cells  102  that may come into contact with a conducting body at some stage, the battery pack  100  may be short-circuited and burnt out. This problem may arise for instance, if a shrink wrap type battery pack  100  were inserted into the first socket  306  of the battery charger  300  of the present invention, and it was not possible to inactivate the first DC circuit for charging the first type of battery pack  200  ( FIG. 2 ) wherein a closed circuit is formed through the first type of battery pack  200  via the contact points  308  ( FIG. 3B ) in the first socket  306  and the terminals  204  on the battery pack  200 . Since the circuit passing through the contact points  308  in the first socket  306  is open and inactive when a shrink wrap type battery  100  pack lacking a switch actuator  206  is inserted into the first socket  306  of the battery charger  300 , the short circuiting problem is negated by the battery charger  300  of the present invention.  
      Whilst an embodiment of the present invention has been illustrated here in detail, it should be apparent that modifications and adaptations to these embodiments may occur to one skilled in the art without departing from the scope of the invention as described.