the invention disclosed herein is of a battery charger with a housing having the capability of guiding and holding the housing of rechargeable batteries such that the battery housing may be properly positioned and supported while the batteries are being charged . such an apparatus is shown in the isometric view of fig1 . here , a battery charger ( 101 ) has two recesses ( 103 and 105 ) into either of which a battery ( 107 ) may be placed . although two recesses are shown , the present invention may be employed in battery housings having one or more such recesses . a battery charger having a similar appearance has been disclosed in u . s . patent application ser . no . 264 , 304 , &# 34 ; battery charger or similar article &# 34 ;, filed on oct . 27 , 1988 on behalf of soren et al . and assigned to the assignee of the present invention . the operation of the electrical portion of a similar battery charger has been disclosed in u . s . patent application ser . no . 361 , 534 , &# 34 ; multiple battery , multiple rate battery charger &# 34 ;, filed on june 5 , 1989 on behalf of johnson et al . and assigned to the assignee of the present invention . user operation of the battery charger of fig1 is accomplished by placing a battery ( 107 ) in one of the recesses ( 103 or 105 ) by elevating the battery ( 107 ) over the top surface and somewhat to the rear of the battery charger housing ( 101 ) and sliding the battery down and toward the front of the battery charger housing ( 101 ) such that the battery ( 107 ) slides against the interior side surfaces ( visible as side surface ( 109 )). once the battery ( 107 ) enters a recess , for example recess 103 , it will engage rib members disposed on opposite side surfaces of the battery housing ( 101 ). one such rib member ( 111 ) is visible in the view of fig1 . another rib member is located on the interior side wall surface directly opposite the side wall surface ( 109 ). this rib member is not visible in the view of fig1 . rib member ( 111 ) engages a slot ( 113 ) in the battery housing ( 107 ) to direct the battery toward charging contacts ( 115 ) and enable the proper charging of the electrochemical cells of the battery . it is an important feature of the present invention that the side surfaces of the battery charger housing ( 101 ) and the rib members ( for example , rib member ( 111 ) of the battery charger housing ( 101 ) cooperate in directing the battery against the battery charging contacts . the battery is held in the proper orientation against the charging contacts ( 115 ) by the rib members and the unique battery charger shape directing the weight of the battery with a minimum of complexity of battery charger design . referring now to fig2 and 3 , which are single point perspective views of a small and large size battery housing respectively , it can be observed that the shape of the battery housings are essentially trapezoidal prisms . the bottom surfaces ( 201 ) of the battery housings shown in fig2 and 3 are surfaces which mate against the housing of the aforementioned cellular portable radio telephone during operation . a sloping surface ( 202 ) as shown in fig2 and 3 have electrical contacts ( 203 ) mounted thereon which are oriented so that the contacts ( 203 ) make electrical connection with charging contacts ( 115 ) of the battery charger ( 101 ) when the battery is placed in the battery charger . the charging contacts ( 115 ) of the battery charger housing ( 101 ) are located on the interior bottom surface ( 117 ) of the housing . the interior bottom surface ( 117 ) is an essentially flat surface parallel with the bottom of the battery charger housing . the sides ( 205 , 207 ) of the battery housing of fig2 and 3 slope inward at an angle 0 relative to a line perpendicular to surface ( 201 ). in the preferred embodiment , the angle 0 equals an angle of 10 °. the difference in size between the small size battery of fig2 and the large size battery of fig3 is primarily a difference in thickness from the surface ( 201 ) to the top surface ( 209 ) in fig2 and 3 . in the preferred embodiment , the battery housing thickness , t 1 , of fig2 is approximately 10 millimeters while the thickness , t 2 , of the large size battery of fig3 is approximately 20 millimeters . the battery charger of the present invention is so arranged that the contacts ( 203 ) of both the large size and the small size batteries are positioned in electrical contact with the charging contacts ( 115 ) of the battery charger when either battery is placed in the battery charger housing . a vertical plane cross - sectional view of the battery charger of the present invention is shown in fig4 . in this view the battery rib member ( 111 ) of recess ( 103 ) and the battery rib member ( 401 ) of recess ( 105 ) may be seen . rib members ( 111 and 401 ) are oriented at an angle φ relative to the plane of the bottom surface ( 117 ) of battery charger ( 101 ). in the preferred embodiment , φ = 30 ° and the rib member is approximately 29 millimeters long and 1 . 35 millimeters thick . the rib members , when engaged with the slots ( 113 ) of the battery housing ( 107 ), produce an alignment in the surface of the battery housing ( 107 ) carrying the contacts ( 203 ) parallel to the base of the battery charger ( 101 ) such that the battery charger contacts ( 115 ) make contact with the battery electrical contacts 203 regardless of whether the battery is the small or large size battery . the circuit board containing electronics of the battery charger is disposed beneath the battery charger base surface ( 403 ). this circuit board ( 405 ) is contained within the battery charger housing ( 101 ) and supports the electric contact members of the battery charger contacts ( 115 and 407 ). power is supplied to the electronic circuitry on circuit board ( 405 ) by way of power jack ( 409 ). a cross - sectional detail view of the side wall having interior surface ( 109 ) and exterior surface ( 505 ) is shown in fig5 . although the cross - section illustrates a solid wall for ease of understanding , it is within the scope of the present invention to utilize a hollow wall construction . a cross - section of the small size battery ( 107 ) is shown contacting the interior side wall ( 109 ). likewise , a cross - section of the large size battery is shown in dotted line and illustrates the position of the large size battery housing when contacting the interior side wall ( 109 ). it is to be noted that the surface ( 201 ) of both batteries is positioned on the same plane . the side wall itself is configured having a tapered cross - sectional shape with the largest area to the rear of the battery charger housing ( 101 ) and narrowing toward the front of battery charger ( 101 ). thus an acute angle 0 is formed by the interior wall surface ( 109 ) of the battery charger pocket or recess ( 103 , 105 ) and the exterior surface ( 505 ) of the battery charger housing ( 101 ). in the preferred embodiment , the interior wall surface ( 109 ) and the exterior surface ( 505 ) of the battery charger housing ( 101 ) are essentially planar wall surfaces and the imaginary planes formed by the walls , when extended , intersect in the angle 0 with the vertex of angle 0 toward the front of the battery charger housing ( 101 ). since both the battery charger housing ( 101 ) interior walls and the sides of the battery housing ( 107 ) have the same value of angle 0 , the battery is guided by the interior side walls as it is inserted into the charging pocket of the battery charger . as the battery is slid further down in the charging pocket , the slots ( 113 ) in the battery housing ( 107 ) engage the rib members ( 111 ) of the battery charger housing ( 101 ) to accurately position the battery and its charging contacts ( 203 ) relative to the charging contacts ( 115 ) of the battery charger . the side wall of the battery charger housing extends to the front of the battery charger . at the front , the side wall curves inward to begin enclosing the charging pocket ( 103 ). the side wall terminates in a protrusion ( 507 ) which is used to captivate one of the surfaces of a portable cellular radiotelephone such as that previously mentioned ( f09hgd8453aa ) and similar to that shown in u . s . patent application ser . no . 255 , 696 , &# 34 ; portable telephone , telephone handset , or similar article &# 34 ; filed on behalf of soren et al . on oct . 11 , 1988 and assigned to the assignee of the present invention . the use of protrusion ( 507 ) and a similar protrusion on the opposite side wall will hold the aforementioned cellular portable in the correct position so that an attached battery ( having a conformal shape ) will be charged while attached to the cellular portable .