diff --git a/stl/battery_pack/battery-pack-contact-nuts.scad b/stl/battery_pack/battery-pack-contact-nuts.scad
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+/***************************************************************
+ Parameterized Battery pack with electrical connections
+  (c) 2010 Juan Gonzalez-Gomez (Obijuan) juan@iearobotics.com
+   This design is derived from the Battery comparment generator
+   (c) Nikolaus Gradwohl (guru (at) local-guru.net)
+    http://www.thingiverse.com/thing:5051
+Other contributors:
+  * Chris Thompson (http://eagleapex.com/): Connection in series along the case
+ -----------------------------------------------------------
+ The nuts (two per battery) are embedded into the battery pack. 
+ The screws (two per battery) are inserted from the outside and
+ touch the batteries.
+-----------------------------------------------------------
+GPL LICENCE
+****************************************************************/
+
+//-- Battery sizes
+
+AA = [ 14.5, 50.5 ];
+AAA = [ 10.5,44.5 ];
+C = [ 26.2, 50 ];
+D = [ 34.2, 61.5 ]; 
+
+// CHOOSE BATTERY TYPE AND COUNT 
+typ = AA;
+num =3;
+
+
+//---------------------------------
+//-- Battery pack parameters
+//-- Can be set by the user
+//---------------------------------
+
+//-- Battery pack thickness
+bottom_thick=1.5;
+fr_thick=3.5;    //-- Front and rear parts
+side_thick=2;    //-- Side part
+
+//-- Distance beween batteries
+distance_bat=1;
+
+//-- Nut parameters
+nut_h = 2.5;
+nut_radius = 6.4/2;
+nut_drill = 3.1;
+
+//------------------------------
+//-- IMPLEMENTATION
+//------------------------------
+//-- Battery dimensions: width, height and length. Change ser for batteries in series along the case.  
+
+ser=1;
+w=typ[0];
+h=w;
+l=typ[1]*ser;
+
+//-- Dimensions of the inner part of the compartiment
+ip_l = l;
+ip_w = w + (w+distance_bat)*(num-1);
+ip_h = h;
+
+//-- Dimensions of the mother cube
+mc_l = ip_l+2*fr_thick;
+mc_w = ip_w+2*side_thick;
+mc_h = ip_h+bottom_thick;
+
+//-- The process of building the battery pack is just substracting
+//-- things to the mother cube
+rotate([0,0,90])
+difference() {
+  //-- The mother cube
+   translate([0,0,-bottom_thick/2])
+    cube(size=[mc_l, mc_w, mc_h],center=true);
+
+  //-- Array of batteries
+  translate([0,0,h/2])
+  cube(size=[ip_l,ip_w,ip_h],center=true);
+
+  translate([0,-mc_w/2+w/2+side_thick,0])
+  for ( i = [0:num-1] ) {
+
+    translate([0,i*(w+distance_bat),0])
+    union() {
+      translate([0,0,h/2])
+         cube(size=[l,w,h],center=true);
+
+      rotate([0,90,0])
+        cylinder(r=w/2, h=l-0.01, center=true, $fn=50); 
+    }
+  }
+
+  //-- Array of contacts
+  translate([0,-mc_w/2+w/2+side_thick,0])
+  for ( i = [0:num-1] ) {
+    //-- Drills
+    translate([0,i*(w+distance_bat),0])
+    rotate([0,90,0])
+    cylinder(center=true,h=l+20, r=nut_drill/2, $fn=50, center=true);
+
+    //-- Room for the embedded nuts
+    translate([0,i*(w+distance_bat),0])
+    rotate([0,90,0]) 
+    cylinder(h=l+2*nut_h, r=nut_radius, $fn=6, center=true);
+  }
+  
+}
+