Simplified frame, the other version did not fit.

cad/battery_holding_frame.scad

@@ -9,40 +9,26 @@ frame_x = 10;
 frame_y = 62;
 frame_z = 3;
 
-bec_x = 35;
-bec_y = 40;
-bec_z = 4;
-
-cage_x = bec_x;
-cage_y = bec_y;
-cage_z = battery_z + bec_z + 3;
-
-
 module cube_centered(x,y,z) {
     translate([-x/2, -y/2, 0]) cube([x, y, z]);
 }
 
 module cube_round_corners(x,y,z) {
     hull() {
-        translate([-x/2, -y/2, 0]) cylinder(d=3, h=z);
-        translate([ x/2, -y/2, 0]) cylinder(d=3, h=z);        
-        translate([-x/2,  y/2, 0]) cylinder(d=3, h=z);
-        translate([ x/2,  y/2, 0]) cylinder(d=3, h=z);        
+        translate([-x/2, -y/2, 0]) cylinder(r=3, h=z);
+        translate([ x/2, -y/2, 0]) cylinder(r=3, h=z);        
+        translate([-x/2,  y/2, 0]) cylinder(r=3, h=z);
+        translate([ x/2,  y/2, 0]) cylinder(r=3, h=z);        
     }
 }
 
 difference() {
     union() {
         cube_round_corners(frame_x, frame_y, frame_z);
-        cube_round_corners(cage_x, cage_y, cage_z);
-        translate([0, 0, cage_z]) cube_round_corners(bec_x, bec_y, bec_z);
+        cube_round_corners(frame_x, battery_y, battery_z + 3);
     }
     cube_centered(battery_x, battery_y, battery_z);
     translate([0, -baseplate_hole_distance/2, 0]) cylinder(d=3, h=3);
     translate([0,  baseplate_hole_distance/2, 0]) cylinder(d=3, h=3);
-
-    translate([0, 0, battery_z+3]) cube_centered(bec_x, bec_y, 100);
-    translate([0, 0, battery_z]) cube_centered(bec_x-9, bec_y-12, 100);
-
 }