This instructable will show you how to make a coin cell battery holder that can be soldered to your project, and will allow easy insertion and replacement of the battery.
Step 1: Gather the Materials
Mini fuse clip
Small piece of thin tin, tin snips
Felt tip marker
22ga copper wire, ~ 2 inches
Small non-serrated pliers
Soldering iron, solder
Small piece of prototyping PCB
Small alligator clip or equivalent
Double sided and regular plastic tape
5 minute epoxy
Step 2: Modify Your Fuse Clip As Needed
Fuse clips come in a variety of forms; mine had a small side extension which I clipped off. Modify yours as needed to look like the one on the right.
Step 3: Prepare the Tin
Insert tin scrap into clip, mark margins with marker, cut out, sand one side with fine sandpaper to aid soldering later, bend one end of tin toward sanded side to form a shoulder.
Step 4: Insulate the Clip
Cut a piece of electrical tape slightly larger than the clip, apply it to the inside of one side of clip, smoothing the tape onto the clip surface, fold the rest over the backside of the clip. Note the smooth application to the curved surface of the clip.
Step 5: Mark the Tin
Lay the pre-cut tin over the tape with the shoulder of the tin pressed down on the upper part of the clip, and hold in place with small alligator clip. Use felt marker to mark the tin where it overlies the curved portion of the fuse clip. Remove the tin and extend this mark onto the sanded side of the tin.
Step 6: Soldering
Place tin, sanded side up, onto doubled sided tape on flat surface, lay copper wire over mark on tin and tape down with regular tape. Note only a small overlap of the wire is desired on the right side. Solder wire to tin, remove from tape, cut off excess wire on right side.
Step 7: Glue It Together
Apply a thin layer of 5 minute epoxy onto the soldered surface of the tin, lay glued surface onto the inner surface of the fuse clip covered with electrical tape, ensuring that the soldered area lies within the curved surface of the clip. Hold together with alligator clip until set.
Step 8: Form the Wire to Fit the PCB
Mark 3 holes on the perforated PBC as shown; the 2 on the same line will receive the pins of the fuse clip. The 3rd, to the side and back one line, will receive the copper wire. Bend the copper wire down so that all fit neatly on the board. When the wire has been bent appropriately, cut off excess, leaving enough to solder. Your holder is now complete and ready to mount on your project. Note: depending on the size of the pins on your fuse clip, the PCB holes may need to be enlarged to accept them.
Step 9: Insert the Battery
Slide your battery into the clip to test for proper fit. Important: the NEGATIVE side of the battery must face the piece of tin. If your battery is too loose, it is easy to bend the opposite side of the clip for a tighter fit. This mini fuse clip will accommodate numerous sizes of cell batteries in this manner. For thicker batteries, such as the LR44, start with a larger fuse clip. For either size, a small rubber band can be added to prevent sideways movement of the battery in the holder.