Compact 18650 Heltec V3 Case for Meshtastic

I wanted a compact case to house a Heltec V3 and an 18650 battery. I was unable to find one I liked, so I designed one. This was designed in OnShape if you would like to make some alterations.

Features

• Changeable faceplate 
• Battery Kill Switch
• Large External Antenna Support (13mm base) 
• Minimal Hardware required
• Cable Routing
• Replaceable battery
• Printed Battery Terminals

BOM

• Heltec V3 Kit with battery connector & SMA Pigtail & Antenna
• M3 Screw 4mm - 8mm
• M3 Heatset Insert (4mm or 5mm diameter) *optional
• Switch SS12D00 (3pin 1P2T 3mm handle) *optional
• Heatshrink insulation (1mm-2mm) *optional
• Extra Wire 28AWG *optional

All models are printable in their current orientation and do not require supports. This includes the main body, it designed to be printed vertical. The eagle eyed will notice something blocking the antenna hole. This is a built in bridge support.

 I've used PLA for everything except for the battery contacts. I think they'll work in PLA, but ABS or PETG would give it the desired spring quality, and less likely to break.

Tips

• Dry your filament - Tolerances are fairly strict. blobs and strings will not help. 
• Level your bed - The face plate will look good, and also the main body is a tall print it can lift off the bed.

Build Guide

Step 1 - Print Options

Choose the files for your hardware. It was designed to be used with the switch listed, and a 4mm Outer diameter M3 insert. If you don't have the switch, you can use a blank faceplate to cover up the hole, And if you don't want to use an M3 insert, there is 2.7mm hole version that should allow an M3 screw to tap its own thread.

Print List

• 2x Battery Contact (Recommend PETG or ABS)
• 2x Battery Terminal Base
• 1x Face Plate
• 1x Bottom Plate
• 2x Buttons (I use long for left button & short for right (reset) button)
• 1x Main body
• Backing Spacers - May not be needed, Print 2 of each if you want to be prepared

Step 2 - Clean up the print

• Clean up stringing 
• Remove the bridging supports in the antenna hole. (Needle nose pliers and small screwdriver work great)
• Clean up the hex hole so that the SMA connector will fit smoothly.

Step 3 - Test fit components, 

• Make sure the board slides in all the way and push through the SMA connector, you may need to screw on the nut to draw it through.
• Install the heatset insert

Step 4 - Positive Wire

• You may need extra wire than what is provided in the heltec kit. For the battery contacts, strip off 40mm of wire (10mm per wind + 10mm extra). Twist the strands together and thread it through one side of the terminal base, and out the rectangular hole.

• Thread the wire through the concave side of the battery contact, and wrap it through the holes. You want to leave a little be of exposed wire on the concave side so you can twist them together. Seat the contact into the base.

• Place the assembled battery terminal on top of the battery, run the positive wire into the main body. 

• Slide the body over battery, pushing the terminal to the end. Remove the battery. The terminal should stay in place from the friction of the wire. If you want a more secure fit you can use glue.

• Once in position, You can install the SMA connector if you haven't already. If using a switch, thread the positive wire underneath the SMA conector pigtail and out the switch hole.
• Cut the JST battery cable to length. The JST connector should extend about 10mm past the bottom of the case, the positive wire runs straight up to the switch hole. The negative wire is routed through a loop next to the heatset insert on the bottom, then routed around the insert and into the battery chamber, where you will need the 40mm of exposed wire (assuming you want 3 winds)

Step 5 - Switch

• Cut 1 leg off, and trim the other 2. Note: when installed, the two switch legs are on the right so that they clear the PCB. (The on position is away from the antenna)

• Solder the 2 wires and insulate them appropriately (heatshrink, tape, glue)
• tuck the wires in, bend them to the left.

Step 6 - Cable Routing & Negative Wire

• Loop the antenna cable around once, you can choose to have the second loop above the PCB or below. I prefer above, there is lots of room next to the screen. Use any of the 3 cable loops, you can thread wires through, or tuck them behind.

• Double check your polarity, The heltec board has markings near the battery connector. 
• I'd recommend leaving the unit switched off during assembly.
• If you haven't already thread the negative wire through the small hole next to the heated insert. 

• Assemble battery contact the same as the positive wire. 

Step 7 - Install Heltec Board

• This is a good time to test the battery switch circuit.
• Clip on the Antenna pigtail, rotate the cable to the left
• Ensure the battery connector is outside the case
• Slide the board in while keeping an eye on the antenna cable.
• When you get near the end, plug in the battery connector
• push everything snug, you can use your finger inside the battery chamber, The board will likely push on the switch wires a little. Make sure none of the wires are getting damaged.

Step 8 - Install Buttons & Face Plate

• Slide the bottom plate under the right side of the main body to level the face

• Drop the two buttons in (longer one for left)
• Install the faceplate by hooking in from the top, and then lining up the buttons. (alternatively you can install the buttons to the faceplate first, and hold them with tape or your thumbs.

Step 9 - Install Bottom Plate

• With the battery in position, The base of the terminal should sit slightly below the edge. Use an appropriate spacer(s) to get the proper fit. 
• You can now attach the bottom plate, by hooking it in battery side first.
• Give everything a good shake, if things are loose, you may need to use more spacers, glue or tape. 

Fin.