USB-C Charger for RETEVIS RT29 / Ailunce HD1

This is a small portable USB-C charger for the RETEVIS RT29 / RT29D and Ailunce HD1.

Instructions copied from original.

Note that tolerances are pretty tight for getting a good firm fit on the radio. Each slicer and printer and filament is different - you may need to do some sanding or adjust the file to get a perfect fit. The STEP file is included should you need to edit it.

Also note that lipo batteries and chargers can be hazardous if things aren't done correctly. Double check your work.

You will need:
* Solid core wire (I used 22AWG)
* A 2S1A usbc charging module, any cheap module from aliexpress works. (I'm using this one)
* Two small 5.1k resistors
* Super glue (required if not using hot glue but recommended aswell)
* Hot glue (optional but recommended)

Note 1: You must add the 5.1k resistors for the charger to function with proper USB-C power supplies. This requires very fine soldering work. Otherwise you will be limited to using “dumb” USB-A to USB-C cables.

Note 2: Too much hot glue will warp the print.

Print Settings:
* 0.2mm layer height recommended
* Supports only holding up the top of the body, not needed elsewhere
* Tree supports strongly recommended (see images in original model)

Assembly:

Several steps of the assembly process are shown in the pictures for this model, refer to the original model to view them.

1. Remove supports and clean up print
2. Cut two lengths of wire and strip ~3cm from one end
3. Loop the stripped wires through the holes to create the charging contacts
4. Solder the ends of the wires back onto themselves carefully - do not melt the plastic
5. Cover the exposed wire inside the charger with kapton or electrical tape to prevent shorting to the board
6. Add a 5.1k resistor separately to each of the two middle pins of the USB-C connector and connect the other end of both resistors to the GND pad in the corner of the board. Check that the resistors are not connected to each other or the other pins of the USB-C connector. DANGER: if this is incorrect, you could create a short that may harm this device or the device supplying the power. Not adding resistors is safe but will limit what power supplies can be used. 
7. After soldering, additionally secure the resistors in place with hot glue
8. Solder the other end of the wires to the correct terminals. Ground is the wire from the contact closest to the USB-C opening in the case, and attaches to the pad labeled GND on the far side of the board. The positive wire is the opposite. DOUBLE CHECK these are correct by looking at the contacts on your battery - they are labeled +/-.
9. Insert the board fully, push down, and secure with hot glue (optional)
10. Attach the back panel with super glue (hot glue works aswell but will warp the back panel)
11. Without a battery inserted, plug the empty charger into a power supply. Confirm the blue light turns on through the small hole in the back panel. Confirm power draw from the power supply is minimal (<1W).
12. Insert the radio/battery into the charger. Confirm the light turns red and the battery is charging. Power draw should be under 10W.

Made from scratch in Fusion 360 with the orginal to base this model off.