Summary

I've now flown many hours with the stock x9d+ battery and it simply does not last long enough for my liking. I had a few spare 18650's (that I use for my goggles) and I figured they would make a great replacement for the stock battery of my transmitter. I found this https://www.thingiverse.com/thing:2990863 design on thingiverse and took inspiration to make my own. My design allows the cells to be easily removed, charged and replaced.

I have included the fusion file is you would like to modify my design. Just know I'm a noob at designing so the file is very messy.

Print Settings

Printer Brand:

Creality

Printer:

Ender 3

Rafts:

Supports:

Yes

Resolution:

0.16 mm

Infill:

15%

Filament: Sunlu PLA White

Notes:

The quality is not to important for this mod to work so you could definitely go with slightly higher resolution.

For supports I used organic supports and they worked amazing but it might even be possible to print this without supports.

Post-Printing

Step 1 : Procure Parts

This project does not require many parts;

18650 x2
2s balance connector (I took mine from the old battery)
Some extra wire + heat shrink (If you have)
Fairy lights (I got some for $1 at the dollar store)
Super glue (optional)

The reason for the fairy lights has nothing to do with the lights but rather the AA battery holder that powers it. All we need from it are the metal contact from the inside of the holder. You can solder off the switch and the lights and remove the plastic casing. What's left should look like the picture below.

Before

After

Step 2 : Finishing the holder

The first step is to solder a long wire to the big metal piece.
For all soldering done to the metal pieces it is easiest to first scratch up the metal a bit with sand paper before soldering to it.
The wire from the big piece runs along the groove in the bottom of the print and attaches to the middle of the connector. I placed some electrical tape over the groove to keep the wire from hoping out. If you are using the connector from the original battery you will need to find your own wire for the middle (I used a wire from a dead lipo).

The next pieces to solder are the little metal pieces. I found the easiest way to do this was first place them in the right spot, bend the metal around the slot modeled in the part and then solder it on the inside.

The pieces seem to stay in place pretty well but if you are planning on using glue to secure the metal parts in place this is a good time to do it. I personally did not just in case I ever decide to print an upgraded version.

On the transmitter the positive wire goes to the left most pin

Step 3 : Cutting

Now you need to cut supports out of back of Taranis. The picture below shows the battery bay after they were cut.

Try not to scratch up the pcb like I did. For the cutting I used a combo of an exacto and some cutters.

Step 4 : Assembly

This is where I had the most difficulty. Getting the battery plugged in after sliding in the 3d printed part was a pain but with a bit of effort I managed. The issue might be avoidable if you have longer wires and plug in the connector first than slid in the plastic part after.

I put a piece of tape around the positive end of one 18650 to have an easier time pulling it out of the battery bay.

The battery bay cover perfectly fits over everything as long as you remove to original foam stuck under it.