I finally got around to building a new battery for my goggles, the one I have been using is over a year old and showing its age. The build turned out to be a lot easier than I thought it would be.

Parts used.

2 16500 Li-ion batteries

1 Male JST-XH – Female Kokam 2S

1 Lipo 2s battery voltage display board

Step 1:
Take your two 18500 cells and solder a 20mm length of wire between the negative (-) and positive (+) terminals at one end of the cells. Be careful to make sure that the wire is well insulated on the positive end as only the center of the pack is positive. If the wire is allowed to make contact between the center terminal and the outside of the cell you will have a fire on your hands. I used a piece of solder wick for this.

Step 2:
Attach a smaller wire to either end of the joiner piece and run it up the middle of the cells and leave it loose at the other end. This will be used for your  middle lead of balance connector.

Step 3:
Secure the 2 batteries together, I used a nifty battery case I found on Thingiverse, but you can use almost anything from  electrical tape to shrink-wrap or even hot glue. The important thing is to make sure they are secured together.
Step 4:
Connect up the two remaining exposed terminals to the main power connector for your goggles paying careful attention to polarity.

Step 5:
Hook up an additional wire to each of the main terminals and connect them to your balance connector as shown in the picture above. If using the voltage display hook that up as well.

Step 6:
Ensure all connections are well insulated as well as double-check that the polarity at the plug is correct. Now you can go out and fly using your new battery pack.