In this instructable, I show you how I made my replacement batteries for my FatShark FPV goggles. I used the famous NCR18650B batteries, two 3d printed end caps, a 2S balancer extension cord, a battery connector and shrink wrap tube for this project.
Here is the link to the end caps I designed for this: https://www.thingiverse.com/thing:2435782
Step 1: Wires and Soldering
The batteries need to be oriented so one battery's "-" connects to the other battery's "+". At the other end of the batteries, the "+" and "-" leads of the discharge cable and the balancer cable are connected. The middle lead of the balancer connector goes in between the two batteries, just like in the photo.
In order to solder these batteries, first roughen the surfaces of "+" and "-" with sand paper, then quickly solder a bit to them and quickly cool them down again. Finally, attach the pre-soldered wires to them by heating the solder on both sides for a few seconds, then cool again. It is important that the battery doesn't get too hot.
Let someone help you if you feel insecure about holding a several hundred degrees hot soldering iron against a highly flammable and under certain conditions even explosive lithium battery.
Step 2: Shrink Wrap
Finally, put the battery pack into a piece of the shrink wrap tube, add the end caps and make sure they sit firmly on the batteries and then shrink the tube around battery and end caps. Voila, your new batteries for the FatShark FPV goggles!