My stock battery is quickly losing its charge now, so I have been exploring other options. I decided to take on the challenge to make 3S LiIons fit nicely as well as provide external power to the Crossfire or Goggles. The model is blank with no name on it FYI. This can accept 2S or 3S so you can use your goggles packs in place as well.
BLACK XT30's are available from AirbladeUAV.
Use quality cells - if it has fire in the name, it will catch on fire. These green cells are Samsung mj1 3500mah from IMRbatteries.com.
The only mod that needs to be done on the TX side is two chunks of plastic need to be cut out - See the picture below.
**After getting a chance to use this extensively over there past few weeks I can say I am thoroughly happy. Using it for 6+ hours then using it for another 3 hours with goggles plugged in I was only down to 11.6V. I decided to charge it and only put back in 1000mah. I have my low voltage alarm on the Taranis set to 10.5.