I've made this Battery Pack with 3000mAh Lithium Polymer (405585) batteries from Ebay. It's Perfectly Fits to the Battery Bay on Taranis Qx7.
Check it out the links for purchases. (405585 Lipo)
https://www.ebay.com/itm/3000mAh-3-7V-LiPo-Polymer-Rechargeable-Battery-For-PAD-GPS-DVD-Power-Bank-405585/121926114344?epid=2008602019&hash=item1c635cdc28:g:ySgAAOSwefVZm6t0
https://www.ebay.com/itm/Lot-5-pcs-3-7V-3000mAh-405585-LiPo-Rechargeable-Battery-For-Power-Bank-Tablet-PC/112535780335?hash=item1a33a7bbef:g:Mz8AAOSwhLJZm7I4
