I appreciate Solaris8x86's concerns re: pricing/selling his replacement battery packs.
Would any of these work?
GForce 20C 2700mAh 2S 7.4V LiPO for WLToys 12423 and 12428 (T-Connector) | Value Hobby
Amazon.com: ZZBAT 2pcs 7.4V 2700mAh 20C 2S Lipo Battery with T Plug for Wltoy 10428-A 10428-B...