Kinda related but for anyone looking for a battery that is a 4s and fits the alpinetech B box for the 250c. This is one of the biggest I could find (please inform if I’m wrong, bigger the better!). I failed to realize it did not come with a 3s lipo connection. Happy building!

Venom 30C 4S 1400mAh 14.8V LiPo Drone Battery with Universal 2.0 Plug (XT60/Deans/EC3) https://www.amazon.com/dp/B0199R5RCA/ref=cm_sw_r_cp_api_wwUSAbD5KR23M