The Batteries

Since the payload would be exposed to temperatures as low as -50°C, perhaps even -60°C, it was worthwhile to think about the impact on the batteries. Especially because I wasn't completely sure about the payload's capabilities to retain such freezing temperatures. In other HAB projects, I had seen them use Energizer's Ultimate Lithium AA batteries. They are somewhat more expensive, but the manufacturer states their operating temperature as low as -40°C. The specification also states their ability to maintain the capacity of 3000mAh under such conditions provided a constant current discharge of 25mA. All in all, the batteries should allow +10 hours functionality of the transmitter.