Alkaline batteries loose almost all their capacity at lower temperatures, and it’s pretty cold up there in the space. At 50,000 ft altitude, the temperature drops to -60ºF and Alkaline batteries would almost certainly freeze. HAB-1 got its power from Energizer Advanced Lithium batteries, which work in extremely low temperatures, plus have larger capacity. There were 10 batteries total: 8xAA for APRS and 2xAA for camera.
Unfortunately, lithium batteries are about 10 times more expensive than Alkaline ones. For testing purposes, I used Rayovac Alkaline batteries with 1,500mAh capacity. Lithium batteries carry 3,000mAh, so I assumed that electronics during the flight would last at least as long as during test, or up to twice longer.
Camera’s battery life
With 2xAA Alkaline batteries, and shooting an image every 5 seconds, my Canon camera lasted for 2.5 hours and took 1,700 photos. Impressive!
APRS tracker’s battery life
With 8xAA Alkaline batteries, Byonics MT-400 APRS tracker lasted for about 2 days before the battery discharged below minimum 9V voltage. Not bad,
Radio beacon’s battery life
With 2,000mAh LiPo battery, and 25% duty cycle (0.5s transmit / 1.5s idle), radio beacon kept going for 4 days. After this test, I reduced the duty cycle to 12% (0.5s transmit / 3.5s idle), at which it should keep working for a whole week. Wow!
LiPo batteries do not work in cold temperatures. I taped a few hand warmers around the battery to maintain its temperature.