Could a larger capacitor be used to increase the time of useful light output?
Several capacitors were studied during the development of NightStar. NightStar currently uses a 1.5 Farad, 5.5V capacitor. A capacitor with an energy storage capability 3 times greater than this is also available (3.3-Farad, 5.5V). However, it would require 3 times longer to fully charge this capacitor. The 3.3. farad capacitor is also larger and would increase the size of the flashlight. We concluded that 30 seconds of charging to produce 20 minutes of useful light was the best compromise.
