Beware of any NIMH system that relies on the you, the user, to unplug the charger. Such systems run the dual risk of overcharging and undercharging. Either can lead to the early failure of the battery, usually the most expensive part of any bicycle light. None of the batteries mentioned above exhibit this disproven phenomena. Why does Nightsun use High Pressure Argon-Halogen lamps.
Halides are reactive elements that include iodine and bromine.
These are added in very small amounts to the inert argon gas in the lamp. No, it just prevents the gradual darkening, typical of vacuum lamps. The hotter the filament the more efficient the lamp. The upper limit to filament temperature is the boiling point of tungsten. This allows a higher filament temperature, greater visible light output and increased efficiency.