Incan FAQs
by TigerhawkT3

1. What does "overdriving" mean?
2. What is "double-tapping"?
3. What is "instaflash"?

1.
Q: What does "overdriving" mean?
A: Every incandescent bulb has a rated nominal voltage, which is basically the manufacturer recommended driving voltage. A bulb connected to a lower-voltage source than is recommended with have weaker and more orange-tinted output, but it will have increased durability and lifetime. A bulb driven above spec will have whiter output, but decreased durability and lifetime. A given bulb's efficiency actually increases along with drive level.

2.
Q: What is "double-tapping"?
A: This refers to a phenomenon involving high-powered bulbs and a protected Li-Ion battery. Such a battery contains one or more Li-Ion cells, each with a protection circuit that cuts power when it detects overcharging, overdischarging, overheating, or short-circuit. The protection circuit determines a short-circuit by checking the current draw at a preset drive level. A common 18650 cell, for example, may have its protection set at around five amps (5A). This comes into play when the battery runs a high-powered incandescent bulb. Incans have lower resistance when they are cold, and the resistance increases with temperature. As such, a bulb with a cold filament may draw too much current for a protected Li-Ion battery, triggering its short-circuit protection. Once this has occurred, however, the filament will be slightly warmer, increasing resistance and decreasing current. This may allow the battery to power the bulb without triggering the protection circuit.

3.
Q: What is "instaflash"?
A: Since an incan bulb is whiter, brighter, and more power-efficient when it is overdriven, it is common practice to push bulbs almost to their bursting point. If a particular flashlight drives its bulb right at the edge, it may sometimes provide too much voltage and current (when the battery is fresh, for example), which will cause the bulb to burn out.