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Nightsun FAQ - Frequently Asked Questions

Things you've always wanted to know
about choosing a bike light.


FAQ's For Bike Light Batteries

What types of rechargeable batteries are used for bike lights?
Until recently two types of batteries have dominated bike lighting, Lead Acid and Nickel Cadmium. Recently a third type, Nickel Metal Hydride, has emerged as the premium choice.


What are the Pros and Cons of Lead Acid batteries?
Lead Acid batteries are about twice the weight of Ni-Cads for the same capacity and can suffer damage if not recharged on a regular basis. The main advantage is their low cost. Because of their limited performance and weight penalty, Lead Acid batteries are most often used in inexpensive, low performance systems.

What are the Pros and Cons of Nickel-Cadmium batteries?
Ni-Cads are 1/2 the weight of Lead Acid batteries, need no special care, are easily safely charged with simple chargers. The combination of moderate cell cost and low cost chargers make Ni-Cads the clear choice for High Performance, High Value systems.

What are the Pros and Cons of Nickel Metal Hydride batteries?
NIMH batteries are the newest battery technology to be used for rechargeable lights. NIMH batteries are up to 40% lighter than even Ni-Cads. This means longer runtimes, less weight, or both. The major disadvantage of NIMH batteries is that they are much more difficult to charge correctly. Unlike Ni-Cads, which can easily tolerate continuous charging without harm, NIMH batteries are easily damaged by even small amounts of overcharge. This means that NIMH powered systems should include high quality "Intelligent" chargers. 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.

What is memory?
"Memory" is a disproven myth. The memory myth incorrectly contends that Ni-Cad batteries must be discharged 100% before recharging or they will "remember" a shallow discharge and fail to deliver 100%. None of the batteries mentioned above exhibit this disproven phenomena.

FAQ's about Halogen Lamps

Why does Nightsun use High Pressure Argon-Halogen lamps.
Greater light output, long life without gradual darkening & resistance to shock and vibration are the primary advantages of Argon-Halogen lamps.


What is "Halogen" and what does do in the lamp?
Halides are reactive elements that include iodine and bromine. These are added in very small amounts to the inert argon gas in the lamp. The "halide cycle" acts to redeposit tungsten evaporated from the filament thereby preventing the tungsten from condensing on the inside of bulb, causing gradual darkening.

Does the Halogen make the bulb brighter?
No, it just prevents the gradual darkening, typical of vacuum lamps.

Why are the lamps filled with High Pressure gas?
The hotter the filament the more efficient the lamp. The upper limit to filament temperature is the boiling point of tungsten. High pressure (around 100 PSI!) gas filling raises the boiling point. This allows a higher filament temperature, greater visible light output and increased efficiency.

Why do miniature gas filled lamps offer improved resistance to shock and vibration?
Miniature high pressure gas filled lamps have much shorter thicker filaments than vacuum lamps. Short, thick wires are much stronger than the long thin filaments typical of vacuum lamps.

What are the effects of "overvolting" incandescent lamps?
Incandescent lamps are quite sensitive to voltage. If a "10 volt" lamp is operated at 12 volts it will produce twice the light, but will suffer a 95% reduction in life. Minor levels of overvolting (10% or less) will improve efficiency without unacceptable reductions in lamp life. Nightsun's Tri-Light and SunSport both use overdriven lamps.

What are the effects of "undervolting" lamps?
Incandescent lamps operated 20% below their design voltage will produce 50% of the light and will greatly extend the life of the bulb. The reduction in light output is much greater than the reduction in power consumption. Extended operation at low voltages can inhibit the halide cycle and result in premature bulb darkening.

What are the effects of "Dimmer" based systems?
In an effort to offer multiple light output levels from a single filament some systems employ dimmers. These devices vary the voltage supplied to the bulb. A 12 watt lamp dimmed to consume 9 watts will produce about the same light output of a undimmed 5 watt lamp. Dimmers will allow longer runtimes, but with very inefficient light output. Multiple filaments, each operated at or slightly above their design voltages are a much more efficient solution.

Nightsun Performance Lighting
995 So. Fair Oaks Ave. - Pasadena, CA 91105 Tel. (626) 799-5074
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