A bit more on lighting systems:

I want to focus on rechargeable lights in this post.

There are three main types of rechargeable systems currently available, and several battery technologies.

Let’s consider light types first. These group by the thing that actually makes the light.

Incandescent lamps: (light bulbs) usually halogen bulbs. This is just a high tech light bulb. It has a filament, and eventually, the bulb will burn out. Halogen bulbs are reasonably bright, and emit a good white light. The problem is that they tend not to do it for very long when mated to a battery. In other words, they are not very energy efficient. There are some very good halogen systems out there. But typical burn times are in the two-hour range.

HID emitter: HID stands for High Intensity Discharge. Think of this as an especially high tech arc light. These are incredibly bright lights. The light is well into the blue end of the spectrum. They are very high-energy output. When mated to some pretty expensive battery systems, HID lights can burn for as much as four hours. Then they have to be recharged. These also tend to be very expensive.

LED: or Light Emitting Diode. This technology just keeps getting better and better. These lights have gotten to the point of being more than adequate for the serious commuter or tourist. I’ve done all night rides with them, and continue to find them a surprising value. The LED is a solid-state device. It uses remarkably little energy to produce the light. One caution, the overdriven ultra brights are sensitive to cooling. Look for lights with good heat sinks. Ideally metal casings.

One note of caution on LED type lights. They emit well into the blue end of the spectrum. This means that the beam is really absorbed in rain, and backscatter glare can be a real problem in rain or foggy conditions.

Batteries:

There are several factors in rating batteries, cost, weight, “charge density,” lifetime, level of maintenance. Most of these are self explanatory, but “charge density” may not be familiar to you. A brief discussion follows, but for those of you not so technically inclined, a higher charge density means it gives more power over a longer time.

Charge Density Explained:

Key terms:

• Voltage: Electromotive force. Unit = Volt
• Current: How much charge is moving. Unit = Ampere (or Amp)

Batteries are electro-chemical storage devices. As such it has long been normal to rate them according to two factors. The first is output voltage. This is a function of the number of cells in the battery’s construction, and the type of cell. Typical voltage per cell is around 1.6 volts. This can vary depending on the chemistry of the cell in question.

The second rating is a current-time rating. For larger batteries this would be AmpHours. A ten AmpHour battery would be capable of delivering 10 Amps for one hour, at it’s rated voltage. Or 1 Amp for 10 hours.

Naturally, in the wonderful world of bicycling, real specifications such as this are hard to obtain. But generally, when I state that a battery type has a high charge density, I am referring to more AmpHours (or AmpMinutes) for a given battery weight.

Alkaline: These are disposable batteries with good power to weight output. You find them in just about every kind of disposable battery light.

Lead Acid Sealed: Rechargeable. Lower cost. Shorter total life. Heavy for the charge density. Very sensitive to deep cycling. (If you want it to last, don’t go close to total discharge)

Nickel Cadmium (NiCad): Rechargeable. Medium cost. A bit longer service life. Slightly less sensitive to deep cycling. Last best if regularly charge cycled. (they like to be used. Shelving them for long periods of time shortens the useful life. Also, do not store partially discharged.)

Nickel Metal Hydride: Rechargeable. More costly than NiCads, but with improved performance. Less sensitive to deep cycling. Best if cycled frequently. Good charge density.

Lithium (Li-ion): Rechargeable. Relatively expensive (but cost is coming down on these) Light weight with extremely good charge density per weight. Best if charge cycled frequently. Do not store partially discharged. Best if recharged immediately after use. Very sensitive to deep cycling.

One last caveat: No battery lasts forever. With good care, Lead Acid sealed batteries can last three to four years. Most of the higher tech types are good for four to five years use. But be advised! The battery is the most expensive component in the system. Replacing it will cost more than half the price of the total system, sometimes as much as two thirds of the system price.

Those are the factors. Pick a system with the type of light and battery that best suit your riding style and habits.

My personal current favorite is an ultra bright LED powered by a Li-ion battery.