You may have noticed that GeoManGear sells primarily LED lights using Li-Ion batteries... Why?
First off, GeoMan has used them all; HID, halogen, and LED. The decision to offer LEDs is based on experience. LEDs are more reliable and efficient.
Light emitting diodes or LED are based on semi-conductors, which
transform the electricity into light. The breakthrough of the LED was
reached in 1992, when Nichia Chemicals invented the white LED. Today,
there is a wide range of white LED models by different manufacturers.
The
standard models are the 3mm model, the 5mm model, the various miniature
SMD-LED and the Lumiled models; the latter being the most important
type to realize a very high performance. The Lumileds of different
manufacturers are quite similar: 120° angle of reflected beam. 2 or 4
connectors in the plastic casing. All LEDs used today produce a bluish
light, which needs to be filtered by various substrates. In this
respect, there are noticeable differences between the several
manufacturers. The substrates affect the performance especially at high
currents. The new LEDs output up to 210 lumens at a current
consumption of 3.5W, which is highly efficient. Another advantage of
this new generation of LEDs is their insensitivity to temperature.
Advantages of LEDs
- Extremely long life span
- Dimming is possible without changing the light temperature
- LED lamps are very durable; robust and shock resistant
- Temperature insensitive
Degree of Efficiency
A
well aligned LED lighting system outputs up to 90 lumens per watt. A
decent halogen lamp can also output approx. 30 lumens per watt. The
Metal Halide Solarc Lamp used by Lupine is different: it outputs up to
60 lumens of light per watt. It is quite evident, the efficiency of the
LEDs produced today, is higher than of any other light source. With
regard to all the other advantages of LEDs, they are the first choice
for a small and compact designed light.
Halogen lamps
dissipate a large amount of the heat to the front via the reflector.
LED lamps, on the contrary, dissipate the heat to the back, i.e. to the
electronics or maybe a cooling element. Transporting the heat sets the
limit for the LED: The higher the temperature, the lower its degree of
efficiency and the shorter its life span. Thus, dealing with the heat
problem is the most important issue. It is a good sign if the lamp
casing heats up quickly. This shows the heat is well dissipated and the
lamp is well tuned.
By the way: The human eye
interprets cold, bluish light as lighter. Therefore, many people prefer
LED and Metal Halide lighing systems. With the same light performance,
an LED will be interpreted as lighter.
Li-Ion Batteries
Li-Ion batteries have several advantages over Ni-MH batteries. The
energy density it at least 40% higher compared with other good quality
Ni-MH cells at a distinctly lower weight. The self-discharge of
maximum 15% in one year is extremly low - Ni-MH: 15% in the first week!
Li-Ion batteries have a better voltage condition under high strain
(e.g. when using 2x 25 Watt) and being cold (down to -40° C). Because of low weight, high capacity, and no memory effect, the Li-Ion
battery is the first choice for serious riders.
The energy density of lithium-ion is typically twice that of the standard nickel-cadmium. There is potential for higher energy densities. The load characteristics are reasonably good and behave similarly to nickel-cadmium in terms of discharge. The high cell voltage of 3.6 volts allows battery pack designs with only one cell. Most of today's mobile phones run on a single cell. A nickel-based pack would require three 1.2-volt cells connected in series.
Lithium-ion is a low maintenance battery, an advantage that most other chemistries cannot claim. There is no memory and no scheduled cycling is required to prolong the battery's life. In addition, the self-discharge is less than half compared to nickel-cadmium, making lithium-ion well suited for modern fuel gauge applications. Lithium-ion cells cause little harm when disposed.
Despite its overall advantages, lithium-ion has its drawbacks. It requires a protection circuit to maintain safe operation. Built into each pack, the protection circuit limits the peak voltage of each cell during charge and prevents the cell voltage from dropping too low on discharge. In addition, the cell temperature is monitored to prevent temperature extremes. The maximum charge and discharge current on most packs are is limited to between 1C and 2C. With these precautions in place, the possibility of metallic lithium plating occurring due to overcharge is virtually eliminated.
Aging is a concern with most lithium-ion batteries and many manufacturers remain silent about this issue. Some capacity deterioration is noticeable over time, whether the battery is in use or not. It should be noted that other chemistries also have age-related degenerative effects. This is especially true for nickel-metal-hydride if exposed to high ambient temperatures.
Manufacturers are constantly improving lithium-ion. New and enhanced chemical combinations are introduced every six months or so.
Storage in a cool place slows the aging process of lithium-ion (and other chemistries). Manufacturers recommend storage temperatures of 15°C (59°F). In addition, the battery should be partially charged during storage. The manufacturer recommends a 40% charge.
