Noblex aspherilux midi LED Mode D'emploi page 16

GLOSSARY OF TECHNICAL TERMS
LED Efficiency
Contrary to popular opinion, the efficiency of light emitting diodes is not
close to 100%. This assumption arises from the hardly perceptible heat
build-up in the typically very low power consumption of a small-sized LED.
Virtually, the efficiency is comparable with that of a fluorescent lamp and
even higher. The high performance of the used LED leads to a significant
power dissipation that requires the LED to be cooled passively. Such cooling
is accomplished through the casing. In case of longer usage, the casing may
heat up noticeably.
Nickel Metal Hydride Batteries
In this lamp, NiMH batteries are used that have no memory effect and are
free of harmful substances such as cadmium and lead. In contrast to the clas-
sic memory effect, the so called lazy battery effect may also occur in the Ni-
MH technology. The causes are basically the same as with the classic memory
effect (permanent charges or partial discharges only). They, however, affect
the positive nickel hydroxide electrodes that, in case of Ni-Cd and Ni-MH,
correspond to each other. Here, the charging voltage decreases slightly only.
Hence, it is recommended not to leave the NOBLEX aspherilux midi LED in
®
the charging station permanently, but to have it discharged until occurrence
of the battery warning signal and to recharge in case of need only.
Working Temperature
When a battery cell is discharged, electrochemical processes are going off.
Depending on the temperature, these processes are accelerated or deceler-
ated. Hence, in case of a low ambient temperature, only a small capacity will
be available. It is disadvantageous that NiMH batteries cannot be used at
very low temperatures. Therefore, it is recommended to wear the NOBLEX
®
aspherilux midi LED in winter time close to the body.
Storage
The on/off switch also separates the control electronics from the battery
pack permanently in order to prevent any power consumption. Neverthe-
less, during storage the available capacity will decrease due to the self-
discharge of the battery cells. In case of NiMH batteries, such self-discharge
amounts to 60% per month. However, when temperatures are low, this
self-discharge is decelerated and amounts to only 30% per month at 5
C. Hence, storage in a refrigerator may be quite useful. Basically, it does
not matter in what charging condition the NOBLEX aspherilux midi LED
®
is stored. In case of any longer storage period (for more than six months),
however, a Ni-MH battery should be stored in fully charged condition and
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