Brighter When Hot - Regulated Not?

jayflash

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My HDS U60, Fenix L1P & Nuwai Q3 show about 20% more brightness, according to my meter, when they warm up. Does that indicate "semi - regulated" or does that mean LEDs are more efficient at higher temps?
 

evan9162

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Batteries voltage output increases when they get warmer because the heat increases the rate of the chemical reactions happening within the cell. This could account for the increased brightness.

Heat affects electronic components, changing some of their characteristics. If the circuitry in the regulators isn't properly temperature compensated, then the regulator could change output current greatly when the temperature varies.

LEDs are less efficient when they get warm, not more.
 

lamperich

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jayflash said:
My HDS U60, Fenix L1P & Nuwai Q3 show about 20% more brightness, according to my meter, when they warm up. Does that indicate "semi - regulated" or does that mean LEDs are more efficient at higher temps?


nope
that means what evan wrotes & the regulation is Voltage sensitive.

LED`s lower Vf at same current(!) if temperatur (ambiente & Die temp) increase. if temp rise flux decrease. but the current can rise more than this.

especially with the HDS it´s not a surprise.
This torch use Constant power& temperatur monitoring. <- very save concept

you see it´s an extrem complex behaviour.
but 20% charging in brightness is nothing. Your led´s feel much saver than direct driven lumiled Luxeon1/3 led´s in california (@>40 degreeC ambiente temp) driven with low resistance NiMH´s or Li-ionen rechargables for a couple of minutes
grinser2.gif
 

jayflash

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Like my PC, I could use more memory and, therefore, don't remember all the details of my different lights. I somehow got the impression some of these lights were current regulated, including my Apex, so that's why I wondered why they gained lumenosity along with the temperature rise. It made sense for the Fenix because I remembered it is voltage reged.
 

lamperich

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jayflash said:
It made sense for the Fenix because I remembered it is voltage reged.

also don´t forget the electronic what evan mentioned.
a good led flashlight is pretty complex thing.


This two curves help

FENIX.jpg

Red plot

AALiAlkComparison1A.jpg


maybe now it´s easy to understand. At least the behaviour with the voltage sensitive Fenix.
 
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