LED voltage vs. battery voltage (a way higher?!)

Audioguru said:

I did not read the entire thread to see what circuit you are using to regulate the current at 2.8A.
If the current regulator works and the battery voltage does not drop too low then the current will stay at 2.8A until the capacity of the battery runs out.


Then in summer they will overheat which might cause a fire.


LED light bulbs are new so maybe they overheat and will not last long. Many LED flashlights also fail soon. The streetlights and traffic lights in my city are all LEDs and you can see the failed ones.

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It has been said that the LED will start overheating soon, that's why current will lower itself from the 2.8 A to 0.7 A, so that the LED does not produce so much heat. However, the person stated that this happens because of only 5°C above Tmax of junction, which is very sad. But the user calculated with this at 25°C calm-wind conditions. That's why I asked, whether current stays at 2.8 A if the temp. of LED is lower by 20 °C (here, 15°C should be in reserve before reaching junction's Tmax). Such current would mean much shorter battery life, but if I understand well, the good news would be brighter light.

So you think that even my single CREE LED will fail soon? I am not an expert, but it is even against my common sense, that it would be able to supply such bright light for eg 10 years. I also think such strong emitter could fail soon. On the other hand, some sources claim "100,000 hour bulb life".

ArminVanBuuren said:

It has been said that the LED will start overheating soon, that's why current will lower itself from the 2.8 A to 0.7 A, so that the LED does not produce so much heat.

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No, an LED does not reduce its own current. Its current might increase a little when it gets hot. If you do not cool it properly for its amount of current then it will not last long.

So you think that even my single CREE LED will fail soon? I am not an expert, but it is even against my common sense, that it would be able to supply such bright light for eg 10 years. I also think such strong emitter could fail soon. On the other hand, some sources claim "100,000 hour bulb life".

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an LED that is cooled properly or operated at a low current will last a long time.

Audioguru said:

No, an LED does not reduce its own current. Its current might increase a little when it gets hot. If you do not cool it properly for its amount of current then it will not last long.


an LED that is cooled properly or operated at a low current will last a long time.

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Sorry, not a LED, but its driver, which operates witch supply of voltage and current to the LED itself. It receives 8.4V, which would destroy the LED immediately - as measured by someone, it reduces the voltage and also operates with the current when overheating:

ArminVanBuuren said:

How do you know the bulb contains a driver that "tells it to consume" only 700 mA?

erikl said:

Because I opened it and measured the current.

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