LED Overpower Current?

Travis2020

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Hi Y'all,

Can you guys provide more insight on this? Thank you in advance. I am planning on using Osram SSL 80GW CS8PM1.PM led. The battery unit will be a 3.7v 3000mah. I want to know what the max current will be, and if we can go over the manufacturer's max current (10-25%) to increase brightness if we design the LED housing to dissipate the heat well? How do manufacturer determine the max current and in what kind of setting? Thank you!
 

Dave_H

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Good design practice is to not exceed manufacturer's maximum current ratings (especially "absolute maximum") especially if you can't meet the conditions for which they are specified e.g. junction or case temperature. It's a good idea to add margin, operating below maximum, if you expect good product life. Trying to squeeze the last bit of brightness out may be a diminishing gains situation compared to extra problems it could cause getting rid of heat.

I any case you'd be wise to do some analysis and testing of heatsinking and temperature to be sure, and there are variables. What type of design is this?

Dave
 

Dave_H

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BTW do you have datasheet and are you familiar with how to read them? There are a bunch of variants of this one (order codes).

Dave

 
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Also worth considering is the fact that people perceive light on a logarithmic scale. Eeking out a smidgen of additional lumens isn't going to yield much of anything in the way of perceived brightness. Considering the multiple headaches that exceeding an emitter's performance limits entails, you would need a pretty compelling reason to do so. Just my two cents.
 

aznsx

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When it comes to engineering, I avoid words which begin with 'over'. They usually spell trouble.
 

Dave_H

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If I'm reading the right datasheet, this LED is capable up to around 4W (1300mA) but characterized at the 1W level (350mA). CRI is down around 70 though.

Relative output drops with higher current, about 10% lower at 700mA v. 350mA. Output drops 10% from 25C to 85C also. So higher current/temperature is diminishing returns, even within spec.

Dave
 

idleprocess

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Overdriving LEDs is a long and storied tradition in the flashlight world (over-driving original 350mA max Luxeon I to 1A with good success is arguably where the Luxeon III came from). A generally low duty cycle, good thermals, and a temperature-sensing driver that dials things back before the LED (or something else) cooks itself to failure all help. But you're going to want to understand the true thermal resistance of your setup and build some margin into that final thermal load.

When it comes to engineering, I avoid words which begin with 'over'. They usually spell trouble.
Terms like overunity? 😂
 

aznsx

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Terms like overunity?

:) Good one!

I was primarily focused, however not on things related to proper / intentional design, but rather things which are (to the average professional (not hobbyists, as they are known to do unwise things for the heck of it) absolutely undesirable and generally to be avoided; such as overvoltage, overload, over-driven, "overpower" (as in the thread title), etc. Those are the type of terms which instantly turn on my red warning light, as they're essentially instinctively, fundamentally, and unambiguously things to be avoided in almost any situation. That's what my 'red flag' was with this thread title - things which are, by definition, bad. I do dig your reference though!
 

Dave_H

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Hi Y'all,

Can you guys provide more insight on this? Thank you in advance. I am planning on using Osram SSL 80GW CS8PM1.PM led. The battery unit will be a 3.7v 3000mah. I want to know what the max current will be, and if we can go over the manufacturer's max current (10-25%) to increase brightness if we design the LED housing to dissipate the heat well? How do manufacturer determine the max current and in what kind of setting? Thank you!
So what is the application, and expected life of product (if it is)?

Also wondering which "max" you propose to exceed? (1300mA?)

Dave
 
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