Current levels for lumen levels?

Hi!

I'm looking to do some LiIon-testing, and I'm wondering if anyone could help me out with information on typical current levels for various lumen levels, such as X amp for 200 lumens. Thinking about LiIon voltage levels here.

Efficiency has changed over the years, and varies for the different LEDs. It's mostly recent LEDs for the last few years that are interesting.

Bonus point if you also have information about typical termination or step down voltages.

The main goal is to be able to test a battery at the right current level (-ish), and conclude "this could have given X minutes of Y lumens".

All very ballpark, mostly to put measurements into something easier to reason about.

Those will be in the emitter spec sheets

( .... oh, and moved to "LED Flashlights" .... )

archimedes said:

Those will be in the emitter spec sheets

Click to expand...

Yeah, roughly, if we ignore driver losses. It's easy enough to look up for a specific light, it's harder to pin down what would be typical for the lights in peoples hands now.

archimedes said:

( .... oh, and moved to "LED Flashlights" .... )

Click to expand...

Thanks.
And sorry for not putting it there in the first place.

I guess I'm not clear on which sort of "ballpark" numbers you are wanting ?

Do you want emitter lumens from a specific current ? Then you need details off the data sheet for an exact emitter bin.

Do you want OTF lumens, from a particular torch and driver, including current levels and runtimes ? Then you need one of the detailed reviews which provide those results, as tested.

Cree has their Product Characterization Tool. You can select an Led and see how many lumens it should output. (Note: choose V Rough as the scale at top, so it will show higher amp ranges).
http://pct.cree.com/dt/index.html

Generally, and here is where arguments and trolls surface, you could expect to lose up to 15% for the reflector and glass and up to 15% for driver and electronics overhead.

In reality, it varies a lot a lot by model and brand and even particular sample but 20% is a reasonable total.
On top of that, Cree's own tolerance is 7%.
So if the PCT says 1000 lumens at 3 Amp, well, that could mean as low as 650 lumens out the front of a flashlight (absolute worst case).

Yes, I typically guesstimate ~ 30% losses

I test my lights for efficiency with a light box and ammeter, although tend to focus on the lower/medium modes, and AA-sized rechargeables (Eneloops and 14500s). I use a ~250 lumen-hrs (eg, 25lms@10hrs or 125lms@2hrs) per cell as my efficient light benchmark with a bit of a bell curve - lights are less efficient on moonlight and at max. If you use Selfbuilt's lumen scale, I'd bump that to ~325 lm-hrs per AA. If you assume an Eneloop and 14500 average out at ~2.5 watt-hrs, this also translates to ~100lms/watt.