Figuring runtime

I have three surefires I would like to do a "true runtime" (not math) test on. What is the safest and best way to do this....I plan to try them in a few different configurations and post the real world results. When I built lights for coon hunting we called it a "dead burn" and when the color changed to yellow you were done or your packs would over discharge.

Any thoughts? :candle:

This doesn't really belong in the review section. I'm moving it to 'General Flashlight Discussion'.

Hello Irishsentry,

It depends on what the intended use of the light is...

If the light is designed to be constantly used, you turn it on, set a timer, and shut things down when the light goes dim.

If the light is designed for momentary use, you then turn it on for 5 minutes, shut it off and let it rest for 10 minutes, and repeat until the light goes dim during the 5 minutes of on time. Add up your 5 minute runs and you have the runtime.

Some lights get hot during a static runtime test. The best way to test these is to turn the light on, note the time, then go for a walk. When the light dims down, note the time again.

If that is not practical, you can always go over to the sink periodically and run a little water over the head of the light to cool things down.

Tom

As Tom has pointed out runtime tests can be constructed to reflect the conditions under which the flashlight will be used. By far the most common method though is a continous runtime test from a fresh but rested pair of rechargable cells of the type you can expect to typically use in that flashlight (eg I don't perform tests with any Energizer E2 lithiums because they're not something I use everyday).

For a continuous runtime test, the only thing I would add in addition to waiting for the light dim in a dark room is to purchase a lux-meter with computer interface so that you can log the change in intensity over time. If you prefer to use your existing light meter, you can use it to periodically note the readings and graph them for yourself. Obviously this is more tedious than having a computer record all the data points for you.

Here's an example of a light meter with a computer interface

It will also depend on the light. Most incans are unregulated and will get yellow and dim as the batteries deplete.

But most decent LED lights have a driver that attempts to get the most out of a battery as possible, so a well regulated light would be almost identical when the battery is almost depleted and when the battery is full.

I was thinking of something like setting up a camera to snap pictures at a designated time and go that way. Or use a solar panel and record the voltage and current at a certain time interval.