Clarification on ANSI FL-1 Standard burn times

[thetcutkid]

Hi,

Apologises, newbie post coming up!

I'm sure this has been done to death on the forum but could I just clarify my understanding of advertised burn times under the ANSI FL-1 standard.

A lot of manufacturers use the line 'ANSI FL-1 Standard: Runtime to 10% of initial output' in the specs for their torches, so am I right in thinking that for a 500 lumen beam, with an advertised burn time of 4 hours, they're actually saying that over a period of 4 continuous hours, that 500 lumen brightness steadily drops to just 50 lumens and therefore, in reality, that 500 lumens output is only really 500 lumens for a fraction of the 4 hour period?

I'm more interest in constant output burn times but not many manufacturers seem to show them or you have to dig a bit to find them.

Some Fenix torches advertise a 'non dimming output', a couple of LED Lenser models have the ability to switch into a constant output mode but not even their UK distributor could tell me exactly what the burn time would drop to, his best guess was to take 2 hours off the burn time in energy saving mode.

Some of the most accurate burn times are those advertised by Lucifer Lights and I did exchange a couple of emails with Petr who was able to explain how rigorously they test their torches and strive to give a much more accurate burn time.

I appreciate that heat build up will always be an issue but are we really saying that a head torch's burn time is only ever going to be as good as its ability to dissipate heat, otherwise some sort of thermal dimming will always be kicking in to reduce the temperature (and therefore beam) as it will always reach maximum heat threshold before it reaches its maximum burn time?

I'm in the market for a new head torch but after several weeks of trawling the internet looking at different brands, checking reviews etc., I've got a bit bogged down with the whole FL-1 standard thing and I'm no closer to actually buying anything - in fact I think I've arrived at the conclusion that there's not really one torch that does everything I really need !

Many thanks for your time.

 

[xxo]

It could stay at full power the whole run time and switch off suddenly when the battery is depleted or it could run at full power for a few minutes and drop to as low as 10% and run at that level until the batteries die or it could do something in between reducing output in steps or continuously until it hits 10%.

You really need to see a run time graph to show you what's going on. Some manufactures publish accurate graphs for their lights, but most do not. You may have to find reviewers who have tested the light you are interested who has created a graph.

 

[desert.snake]

You learned more in a few weeks than I did in a few years))

 

[thetcutkid]

Thank you both for your quick replies.

xxo where you say...

It could stay at full power the whole run time and switch off suddenly when the battery is depleted...

That would still be under the ANSI FL-1 standard? That sounds more like a constant output kinda thing?

I know what you mean about the run time graphs, I also emailed Fenix and they were kind enough to send me through the graph for a model I was interested in but they still couldn't clarify the wording on some of their specs where so called turbo modes are concerned.

It really is a can of worms all this lol

 

[xxo]

Yup a light could theoretically stay at 100% the whole time and shut off. Lights are often designed to do that to keep the battery from over discharging and will shut off when the Voltage hits a certain point. Some lights will step down based on time, usually to increase battery life and others will step down based on temperature to keep the light from overheating, while others will direct drive and slowly dim as the batteries are depleted.

 

[thetcutkid]

Ok many thanks, I clearly can't just assume that if I see ANSI runtime to 10% in the specs it'll be a torch that steps down over the period of the advertised run time, as you say, run time graphs are the things to go by.

 

[3_gun]

Biggest tip if you're looking for run time at a constant level is avoid turbo & high levels. I have a couple of lights that brag about 3000+ turbo but the sweet spot is the 400L medium that will hold 400 for 8hrs or so before quickly stepping down to 100 for a bit & again to run at a low level for 5-10min; acting as a unmistakable warning to change/charge the battery. Plus check to see if the light has built in charging, many lights will work at lower levels while plugged in letting you use a power bank as a main source that can be 4 or 5 times the size of the on board battery. Good thing about the lower levels is that heat seldom is an issue unlike the numbers they like to highlight on the package.

Also the F1 is output at 30sec to 10% of that level so 500L on MIGHT be 400 at 30sec which would make 40L not 50L the tests end. It IS worthwhile to see the run time left at that 10% level as a few lights go out a few minutes after that step down, not giving you much time/warning to address the issue before total darkness.

Also make it a HABIT to use & BELIEVE the saying "one is none & two is one" if anything you're doing under light from a flashlight is in ANY WAY hazardous/dangerous. If it can go wrong it WILL at some point. It's not unusual for me to have 3 tested/trusted lights on me if going somewhere unfamiliar

 

[thetcutkid]

Excellent advice 3_gun 👍

I've worked with pro fireworks here in the UK on and off over the years and I used to take two of pretty much everything to cover every eventuality from weather to PPE.

 

[bykfixer]

The ansi spec was adopted before the regulated LED flashlights were the norm. It was kinda like a candle maker is allowed to use the term "4 hour burn time" if it took 4 hours to burn down to 10% of the candle stick remaining. But with ansi and flashlights it would be like starting out with 10 candles burning and after a stated time by the manufacturer 1 candle burning. ie 10% brightness remaining.

Many manufacturers still produce non regulated flashlights so they start dimming as the battery voltage drops. They continue to dim as the voltage continues to drop and in order to meet ansi must be at 10% of the original brightness st the amount of time stated by the manufacturer. Yet the batteries themselves can affect the outcome based on how well they hold (or don't) hold a steady voltage. A lithium double a will hold voltage steady longer than an alkaline double a for example. Alkaline more than a carbon zinc.