Low-voltage-warning with electronic regulation?

Higher quality flashlights have electronically regulated brightness, to prevent dimming over the course of the battery runtime. For example the Fenix LD 22 has that feature.

How can I know with these electronically regulated flashlights, how much battery runtime is left, without using a separate volt meter?

And do I get some form of warning, before the light suddenly goes out, leaving me in pitch dark? This is important IMO, since I may use the flashlight in an emergency situation, without having a backup flashlight in my EDC.

On my lights with non-protected batteries, the light goes dim near the very end. There's no meter, but at least I'm not left in the dark like protected batteries.

snakyjake said:

On my lights with non-protected batteries, the light goes dim near the very end. There's no meter, but at least I'm not left in the dark like protected batteries.

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What do you mean with: "lights with non-protected batteries"?

get a regulated light with a digital display

Philip2 said:

How can I know with these electronically regulated flashlights, how much battery runtime is left, without using a separate volt meter?

And do I get some form of warning, before the light suddenly goes out, leaving me in pitch dark? This is important IMO, since I may use the flashlight in an emergency situation, without having a backup flashlight in my EDC.

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there is no way to know on most factory lights, and you can't get warning. some lights you can spot it when high mode drops after a little while. but not all. using unproected cells might help a bit, but cut off on many protected cells is 2,5v lower than minimum voltage of the driver, so your driver will pbly let you know cell is low before protection kicks in. some offer lcd display but there are not many of those.

Jetbeam, Sunwayman, and perhaps others, have some sort of indicator.

Philip2 said:

How can I know with these electronically regulated flashlights, how much battery runtime is left, without using a separate volt meter?

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Well for starters some of these lights have built-in battery meters that will tell you exactly what the voltage of the battery is under load. The other option, for lights that do not have this, is to do actual run-time tests and figure this out before you need to know this information in the future. I personally do that for all my lights on the higher levels.

Philip2 said:

And do I get some form of warning, before the light suddenly goes out, leaving me in pitch dark? This is important IMO, since I may use the flashlight in an emergency situation, without having a backup flashlight in my EDC.

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This is going to depend on the manufacturer. With some the light completely goes off without any warning with others it will put you into the lower levels.

Philip2 said:

What do you mean with: "lights with non-protected batteries"?

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I run lights with batteries that do not have protection circuits that cutoff the light when a low voltage threshold has been reached.

If the OP wants to estimate how much time is left on the battery, there are lights that have voltage indicators.
If the OP wants to not be left completely in the dark, non-protection circuit batteries are offered. The "indicator" will be low light, and it provides me enough time.

An indicator and non-protected batteries is the ideal solution for me, but I don't want to be limited on my light choices.

Jake

Knight_Light said:

do actual run-time tests and figure this out before you need to know this information in the future.

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The run time changes as the batteries age or when you swap batteries.
I don't use all my battery's power at one time, therefore I don't keep track of the cumulative runtime. I can go a long time between charges.

Not all lights or dropins that have regulation also have low voltage warnings. The Malkoff dropins are excellent: they're regulated, but they don't have low voltage warnings - you need to watch the light dim. I have some triple dropins from EDC+ and they are regulated and they provide low voltage warning/cut off. I have triple dropins from Oveready, they are regulated between 4.8 and 9.5 V, recognize if you are running 1 or 2 cells (and Li-ions vs. primaries) and provide low voltage warnings. Very few lights (and none that I have) provide voltage readings. I have a small, simple volt meter from cottonpickers that I use to check my cells. I also use protected cells in lights/dropins that don't have low voltage warnings. Over discharging can ruin the cell and be dangerous. I don't check the voltage of my cells everytime I go for a walk with the dog, but if I'm going to need the light for a long period, then I check the cell before leave the house. I also carry extra cells. Being a flashaholic, I enjoy checking the v on my cells and topping them off if they are below 3.9v. Li-ions don't have memory and this isn't bad for them (and probably good for them because I won't be in a position to over discharge them).