Flashlight with NO low voltage protection

Lots of quality older flashlights have no low voltage cut off. Most of my AA - 14500 dual fuel lights are like that.

In most modern lights it isn't "one less thing to fail" because usually LVP takes no extra parts. The microprocessor can already read voltages and basic LVP only needs a few lines of code.

Low voltage feature in flashlights is becoming more popular. As you know 2.50v is the level that a lithium ion battery does no want to go below. I like this new feature that companies are putting in their lights, but in most cases you can tell well before the 2.50v low level that you need to stop using and recharge the battery. That's because the forward voltage drop across an LED is around 3.00 volts. Battery voltage below that level would require the flashlight driver to switch to boost mode. Most don't have a buck-boost driver. Thus once the battery voltage hits at or slightly above Vfwd, the light dimms and you can't hit the higher modes. At least that has been my observation with the lights that I have. By then the battery is pretty much depleted anyhow and no point in continuing to use it. Most of the time I never allow the battery to get that low before recharging. (Most of my 18650 batteries are non-protected and so I am a little more conscientious of things). The only exception would be a run time test but I always use a protected battery for those tests.

When LVP kicks in from a Protected Cell the light goes dead, not a useful thing to happen at the best of times, sure you can monitor your usage and replace the cell before it shuts down. But then you could use an unprotected cell and do the same thing. I'd be happy to get out of a stcky spot and lose a cell than be left in the dark.
A low voltage warning, like a flash or gradual dimming is a good option, Oveready use it, but given my druthers I'd be happier with no extra bells and whistles. But then I'm a weirdo.
P

LVP is important in lights with boost drivers, such as Zebralights. Otherwise, the light could easily drain the battery far too low, without you noticing.

In lights with XPL/XML/XPG emitters that generally require buck drivers, you probably don't even need LVP. I find that those lights of mine without LVP will dim well before the voltage gets below 3.0v. They usually shut off completely below 3.0v. The LED just won't work when the voltage gets too low. However, I'm not certain if the driver shuts off completely, so it's possible the voltage continues to drop, but it doesn't appear to drop very fast.

Finally, LVP can be kind of useless in multi-cell lights. One cell could be weak, but the entire pack still above a decent voltage.

Personally, I prefer lights that warn me when the battery is starting to get low (switch indicator or some kind of flashing), well before any LVP would be needed.

^^ Exactly.
And in answer to your secondish question, it's not necessarily a sign of a cheap light. None of my Malkoffs have this feature, and while they're not expensive, they sure ain't cheap.
P

WalkIntoTheLight said:

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Finally, LVP can be kind of useless in multi-cell lights. One cell could be weak, but the entire pack still above a decent voltage.
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Error! Error! Warning Danger! Warning Danger!

StandardBattery said:

Error! Error! Warning Danger! Warning Danger!

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Fair enough. I'd rather have it than not. But, I don't rely on it in multi-cell (series) configs. You could have a 4-cell light with a 11v or 12v LVP, and in theory one cell could be dead, at least at low current draws. I make sure to recharge cells in multi-cell lights well before there's any indication of low voltage. In single-cell lights, not so much, though I usually end up charging when they're about 50% depleted, just because I like having full charge if I need it.

Like others have said, I don't think it's necessary in single cell lights. Since most white LEDs run at around 3v, they are mostly self limiting on one cell - the LED dims and uses less and less power as the voltage goes down. This gives a visual indicator and almost protects the battery anyway. I prefer to have the option of running it down to zero if it is an emergency, also. Replacing a lithium battery isn't the end of the world if I really need a flashlight in an emergency.

Have you ever been deep in a cave and had your only flashlight die? I have....

Number21 said:

Have you ever been deep in a cave and had your only flashlight die? I have....

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I'm thinking only you, since that is everyone else's worst nightmare. lol

Wait, of course you had extra batteries though. Whew.

Hoop said:

Wait, of course you had extra batteries though. Whew.

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Nope...I climbed out several hours later, my clothes shredded and bleeding from head to toe from feeling my way through the sharp rocks in complete darkness. And yes, I should have had a backup. This was in the days of light bulbs and NiCd batteries.

Probably why I'm so fascinated with super bright long lasting LED lights now.