Looking for light that doesn't shut off suddenly when batteries are low

I've been carrying one or two EDC lights for the past 20 years or so, but I've had reliability issues with every one of them except Fenix. They either quit working or developed intermittent switches that got worse over time.

The other problem is regulated output that leaves me in the dark with no warning when the batteries weaken. If I need to I will start carrying extra batteries, but I would prefer to have something like my beloved Fenix LD20 that I lost a few months ago. That one would dim gradually as the batteries weakened. I used Eneloops and got months of use between charges.

I've been looking at these new Fenix models available at REI, but I would like to know if they will shut off suddenly instead of dimming gradually:

PD35: https://www.rei.com/product/124309/fenix-pd35-tac-flashlight

LD12: https://www.rei.com/product/143377/fenix-ld12-flashlight

LD22: https://www.rei.com/product/143376/fenix-ld22-flashlight

Fenix lights usually don't have hard low-voltage shutoffs. They often blink when they get low, and usually do become dimmer. If you run a protected Li-ion battery in any of those, the battery itself will shut off suddenly when the voltage gets low enough.

Nightrider202 said:

I've been carrying one or two EDC lights for the past 20 years or so, but I've had reliability issues with every one of them except Fenix. They either quit working or developed intermittent switches that got worse over time.

The other problem is regulated output that leaves me in the dark with no warning when the batteries weaken. If I need to I will start carrying extra batteries, but I would prefer to have something like my beloved Fenix LD20 that I lost a few months ago. That one would dim gradually as the batteries weakened. I used Eneloops and got months of use between charges.

I've been looking at these new Fenix models available at REI, but I would like to know if they will shut off suddenly instead of dimming gradually:

PD35: https://www.rei.com/product/124309/fenix-pd35-tac-flashlight

LD12: https://www.rei.com/product/143377/fenix-ld12-flashlight

LD22: https://www.rei.com/product/143376/fenix-ld22-flashlight

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"Regulated output maintains consistent light output over the lifetime of the batteries"

That means the lights shut off when there's insufficient power to drive the LED at the selected output level. If you have a multi-mode light, usually that means you can still have light on the lowest setting, but when that's not possible you get ZERO light. This is done to protect lithium batteries. Otherwise, deep discharge can damage them. NiMH is probably not as sensitive, but they can be worn down from repeated deep discharges.

Generally, if you're finding yourself running low on batteries enough to have this concern, then you're not managing your batteries properly. Keep a spare cell with you, or at least check the charge level before you go out.

Some flashlights will let you know the current voltage level. I don't know if Fenix provides this feature now. But you can find it on Nitecore and others. Very useful. Or just get yourself a good charger that has some kind of built-in battery level test. Then you won't be limiting yourself to lights that aren't regulated.

All my Zebralights are regulated, but when the battery gets very low they will ramp down to a low level and remain there for hours. You won't be able to get high output on a very low battery, but you'll have plenty of time to get somewhere to change it. This is for both their AA and 18650 lights.

I have never had a light shut off dead when batteries get to low.should only have that problem with rechargeable batteries when the protection circuit cuts in.

When the battery can no longer support the current level, HDS lights step down to the next lower level and will continue to step down until the battery can't support the lowest possible level (< 0.1L). The HDS light has different thresholds for CR123A and li-ion cells so it'll suck every last bit of juice from a CR123A, but won't draw a li-ion cell down enough to damage the cell.

In practice, this means the light gives you warning hours before the light goes dark.

--flatline

thermal guy said:

I have never had a light shut off dead when batteries get to low.should only have that problem with rechargeable batteries when the protection circuit cuts in.

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I have a Manker T01 that cuts off completely when the battery starts to die (a AA Eneloop). If you're watching carefully, it does start to dim a few minutes before that, but IMO that's not nearly enough warning. I want hours of dim light before it cuts out, not minutes.

I also have a few other lights that will give only a few minutes warning, but at least they're annoying about it by doing things like flash warnings. Still not nice, but better than no warning.

Out of all my lights will full regulation on all levels, I think only the Zebralights give hours of warning. Though just about all my unregulated or partially-regulated lights give hours of warning, too.

I ended up buying the LD22 and LD02. The LD22 is the updated version of the LD20 that I lost, and the LD02 is the updated version of the LD01 that I have on my keychain.

I use Eneloops in these. The way I've always managed my flashlight batteries is to do a refresh & analyze in my Maha MH-C9000 when they run low. I get more runtime if I do that. When I only do a charge cycle the battery life sucks.

I was in a dark cave years ago, had my Foursevens Quark Pro 1AA on high then all of a sudden it cut out (was using an Eneloop), I was shocked, I reached into my pack and grabbed a spare Eneloop and it powered back on again with the new battery, but I never felt comfortable using this same light and battery combo again.

At the time, I then switched my EDC to a Streamlight Protac 1AA which I tested for good gradual output decline at the end of the alkaline battery. My Protac 1L and Protac 1L-1AA also gradually lower the output towards the end of battery life and start flickering.

My Elzetta Alpha on a CR123 has good declining output.

However no one beats how HDS lights step down, I'm still on my first CR123 and after 9 months it steps down 1 level when I use it on max (started after 7 months of usage), if I use it a bit longer than 10 secs it steps down a another level. This step down is very clear and informative to the operator as it turns off for a split sec. Love it.

Along with durability, reliability, reverse battery polarity, runtime, output, and simple UI, the ability to gradually decline in output near the end of batter life is always of the up-most importance to me when buying lights.

Sorry, my post didn't really answer your question about the newer Fenix models you're looking at.
BTW love my Fenix lights too (LD20 and E01), both have seen lots of use and have never left me in the dark ever.

that is why i like DD lights. you see led dim, and know cells are low, and no drivers to burn, too bad leds that can take 4,2v are no longer made, i made a light with p7 4,2v, it still works, i built it in 2011

Ya DD is awesome Malkoff lights gives you several hours to let you know it's time to change batteries

Nightrider202 said:

I use Eneloops in these. The way I've always managed my flashlight batteries is to do a refresh & analyze in my Maha MH-C9000 when they run low. I get more runtime if I do that. When I only do a charge cycle the battery life sucks.

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Sounds like something is wrong with your charger. Eneloops don't need to be cycled, and a simple charge from any level should give them a 100% charge.

Okay, they will benefit from 1 or 2 cycles when you first get them. You'll gain a few percent more capacity. But after that, there's no gain in capacity from cycling.

Nightrider202 said:

I use Eneloops in these. The way I've always managed my flashlight batteries is to do a refresh & analyze in my Maha MH-C9000 when they run low. I get more runtime if I do that. When I only do a charge cycle the battery life sucks.

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WalkIntoTheLight said:

Sounds like something is wrong with your charger. Eneloops don't need to be cycled, and a simple charge from any level should give them a 100% charge.

Okay, they will benefit from 1 or 2 cycles when you first get them. You'll gain a few percent more capacity. But after that, there's no gain in capacity from cycling.

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It's a traight of the MH-C9000. If you want your cells topped right up you have to leave them on to trickle charge for 1-2 hours after they have completed charge as the termination is a bit early.

I disagree with you there. In my experience Eneloops do benefit from an occasional refresh once and a while after they have been cycled many times. However, it does not need to be done often.

alpg88 said:

that is why i like DD lights. you see led dim, and know cells are low, and no drivers to burn, too bad leds that can take 4,2v are no longer made, i made a light with p7 4,2v, it still works, i built it in 2011

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There are many regulated lights that give you plenty of warning once they fall out of regulation. To me, DD is something that should have been left back in the 90's for all but, the most powerful hot rods. But, to each their own of course.

Here is a perfect example of what a regulated lights output should look like imo...



Runtime graph courtesy of Sean👍.

Tachead said:

In my experience Eneloops do benefit from an occasional refresh once and a while after they have been cycled many times. However, it does not need to be done often.

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I agree. I usually only needed to do a refresh & analyze on the Eneloops that I used in the Fenix LD20. I'll see how things are with the new LD22.

I use Eneloops in my Uniden portable scanners and never have to do a refresh & analyze.

Tachead said:

There are many regulated lights that give you plenty of warning once they fall out of regulation. To me, DD is something that should have been left back in the 90's for all but, the most powerful hot rods. But, to each their own of course.

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yes, there sure are, but this is not one of those reasons i like DD. or an issue i'm worried about, unlike op, but driver failure is one reason i still like DD. if i had a penny for each burned driver since i got my first driver, i'd have about 50c. i just wish i could still get my hands on old 4,2v p7 leds,

alpg88 said:

yes, there sure are, but this is not one of those reasons i like DD. or an issue i'm worried about, unlike op, but driver failure is one reason i still like DD. if i had a penny for each burned driver since i got my first driver, i'd have about 50c. i just wish i could still get my hands on old 4,2v p7 leds,

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You must have bad luck man. In more then 25 years and many, many lights from many manufacturers I have only had a driver fail on Armytek lights(3 out of 4 of them lol). Not sure if it is the reason or not though but, I generally stay away from the cheap stuff(tiny bedside lights aside), am not into mods or modding(light electronics anyway), and try to stick to lights with potted or conformal coated electronics. If I need added peace of mind though, I just carry a backup.

Tachead said:

You must have bad luck man. In more then 25 years and many, many lights from many manufacturers I have only had a driver fail on Armytek lights(3 out of 4 of them lol). Not sure if it is the reason or not though but, I generally stay away from the cheap stuff(tiny bedside lights aside), am not into mods or modding(light electronics anyway), and try to stick to lights with potted or conformal coated electronics. If I need added peace of mind though, I just carry a backup.

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i am, very much so. factory lights i had maybe half a dozen failures, but then i do not have many factory lights. some drivers i'm responsible for burning\damaging, some failed after drop, so i feel i have some responsibility as well, but the rest worked fine at first then quit.

That's why I use LiFePO4 LFP batteries.