Suddenly running out of juice?

Does anything like this ever happen to you? It's happened to me a couple of times now, both with my Lumens Factory P7M turbohead on my SF M3, and with my Jetbeam M1X.

I was walking out to my shed last night to get my 12' tall ladder. My hourse sits on 5 acres, and I have no lights on this whatsoever, so it's quite dark here. Anyway I take a flashlight with me (in this case the M1X) so that I'm not attacked by Ninja's while walking out there. Well, OK, we don't actually have any Ninja's out here, but we DO have skunks... (My policy is Mr. Skunk always gets the right of way!) Anyway, I'm walking along, and suddenly: my light goes out!

This isn't a big deal - I have another light on me, but it occurred to me that I'd been using the M1X well past the 50% brightness point, and the batteries (I'm using the extender with 2x 18650's) finally collapsed to the point that they couldn't power the LED any longer. (The light powered right back up once I changed the batteries.)

The thing is - 50% of an MCE is still bright as hell, and plenty to illuminate my yard quite effectively.

Anybody else find it hard to notice when these lights are really dimming? Older (luxeon I, III & V based) LEDs I have are dim enough that I guess once they start to fade, it's pretty noticeable. But both my P7M & M1X really seem able to surprise me by running out of juice quite suddenly. Or perhaps I'm just unobservant?

Am I correct in concluding that these things just provide way more than enough light for most purposes until they don't provide any light at all? Because that's how it seems to me. Or is this a property of the rechargeable Lithium ion cells? (My older lights always used primary CR123A's.)

I will say that I am utterly amazed by the output of these newer LEDs.

If you are using protected LiIon batteries, they will shut down before they are discharged to much, i.e. the light will go out, because the batteries turn the power off.

With unprotected LiIon batteries it is a very bad idea to wait until the light goes out, before charging them.

HKJ said:

If you are using protected LiIon batteries, they will shut down before they are discharged to much, i.e. the light will go out, because the batteries turn the power off.

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OK, thanks, that explains it. I am using protected LiIon batteries in both lights.

It's important to use protected cells in multi-cell arrangements so that weaker cells don't over-discharge before you notice that you're low enough for a recharge.

For NiMh cells, you just have to accept that in multi-cell arrangements, you're probably going to have reduced life expectancy for your weaker cells, so it helps to have a smart charger that can quantitatively describe the health of each cell when charging.

Personally, I just use single cell lights to avoid the headache.

--flatline

conversely, if you want the light run down into a pale yellow glow, you can pick up a 2cell incan with a PR base bulb...

The Ghost Hunters lights go out when a powerful spirit sucks the energy from their batteries. just having fun :naughty:

I find that with the Nitecore EX10, with no warning , other than that, awesome lamp. Of course now that I know that, we always carry back ups.

pockets said:

The Ghost Hunters lights go out when a powerful spirit sucks the energy from their batteries. just having fun :naughty:

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LOL! Too funny! Funny you should mention that.

I recently took a ghost tour recently in Eureka Springs. They made a big deal out of having been investigated by Ghost Hunters. You know something? Touring a haunted hotel is a lot lower thrills per minute than I expected. And my expectations were pretty low! My wife got bored and decided to bug out to the bar.

I noted no effect on my flashlights or camera battery after the tour. :tinfoil:

MrBenchmark said:

LOL! Too funny! Funny you should mention that.

I recently took a ghost tour recently in Eureka Springs. They made a big deal out of having been investigated by Ghost Hunters. You know something? Touring a haunted hotel is a lot lower thrills per minute than I expected. And my expectations were pretty low! My wife got bored and decided to bug out to the bar.

I noted no effect on my flashlights or camera battery after the tour. :tinfoil:

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That's Great!! :laughing: (and probably typical)

LumensMaximus said:

I find that with the Nitecore EX10, with no warning , other than that, awesome lamp. Of course now that I know that, we always carry back ups.

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You must be using protected Lithiums also I would hope. My EX10 drops to lower levels when it cannot sustain a certain level.

MrBenchmark said:

OK, thanks, that explains it. I am using protected LiIon batteries in both lights.

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If you go here and scroll about halfway down, there are some nice graphs that show exactly what you've been experiencing. You'll also see that the CR123s exhibit the more "normal" behavior that you remember, with the light tapering off down to almost nothing before going out.

pockets said:

That's Great!! :laughing: (and probably typical)

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Oh well, I don't believe in ghosts, but I do think it's interesting to observe people who do. The stories about the hotel were fun. It was a hospital for a time where some very, very bad medicine was practiced.

Apparently, though, being psychic doesn't endow one with awesome story-telling ability, because it took a long time to get to the good parts. (And my B.S. meter stayed in the red zone most of the time!)

Thinking this through a little bit, I wonder if I can set something up so my batteries are drained just about the time I'm walking by a graveyard with one of my friends, while I'm telling them how the crazy guy at the hotel said "ghosts often drain direct current energy sources." It would be perfect if the light went a bit after I said that, but while we're in the vicinity of someplace spooky! Going from "really bright" to "off" gets your attention.

Heh heh heh. :devil:

Yeah, I'm pretty much going to hell when I die.

With decent regulation it can be pretty hard to tell when the lights going out. It can be a very sudden dimming that occurs within 3 minutes.

That's why I got an LF5XT, so I can have the light blip out what the battery voltage is, so there are no surprises.

Also, IMHO the cutoff voltage on protected cells is ridiculously low. I'd like to see 3.2v under load as the cutoff, or 3.0 at the WORST. 2.5 is utter crap and although it might not cause fires, I suspect that it dramatically weakens the cells.

(I had a Nitecore D10 that I used protected 14500's in, and it would frequently accidentally turn on and drain the batteries to the cutoff while in hi output. I eventually checked how many mAh were put back into the cells, and the capacity was 1/3rd of the original capacity.)

LumensMaximus said:

I find that with the Nitecore EX10, with no warning , other than that, awesome lamp. Of course now that I know that, we always carry back ups.

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i ended up using some soshine unprotected 16340s in my EX10 as the trustfire protected 16340s wouldnt fit, well, thats not entirely accurate, the bezel could still screw in all the way but then the piston wouldnt function so i would have to use it in momentary and have no means of changing light levels.

I found that once output on max starts dimming, its time to check the voltage and recharge.

this works for me and i always make sure that the cells are fresh or have a spare or 2 on me.

Stuff like this is the reason i use no protected cells at all.

I rather ruin 10 cells than having a light that literally could stop dead every second.

IMSabbel said:

Stuff like this is the reason i use no protected cells at all.

I rather ruin 10 cells than having a light that literally could stop dead every second.

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i use exclusively protected cells because i don't want it to blow up in my face. I don't what are the chances, but regardless i chose to avoid it when possible.

You can avoid it shutting off on you by keep watch on the time, when its close to its anticipated deadline, turn it to a lower level then change battery when you can?

berry580 said:

i use exclusively protected cells because i don't want it to blow up in my face. I don't what are the chances, but regardless i chose to avoid it when possible.

You can avoid it shutting off on you by keep watch on the time, when its close to its anticipated deadline, turn it to a lower level then change battery when you can?

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I don't understand the big deal. When my Li-Ions shut off (protected AW's, all sizes), I just wait a couple of seconds for the rebound. Most of my lights have memory and it comes back on at the unsustainable level. I quickly switch it to a much lower level. I've gotten about one hour more of use out of cells like this . . . granted lights are like tools and if you're carrying a 500+ lumen MC-E, it's lowest mode probably won't do for the task at hand. Still, better than nothing.

Plus, knowing this little trick will alleviate the pain from having to carry a back up constantly . . . unless you're like me and your backup is a beautiful little Ti hanging off your neck.

So.... then it's really not a big deal to run your 18650's until the protection kicks in? I have a light that uses two in parallel, and I was under the impression that it was bad to do so. :thinking:

If you routinely engage the protection by draining the cells that low, you are permently damaging the cells. Frequent recharging LONG before they reach that level is best.