Lithium's and the L1P

propcut

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Newby Question?
I am getting ready to order a Fenix L1P. I have been reading here on CPF all I can about this light. I am well convinced that it's the right light for me. I would like to know if anyone can tell me if there is any danger to the L1P by using a lithium as opposed to an alkiline battery? Is the danger only to my wallet. I have some other small LED flashlights. One is the River Rock AAA .5 watt. It seems to me that when I load it with lithium's as opposed to alkiline's there is a slight increase in it's light output. I have read much here about overdriving LED's but there is much I don't understand. Does the use of lithium's present any overdriving danger or is it just a better battery and presents no risk to a circuit. Thanks in advance for any help.
 

randyo

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Shouldn't be a problem. Sure, they're slightly higher at around 1.75 V when new, but that ain't much. You should see the output when you feed it 3V!!
Just don't do it for very long.
 

Yooper

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I've been running Energizer E2/L91 lithium primary AA's in my L1P for quite a while with no problems. It is slightly brighter on the lithiums compared to a NiMH rechargeable. It's also noticeablly lighter in weight and the battery lasts much longer than an alkaline.
 

Chris201W

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Not to discredit what's been said already, but can anyone really say that you can run lithiums in a light that hasn't been approved for lithiums without running it for thousands of hours and verifying that there's no damage to the LED? I mean, maybe you could run lithiums in an L1P for a year without any problems, but then after say, 5 years, the tint changes, gets dimmer, stops working, or however else an LED fails. Maybe people realize this and don't care because in 5 years, newer and better lights will be out anyway, I just thought I would point that out.
 

Grubbster

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Chris201W said:
Maybe people realize this and don't care because in 5 years, newer and better lights will be out anyway, I just thought I would point that out.

You hit the nail on the head! :naughty:
 

Yooper

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Chris201W said:
Not to discredit what's been said already, but can anyone really say that you can run lithiums in a light that hasn't been approved for lithiums without running it for thousands of hours and verifying that there's no damage to the LED? I mean, maybe you could run lithiums in an L1P for a year without any problems, but then after say, 5 years, the tint changes, gets dimmer, stops working, or however else an LED fails. Maybe people realize this and don't care because in 5 years, newer and better lights will be out anyway, I just thought I would point that out.


I'll probably lose mine before then, or drop it in a lake or flush it or something. Life is short. Burn your LEDs bright!
 

lamperich

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Chris201W said:
Not to discredit what's been said already, but can anyone really say that you can run lithiums in a light that hasn't been approved for lithiums without running it for thousands of hours and verifying that there's no damage to the LED?

iam with you
but not in this price class!

look at surefire torchs.

They are silly priced. consumer expect (too) much ~370 EUR for U2 here in Europe
sick2.gif


If you worry about such things in a 40 EUR light
don´t use NOT recommended batteries.
 
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bucken

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randyo said:
Shouldn't be a problem. Sure, they're slightly higher at around 1.75 V when new, but that ain't much. You should see the output when you feed it 3V!!
Just don't do it for very long.
I have a couple Blaster Jr.'s that have been driven with 6V DD for a couple years, now. Sometimes being run for well over an hour at a time. Have never had any problem but, granted, the Blaster series all have EXCELLENT heat-sinking.

Oh, I'm running Lux III's in the Blasters... Could that be the difference? Or will the higher voltage damage the circuit on a Fenix and make it inoperable?
 

wasBlinded

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A lithium AA cell will quickly drop down to the 1.5 volt range when being asked to supply the kind of current the L1P likes to be fed. I think it unlikely there would be any problem.
 

nzgunnie

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I put 2 Energizer E2 Lithiums into a stock AA minimag and ran it for about 20 minutes, that was enough to drop the voltage from 1.8v down to 1.55v. For the short period that the light is operating at 1.7v I doubt it would be a problem as it will no doubt drop pretty fast.
 

NewBie

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Chris201W said:
Not to discredit what's been said already, but can anyone really say that you can run lithiums in a light that hasn't been approved for lithiums without running it for thousands of hours and verifying that there's no damage to the LED? I mean, maybe you could run lithiums in an L1P for a year without any problems, but then after say, 5 years, the tint changes, gets dimmer, stops working, or however else an LED fails. Maybe people realize this and don't care because in 5 years, newer and better lights will be out anyway, I just thought I would point that out.


Yes, I can, from the LED's perspective of what the converter drives it at.

The converter in the L1P doesn't even drive the LED to its rated 350mA until you get to 1.46V input, and remember, cells sag under load. And the cell voltage drops as it is depleted. So you'd be slightly overdriving it, and also slightly underdriving it over the life of the battery. This might vary, if you got an L1P with an extraordinarily low Vf, or one that was high.



fenix.png
 

Chris201W

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NewBie, I'm not entirely sure what that chart means, but if you're saying what I think you're saying (that lithiums in the fenix really won't reduce the life of the LED by that much), I'm gonna get me some lithiums for my fenix!
 

paulr

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Oh my, that graph is pretty disappointing, basically 50% efficiency over most of the useful voltage range of most AA cell types, though paradoxically more efficient as the battery is on its dying legs. That compares unfavorably with the Arc and Dorcy circuits which tended to be about 80% efficient. In practice that means with a better circuit, the L1p could have about 1.5x as much runtime (to 50%) on any given battery type as its currently has. Alternatively it could be around 40% brighter (35 lumens out the front instead of 25, say).

I still do think the L1p is getting close to the end of the evolution of the Luxeon pocket light as we know it.
 

lamperich

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paulr said:
though paradoxically more efficient as the battery is on its dying legs. That compares unfavorably with the Arc and Dorcy circuits which tended to be about 80% efficient. .


Where do you got this information about the arcAAA you are talking about AAA arc don´t you ?

the "cpf holycow" arc AAA could also run longer if more efficient


It´s not made by me. Some of the cpf members creat this chart a couple of moth ago.
That´s not really a surprise.
Iam also keen on such information about the V2.0 Fenix and why it peform like a Fenix "XT"...
 
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socom1970

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Is it OK to use lithium AA in Fenix L1P?

Does anyone know FOR SURE if it is OK to use a lithium AA 1.5v cell in the Fenix L1P? I know lithium AA's can be as high as 1.78 volts when new. I may be getting one soon and I want to use lithiums in it, but I don't want to ruin it and I have read that using lithiums in it are at our own risk. Does anyone have knowledge of this? Also does anyone know runtime with a lithium AA in the L1P? Thanks.
 

lamperich

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Re: Is it OK to use lithium AA in Fenix L1P?

@socom

if something isn´t reommended by the manufactur than it´s always used at our own risk. tháts right.

yes l91(&clone) are 1,7-1,9V BUT without load!
With load it goes down. (Further information on that Batterie shootout´s made by silverfox)
LR6 typicaly also have over 1,6V!!!
The question is how fast. will the voltage drops for example if you use "momentan On" action very often.

My advise: If you are a "scaredy-cat" than always do what the manufactur says.


There are severel threads with L91(or Clone) runtimeplots. Use the serachfunction.


FenixRuntimeGraph1.jpg
 
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Blazer

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Re: Is it OK to use lithium AA in Fenix L1P?

socom1970 said:
Does anyone know FOR SURE if it is OK to use a lithium AA 1.5v cell in the Fenix L1P? I know lithium AA's can be as high as 1.78 volts when new. I may be getting one soon and I want to use lithiums in it, but I don't want to ruin it and I have read that using lithiums in it are at our own risk. Does anyone have knowledge of this? Also does anyone know runtime with a lithium AA in the L1P? Thanks.

I don't have any technical data but only practical experience.
I bought two Fenix L1Ps at the same time, one stays in the box (future gift or replacement for my EDC). As an EDC I put an Energizer Lithium in it. Use it for about 2-5 min per day and so far so good. I haven't noticed any drop in output but again, only a couple of min per day over the last 3-4 weeks. I'll see how it runs in the long term, but that's one of the reasons I got the second, as a backup/replacement in case I mess up the first one. At the price it's a great flashlight and worth getting more than one.
 
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