seeing the difference in light output by switching from NiMH batteries to Li-ion in a few lights got me dreaming of a greater lumen/mass ratio. now I know the only lithium-air batteries exist experimentally, but hypothetically when/if they become available commercially will they offer anything more than greater capacity? will I one day be able to slip a AAA size Li-air battery in my EDC torch for more lumens?:thinking:
hypothetically, what will lithium-air batteries mean for flashlights?
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ronkar
Newly Enlightened
It appears that lithium air batteries require exposure to air.
So, hypothetically, I would say that lithium air batteries would ensure that your flashlight is vulnerable to water, dust, pocket lint, and possibly, explosive atmospheres. Does not sound like a viable combination for EDC.
So, hypothetically, I would say that lithium air batteries would ensure that your flashlight is vulnerable to water, dust, pocket lint, and possibly, explosive atmospheres. Does not sound like a viable combination for EDC.
RedForest UK
Flashlight Enthusiast
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To be honest, I don't know anything about lithium air cells :thinking:
But as far as I know, more lumens in the same light can only be produced by a higher voltage cell. As most lights designed for Ni-mh cells can't even deal with the 3.7v nominal voltage of li-ion cells then you would probably need a different light for any higher voltage if the new chemistry offers that. Basically, the limitations on lumen output on most flashlights are due to what the led, driver and heat sinking can handle.
What advances in battery chemistry will offer in general will be an increase in capacity stored in the cell. Meaning longer runtimes. Of course we can all hope that this will be mirrored by increases in led and electronic technology which will then be able to harness this capacity and turn it into more lumen output. Basically, the cell will be able to be driven harder and so flashlights could be brighter.
But if you want to stick it in a light you already have then it will either not increase it's output very much, or simply make it go
But as far as I know, more lumens in the same light can only be produced by a higher voltage cell. As most lights designed for Ni-mh cells can't even deal with the 3.7v nominal voltage of li-ion cells then you would probably need a different light for any higher voltage if the new chemistry offers that. Basically, the limitations on lumen output on most flashlights are due to what the led, driver and heat sinking can handle.
What advances in battery chemistry will offer in general will be an increase in capacity stored in the cell. Meaning longer runtimes. Of course we can all hope that this will be mirrored by increases in led and electronic technology which will then be able to harness this capacity and turn it into more lumen output. Basically, the cell will be able to be driven harder and so flashlights could be brighter.
But if you want to stick it in a light you already have then it will either not increase it's output very much, or simply make it go
jhellwig
Newly Enlightened
You would need a Gatling gun light.
from what I have read, one of the reasons that Li-air batteries are not available yet is the challenge of letting air in while keeping water out. since ambient air has moisture in it, and the whole point is to use ambient air as the cathode, there has to be some sort of membrane implemented in the battery to block out everything but what is needed. there won't be any Li-air batteries used for any purpose until that problem is solved.
To be honest, I don't know anything about lithium air cells :thinking:
But as far as I know, more lumens in the same light can only be produced by a higher voltage cell. As most lights designed for Ni-mh cells can't even deal with the 3.7v nominal voltage of li-ion cells then you would probably need a different light for any higher voltage if the new chemistry offers that. Basically, the limitations on lumen output on most flashlights are due to what the led, driver and heat sinking can handle.
What advances in battery chemistry will offer in general will be an increase in capacity stored in the cell. Meaning longer runtimes. Of course we can all hope that this will be mirrored by increases in led and electronic technology which will then be able to harness this capacity and turn it into more lumen output. Basically, the cell will be able to be driven harder and so flashlights could be brighter.
But if you want to stick it in a light you already have then it will either not increase it's output very much, or simply make it go
well take a Fenix LD01 for example. it's not designed for any greater voltage than a AAA NiMH battery can provide (1.2v) but if you put a 10440 Li-ion cell in it (4.2v) it doesn't explode but does have greater output. it will get hot rather quickly, but for momentary use it works quite well. obviously though that specific light wouldn't tolerate higher voltages infinitely, and at some point it would
even with just momentary use.anyway that is tangential to my question, which would perhaps be better stated as "will Lithium air batteries offer higher voltages (compared to Li-ion batteries of the same size) or simply increased capacity?"
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Lithium Air cells use metallic lithium ( anode ) and carbon ( cathode ) plus manganese as catalyst. A lithium foil is pressed into a nickel mesh which is then coupled with an air cathode made with carbon layers containing the catalyst. Non aqueous electrolytes are used to prevent water reaction with the lithium metal. A telfon film is in place to seal out atmospheric moisture while air is allowed through O2 diffusion. The nominal voltage is 3.0V and has a very high theoretical energy density. Performance is temperature dependent. Rechargeable version is still under development. Safety is a big concern with the use of metal lithium.
DM51
Flashaholic
Battery Guy
Enlightened
The advantage of lithium-air will be in its extremely high specific energy (Wh/kg). This means that they are relatively light weight. However, the energy density for a practical lithium-air is equivalent to a zinc-air cell. Since most people reading CPF are going to be working within constraints of volume and size, not weight, energy density is really the more important performance parameter.
So, what you should really be asking is "what about zinc air?" The problem with zinc air is that although the energy density is high, the power density is low because the discharge rate is dependent on the rate of oxygen reduction on the air electrode. Also, your battery compartment would need to be vented so that oxygen could get to the cells.
So air batteries (both zinc and lithium variety) may be great for some applications, but I think that for most flashlight applications, you would be better off looking to other battery chemistries.
Cheers,
Battery Guy
So, what you should really be asking is "what about zinc air?" The problem with zinc air is that although the energy density is high, the power density is low because the discharge rate is dependent on the rate of oxygen reduction on the air electrode. Also, your battery compartment would need to be vented so that oxygen could get to the cells.
So air batteries (both zinc and lithium variety) may be great for some applications, but I think that for most flashlight applications, you would be better off looking to other battery chemistries.
Cheers,
Battery Guy
I see. that's a very good explanation thank you.
Bronco
Enlightened
I hope the mods don't mind my dredging up an old thread, but it seems as if researchers have recently overcome a few hurdles in their ongoing development of a viable lithium-air (or lithium-oxygen) battery. Given that this older thread addressed some of the perceived shortcomings of the technology's potential application vis-a-vis the flashlight world, I thought it was worth revisiting as a way to provide some context before adding a link to the new article.
http://www.theinquirer.net/inquirer...-extend-life-of-smartphones-and-electric-cars
Without knowing what the limitations of the eventual commercial cells will be, it is way too early to say. Extending 2010 limitations of Zinc-Air to Lithium-Oxygen in 2025 is akin to basing today's LED limitations to LED technology in 2000, it's just not applicable ... though there was likely a clearer path for LED.
All we can do is guess. Odds are it just means more run-time, not higher powered lights .. but that's a guess. It may be as surmised be a complete non-starter due to limitations in the oxygen exchanged.
Semiman
This is incorrect. The 2010 limitations of Zinc-Air mentioned above are exactly applicable to Lithium-Air in 2025 with regards to flashlights, because they are limitations from the flashlights, not the batteries used. Both chemistries gain their light weight and energy density by having one of the reactants (oxygen) come from the surrounding atmosphere instead of being stored inside the battery all the time. For flashlights, this is an obvious problem, since most flashlights are designed to isolate the battery and electronics from the surrounding atmosphere for the purpose of being waterproof. No atmosphere, no oxygen, no metal-air battery function.
KeepingItLight
Flashlight Enthusiast
I love hearing about new battery technologies. No matter what is said, however, it's all pie-in-the-sky to me. Usually you get a caveat that 5 years will be needed to complete development. This time, it was 10.
A good first-order approximation for such announcements is that 5 years = infinity. There are zounds of battery breakthroughs that have already had their 5 years, and we are still waiting.
A good first-order approximation for such announcements is that 5 years = infinity. There are zounds of battery breakthroughs that have already had their 5 years, and we are still waiting.
You are assuming an operating mode of high power, but most flashlights don't operate at more than a few watts. Having a vented battery compartment is not insurmountable and you will notice recent advancement does not require completely dry.
