As others have said, a LiFePO4 cell flashlight is possible. It wouldn’t necessarily take a lot of modification. Your specifications for “the stud” flashlight don’t really seem relevant to using one battery chemistry or another.
For a single cell light you would need a low enough Vf LED to use with linear or FET drivers, and to modify the low voltage protection.
For a 2 cell in series light (but single 3V LED) that uses a buck driver you could put in 2 LiFePO4 cells and it should work, but again the low voltage cutoff would have to be modified.
I don’t think LiFePO4 cell flashlights will ever be popular, but you can make your own simple one easily. You could simply connect the cell directly to the LED with no driver. The brightness will depend on the LED Vf, but it should be pretty constant because of the very flat discharge curve of the cell. It should also be pretty easy to modify the low voltage cutoff of a linear or FET driver which would give you ability to dim the light and have modes.
Serious question. I don’t believe any of my chargers will charge a LiFePO4 cell, what happens of I accidentally put one in there? Not interested in upping the danger level in my life or burning the home down.
It has been claimed by many that the LiFePO4 cell chemistry, even though it has a lower nominal voltage, can survive overcharge. I just recently bought a new 4 bank charger that has 3.7V cut-off option for LiFePO4. I have been using Soshine 14500 LiFePO4 cells for a while now, charging them on my Nitecore i4 charger. They seem to be okay, but I needed a new charger for other reasons, so I made sure it had the 3.7V cut-off while I was at it. I’ve read about people building e-bike packs out of LiFePO4 cells and purposely overcharging them as a means of balancing so they didn’t have to use a BMS. None of that is recommended, but it seems it was working for them at least for a while. I’d like to see a follow-up, but I can’t remember what site I saw that on.
The idea is long from being produced. I will be giving insight from Engineering background. Why would one use LiFePO4 cells with lower capacity and less run time? The Li Ion cells are more readily available.
The design to incorporate the correct circuts, boards, etc… will take a lot of time. To top that other li ion cells could not be used effectively if one needed a backup power source when LiFePO4 cell NOT AVAILABLE.
Lights running these LiFePO4 fail easy. Take a look at Maglite Magtac Rechargeable flashlight as example. Fails BIG TIME. Mind you I like the design and look of flashlight.
In end producing LiFePO4 flashlight will not cost effective for sure.
The entire point of using li-ion batteries in flashlight is because of the highest Wh/kg and Wh/L of batteries.
The only real advantage that LiFe has is safety, and if someone actually wanted high safety they would use NiMH which is much safer than even LiFe.
More charge cycles isn’t really an advantage in this case because people have so many Li-Ion batteries and they get replaced so often anyway due to battery evolution and improvements.
Also I don’t think many people recharge their flashlight batteries every single day over 5 straight years anyway.
What are the benefits on a flashlight of Lifepo vs Li-ion again?
Most of the time Lithium related accidents are directly related to the device, not the battery itself. Anything can be dangerous under the wrong circumstances.
High voltage low current is the future of LED, I just don’t see why go backwards.
Sorry I’m not going to use any of those newfangled batteries. I’m still using my Edison batteries. These don’t tinker around with the atmosphere which is why they are used on submarines.
I don’t know. I think most people here only have Li-ion batteries because of their flashlights; but it’s true they’re not discharging them daily.
But also there’s this:
No for this discussion it needs to have regenerative jacking charging for all the jacking off the offbeat (see what I did there?) commenter’s are doing.
Be charged full in no time !
Got a good idea for that pogo stick as well,….but this a family forum yeah right anyway.
The move to 48V is prompted by all those things mentioned, but mostly for the new starter-generator system most vehicles will employ to enable rapid start-stop capability
NiMH doesn’t make sense for a lot of reasons, not the least of which is the cell voltage of 1.2V.
Look at all the complaining about losing half-a-volt with LiFePo4.
I’m just coming at this from a fresh perspective. I’m not mired deep into the depths of the flashlight world where groupthink tends to prevail. Same with the world of firearms.
To me it’s clear: LiFePo4 is a better battery. So let’s make flashlights designed for them. It’s just that simple.
Well, almost that simple. To me, it would be wise to look onto the horizon and see what chemistry and voltage the next promising batteries will offer in the 18650 form factor. If it looks to be closer to 3.2V than 3.7V … then it would make sense to go ahead and start building these slightly-lower-voltage LED lights.
Barry, in my opinion you are not going to convince many people with your opinion. And you are coming across as a bit condescending which won’t help.
If you feel so strongly about LiFePO4 you can at least modify your own flashlights to work with them. See my and other’s posts to get an idea of how you would move forward to do that. I’m sure you would get helpful direction if you wanted to do that.
But yeah, a lot of people have lent me some valuable tips and expertise. Almost too much, in that, there are obviously many ways to go about this — coupled with me knowing too little about LED circuit design (drivers and such).
I was kinda hoping for something like:
“Alright. Doing it like this offers best compromise between simplicity, price, efficiency, off-the-shelf and readily-available components…”
Or even:
“This already exists, and it’s cheap. See this product: …” … or … “Take this particular $20 light and do this one simple trick: … ”
Even better:
“I think your hybrid LiFePo4 flashlight / suppressor-building-block design is brilliant. Let’s go ahead and get this on the drawing board. For sure it will sell 10,000 units next year. You will get 30% royalties for this truly inspired idea.”
If you like LFP that’s fine, but clearly not many are yet swayed by your arguments.
Seems it would be best to start with some market research. Who are you marketing these towards, flashlight enthusiasts, regular supermarket shoppers, LEO/SAR professionals? What advantages do LFP cells have for the group you chose and how do you convince the group of these advantages? What type of flashlights does the group want?
I think you are getting ahead of yourself trying to design a product with no indication that anyone besides you would want to buy it. Sadly, that is almost never the start of a successful business.
It can be done right now, pretty much no mods required.
An XP-G2 has a fairly low Vf, 2.9V-3.1V, so you can limit current with a bunch of 7135s. Overhead is 0.1V, so even on the high end of 3.1V that fits well with the cell’s 3.2V.
So grab an S2+, stick a 7135-based driver in there if you don’t like the come-with one, and drop in an XP-G2 triple with TIR lenses. Done.
It won’t be a screamer, but I already got LFP cells in 14500, 18650, and I think 26650 for when I wanted to stick one in a C-cell light.
And it’ll be perfectly regulated from right out of the charger to cutoff, with little waste from, say, a 3.0V to 4.2V difference (LED vs cell).
So… not sure why everyone’s getting all worked up.
yeah right anyway.