Low temperature 16340 battery?

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ssssnake529

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I was wondering if anyone knows of a low temperature 16340 battery.

I've got a Fenix headlamp (HM50R V2) that takes this size of battery. I thought about just using non-rechargable lithium CR123A batteries in it for cold weather, but the Fenix website cautions against this.

Anyone have advice about low temperature battery options for this headlamp?
 
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aznsx

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I was wondering if anyone knows of a low temperature 16340 battery.

I've got a Fenix headlamp (HM50R V2) that takes this size of battery. I thought about just using non-rechargable lithium CR123A batteries in it for cold weather, but the Fenix website cautions against this.

Anyone have advice about low temperature battery options for this headlamp?
I own and use (constantly) 2 HM50R v1 headlights, and am also interested in possibly also getting 1 or more of the v2 version which has replaced it, so I'm interested in these related questions.

First, let me start with 'I don't know' regarding your specific question. I'm familiar with other 3.7V Li-ion cells (particularly 18650 size) which are optimized for low temp operation (and advertised as such), but don't recall seeing any 16340 cells advertised with that 'feature'. There may be some, but I'm unaware of them. Someone else here may have knowledge of some if they exist.

As a 'side' point, both the v1 & v2 versions are advertised as supporting LFP (LiFePO4) 16340 cells (which I use in a number of my lights), and which are of course secondary (rechargeable) cells (although they cannot be recharged internally in an HM50R). Although the LFPs are generally of lower capacity than other '3.7V' chemistry cells, they MAY offer better low temp characteristics than the 3.7V LI-ion cells, and therefore MIGHT be an option for low temp environments - in lieu of CR123A primary cells. The 'operating range' temperature specs on my K2 LFP 16340s are very close to those listed for primary CR123A cells, but I don't have any exact specs for how their performance (may) actually be affected by such low temps. It's an open question, and hopefully someone else here may know more regarding LFP cells in low-temp applications. They could be an alternative option to 3.7V Li-ion cells in cold weather, particularly until we can understand the totally ambiguous 'Caution' regarding use of CR123A cells in the v2 version (which, like you, I would like to use in cold weather).

To your point regarding the use of primary CR123A cells in these lights, they are specifically recommended for use in the v1 version, specifically for use in low temp applications; however there is a 'Caution' regarding using them in the v2 version light, and probably like you, I am interested in getting more info regarding that very ambiguous (unexplained) 'Caution' note on the CR123As in the v2 version.

I'm going to attempt to get clarification from Fenix regarding the CR123A 'Caution' note in the v2 documentation, and will inform the forum when I get that. In the mean time, we'll see if any others know of a 'low-temp' 3.7V 16340, and you might want to explore the LFP16340 option, and others here who (hopefully) have more expertise on cells / batteries than I do (which isn't much) may be able to speak to any low temp advantage they MIGHT offer vs other 16340s of the 3.7V type chemistries.

In the mean time, stay tuned for whatever info I can get from Fenix re: the use of CR123As in the new v2 version. I think it could be as simple as a 'language issue', but want to clarify that with Fenix themselves before suggesting it. One cannot guess or speculate when product liability issues are potentially involved.
 
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flashflood

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The only note of caution is that LiFePO4 cells have a lower nominal voltage (3.2V) than standard Li-ion (3.7V). Under load a LiFePO4 cell will have more like 3.0V, which would trigger the under-voltage cutoff for many standard LED drivers.
 
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aznsx

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The only note of caution is that LiFePO4 cells have a lower nominal voltage (3.2V) than standard Li-ion (3.7V). Under load a LiFePO4 cell will have more like 3.0V, which would trigger the under-voltage cutoff for many standard LED drivers.
Good point, but keep in mind my mention of LFP was only as a possible cold temp alternative to CR123A (if those are not approved, which has not been verified yet), not a general substitute for 3.7V 16340s at normal temps in that light. Also, while LFPs do eventually get below 3.0V, it's well out into most of the discharge curves - far further out than for a CR123A. But yeah, once anything goes below 3.0V, that light likely considers that territory to 'step down' output, so certainly a valid point (it will not shut off at 3.0V though). This assumes that this light doesn't automatically determine 3V vs 3.7V cell at time of installation and power-up, which several of my 16340 Fenix lights actually do (RC09, etc).



Edit: I hope to find out more as to the v2's compatibility with CR123A cells &/or what "caution"s come into play when they're used. They're listed as 'caution' in the battery table in the documentation, but not as being completely disallowed (as far as I can see). Knowing that will determine the relevance of any or all of these other issues / points.

As for the other question: Do you know how seriously cold temps affect LFP performance relative to 3.7V chemistry 16340s? That would determine their viability as an option to 3.7V 16340s in cold temps in lieu of CR123As. My cold weather experience with LFPs is rather limited given where I live!

.
 
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aznsx

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I was wondering if anyone knows of a low temperature 16340 battery.

I've got a Fenix headlamp (HM50R V2) that takes this size of battery. I thought about just using non-rechargable lithium CR123A batteries in it for cold weather, but the Fenix website cautions against this.

Anyone have advice about low temperature battery options for this headlamp?

I got busy and have not yet followed up with Fenix on the issue of the HM50R V2 compatibility (or lack thereof) with CR123A, but before I do, I have a question. What web site and info were you referring to when you commented that "the Fenix website cautions against this"? I just want to check whatever info you've seen before I communicate with them.

You may be referring to this 'fenixlighting' site info, under 'Operating Instructions' tab in the 'Battery Specifications' chart, where 'CR123A' is marked 'Caution'. This is what I'm going to follow up with them about:


Also keep in mind that at the 'fenix-store' site in the FAQ for the HM50R V2, there are three (3) questions with answers that all indicate that it's 'compatible with non-rechargeable CR123A battery'.


I think I may know why it may be 'compatible with' but perhaps not fully recommended, or only so with a caution (beyond obvious charging cautions), but I'll hold off speculating until after I find out what the official word is. In the mean time, let me know what info you've seen on the subject. Also, if you have one, what do your hard copy instructions say? I've seen some rather conflicting info out there, including with a distributor or two, so this is worth clearing up. I also want to know before I order one (which I'm considering).

Thanx!
 
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Stefano

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I have now looked at the manual for this model on the Fenix website.
It says: "Caution" with CR123A but then it is specified below why "High mode c'ant be entered when using the CR123A battery"
 

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aznsx

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I have now looked at the manual for this model on the Fenix website.
It says: "Caution" with CR123A but then it is specified below why "High mode c'ant be entered when using the CR123A battery"

Thanx Stefano. That's exactly the info I was seeking, and exactly the info I was expecting as well! I'll still confirm all my assumptions with Fenix, but you provided exactly what I really needed. It's fairly obvious to most of us here that one isn't going to have much luck powering 700 lumens with a single CR123A, but for the average buyer, such a 'caution' note is entirely appropriate. Unfortunately they omitted that note from the 'fenixlighting' info that I linked to, but I'll make them aware of that when I communicate with them.

Thanx again for the help!
 
ChrisGarrett

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My guess is that the Fenix HL exceeds the ~1.5A rating of the CR123A at 700LM.

Chris
 

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