RCR123A 3.0v or 3.6v?

AardvarkSagus

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I am running into a little bit of a dilemma. I have gotten to the point where it may well turn out that rechargeable 123 batteries may be more financially reasonable for my usage levels than primaries. I now have a couple of lights that get used on a regular basis and prefer the concept of knowing I have a fully charged light handy at all times. My question now becomes one of which ones to choose.

When I first started looking into RCR123A batteries it was when my company purchased a fair number of Fenix P2Ds (15-20) for the Printing department. I had read here somewhere that full 3.6v RCRs would eliminate the ability to use the lower light levels in that light causing it to instead go into direct drive. At this point I ran across a decent deal for some Tenergy 900mah (claimed) 3.0v protected RCR123As that seemed to be a good fit. I suggested them to my employer and they went ahead and purchased several of them along with a couple chargers.

Now at this point, I am curious about whether or not those are the best way for me to go or not. At the moment I am looking at 3 lights that use 123s and one of them is in the role of long term storage emergency light and therefor isn't really needing rechargeables anyway. Other than that I have a Pila GL2 with Cree LED Module and a Nitecore EX10. My initial thought is to go with the 3.0v even though they likely have reduced capacity over the 3.6, because that way I can completely view them as direct replacements on a 1:1 basis with primaries for any light. The more I think about it however, the more I see some reasons not to head that direction. Both lights I will be using RCRs on are capable of using the 3.6v batteries. The EX10 claims to have full compatibility and the GL2 drop in also works in the GL3 running either 9v of primaries or 2x300P rechargeable li-ions.

Since these 2 lights are all I am considering at the moment, what advantages would I be seeing from 3.6v's over the 3.0v's? What brands are quality and hopefully not too terribly expensive either?
 
The 3.6volts will make the light brighter but you also have to consider the 3volt which would be compatible with almost any light thats out there now........with the 3.6 you have to make sure that your new light purchase will be able to handle that voltage because when fully charged the voltage of the cell will be higher. I use 3volts only and fresh of the charger there around 3.2-3.4volts which all of my lights can handle. I was also taking a look at the Tenergy's so please let me know how they do.
 
I have not had much luck with using 3.0 volt RCR123's in Fenix and other lights that go direct drive and loose thier low levels. That was one of my big gripes about Fenix. My solution was to buy other lights :) but if you have a bunch of Fenix lights it may be your best solution to try the 3.0 volt RCR's - but as you may know their are a couple types of these. One uses a circuit board to limit the voltage whereas the other uses a different chemistry that is closer to 3.0 volt. Closer is key though as it's usually still a bit higher than primaries fresh off the charger and you still may not see much difference on your low settings.
 
I use those Tenergy batteries in my Olight T-10 and they work fine at all levels.
 
taking the Fenix's out the of the picture, looking at just your lights as a separate problem to tackle, the best way to go is the 3.7V protected RCR123s, AW or BatteryStation brand are reliable and of correct dimensions :) (some alternative brand RCR123s are oversized).

The "3.0V" Tenergy "900mAH" cells are actually just 3.7V cells, even smaller than a regular RCR123, that has a diode voltage reducer of sorts slapped into the circuit. (this combined with the PCB brings it back up to full length) The result is a lower capacity cell, probably around 3.7V 450mAH, but since the "amp hours" are being "stretched" out by the reduced voltage, the result in effect is a lower voltage higher mAH cell than what is contained within, but the voltage reducing diode is not 100% efficient, probably close to 80-90%, so a chunk of available capacity is lost. My general rule of thumb is to figure that a 3.0V "regulated" cell will have about 25-33% less watt-hours of available energy compared to a 3.7V cell. ....Also-: Expect about 1/3 the runtime you get on regular primary CR123s.

The charger for these types of cells (3.0V regulated) has to put out 4.4V to overcome the diode backwards to completely charge the cell. Having these chargers around in large quantities IMO is very dangerous as all it takes is for 1 person to think he knows better, and go trying to use it to charge some 3.7V cells, in which case they will be severely overcharged.

am I complicating things yet?

I guess you could say that I have pointed out some of the pitfalls of those 3.0V cells, so maybe that will help you see why the 3.7V cells are a little better for compatible applications. Just please, make sure to get your own charger designed for 3.7V cells.

I wish I could have been there to speak up against the investment in P2Ds, it's a nice light, but 9 times out of 10, people on here decide to go rechargeable and are stuck with lousy alternatives.

Another popular option is the LiFeP04 cells, which I tend to recommend over the 3.0V regulated cells. They actually have even less true capacity, but I believe they could potentially be more reliable as they have no protection circuit to fail, no voltage reducing circuit to fail, longer cycle life, etc etc. It's a safe chemistry that can tolerate some mild overcharge and over-discharge without much trouble. Oh.. and since the chargers only charge to ~3.6-3.8V, you don't have to worry about it being misused to blow up another type of li-ion cell.

Eric
 
@mdocod: Thanks for the info. I also read much of your rechargeable battery thread in your sig. Good information there. Now my question becomes, where would I be able to find some of those LiFePO4 type batteries. I like the concept of those being much closer to 1:1 replacements but I have no ideas of the priceing. Also where are the best locations to purchase the standard 3.6vRCR123A's? I haven't completely decided yet which direction to go. When it really comes down to it, I haven't even completely decided not to just continue to use Primaries.
 
The "concept" of being closer to 1:1 voltage wise should be all-together dropped and ignored... I noticed this in your original post:

...because that way I can completely view them as direct replacements on a 1:1 basis with primaries for any light.

The problem is even though they say 3.0V on the label, they are NOT direct replacements for a CR123 in any light. Under a load, every 3.0V rechargeable cell out there behaves much differently than a CR123.

I'll start with a link to a LiFeP04 cell, similar cells are often sold by other resellers as "3.0V" cells:
http://www.cpfmarketplace.com/mp/showthread.php?t=125353
notice how AW has listed them as a 3.2V cell? It's because that's what they are :) And fresh off the charger, they will be ~3.6V, a pair of these dropped into almost any incandescent CR123 powered flashlight, or any "resistored" LED light, will experience overdrive and premature failure.

Here's another place to buy them:
http://www.batteryjunction.com/rc375reliba.html
notice they are being sold as 3.0V cells here, this is consistent across the board from there on out, every other place I have seen a LiFeP04 RCR123 size cell being sold, it is being sold as a 3.0V cell. But if you look for a LiFeP04 cell in a different size (not consumer common size like CR123), you'll find that they are 3.2V rated.

In the sales thread for the AW brand cell, scroll down to the second post in that thread and check out the discharge graph. At 0.5-1A loads the cell spends a good chunk of it's discharge above 3V...

now go here:
http://www.candlepowerforums.com/vb/showthread.php?t=67078
have a gander at those discharge graphs. You'll see that under a 0.5-1A load, standard CR123s are not 3V at all, they are more like 2.5-2.7V, much lower than the 3.0-3.3 that the LiFeP04 cells were operating at.

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Now... going back to the 3.0V cells like the "tenergy 900mAH" .... Like I was saying before, these are technically a 3.7V cell with a voltage bucking circuit on the output. As I understand it, these are not using any kind of fancy or expensive voltage regulation on the output to simulate a CR123 directly, they are using a pretty standard diode, probably something with a 0.7V drop, the cell probably starts off into most loads at ~3.3-3.4V much like a LiFeP04 cell does, and probably drops off semi-steadily to around 2V when "dead." So again, we have a cell that is being sold as a 3.0V cell, but does not exhibit the discharge behavior of a CR123 3.0V cell.

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This is not a surprising situation at all, it is very common for primary cells to be given a label voltage close to their open circuit voltage, or voltage under a very very light load. While at the same time, it is very common for rechargeable cells to be labeled according to a voltage that is more "middle of the road" on their discharge. So when you buy a 1.2V NIMH cell you are in fact getting a cell that performs in place of a 1.5V alkaline very well, they would have to come out with a "2.5V" rechargeable RCR123 to really replicate the discharge behavior of a CR123 :) (hypothetically speaking)..

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In conclusion: Don't consider any 3.0V cell to be a direct replacement for a CR123 in any device, instead, pick out a rechargeable chemistry and working voltage that is compatible with the devices that are going to be using them. Ideally, if the device can handle the 3.7V cell type correctly, then that is the best way to go for longest runtimes...

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I was reading last night that the EX10 is actually just a boost regulated light much like the Fenix L1D/L2D and goes into direct drive on a 3.7V cell and operates a fair bit brighter when the cell is fresh than it does on CR123s, but the dimming function is PWM controlled so you don't loose multi-mode on a 3.7V cell like you would on the fenix. I would have to assume that they are picking LEDs with Vfs that aren't going to be at a critical point when direct driven on a RCR123, they are selling it as compatible with up to 4.2V input, but I think it relies of the voltage sag of the cell under a load to keep from really overdriving the LED. I don't know why I'm bothering to bring it up, just something worth pointing out I suppose. :)


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Places to buy 3.7V related stuff:
http://www.lighthound.com/index.asp?PageAction=VIEWPROD&ProdID=1155&HS=1
http://www.lighthound.com/index.asp?PageAction=VIEWPROD&ProdID=2190
http://www.batterystation.com/cr123a.htm
http://www.cpfmarketplace.com/mp/showthread.php?t=180449
http://www.flashlightz.com/product.php?p=pila_bc01-ac01&product=171829
http://blackforce.stores.yahoo.net/pilaibccharger.html
 
You showed 2 links to Pila IBC chargers there, will those then work to charge more than 18650 batteries and run the 16340's such as the AW cells as well? I assume that the answer is yes with spacers but would like to hear it from an expert before taking that assumption to task. I may have access to an IBC charger free of charge here at work. Plus that way if I choose to pick up some decent 18650 batteries I am good to go with the Pila GL2 in a rechargeable option at the same time.
 
The Pila IBC is the most highly recommended simple bay style li-ion charger around here. It is good for charging everything from RCR123/14500 size cells, up to 18650s. (but nothing smaller than RCR123 as the charge rate would be too high)...

You will need some spacers for RCR123 size cells, ... I'm not sure if it already comes with spacers for 50mm cells or not...

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HOLD ON A SEC... I SCREWED UP:
I was reading and thinking G2L, NOT GL2!!! EEEK.. different animals...

Anything I have said previously about the GL2 please ignore....

At this point maybe it's time to back way up... I was thinking a SureFire G2 and now realize I was supposed to be thinking Pila, I get ahead of myself like this all too often :) ....

I honestly have no clue about the Pila LED module and whether it is compatible with higher input voltage or not, or whether it even runs in regulation on a single li-ion cell or not...

It may be best to run that GL2 on an 18650, for longest runtime, it has been my experience that most LED modules rated for use on 1x18650 OR 2xCR123s typically don't regulate all that well on an 18650, but you get almost double the runtime compared with CR123s with steadily declining output.

Ok.... so a Pila IBC charger is looking much more attractive now than ever considering it can charge the 18650 that may be your best option., lol.... Just keep in mind it is only designed to charge 3.7V cells, no "3.0V" style cells.

Sorry

Eric
 
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