Please help me understand CR123's

[ab1ht]

Hi all,

Total noob question, I know. Feel free to point me to a link or thread that will answer this.

I don't currently have any lights that use CR123. Part of the reason for this is that I don't understand them. Here is some of my confusion:

* I've heard that rechargeable CR123s are not the same size and/or voltage as primaries.
* There are CR123s and CR123As. Is there a difference?

I could be confused about these. Please use small words and draw pictures if necessary for my pea-sized brain to understand this.

Thank you for any insights.

 

[donn_]

It's fairly simple.

123 is the common denominator in the name.

Surefire call's theirs SF123A

Duracell and Ultralast calls them 123

Panasonic and Titanium = CR123A

Those are all 3V primary cells, and cannot be recharged.

Tenergy (and some others) make a 3V rechargeable, using a different chemistry (LiFePO4). They call them RCR123A.

AW and others make a 3.7V 123 sized cell which is rechargeable. AW has two different ones; the standard is the black jacketed, silver labeled, protected ICR123. The latest one is the red jacketed IMR 16340 (16mm diameter, 34mm length. The 0 indicates it's a round cell).

Capacities (mAH) vary and current handling capabilities vary, but the sizes are all very similar at 16340.

 

[Oddjob]

To add to donn_ post, 3.7 volt rechargeable cells come off the charger at around 4.2 volts so if you are using them in a light you have to be sure that the light can handle the voltage. They also provide around half the capacity of primary (non rechargeable) cells.

A big advantage of using these RCR123's is the cost savings because they can be recharged frequently and often. Primaries on the other hand are simpler to deal with because the safe use of Li-Ions require a little diligence to avoid any dangers in the recharging process. Also if you use a protected RCR123 (a cell that has a built in protection circuit to prevent overdischarge) and if the light you are using does not have any low voltage warning, you can find yourself suddenly without any light (not a problem for most flashaholics since we tend to carry a spare light or battery or both).

 

[ab1ht]

123 is the common denominator in the name.

Surefire call's theirs SF123A

Duracell and Ultralast calls them 123

...

AW and others make a 3.7V 123 sized cell which is rechargeable. AW has two different ones; the standard is the black jacketed, silver labeled, protected ICR123. The latest one is the red jacketed IMR 16340 (16mm diameter, 34mm length. The 0 indicates it's a round cell).

Thank you. This is good information.

Why do some companies put the "A" at the end of 123?

Why does the rechargeable CR123 work at 3.7V and not 3.0? Isn't that kind of dangerous to the consumer (getting a higher voltage than expected)?

@Oddjob: How does one know if a light can handle 3.7V? Should a rechargeable 123 only be used in a light with voltage regulation (boost/buck)?

 

[yellow]

forget anything and get a light using 1*18650
it is the same size, You have only half the number of the cells with You, can not musmatch used and fresh ones and - best of all - they pack way more power.
Out of 2*AA, 2*CR123, 1*18650, the 18650 is the star.

one con: 18650 is no size one can get primary batteries, thats rechargeable only

 

[Oddjob]

@Oddjob: How does one know if a light can handle 3.7V? Should a rechargeable 123 only be used in a light with voltage regulation (boost/buck)?

Typically lights will publish their specs as to what their lights can handle. If in doubt ask here or contact the manufacturer or distributer. RCR123's can also be used with other kinds of circuits. IIRC the Flupic in my old Firefly III could only take RCR123's and would not work properly with primaries. Buck/boost circuits are good for regulation.

 

[45/70]

Why do some companies put the "A" at the end of 123?

Just as info, I posted this somewhere else recently, but the answer to your question.....

The description of these cells originally comes from the fact that they are 1 (quantity) 2/3 (two thirds the length of an "A" cell) "A" size battery cell.

Dave

 

[ab1ht]

The description of these cells originally comes from the fact that they are 1 (quantity) 2/3 (two thirds the length of an "A" cell) "A" size battery cell.

Ah! That's makes sense now. Thank you!

 

[awesometools]

to make it even more confusing , the RCR123 3 volt batteries you would think are good to replace the 123Lithiums. My understanding was that the "3V" 123's were a voltage regulated Li-ion( 3.7V) , well there is a 12 milisecond delay to voltage regulation that will take out most incandescants while most LEDs don't mind.
the 3.7V ( 4.2V off charger ) Li-ions over power the regulation in most Fenix applications leaving one setting - bright. Have not seen damaged lights due to this . The 186650 battery is better but could push size beyond edc for you.
Any ideas on the best brand of 3V 123? They require a different charger than Li-ion. I have not figured that one out yet . .
The following pic is a cytac charger that had a 18650 battery in one side , and the owner did not want to wait for it to charge so he could put his 123's in crossways . .he dropped them in alongside the 18650 ( hey they fit . . ) instantly boom. He was seriously spooked with the power in these lithium cells. ( sorry can't get the picture to paste - help ! )

 

[flatline]

Just as info, I posted this somewhere else recently, but the answer to your question.....

The description of these cells originally comes from the fact that they are 1 (quantity) 2/3 (two thirds the length of an "A" cell) "A" size battery cell.

Dave

What's the length of an "A" cell? Same as AA? AAA?

--flatline

 

[CaseyS]

What's the length of an "A" cell? Same as AA? AAA?

--flatline

AA ~ 50mm
AAA ~ 44mm

 

[FlashInThePan]

Totally understandable. In fact, I'm a bit jealous - I wish I'd asked all these questions early on too, instead of just trying to glean everything from a million different scattered posts!

CR123s are a great battery for flashlights because they're very compact and very powerful. As a result, you can create really bright, really small flashlights. The CR123s also use lithium, which is lighter in weight, stores better than alkaline AAs (which is great for emergency kits); and works better in cold environments. Lots of advantages! You can see why people like 123s...

As others have mentioned, the 123s fall into two categories: primary (non-rechargeable) batteries called CR123s, and rechargeable ones called RCR123s. Primaries are generally very safe and easy to use, while rechargeables require just a few caveats before use. (Mainly, you want to make sure that they're properly recharged, and used with other batteries that have a similar charge.)

One of the things that really confused me when I first started reading about flashlights was voltage. I was a little hesitant to use 123-based lights because I didn't want to damage them; people were saying all sorts of things like "this light works on 3-8.4 volts"...and I had no idea what that meant. Turns out it's pretty easy!

Voltage is basically a measure of the strength of a battery. Imagine a fire hose: if you turn up the pressure, water shoots out with a lot of force. That's voltage ("V"), and it helps determine how hard you can drive an LED (or the filament in an incandescant light).

Some lights are really finnicky about their voltage. For example, Surefire's P60 bulbs require 6 volts. As a result, two regular 123 batteries, which create 3 volts each, will work perfectly (3+3 = 6). But if you try to use rechargeables, which have a slightly higher voltage (3.7v), you'll blow the bulb, because 3.7 + 3.7 = 7.4v. (Sadly, I have no idea why rechargeables have a different voltage than primaries.)

Sometimes you'll see lights that can take a whole range of voltages - for example, "from 3.8v to 9 volts." That makes the light very versatile, and lets you use lots of different battery types. In other words, any combination of battery voltages within this range will power the light. So that 3.8-9v light I just mentioned could take either 2 regular 123 batteries (3+3=6v) or 2 rechargeables (3.7+3.7=7.4). If you wanted a longer runtime, you could even use 3 primary batteries, since 3+3+3=9. This would give you 50% more runtime, and the light would still be fine.

Hopefully you'll overcome your aversion to 123-based lights; all the best lights use CR123s!

Hope this helps!

- FITP

 

[brted]

Out of 2*AA, 2*CR123, 1*18650, the 18650 is the star.

Since it has been brought up . . . Since a 3.7V 18650 takes the place of 2 3V CR123 cells (6V total), is the light boosting that somehow? I know that some lights can take a 3.7V 14500 instead of a 1.2V NiMH and are much brighter. So is the converse true, that a light that goes from 6V down to 3.7V gets dimmer?

 

[CaseyS]

Since it has been brought up . . . Since a 3.7V 18650 takes the place of 2 3V CR123 cells (6V total), is the light boosting that somehow? I know that some lights can take a 3.7V 14500 instead of a 1.2V NiMH and are much brighter. So is the converse true, that a light that goes from 6V down to 3.7V gets dimmer?

It depends on the driver. Look at the graphs comparing 18650 to 2xCR123a on the Eagletac T100C2. 18650 loses nothing:

http://light-reviews.com/eagletac_t100c2_mark_ii/

 

[45/70]

AA ~ 50mm
AAA ~ 44mm

An "AA" is ~14.2x50mm, and an "A" is ~17x50mm

Interesting to note that an 18650 is a 4/3 "Fat A" (being four thirds the length of an "A" and 1mm larger in diameter) and a 17500 is pretty much a standard "A".

I had a better one, but this site has a decent chart.

Since it has been brought up . . . Since a 3.7V 18650 takes the place of 2 3V CR123 cells (6V total), is the light boosting that somehow? I know that some lights can take a 3.7V 14500 instead of a 1.2V NiMH and are much brighter.

brted, an 18650 replaces 2 x 123 only in approximate length. The diameter of an 18650 is larger than a 123. Most lights that run off 2x123's use a "buck" circuit, which reduces the ~ 6 Volts down to the designated Vf of the LED (usually 3-4 Volts). When you run a 2x123 light off an 18650, the circuit "bucks" (reduces) the 4.2 Volts of the 18650 until the voltage reaches the Vf of the LED, then it runs in DD (Direct Drive). This is why most lights (unless they have a "Boost/Buck" circuit) with regulated circuitry, will dim after running a while with an 18650, as the voltage eventually falls below the LED's Vf (reducing the drive level proportionately, as the cells voltage falls).

Single AA lights run a "Boost" circuit, which increases the voltage from the 1.2-1.5 Volts of an alkaline or NiMH cell, to the Vf of the LED (again approx 3-4 Volts). When you run one of these lights with a 4.2 Volt 14500, the boost circuit is effectively bypassed, and the light runs in DD directly from the 14500. In some cases running a light with a 14500, overdrives the LED (and thus makes for higher output), the driver circuit, or both. You have to be careful here, and make sure the lights LED/circuitry can handle the extra load. Also, with some circuits, the voltage of the 14500 can be run dangerously low because the circuit "thinks" there is a 1.2-1.5 Volt cell installed.

So is the converse true, that a light that goes from 6V down to 3.7V gets dimmer?

In most cases, no.

Dave

 

[KiwiMark]

AW and others make a 3.7V 123 sized cell which is rechargeable. AW has two different ones; the standard is the black jacketed, silver labeled, protected ICR123. The latest one is the red jacketed IMR 16340 (16mm diameter, 34mm length. The 0 indicates it's a round cell).

To add a little here - AW also has a 3rd 16340 (123 size) cell - the LiFePO4. This is worth considering because the nominal voltage is 3.2V and the voltage fresh off the charger is 3.6V. 3.6V IS more than the 3V of the primary cells, but not nearly as much as 4.2V from a freshly charged LiCo or LiMn cell. The LiFePO4 cells are also considered 'safe' - they can be damaged by misuse but they don't tend to 'vent with flame' when they fail.

A big advantage of using these RCR123's is the cost savings because they can be recharged frequently and often. Primaries on the other hand are simpler to deal with because the safe use of Li-Ions require a little diligence to avoid any dangers in the recharging process.

Not to alarm anyone or fuel any paranoia - but I believe that it is much more common to have the non-rechargeable 123 cells explode than the Li-ion ones. The rechargeable cells only have Lithium ions (normally anyway, there are conditions that can cause Lithium to deposit and then there can be a danger) whereas the Lithium primary batteries actually contain the standard form of Lithium - a highly reactive metal.

Anyway - with a little care and using a good charger I don't believe the dangers of Li-ion are really that bad. If the risks were severe then there would be a problem with all the cell phones & laptops and digital cameras - but problems of the flame & explosion kind are very rare.

 

[ab1ht]

FlashInThePan,

That's a good discussion, thanks.

Really exemplifies the need to look carefully at the specs of a light before purchasing and evaluate the pros and cons.

 

[rumack]

I want to thank those that have contributed to this thread. I seem to be good at finding very technical info here but I don't have any background in electricity or electronics, and haven't had good luck at finding the basic info I need to fully understand the tougher stuff. This thread has definitely helped me. I'm sure you have posted similar info many times and I appreciate that you took the time to do it again. Thanks!

From what I have seen here at CPF, I'm starting to lean in the same direction as KiwiMark - that lithium primaries may require more careful use than rechargeables. When I first started here, I read about the care required for rechargeables and decided that I would go with primaries because they were easier and I probably wouldn't use many. Then a couple of months ago I ran across threads talking about the dangers of using mismatched primaries in multi-cell lights. Someone recommended using a ZTS tester on lithium primaries, always testing each cell twice with 5 seconds between each test. There was a technical reason why the second test was more accurate but I don't remember what it was. Out of curiosity, I tried testing the same SureFire cell multiple times with my ZTS Mini and got a wide variety of values that seemed random. Other SureFire cells produced similar results. Now I have no faith in my ZTS Mini and I am uncomfortable using my multi-cell lights for longer than a few seconds at a time.

 

[KiwiMark]

From another thread I thought of this:

Almost all my batteries are rechargeable and I think in some cases it could be cheaper to have primary cells instead. But I don't want to do that!

Why:
When I have rechargeable batteries in a light then I am free to play with that light whenever I want to - it doesn't cost me anything.
When I have primary batteries in a light then every time I use it I am aware of the money flowing down the drain.

Why would I aim to put myself off using a light that I paid good money to own?


Just something to consider when tossing up between primaries or rechargeables.

 

[rumack]

Good point, KiwiMark. Now that I am starting to embrace Eneloops and saying goodbye to evil alkalines, I have experienced those same thoughts with my AA and AAA lights and I enjoy playing them even more than before. When I have the money, I think I will look into making the switch to rechargeables for my CR123 needs too.