# Battery: Why 18650, AA, CR123A



## tuborg (Jun 5, 2009)

I'm about to purchase 1 or 2 good lights for camping / hiking. I have a MAHA charger for AA's. 

I notice a lot of Fenix lights and forum users use 18650 & CR123A batteries.

What's the advantage of using an 18650 light, versus one that uses 2 or 3 AA's?

Should I invest in 18650's and another charger?

(A also hope to build a bike light - following nightrider on the diy bike led page - so would likely have a 14.8V 18650-based battery back - but I guess that one needs its own independent charger, too).


Thanks.


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## VidPro (Jun 6, 2009)

because they were lithium. packs more power for weight/size. Can maintain a higher output current in smaller package too.

so the 123 revolution came about because the light could be small, even though most arent at least the battery tube is 
cause if your gonna pay 50+ for a light might just as well pay 50+ for batteries for it?
because Alkalines Sucked, for high continuous loads, even though there were many great rechargables to replace them.
I donno , you tell me , when they, here, almost totally abandoned the normal consumer batteries for all the great lights , i didnt know what the purpose even was , they all crasy i tell ya lovecpf

the 18650s are a power house of capacity and ability to handle load, then the fear of the battery EXPLODING , caused people to waver around wondering what to really do (remember the FEW laptop fires and that panic).
the 18650 has about as much power as 3 ni-mh AAs , yet is in a very pocketable size and is lighter, until they put a Flashlight head on the light the size of a elephant  and enough metal to make a club out of it.

many 2x123 lights that will use both the 2x123 AND the 18650, run the 18650 at lower power, just because the curcuit in them was desinged for more voltage, there ARE lights that stay fully regulated with both, but many were (sorta) direct drive with a 18650, giving the advantages of very very long dwindling runtime.
of those types of lights (using both) you could still use BOTH and get the advantages of both depending on the need at the time.

and dont forget there are 123s AND rechargeble versions of the 123 ALSO, so not only is there the rechargable 18650 li-ion , and now safer versions, but there is also rechargable li-ion 123s of many different types, each with some differences too.

if your going to use a 14.4v 4 X li-ion pack for a bike light, then a hobby balancing charger is going to come in VERY usefull. because you are going to want to either charge as seperate pieces, or charge using a Balance charger which will treat each cell in the pack to a proper charge.
Sooo
a hobby balance charger will usually ALSO charge single piece li-ion cells, giving you a tool that will do both.
And
once you had one of them things, then you will certannly want to get other li-ion batteries, or mabey even li-fe-po one of the safer versions of them, so you would want to get a charger that can do both.

at any rate if you step off into the land of Flashaholic and use lithium primaries (throwaway), then you should heed the DON'T MIX rules , dont mix brands type age and discharge levels in a device when using series batteries.

and if you go rechargable Li-Ion , make sure you know some of the specs and care needed to use them properly.
and if you get li-ion make sure you know what your getting in type, so you can know how to deal with it. learn what protected is.
THEN
everything will be fine and it will be a great battery type, and kick butt and be really lite , rechargable, and have lotsa runtime for you.

if you dont want to Think, read specs, understand, or deal with it, then get some of the great AA type of lights, and you can put AAlithium cells in (most) of those TOO, and get lightweight long runtime, and still have the power of lithium in your hands. still would want to check to see if the light will handle lithium cells.

at any rate for hiking, the LED is one of the biggest helps because you dont haveta haul so much power around, because it doesnt USE as much power, then on the other hand, you want to be carefull how BLUE your leds are , because there isnt anything blue outdoors 

just from one Hiker to another.


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## phantom23 (Jun 6, 2009)

VidPro said:


> the 18650s are a power house of capacity and ability to handle load, then the fear of the battery EXPLODING , caused people to waver around wondering what to really do (remember the FEW laptop fires and that panic).


There should be more fear using CR123 batteries because they explode with no reason. Li-Ion may explode when you overcharge or overdischarge it too much (like in laptop - "our laptop runs 5 minutes longer than yours!") 


VidPro said:


> the 18650 has almost as much power as 3 ni-mh AAs , yet is in a very pocketable size and is lighter, until they put a Flashlight head on the light the size of a elephant  and enough metal to make a club out of it.


Good 18650 cell has as much power as three Sanyo 2700mAh Ni-MH, if you have Eneloops or other cells it's even more.


VidPro said:


> and dont forget there are 123s AND rechargeble versions of the 123 ALSO, so not only is there the rechargable 18650 li-ion , and now safer versions, but there is also rechargable li-ion 123s of many different types, each with some differences too.


All rechargeable 123s have very very low capacity...


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## vali (Jun 6, 2009)

18650:
- High capacity & High discharge.
- Need care.

AA
- You can find them everywhere.
- Not danger if you are dumb.

CR123A
- Size and brightness.
- Low capacity.


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## Tekno_Cowboy (Jun 6, 2009)

CR123A batteries have a similar capacity to a 2400-2700mAh NiMH battery, depending on the brand.


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## cave dave (Jun 6, 2009)

Tekno_Cowboy said:


> CR123A batteries have a similar capacity to a 2400-2700mAh NiMH battery, depending on the brand.



Thats about true for LiIon rechargable LiIon RCR123s, but primary (aka non-rechargable) Cr123's have more stored capacity.

It is the opposite case for high drain AA devices. Rechargable Nimh AA's have more usable capacity than primary Alkaline AA's.

Each technology has its pros and cons.


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## Tekno_Cowboy (Jun 6, 2009)

cave dave said:


> Thats about true for LiIon rechargable LiIon RCR123s, but primary (aka non-rechargable) Cr123's have more stored capacity.
> 
> It is the opposite case for high drain AA devices. Rechargable Nimh AA's have more usable capacity than primary Alkaline AA's.
> 
> Each technology has its pros and cons.



Energizer L91 Lithium Primaries have more capacity than NiMH batteries, and probably more than most CR123's.


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## cave dave (Jun 6, 2009)

Given a choice I really prefer the single AA form factor in a light.

In a light like the Nitecore D10 I can use:
LSD Nimh (my 1st choice for ease of use)
High capacity Nimh
Li Primary L91
Li Rechargable 14500
Alkalines
Heavy Duty (last resort)

However, some really great lights don't use AA's. I really like the UI and beam of the Ra Clicky so sometimes that wins over battery type. I use AW RCr's in that almost exclusively, with primaries as backups.


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## tuborg (Jun 9, 2009)

Thanks everyone. What a whole new world to learn.

I followed cave dave, and ordered:
NiteCore SmartPD D10 R2 Edition (AA)
and a
Fenix LD01 Q5 (AAA) 

The Fenix price was hard to resist ($45 CDN).

I'm thinking of ordering a W-139 charger and some protected AW14500 to get better performance out of the NiteCore.

But then, if I ever do the bike light thing, I'll still need to get a bigger battery pack (18650) and a hobby balanced charger.

So I might hold off on the W-139 / 14500's for now, as I learn. I'm wondering if a smart charger, could also do 14500's. The basic setup from the diyled-bikelight place (http://bikeled.org/) is:
battery (*14.8V 4000mAh Li-Ion Battery)*: http://www.batteryspace.com/index.asp?PageAction=VIEWPROD&ProdID=2486

charger: http://www.batteryspace.com/index.asp?PageAction=VIEWPROD&ProdID=2488


Thanks again.


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## boomhauer (Jun 9, 2009)

Now all you need is a 10440 li-ion (and a charger) for that LD01, and you're really in business. :devil:


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## mdocod (Jun 9, 2009)

Hello tuborg!

If you are planning on investing in a nice hobby style charger with adjustable charge rate and all the fancy stuff, don't bother with the WF-139, just get a cheap spring loaded charger (or a couple-few) to "gut" to use as charging bays for the nicer charger. 

The only charger I can really recommend knowing it won't over-charge or have some other improper charging behavior or method, would be the Pila IBC. Rather than spend the $50 on that, just allocate that $50 towards getting the hobby charger first.


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## tuborg (Jun 9, 2009)

boomhauer said:


> Now all you need is a 10440 li-ion (and a charger) for that LD01, and you're really in business. :devil:



Cool - I didn't even know there were Li-Ion batteries. More learning to do. Thanks.


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## tuborg (Jun 9, 2009)

mdocod said:


> Hello tuborg!
> 
> If you are planning on investing in a nice hobby style charger with adjustable charge rate and all the fancy stuff, don't bother with the WF-139, just get a cheap spring loaded charger (or a couple-few) to "gut" to use as charging bays for the nicer charger.



Good idea. I've seen a few threads on that - I guess I should learn. I'm ok with the gutting/soldering - it's figuring out what molex-connectors you need to connect the battery holder and everything.

Thanks again - great forum.


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## Illum (Jun 9, 2009)

vali said:


> 18650:
> - High capacity & High discharge.
> - Need care.
> 
> ...



?!
AAs can be a real PITA when it comes to a dead short too...

CR123A doesn't have low capacity, unlike alkalines it can maintain its capacity while being drained at a heavy load, making them suitable for high current applications.

They are only _low capacity_ when you've been spoiled by LiCoO2, LiFePO4, etc Li-ions :nana:


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## garden (Mar 14, 2010)

boomhauer said:


> Now all you need is a 10440 li-ion (and a charger) for that LD01, and you're really in business. :devil:



No, otherwise you'll blow the LED, the LD01 is rated at 0.9 to 1.6V max.


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## hoongern (Mar 14, 2010)

garden said:


> No, otherwise you'll blow the LED, the LD01 is rated at 0.9 to 1.6V max.



Honestly, I wouldn't worry so much about the LED/circuit (which can be damaged), but I'd be more worried about the Li-Ion cells exploding... which could potentially happen as the LD01 on 10440s goes way above the cell's discharge limit.


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## old4570 (Mar 14, 2010)

You can build a light that can run / CR123A / 18650 / 2xAA 

Why chose one , when you can run them all !


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## yellow (Mar 14, 2010)

* when one does not already have a GOOD (= expensive) charger for Ni-Mh and cells (LSD), then the Li-Ion 18650 route is way cheaper
* (almost) similar sized light is more powerful and/or runs for longer time (1*18650 vs. both 2*CR123 and 2*AA)

PS: try out a good 1*18650 light - for me thats enough to do MTB night rides, same for most everyone around me.
If I would use quad-led / multiemitter lights, thats as bright as day. So why not ride in day, then.  
When doing nightrides, I want to ride in the night 
Brutally better size/weight ratio. Usually I lent out the 2-4 18650 lights I brought as spares. To the ones with these "powerful" lights - when their batts are depleted in the cold after some 1.5 hours.


PS: cheap "solution" to charge a _proteced_ 14.4 V pack:
Wall plug thing for Your laptop, 12 V Halogen-lamp in series with the battery.
The halo ensures a safe charging current, when it goes out, the pack is charged.
Choose 20W (quick), or 10W (slow charging) bulb.
A special Li-Ion charger is safer, of course


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## carrot (Mar 14, 2010)

Wow, this is a pretty old thread, but I'll roll with it.

CR123 actually has nearly twice the energy density of an AA battery. The higher voltage also allows electronics to run more efficiently. Hence, when picking primaries to use for long trips, CR123 is the best choice if you plan to pack in and pack out everything you need. They are lighter, are more powerful, and are smaller than AA.

18650 only has more than double the energy of a CR123, because it more than double the size. It is an excellent form-factor, especially in lights that can take 3.7-6.0v because then you can interchangeably use 18650 or 2xCR123. Rechargeable makes it conveniently cheaper over time.


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## puchu (Jan 22, 2013)

this thread is pretty old but, its ok, got some info

I am trying to make an autocut circuit for 18650s I got from 2-3 laptop batteries

2 sets have a 5600Wh rating
1 set has a 4800Wh rating

I was thinking I might use a phone battery circuit for the charging of single 18650 as this sounded a good idea, but can someone confirm that they have made it or seen it being used somewhere , as IMO the batteries are going to drain a lot of current at least for first 10-30 seconds until the terminal voltage comes close to supply voltage. But if I put one 1watt resistor or something like that to make it current controlled or a 555 based oscillator to be used as an SMPS which would act as a VCO (driven by battery terminal voltage) or something like that to control the circuit and avoid any overheating or anything, but my main concern is how to put an autocut circuit in it.

Any help would be appreciated.


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