# Newbie battery question - CR123A or 18650 battery?



## davecla (Jun 8, 2011)

Sorry, this is probably really simple however.......

I brought a new olight M20 today (awesome) - I see it takes either two CR123A or one 18650 battery. (I've currently got 2 x CR123's in it)

I'm thinking 2 x CR123 @ 6v will give me more light (because of the higher voltage) but not last as long as 1 x 18650, - is this correct?

Also, while I'm asking, the M20 comes with a battery tube thing, I'm guessing this must be for the 18650 as I cant fit the CR123 in there (too fat) - is this what its for? The CR123 rattles around a wee bit in the touch, wondering if I can widen the tube a wee bit (sandpaper perhaps) so they will fit.

Thanks in advance,

dave


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## RBWNY (Jun 8, 2011)

You'll get the same brightness regardless of which cells you use. From my knowledge (correctable of course) 2x 3v doesn't necessarily equate to more voltage power, vs. 1x 3.7

I'm sure the instructions included with the light indicate that the "tube thing" is indeed for 2 CR123's.


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## peterharvey73 (Jun 8, 2011)

Yes, the CR123 disposable primary batteries are only 16mm in diameter, while the 18650 is 18mm in diameter - so the plastic tube converts the two CR123's to fit into the flashlight which is designed for the bigger 18650 battery - to prevent battery rattle.

In the old days of tungsten and krypton filaments, the 2xCR123 3 volts would indeed equate to greater brightness, however today, flashlights are "electronically regulated", so 2xCR123's may, or may not give greater brightness - it depends on the individual electronic design, and it varies from flashlight to flashlight; some flashlights will give greater brightness, others won't. Must read manufacturer specifications, or test them yourself...


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## davecla (Jun 9, 2011)

Thanks for your replies.


Given the olight is a quality touch, I'm a bit puzzled why the CR123 dont fit inside the tube. Its not just mine, a guy down the road brought one from the police supplier and he has the same problem.

There is an instruction manual - of surprisingly poor quality, with more than a few examples of chinglish.

Any suggestions as to whether I'd be better off with using CR123A or 18650 batteries? (it came with CR123)

Thanks

dave


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## LilKevin715 (Jun 9, 2011)

Selfbuilt did a review of the M20 with various battery configs, you will find your answers here


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## peterharvey73 (Jun 9, 2011)

A disposable CR123 costs some $10-15 each from department stores etc.
On-line is cheaper, but then you have to pay for freight!
Bulk in really cheap, but you must use dozens a year.

Rechargeable 18650 is the best, coz cheap, and you can use it as much as you like, without worrying about costs.
Furthermore, often an 18650 gives more runtime than 2xCR123, depending on the light.

The brand AW is the best.
Get the AW Protected 18650 from this supplier on-line. He is very good price!
http://www.cpfmarketplace.com/mp/sh...LiIon-Batteries-Sales-Thread-*Part-12*/page43

Get a Pila IBC charger. It's the best charger.
http://www.candlepowerforums.com/vb...sumer-Li-Ion-quot-cradle-quot-charger-roundup


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## DasFriek (Jun 9, 2011)

I have the M20s also and find it odd the CR123's don't fit in the tube.
I know ive fit Tenergy and surefire 123's in mine just fine. BJ has Titanium brand CR123's for $1 each. But i havent tried fitting them in a tube yet, But ill do it now as my supplies are next to me. BTW these are highly rated cells despite their low cost.
Yeah, They fit also. What brand you using?
You dont have to use the tube, It just keeps the extra cells together and from rattling.






The M20 review taught me a few things in the pic above taken from the thread. That is i prefer to keep CR123's in my light as on High it will give the best amount of lumens longer. But i need to swap to new cells at 2 hours and if im gonna keep using the light extended periods ill use 18650 cells.
The Li-Ion 18650 last almost another hour on high and longer on lower settings.
The light also regulates the 2x CR123 cells on high since they are 6v, Thats why you get 100% power on high longer. The 18650 cell runs direct drive on high and starts sloping voltage wise right away. But on medium and low the 18650 wins.

Ebay can set you up with some good 2400mAh Trustfire 18650's and an ok charger which rate well in tests here also. Its in the USA and $30 if that makes it any easier to find. I think they don't allow members to pass along info on deals in posts is why everything must be so vague. The charger is a Trustfire TR-001 which works great for me so far and can be bundled with 2 cells for $30. It doesn't get hot, But i leave my cells in the charger even after the light goes "Green" and it trickles the cell still. I stop mine at 4.2v and nothing even gets warm. The Pila charger is much better of course, But i don't have many Li-Ion cells yet to justify the purchase of the Pila. Seeing that Li-Ion is alot less maintenance than NIMH cells its no big deal for me anyhow.


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## davecla (Jun 10, 2011)

The batteries I have are Cytac 1500mAh

According to my calipers the outside diameter of these batteries is 16.7mm. The inside diameter of the tube is also 16.7mm.

Too tight to fit.


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## DasFriek (Jun 10, 2011)

Id just skip the tube then, Its only for keeping smaller cells from rattling and keep two cells together for easy loading one handed or in the dark.
If your gonna use the light for extended periods alot id invest in the 18650's, The cheaper chargers need more attention since many trickle charge past 4.2v but mine goes green at 4.18v and it take almost two hours to hit 4.2v while trickling.
4 cells and TR-001 charger all made by Trustfire cost me $40 shipped. With the two 12 packs of CR123's i wont run out of juice for years.
I have to make excuses to use my light more as i like lights as a hobby more than a have a required job for them.


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## peterharvey73 (Jun 11, 2011)

DasFriek, you are an exact man.
That Selfbuilt graph illustrating the performance of the M20 Warrior on different batteries is awesome!

It is interesting to scientifically understand how the highest 3.7x2 voltage pair of rechargeable 123's have the highest performance, then fall flat all of a sudden.
Then comes the next highest 3.0x2 voltage pair of disposable primary 123's, with a more gradual fall in performance, and much longer run time.
The lowest performance actually comes from the 3.7x1 volts 18650 with an immediate fall in brightness over time, but possibly the longest run times...


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## peterharvey73 (Jun 11, 2011)

DasFriek said:


> I have to make excuses to use my light more as i like lights as a hobby more than a have a required job for them.


 
PS, initially I had a 18650 light.
I found it so hard to carry in my jeans pocket, and in my coat pocket.
I also found it harder to hold and press the tail end switch.
Also, at 2 am in the morning, the low is way too high.

Then, I got myself a single CR123 size flashlight - it is so easy to carry in my pocket, so much easier to hold and press the tail end switch, the light has a continuously variable control ring and a low of only 0.003 lumen, and the flashlight is so much floodier/wide beamed and more practical at short distances and indoors - thus, I get to use my flashlight much more...
The only con is that it doesn't have the throw, nor the long run time of the 18650.

I still have the 18650, but it's not used as often.
In future, I will buy a 2x18650 with 1000 lumens to blow the whole place up!
However, the single 18650 has a balance between semi-compactness and performance...


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## DasFriek (Jun 12, 2011)

Ive done lost my mind and ordered four more lights for myself and one for my mom, All in varying sizes and battery configurations so i get to play with everything possible.
I do keep my Olight M20s next to me in my recliner/bed and i have an ITP A3 EOS Upgraded that fits perfectly under an elastic strap on a Maxpedition knife pouch so im always in arms reach of a torch. The A3 is a rocket with some good lithium primaries in it, Yet is perfect for reading in low light on low.

One reason i like the M20 is the choices on cells you can use to match the job your doing if you have time to think ahead, I keep 2 x CR123's in it for "General Purpose" reasons. But i have Trustfire 18650 2400 black/red cells on hand for extended runs if i need to use it as a candle with the optional tail stand end i added.

Im in no way anything close to an expert, Im just learning as i go and having fun doing it.
Im sure my next step after ive learned and tricked out and found the best battery options for the four new lights i have coming will be to start modding them.

Since you mentioned 2x18650 lights i had to link one of the lights i just ordered today from DX, Ill die an old man before it gets here but when it does it will be amazing im sure. I do like the option to break it down to run one cell at a time when max lumens aren't needed. It will be my 18650 cell test bed im sure since it can most likley bring ANY cell to its knees pretty quick.
SKU 55109
"BeamTech T6 Cree XM-LT6 5-Mode 850-Lumen White LED Flashlight with Strap - Black (2 x 18650)"

I mainly tried to get every torch that was differant in size and what cells it could use so i could do as many things as possible.
SKU 44713 is another light i bought that should be fun as heck figuring out what cells work best at what jobs, Im not going into detail as i could type all night about this one.


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## Adriano (Jun 6, 2012)

*Better to use 2 CR123A or 1 18650 batteries?*

Just to know: if my flashlight indifferently uses as CR123A as 18650 batteries, what is better to use? That is is it better 2 CR123A or 1 18650 battery? What differences? THANKS


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## shane45_1911 (Jun 6, 2012)

*Re: Better to use 2 CR123A or 1 18650 batteries?*

Depends what light you are using.

2 x CR123 = 6V
1 x 18650 = 4.2V

Make sure your LED/driver can handle 6V if you use two batteries. Some can't.


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## Adriano (Jun 6, 2012)

*Re: Better to use 2 CR123A or 1 18650 batteries?*

OK! They are the specs of my flashlight:
Operating voltage: 2.7V - 12.6V
It can be powered with 2 CR123A batteries, 2 RCR123A batteries, or 18650 li-ion battery.
I repeat my question: can I use the rechargeable RCR123A batteries? It seems that I can, therefore: is it better to use 2 RCR123A or 1 18650 rechargeable batteries?


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## shane45_1911 (Jun 6, 2012)

*Re: Better to use 2 CR123A or 1 18650 batteries?*

There is no "better". Depending on the driver of the light, you may see increased brightness using multiple RCR/CR123 cells vs. a single 18650.

I don't necessarily like the idea of 2 x RCR123s - unless you don't run the light for extended periods of time and you recharge frequently. There is the potential to overdischarge one of the cells if you use the light for long periods of time, and when you go to recharge it - there is the possibility that the cell may explode. Reverse polarity is always an issue when you use multiple rechargeable cells. IMR chemistry is a bit safer in this regard. I would suggest using IMR 123 rechargeables vs. Li-Ion RCR's if you decide to go with multiple cells.


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## Slumber (Jun 6, 2012)

One 18650 is more convenient, USUALLY yields better runtime, and the battery won't rattle. For weapon mounting, I'd suggest primaries.


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## 127.0.0.1 (Jun 6, 2012)

*Re: Better to use 2 CR123A or 1 18650 batteries?*

what is better depends on what YOU personally want to do

primaries are inherently less dangerous, but some risk because there are 2 and if there is a big voltage diff, poof
RCR123 are more risky than that
18650, less risky
protected 18650 less risky
---
if I had to say: I would recommend 1 protected 3100mah 18650, AW or EagTac, less cost in the long run

123 primaries will get eaten and you will be replacing them


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## aau007 (Jun 6, 2012)

*Re: Better to use 2 CR123A or 1 18650 batteries?*

Using multiple Li-Ion in series almost always run into cell balancing problem sooner or later. Even when bought together, charged together and always used together. Over time, there is a good chance that one will become weaker than the other, especially capacity loss and discharge rate. As the differences run further and further apart, you have a bigger and bigger chance of destroying one of them.

When using them in series, every once in a while, before recharging, measure the remaining voltage. If they differ by more than 0.2 volt, you know you are getting there.


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## novice (Jun 6, 2012)

*Re: Better to use 2 CR123A or 1 18650 batteries?*

+1 to aau007's advice. I'm not very good with digital multimeters for other uses, but I was able to pick up one at Harbor Freight for $4.99, and there is a video tutorial on youtube showing how to use the settings on this particular model just to test batteries. For my A2, I use Tenergy '3 volt' RCR123a cells (there is a designated Tenergy charger), and I only use AW protected li-ions for my other lights (except for some AW 18350 cells, because there isn't a protected version), and they only get charged on a Pila IBC. Every time I am going to use more than one Li-ion cell together, I test the voltage. A .02 voltage difference is the maximum I will allow between multiple cells.


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## skyfire (Jun 6, 2012)

*Re: Better to use 2 CR123A or 1 18650 batteries?*

i like lights that can take either. so it really depends on how the light is being used.
if its one of mine or my family's house/car/emergency lights, i load it with primaries.
if its a daily use work light, i use 18650.

i also used to check my li-ions all the time with my multi-meter. before and after putting it in a light or charger.
i honestly got tired of it:laughing: and the only li-ion i still use are 18650, and never more than 1 in a light.


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## ecrbattery (Jun 7, 2012)

davecla said:


> The batteries I have are Cytac 1500mAh
> 
> According to my calipers the outside diameter of these batteries is 16.7mm. The inside diameter of the tube is also 16.7mm.
> 
> Too tight to fit.




Try another brand of CR123A:

I just measured the diameter of CR123A cells from Panasonic, SureFire, Duracell, Energizer, Rayovac, StreamLight. They all read 16.5mm so they should fit in the plastic tube spacer.


The EagleTac CR123A cell i got measured at 16.7mm so don't use that.


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## vmaldia (Jun 30, 2014)

my friend has a flashlight (one of those chinese generics). It runs off 2 C123a's.

Now rechargeable CR123a's operate at higher voltage then primary cell C123a's so unless the manufacturer says its ok you might destroy a 2 x C123a flashlight. Problem is the manufacturer doesnt say anything on the box. So I dont think we will try it. Since a 18650 is of lower voltage I guess that its safe to try it. Either it doesnt work, it works or its a little less bright but it wont destroy the flashlight

Problem is the 18650 is a bit too fat for the battery tube. Is there another rechargeable thats the same diameter as a C123a but twice as long? I'm amenable to making a spacer if its a bit too short


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## GhostMatador (Jun 30, 2014)

There may be a more recent post of this. This details all the sizes of 18650s so you can find one that will fit your light. 

http://lygte-info.dk/review/batteries2012/Common18650Summary UK.html


Sent from my iPhone using Candlepowerforums


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## Kueh (Jul 5, 2014)

vmaldia said:


> Problem is the 18650 is a bit too fat for the battery tube. Is there another rechargeable thats the same diameter as a C123a but twice as long? I'm amenable to making a spacer if its a bit too short



There are LiFeO4 16340 cells, but you will need a special charger for those.

Cell voltage 

Min. discharge voltage = 2.8 V
Working voltage = 3.0 ~ 3.3 V
Max. charge voltage = 3.6 V

They will probably be safe for that flashlight. Bonus that they are considered safer cells.


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## Overclocker (Jul 5, 2014)

vmaldia said:


> my friend has a flashlight (one of those chinese generics). It runs off 2 C123a's.
> 
> Now rechargeable CR123a's operate at higher voltage then primary cell C123a's so unless the manufacturer says its ok you might destroy a 2 x C123a flashlight. Problem is the manufacturer doesnt say anything on the box. So I dont think we will try it. Since a 18650 is of lower voltage I guess that its safe to try it. Either it doesnt work, it works or its a little less bright but it wont destroy the flashlight
> 
> Problem is the 18650 is a bit too fat for the battery tube. Is there another rechargeable thats the same diameter as a C123a but twice as long? I'm amenable to making a spacer if its a bit too short










the best rechargeable option for 2x CR123A lights! KeepPower 16650 (sanyo UR16650ZT cell). same length, same diameter

forget about using low-capacity 16340, two of which always end up being a lot longer than 2x CR123. 

2x lifepo4 16340 have even lower capacity, are unprotected, not exactly a good idea to use in series though lifepo4 is a "safer" chemistry


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## kbuzbee (Jul 6, 2014)

vmaldia said:


> Problem is the 18650 is a bit too fat for the battery tube. Is there another rechargeable thats the same diameter as a C123a but twice as long? I'm amenable to making a spacer if its a bit too short



There are also 17650s that should fit if you can't find an 18650 that will. I put one in an old Fenix PD30 and it works great. I'm not a fan of running two CR123s in series.

Ken


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