Quark 123² can use 17670, 18650 can't fit.
Most flashlights that uses 2 x RCR123 (16340) or 2 x CR123A can use 1 x 17670 (e.g. Surefire LED range). With some, you can also use 1 x 18650 (e.g. EagleTac, JetBeam) if it explicitly said so. However, do note that not all cells are made the same length and width. That 1mm width between 16340 and 17670 could be an issue in fitting for some lights. Do NOT force the cell in if it doesn't fit, even when it's already half-way in.
A tip from AW for his AW protected cells, you can remove the sticker label to reduce the cell's diameter. This has work for fitting AW 17500s into my Fenix TA30.

Note: all references are made to protected Li-Ion cells.

OK, thank you. That's the problem with flashlight collection, there are just too many different types of batteries and chargers requires....

So, the best replacement for 2 x RCR123/CR123A is to use 1 x 17670, ie, the quark 123^2 can take this 17670, correct?

This post has been edited by jwyj: Aug 17 2009, 04:34 PM

It is always best to check on the specs whether the light is able to run on specific types of batteries. If it is not specified by the manufacturer, a check in CPF is your best bet. Those 'ang mohs' really ask all sorts of questions pertaining to power configurations for their lights.

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Added on August 17, 2009, 5:11 pmHey guys, if anyone is interested in a 18650-capable SF U2A, I have one for sale currently here : For Sale. Also some other small stuff. Please let me know if you are interested.

This post has been edited by alantch: Aug 17 2009, 05:11 PM

Most of the time, yes. But as you get to research more, you will come to realise that there are a few more factors that determine compatible form factor replacement, e.g. Voltage, discharge current, etc.

Right! And our local LYN member is selling these: justin78

EDIT: my bad , actually, given the choice, the best rechargeable replacement for 2 RCR123/CR123A is to use 1 x 18650 IF the body can accomodate the cell. 18650 cell has higher capacity and thus gives you longer runtime over 17670 cell. I like what Olight and EagleTac has done in their 18650 offering where they include a battery magazine for 2 x RCR123/CR123A to reduce the rattling in the battery tube.

This post has been edited by RookieDaddy: Aug 18 2009, 04:16 PM

There are two important factors to consider whether 2xCR123 or 2xRCR123 can be replaced with 1x18650

1. The LED driver rating e.g 2.6v - 6v
2. The Flashlight bore dimension

If the LED driver rating is 2.6v - 6v yes we can use 1x18650 (3.7V) provided the bore size can accomodate it. (normally the length is accommodating due to springs at the tailcap or even both at the tailcap and LED assembly. If the bore size is smaller diameter, then 1x17670 (also 3.7v) can be used.

My favorite for Surefire is 17670 instead of CR123.

I think I jump in too fast. I've spent too much $$ buying all sorts of branded and non branded flashlights. I should go slower and do it systematically, such as trying to group them into battery sizes.
I will probably concentrate my collection into groups according to battery sizes.

1) 3 x AAA only,
2) 2 x AA only,
3) 1 x 18650 only,
4) 2 x 18650 only.

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Added on August 19, 2009, 10:18 amMaybe I will also add in,
5) 17670 too, since I ordered a few Surefire in US.

I will forget about single AAA or or single AA or 123 or C or D batteries sized flashlights.

My current favourite are 18650 battery based flashlights.

This post has been edited by jwyj: Aug 19 2009, 10:20 AM

I also went thru the same problems in standardizing my lights based on battery size. That works, but only up to a certain point. Going for lights that can take both primaries and rechargeables is the way to go. That way, I can use them on rechargeables when I'm home and take the primaries with me when I go travelling in which case I don't have to bring the charger. My standard battery types now are CR123, RCR123, P17670 and (P)18650s. I try to avoid 3x123 lights and have none of those at the moment.

jwyj, what Surefires are you getting from the US?

Batteries, brightness, size, run-times, beam......

So many to choose from!

Haha!

I still haven't played with any 18650 lights yet. I 'de-modded' my ET T10LC2 to not accept 18650 xD.

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Added on August 19, 2009, 11:35 amBut doesn't rechargable batteries last longer?

I got the cheapest that I can find in Amazon,

1) G2 original - USD 34.98
2) 6P LED - USD69.99
3) TerraLux 220LED - USD33.94
4) G2Z original - USD64.99
5) E2E original - USD69.00

Maybe plus 2 or 3 more, but I will limit the price of each to <USD70.

Streamlights seems to be popular too, but too many choices. I only want to get those hard-to-find in Malaysia flashlights.

Others I can buy in this forums.

This post has been edited by jwyj: Aug 19 2009, 11:35 AM

Whoa! That's a lot of lights! Won't shipping from Amazon be very expensive? Why not buy from Ebay or some online retailer?

How much are you paying for shipping?

Those are the lights I already bought, all cost including shipping to my Uncle's house in Houston, US. He will bring them to Malaysia when he visit me end of the year or next year...

Early this year I got a whole lot of Vitorinox & Leatherman multitools plus 10 AAA/AA maglites. Luckily, customs/immigration not interested.

This post has been edited by jwyj: Aug 19 2009, 11:41 AM

hye guys... looking for super thrower (the cool white -- is it the yellowish one?) and a good charger along with 2x 16850 batteries...

Ooo ... that's a lot of Surefires

Me too also looking for super thrower using 1 or 2 x 16850 batteries.. My lists are
1) Tiablo A10-G
2) Dereelight DBS v3
3) EagleTac M2XC4

Best of all is that, they are all available here... Fenix brand got thrower or not??

I'm also buying a few cheap ones from DX.
Some of the 'police/Cree/FBI' are good throwers too.

i think u mean 18650

havent heard of 16850 yet

also the olight M30 also a good light
http://forum.lowyat.net/index.php?showtopic=871609&hl=

or jetbeam MX1
you can PM nexro if u want 1

my bad... it's 18650

I only go for CR123 and 18650 lights. Nothing else!

Wow V2 already. I'm so outdated. hahaha. Nightstalker, u shud link to V1 in the first post.

I have read all the 131 pages of V1, and now I am re-reading them all over again. .... and learning new things too.

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Added on August 19, 2009, 6:46 pmWhat a good idea. Maybe that's what I will try to do also, as I slowly remove those that take in AA and AAA batteries.
CR123 and 18650 batteries have more "WOW" factors.

This post has been edited by jwyj: Aug 19 2009, 06:46 PM

I've got a streamlight scorpion. Nice bright incan, rubberise body with a spare bulb included.