18350 and RCR123A

[mastershake]

I just got a laser that calls for 2 x 18350 3.7v batteries. I don't happen to have any of these on hand but I do have a few RCR123A that say 3.7v. My question is are these interchangeable with 18350? They are both 3.7v which is what I thought was the most important thing(correct me if I'm wrong, I don't know anything about batteries).
Also I was under the impression that 2 x 18350 were the same as 1 x 18650. I thought that stacked on top of each other 2 x 18350 were the same length as 1 x 18650 and the same diameter, however when I put a 18650 in my new laser it was too tight a fit so this threw off my theory(again correct me if Im wrong, I really dont know anything about these batteries).

Any way, I hope this was all comprehensible, and thanks for reading. Id love some advice.

Thanks

 

[BowtieGuy]

Your 2 18350's are the same as an 18700 battery, which is 50mm longer than a 18650. The 350 in the description is the battery length in millimeters, so 2 x 350 = 700 millimeters long.
This combination will fit in some hosts and not others. Also, remember 2 18350's will give you 8.4V when fully charged vs. 4.2V from 1 18650 battery

Those RCR123A batteries are the same size as a 16340 battery IIRC, so that would make them a little shorter, and also smaller in diameter; 16mm vs 18mm.
These would probably work, although they would fit rather loose in your battery tube; you could always make a sleeve to make them fit better if desired.

 

[Pman]

The issue with the RCR123A is that they are probably 3.0V rather than 3.7V. They may work absolutely fine depending upon what the driver requires for voltage. Do you have a link to the unit or some pics of it? If it takes (2) 18350 then it's definately calling for 3.7V batteries which are actually 4.2V fully charged each for a total of 8.4V. They will most likely be slightly longer and wider than the RCR ones. you can also use (2) 16340 which again will most likely be slightly longer and wider. Don't rush it and make a big mistake and blow the driver or diode. Easy to put the batteries in backwards.
AND, whatever my friend Jeff said

 

[mastershake]

The issue with the RCR123A is that they are probably 3.0V rather than 3.7V. They may work absolutely fine depending upon what the driver requires for voltage. Do you have a link to the unit or some pics of it? If it takes (2) 18350 then it's definately calling for 3.7V batteries which are actually 4.2V fully charged each for a total of 8.4V. They will most likely be slightly longer and wider than the RCR ones. you can also use (2) 16340 which again will most likely be slightly longer and wider. Don't rush it and make a big mistake and blow the driver or diode. Easy to put the batteries in backwards.

The RCR123a's I have are 3.7v, or at least thats what it says on the battery itself. The 3.7v matches the 18350s i have found online so thats why I thought it might work. The laser I got is the SANWU Challenger 2, great looking and feeling unit BTW. Any way just trying to figure out if I have any other options. Thanks for the help!

 

[ElectricPlasma]

Like BowtieGuy said, it does depend on the host, but it is workable. You will be able to operate the laser with that battery setup (2*cr123a), but the trick is getting them to fit without smashing around in the host. I'd recommend some neodymium magnet battery spacers to compensate for the extra space, as CR123As are a tad bit smaller than 18350s.