2x16340 = 2x18650 ?

[whiteoakjoe]

If I can run a light off of 2x16340's I should with longer tube be able to run 2x18650's with the same head, right? The light will get the same voltage correct? or is there another issue that I'm not seeing?

 

[HKJ]

If I can run a light off of 2x16340's I should with longer tube be able to run 2x18650's with the same head, right? The light will get the same voltage correct? or is there another issue that I'm not seeing?

Theoretically yes, but there can be some heat issues, because the 18650 can keep a higher voltage for considerable longer time.

 

[Trevtrain]

Perhaps you could tell us what light you are looking at but in principle the answer to your question is yes.

About the only difference I can think of is that 16340s generally can't supply the same current as 18650s so if the driver is poorly regulated it may lead to more heat. I've only seen this on a dropin fron a Trustfire TF-R2 that drew significantly more current from the larger cell. This was a single cell XR-E dropin though.

 

[whiteoakjoe]

Thanks HKJ, that's the answer I was hoping for. I thought that was right but never did see that spelled out for me. Only voltage numbers were quoted so I assumed that's all I needed to know, but its easier to ask before something goes (POP) and won't come on anymore. I think since I want a warm white light around 200 to 300lm with flood beam I should be OK for heat sink. not looking for a high power light just long runtimes. Trevtrain I'm using a surefire 6P and building a light, was going to get a bored 9P body to use with the head and pill (Nailbender or Malkoff maybe a Nachia 219) that can take 9v input. But all I saw was them running on 2 16340's.

 

[Vortus]

For a 6p, 2 16340 are the same as a 2 cr123 size wise, they are just rcr123 batteries. You can generally fit two 18350 in the same space as a 18650, though run time will be less, voltage will be higher. For a 9p, you would need two 18500's if I am not mistaken. That would run longer than a single 18650 and still give the higher voltage. In a lower lumen light like your mentioning, imr are not needed, just normal protected versions.

 

[alpg88]

more like 17500, not 18500. surefire normaly is too small for 18xxx, ppl bore out the tubes to fit 18xxx

 

[Cereal_Killer]

You can bore your own surefires for about $25 if you have a drill and a vise to hold it steady. I have done all of my own, a 3/4" step bit and an $8 drill bit extender.

Wrap the bit extender in Electrical tape to make it exactly match the diameter of the largest step (to act as a guide so you don't wobble it off axis) and go for it, takes all of 3 minutes to setup and 90sec to drill it out. It's not shop/lathe mirror finish quality, but its more than acceptable and accepts everything up to m 3100's (don't own any 3400's)

 

[Trevtrain]

Thanks HKJ, that's the answer I was hoping for. I thought that was right but never did see that spelled out for me. Only voltage numbers were quoted so I assumed that's all I needed to know, but its easier to ask before something goes (POP) and won't come on anymore. I think since I want a warm white light around 200 to 300lm with flood beam I should be OK for heat sink. not looking for a high power light just long runtimes. Trevtrain I'm using a surefire 6P and building a light, was going to get a bored 9P body to use with the head and pill (Nailbender or Malkoff maybe a Nachia 219) that can take 9v input. But all I saw was them running on 2 16340's.

If you are not looking for high power, then your Nailbender or Malkoff dropins will be fine with 18650s (as long as you check/specify the correct voltage range). Both are very well-regarded products. I've not had any experience with Surefires but others here have posted advice regarding boring and so forth.

I'm thinking personally that a 2*18650 with a P60 head would be a little unbalanced or unwieldy - I'd probably lean towards a single 18650 body and just cary a spare cell if you need extended runtimes. The reason "most" people choose 2*18650 seems to be for higher output.
YMMV :)

 

[whiteoakjoe]

Trevtrain It seems like a big light for such a low output but it has a specific purpose. I'm using it for bowhunting and trailing game after dark. I want a light to use looking at the ground at my feet. So big lumens aren't necessary and you never know how long you will be out it may be an hour it may be 5hours. so I want 2 18650's with 2 in the pack as backup. I have a piece of ground with 80acers of forest and set on the border of 9000acers of state land. I want a light that's good for outdoor colors and has big runtimes, because I never really know when I go out how long it might be until I come back in. Big lumens just don't help much in the woods when the leaves are on you cant see 50 yards out because of foliage anyway. Running out of juice in the middle of a state forest can be dangerous, your inclination is to walk back but its easy to catch a stick in the eye or take a fall. I have a headlamp in the pack now, but want the backup of having a flashlight with me also. Is it needed no, but as a flashaholic needed is not always that important, sometimes its just an excuse to get another light :)