A while back I saw a post that spoke of 18650 batteries that were tight fitting in the tube. Someone, actually a few a BLF's listed the 18650 batteries that had the thinnest diameter. I could almost swear that it was mentioned that Olight or Nitecore were the thinnest but for the life of me I cannot find that post.
Can anybody help with that, please?
The next question I have is batteries and FET drivers. Richard had stated that the FET was unregulated and limited only by the battery. To be 100% sure, does that mean that I can definitely control max output solely via battery selection? I normally use the 18650B's at work but I do have a couple BD's also, and quite a few Sanyo 2600's.
I ask because I want to attempt to assemble a couple units with FET drivers to play with but also use if needed.
With the FET, output current depends on both the input voltage under load, and the forward voltage of whatever LEDs are connected. 3 LEDs in parallel will run at a higher current than a single LED with no other changes. Similarly, a battery with less voltage sag will run at a higher current than one with more voltage sag.
It's hard to estimate beforehand since each part both affects and is affected by all the other parts.
I dont know which 18650 are the smallest in diameter but as far as i can tell you, my Keeppower 3400mah is fattest 18650 around and it almost stuck in my olight m20sx, second goes to Tank007 18650 2600mah, get unprotected if you want thinner
I can't help you yet, but I'll be working on a project that will allow you to filter a library of batteries. It should allow you to sort 18650's by diameter.