If you are trying out the iLauke IR flash light, the 14500 batteries give it a lot more power. The whole flashlight casing gets warm. I purchased the following regular flashlight w/ batteries for $9.99 US that turned out to be the exact same flashlight housing with a regular visible light led (at least I will have one usable flashlight at the end of this experiment, I love flashlights . ) It gives a rough idea of the beam focus since you can see it plus the rechargeable Li batteries/charger. However it is a single led vs what appears to be 4 IR, so the focus may be bit different, hard to tell since I don't have night vision gear.
https://www.amazon.com/gp/product/B00VY795ZO/ref=oh_aui_detailpage_o00_s00?ie=UTF8&psc=1
https://www.amazon.com/gp/product/B00VY795ZO/ref=oh_aui_detailpage_o00_s00?ie=UTF8&psc=1