Hi, I'm extremely knew to the flashlight scene. I purchased a twin pack of keenstone 1500 lumens for my son's to keep in there vehicles and I was bitten by the flashlight bug. lol. So, I started looking for a flashlight to start a collection of lights with. I chose the trunite tn40s. Now I have to learn about batteries, because tbe light doesn't come with any. The manufacturer cites that I need a 18650 3400mah , at least 10a protected button top which has to be minimum 67mm. So this is my dilemma finding a battery. I saw threads that went over this, but was hoping more information was out there now. Can anyone tell me which batteries will offer the best balance of performance and run time?