Shannon,
Not so sure about the tube diameter being exactly 1" or not, but I would say a lot of my 18650 battery flashlights are about that. Let me ask you a question. Would you rather stick with a light that ran off of AA's or would you rather go with one that ran off of lithium ion. Most of my flashlights run off of 18650 lithium ion batteries. I typically use protected cells. 18650's from what I have heard are the same batteries that are inside the laptop battery packs. Now as you know lithium ion is the technology that the cordless drills are now using because of their ability to hold a charge longer and can be charged over and over again and last a very long time. But one should have a good multimeter and check the voltage after charging the 18650 batteries to make sure they are around 4.10 to 4.20 volts and that will depend on your charger. And if you want to go the AA route, you can always use NIMH rechargeables like Duracell, Energizer or Eneloops. I can't tell you how much longer runtimes I get with the Duracell NIMH 2450mah batteries in my digital camera vs using Duracell alkalines. The performance is just a lot better from what I have seen vs alkalines.
