Originally Posted by
Tyrell
I don't think you're comparing apples to apples. You can't simply compare "turbo" to "turbo" without considering the #'s that comprise "turbo" for each. In one example, 2x AA's in a L2DQ5 will last for 10.5 hrs @ 53 Lumen where 2x 123 batteries in a P3DQ5 will last 13 hrs @ 53 Lumen as quoted by Fenix. Of course this comparison is still not perfect because I'm comparing two different flashlights - a perfect comparison would be comparing the two batteries' performance in the same flashlight but I'm not sure if that's possible.
So I guess my point is that the apparent advantages of 123 batteries are longer burn times for the same brightness levels of AA's, higher brightness potential, and smaller form factor/lighter weight. Disadvantages would be $$ and that they're not common in most households though they are a common photo batt.
There are two prtoblems with your logic; the first being that 53 lumens isn't enough for the purposes of the bike commuter. The second is that you are comparing primary C123 cells (non-rechargeable)to rechargeable AA cells. Rechargeable CR123 cells have a much lower run time compared to primary C123 cells. Using primary cells in a Fenix for bicycle use is expensive and mighty wasteful.
It seems for some reason you have your heart set on using CR123 cells. Do a search and see some of the comments of users. Then look at what AA users say.