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wasBlinded said:
The 2400 mAh 18650 will give you 2-3 hours runtime on the second highest level, but on the brightest level will be somewhat less than you can get with fresh CR123 cells.
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Actually, somewhat more, surprisingly. The 1800mAH are the ones with less runtime than CR123s, but ever since the upgrade to 2400mAH, wow /ubbthreads/images/graemlins/smile.gif it just keeps tickin'..
The U2 is a little bit of a battery hog at full power when using CR123s, but it wasn't meant to be run at full power all the time, that's why they let you dial it down. I find level 5 is perfect for getting double the runtime for not that much less light.
Update: I just finished a runtime test on my U2 with 4sevens' 2400mAH LG Chem cells. As I do not have a light meter, I relied on a more primitive method - measuring how long till I completely lose level 6, ie. there is no discernable difference when I turn the dial.
I'm referencing
kj's runtime charts. His U2 in particular has a regulated level 5 of 1400 lux, which can be correlated to his level 6 graphs, which reach 1400 lux after 55 minutes on Pilas. In other words, he has 55 minutes till his lightmeter cannot tell the difference between level 6 and level 5, which is the defined endpoint of my test.
I managed to get 85 minutes till it reached that point on a cell that was charged to 4.10V before the test began. Probably more if the cell had been charged all the way up to 4.2V, maybe as much as another 5-10 minutes. So yes, these are better than CR123s even /ubbthreads/images/graemlins/smile.gif
The cell measured 3.59V at test termination.