U2 runtime on 18650 cell?

I'm trying to decide if its worth boring my U2 body out to fit an AW 18650 cell from lighthound. Is in comparable to 2 primaries? I already have the charger for it, which is why I'm considering it. I'm also thinking of getting the A21 adapter and doing the ol' grnamin U2 Shorty trick. Suggestions?

I get 1 hour 42 minutes on a LG2600mAH 18650..... on highest level.

MSax

You'll get about 40% to 50% longer runtime than with a 17670, which will fit your U2 now, and a somewhat longer runtime on high than with two CR123 cells, though with an almost undetectable (by eye) reduction in brightness. Like Msax, I get about 100 minutes on high with an LG 2400 Li-ion cell before output begins to drop quickly.

MSaxatilus said:

I get 1 hour 42 minutes on a LG2600mAH 18650..... on highest level.

MSax

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Same here, im using LG 2600mAH 18650. @ batteryjunction. 24hr shipping. im lucky though because im quite near at their warehouse. they are doing price match and plus 5% off to CPF'ers. shipping is $3.50

I probably would have sold off my U2 a long time ago if it didn't take 18650 cells... or maybe I never would have bought it in the first place. I get my 18650 cells basically for free, from old "dead" laptop packs. Be careful taking them out so they don't go boom.

All of my 18650 cells are heavily used, but I still get about an hour of full brightness, followed by another half hour until it drops down to 50% bright.
http://candlepowerforums.com/vb/showpost.php?p=1469356&postcount=68

FlashKat likes his U2 bored out for 18650, too:
http://candlepowerforums.com/vb/showthread.php?t=127498

Not some of AW's cells, but this should give you an idea how it will do. https://www.candlepowerforums.com/threads/128188

runtime on AW's cells... just click "runtime graphs": http://www.cones-stuff.co.uk/

-David

Its worth it! You will lose a little output going from 2xCR123a to a single 18650 but nearly 2 hours of output on the highest setting makes it all worth while.

The output reduction is just on the highest setting, correct? All the other settings are the same as on primaries I hope. They are on a 17670, so I imagine they would be on an 18650.

Whats' the best way to bore the body out? 18mm drill bit with cutting oil? I've worked with aircraft aluminum before (building ultralight airframe).

I used a 18.5mm reamer... most 18650 batteries measure 18.2mm-18.4mm. I had to use a mill and reamer since I had no access to a lathe. Just be careful and take your time, because the aluminum is hardened and it makes it a little tougher to cut. I know other people have bored it out with a lathe and a boring bar.

KDOG3 said:

The output reduction is just on the highest setting, correct? All the other settings are the same as on primaries I hope. They are on a 17670, so I imagine they would be on an 18650.

Whats' the best way to bore the body out? 18mm drill bit with cutting oil? I've worked with aircraft aluminum before (building ultralight airframe).

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KDOG3 said:

The output reduction is just on the highest setting, correct? All the other settings are the same as on primaries I hope. They are on a 17670, so I imagine they would be on an 18650.

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The output reduction on high is about 10 lumens between 123's and the 18650, but from level 5 down , it is less than 1 lumen lower between them.