ok i bought a sparkly new red ultrafire sk68. i have some cheap 14500’s and they make this thing absolutely awesome. i also have some aa ni-mh’s on the way. but my complaint is that my runtime with the 14500’s seems to be 30 or so minutes. but with an alkaline aa i got about 1hr45mins before it started to get noticeably dim so would the ni-mh’s be better than an alkaline and is the 14500 time normal for these or if i spent more money on an expensive set would the runtime be better?
My runtime has been 1:10 at most on an alkaline AA and some better on a nimh, but only 27 minutes on the 14500 I had. Your numbers sound about right to me.
ok i guess i’ll be keepin some spares in my well everywhere. lol. 30 mins just seemed a lil short i thought for sure i’d get at least 45 to 50 minutes
Don’t take my word for it alone as the 14500 I had was likely low-capacity (won it off ebay nearly two years ago and it has since died), and the problem with most GOOD cells that are 14500s and 18500s is the low capacity, so maybe you’d do a little better with a Keeppower cell, but I can’t imagine the improvement being that much. I got away from those for that reason.
And you have to remember that the advantage of the AA format is practicality. It’s nice having a pocket-banger light that runs on something that can be bought in any corner drugstore, but the longer you run those little lights on 3+ volt li-ions, some have said you lose the ability to run them again on AAs due to voltage issues (a number have said this about their lights if you’ll search some threads and ask around).
I’d keep the 14500 for backup and “wow” use and run standard nimh’s in it. I use mine with Eneloops only now and the output is dandy, IMHO.
i got 3 more on the way. i think this will be my “wow” and mod light. the others will get the Ni-Mh’s and i might look into the eneloops when my budget permits. that seems to be everyones favorite on here
When you have all of the lights together, take freshly charged cells and compare the tail cap amperage draw rates of the different lights on both.
You’ll likely find that each light performs somewhat differently as to how much draw there is using the exact same cell - AND - probably even using different brands of the same cell type.
Some of the lights will probably give you longer run time OR be brighter using the same type of cell. And, some of the lights will be better for one type of cell, or the other.
In general, 14500s don’t have a lot of capacity and printed capacities can be very misleading on many brands. Some reports put true capacity at 1/2 to 1/3 of listed except for a few high end brands.
If you have a 1A draw rate with a 14500 and the true capacity is only 500mAh instead of the listed 700 it’s not going to last very long. Typical for SK68s seems to be ~1A +/- .25A. If you have one with a higher rating it may well be brighter (or it could just be less efficient). And a lower draw will have longer run time.
Everything seems to be a lottery with these beloved SK68s.
“Pocket banger”……sounds like something that banggood would sell
The SK68 typically has a shorter runtime with Li-ions, due to its circuitry. The nimhs should outperform the alkalines - the SK68 draws a lot of current and nimhs preform much better in with high current draws.
Howdy, the SK68 is a cool little light. What I like to do is put an XP-G2 in the light. They are not very much money and it’s very simple. Just two wires to solder. Then you get rid of the ring on the beam and it’s almost as bright with a Nimh as it was originally with the 14500. If you really want to get adventurous soak the XP-G2 in gasoline until the dome falls off the emitter and you will get a more neutral tint and twice the throw (distance) and still no goofy ring.
Of course if you go down this road you will find yourself finding more and more reasons to make lights better and run the risk of becoming a modiholic like far too many of us. 
Do you think the price is ok for 2nd generation eneloops?
Not really. Over at amazon it’s $10 per 4 for 2nd gen, or $13 per 4 for 3rd either with free 2 day shipping.
Link please? International free shipping?
http://www.amazon.com/gp/aw/s/ref=is_box_electronics?k=1800+eneloop+AA
The FT price might be a good deal depending on where you live.