U2 Alternative Power Source?

I just recently got a surefire's U2 for $100 and was wondering if a 17650 will fit or a pair of AW's RCR16340 will work without frying anything.

Yes, I just recently got the E2L as well But no AW power source yet lol.

Anyone with this light care to shed some light? It's a year older than the newer models since it's gold coated on the inside.

I guess once you start collecting them, you're hooked. ^^

What year is the U2 from? Which LED is in there?

That may make a difference. I'm not sure on the newer ones.
I have an older U2 and it loves to run on 1 li-ion.

My older U2 loves AW18650.

How old is your U2? Does it have 4 sides or three? The sections that have the writing. My old U2 has two black spots at 12 and 6. At 3 and 9 it has U2 writing, and Surefire.

Anyway back to the OP, the early U2s could hold 18650 as oldways mentioned. Mine is running on those.

I dont know if you can run 2xRCR123 though. It is all the same with kromas as well. you can get a 17650 and it will work. Just not last as long as a 18650.

Tiresius said:

I just recently got a surefire's U2 for $100 and was wondering if a 17650 will fit or a pair of AW's RCR16340 will work without frying anything.

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I can't exactly help you on the U2 (great snag BTW, I probably would have ponied up $100 for a used one), but I did some reasonably in-depth calculations here indicating that 1x 17670 can provide ~45% more stored energy than 2x RCR123, and 1x 18650 (if yours is one of the really old ones or if you get it bored) can provide ~120% more stored energy than 2x RCR123. Although your particular U2 may obtain somewhat less output on a single 3.7v LiIon (others here know more about the U2s and should be able to help) than 2x RCR123, you would be able to get excellent runtime - I personally wouldn't mind not being able to run 2x RCR's. My two lumens,

The guy I got it from said he bought it from a 1 and a half year ago. After he retired as a pilot, he decided to let this one and his burnt out A2 aviator go.

It's a 3 sided body. Under the clip is the side with a blank, the surefire logo on 1/3 and the digital 2 ultra on the 1/3. Holding the tailcap facing me, the surefire logo is to my right of the clip.

Now I have something I can use for my night job that has multiple outputs.

Whether it be an old model or not, I still think it was worth the $100 USD for a used but very well kept with no scratch or dings.

great buy on a great light.

Kestrel said:

I can't exactly help you on the U2 (great snag BTW, I probably would have ponied up $100 for a used one), but I did some reasonably in-depth calculations here indicating that 1x 17670 can provide ~45% more stored energy than 2x RCR123, and 1x 18650 (if yours is one of the really old ones or if you get it bored) can provide ~120% more stored energy than 2x RCR123. Although your particular U2 may obtain somewhat less output on a single 3.7v LiIon (others here know more about the U2s and should be able to help) than 2x RCR123, you would be able to get excellent runtime - I personally wouldn't mind not being able to run 2x RCR's. My two lumens,

Click to expand...

It's not based on preference of power source. I have the 2x RCR's in my old G2. I just need to gather some information about whether it's capable of fitting an 18650 or a 17650 before I end up ordering a battery when it's capable of fitting another, yet better battery.

Based on Kestrel's readings, I'll get a whole lot more run time with an 18650 and it would be favorable over the 2x RCR 16340 or the 17650. But I can't be buying the 18650 if it doesn't fit.

Just one more question. Is the beam supposed to have a hole in the center the more further it goes?

Current production starting a few years ago only supports CR123 and 17** cells, that is true for most all SF lights.

Leef for awhile was making 18650 compatible bodies, I have one of the grooved version, it swallows up 18650 cells happily. There are also the 4 flat SF stock bodies from many years past, which with removal of the black plastic sleeve accept 18650's form the head side only.

You can have a stock body bored out for 18650 cells, but it's not readily available from any machinists on the forums since it's not an easy light to grip in a lathe.

All U2's I have owned have worked on 18650's one had a slight issue dropping out when the cells got discharged only a little, but it was intermittent at worst.

U2 donut holes are fairly common, and pretty much have to be lived with.

Stick and SST-50 in it and the hole goes away. :thumbsup:

If the U2 uses a Lux V LED, then 1xLi-ion works fine since the light uses a boost driver. 2xLi-ion results in Vbatt>Vf, and you risk frying the light.

If the U2 uses a Seoul P4 LED, then 1xLi-ion still works fine, although you won't run in full regulation. It also appears that 2xLi-ion works with the buck driver used in the Seoul P4 version of the U2. I've run my P4 U2 (the U2A) with 2xAW16340 without any issues.

Yes, the NEWER ones will work with 2X 16340s, the older ones with the Lux-whatever LED will 100% DIE!

This was asked a while ago, and I told in that thread, I ran it without any problems on 2X AW protected black ones, and/or the IMR orange ones.

This guy tried it and... instantly fried the light :mecry:

So, be warned... if not sure, you'd better not do it (or try it with protected batteries first, which are 80% depleted before trying).

Timmo.

Pretty interesting information. Sounds like the OP needs to take a close look at the emitter & discern if it's the LuxV or the SSC model. There was an excellent thread a while back with some close-up photos of both U2s, with particular attention to the appearance of their emitters.

Just ran 'search' & came up with these threads:
https://www.candlepowerforums.com/threads/258189
https://www.candlepowerforums.com/threads/232860
https://www.candlepowerforums.com/threads/210113 <- deals with 17670 compatibility
https://www.candlepowerforums.com/threads/217064

Looks like the best thread is here though: https://www.candlepowerforums.com/threads/205637
Lots & lots of good reading, 7 pages of CPF goodness in that link.

Edit: OK you U2 folks, I'm guessing that if the OP is getting a slight 'donut' in the beam (post # 8) it's the older LuxV emitter?

98.8% Yep.

Yes, I have the older lux5 head. I don't have the 4 metal pieces sticking out like a sore thumb from the emitter. I can only see the grid on low mode--can barely make out the lines while off. The body is a newer model since the older one contains 4 sides--2 blank and 2 labeled.

I've looked at the beam comparison between ssc p4 and lux5. Good thing I got this light as a flood-type and low-light usage. It has a warmer tint than the p4. Fits exactly what I've had in mind except no 18650.

Thanks for the information. I'll be ordering a pair of 17650 sometimes later and avoid the hassle of hunting someone down to get it bored out for a 18650.

Sgt. LED said:

98.8% Yep.

Click to expand...

make that 100% yup

If you send it to Milkyspit (forum name) he can make it over 3 times as bright, bore it for 18650s and it will still run just as long. He made me one with a warm white MC-E and it is perfect.

Sverre

PS! The U2 is still great with the old LuxV it is just overly awesome with a MC-E