Did i just buy a U2 or U2A?

Hello everyone, i am very new to this hobby and after scouring the forums for days i decided to purchase a U2 last night. I went to my local surefire dealer and picked up what i think is a U2. I have been reading that the U2 has a black inner sleeve that needs to be removed in order to fit the larger 18650 lion's and my light does not have that. Anyways here are some pics (they link to larger images) any help would be greatly appreciated because i would like to buy some rechargeable's asap.

:welcome:
The way to tell the U2A from the U2 is by it's LED - show us a photo of it and we'll be able to tell whether it's a U2 or U2A.
The body has not had the insert tube for some time, long before the U2A.

Thank you for the warm welcoming. It was tough getting a picture of the led, but i think it came out alright. Can you tell from the earlier pictures if it will accept the 18650 cells? Thanks again!

Thank you for the warm welcoming. It was tough getting a picture of the led, but i think it came out alright.

diablo266 said:

Thank you for the warm welcoming. It was tough getting a picture of the led, but i think it came out alright. Can you tell from the earlier pictures if it will accept the 18650 cells? Thanks again!

Click to expand...

That looks like the Luxeon V LED in my U2. That would make your U2 the original, not the U2A.

Also, unless you got a really old body, your U2 won't accept 18650 cells. You can always put a 17670 in there though, and the only downside is that the capacity is lower.

By the way, welcome! And, a great choice on a the U2.

Ah yes, the U2! A great light, and one that I still use a lot! Congratulations on your purchase!

Welcome to CPF!

Yep getting a good picture of an LED can be tricky but you did well. Definitely a U2. Luxeon V LED in there.

But the good thing is if you get bit really hard by the flashlight bug and hang with the rest of us crazy people (run away now to save your wallet), you can have that old emitter swapped out for a newer one.

:welcome:

Oh btw, the "newer" U2s aren't 18650 compatible anymore. An older version had the removable sleeve but SF decided it wasn't in out best interest to use 18650s or something like that. So you should get out some calipers and measure the internal diameter before going the next step and ordering 18650s. They may not fit. :sad:

You can buy a new body for your U2 which accepts 18650 cells though - leef used to make them and lighthound used to sell them - maybe he still does.

Upgrading the LED is a marvellous idea... I had an XW0S put in a few months back but I think might put a MC-E 5A in very soon

Wow thank you all for the replies. I can tell i'll definitely be spending more time here. I measured the inner diameter of the tube and it came out to 16.97mm so i guess the 18650's are out. Does anyone know about possibly machining the extra millimeter out to make room, lighthound's site says they are 18mm? I have access to the machinery to do that but i'd like to know of some others experiences before i dive into that. I'd just go with the 17670's but from what i understand they are a significantly lower voltage?

*edit*
i also checked lighthound for that custom body that would accept the 18650 cells but i didnt see anything, maybe i just dont understand the model #'s?

diablo266 said:

Wow thank you all for the replies. I can tell i'll definitely be spending more time here. I measured the inner diameter of the tube and it came out to 16.97mm so i guess the 18650's are out. Does anyone know about possibly machining the extra millimeter out to make room, lighthound's site says they are 18mm? I have access to the machinery to do that but i'd like to know of some others experiences before i dive into that. I'd just go with the 17670's but from what i understand they are a significantly lower voltage?

*edit*
i also checked lighthound for that custom body that would accept the 18650 cells but i didnt see anything, maybe i just dont understand the model #'s?

Click to expand...

Looks like the custom bodies for the U2 are all gone, I seem to remember they were $50.00. There's a company called TnC - they might have made some? You could also try posting a in the lights buy section of CPFM (cpf marketplace) for a custom body or an old U2 body.

I'm not sure about boring out the SF U2 - not familiar with this at all - but I would hazard a guess and say that there's enough material there to bore it out since older ones used to come pre-bored for 18650. If you drilled out your body, then you'd lose the chemkote on the inside. The reason I'm a little hesitant is that boring out 6P for 18650 is pretty close because there's less than 1mm clearance in places. But I think that U2 bodies are thicker than 6P bodies.

Rechargeable batteries can be confusing! The most popular 17670 and 18650 batteries that run in the U2 have the same chemistry and therefore have the same voltage. Don't bother with anyone apart from AW (a member on CPFM), pila or wolf-eyes for safety and reliability reasons. Both 17670 and 18650 run the U2 with a small drop in brightness (compared to primary (non rechargeable) cells). 18650 cells are rated for about 2200 mAh whereas the 17670s claim about 1600mAh. Don't try running 2xR123 (also called RCR123 or 16340) in the U2 - you'll blow it up. So to sum up, you'll get shorter runtime with 17670 - but it's not that big a deal in my opinion.

I would strongly recommend you have a look for mdocod's excellent guide to rechargeable batteries - you'll need a coffee or three to read it though! Lithium batteries - especially rechargeable ones - are not inherently safe and you really should know about their dangers before you use them.

This graph will show the differences between the battery options here. The Pila 168S is the same as a 17670.

Depending on your preferences, you may want to consider returning your U2 and ordering a U2A from one of the many trusted sponsors on this site.

I haven't paid a bunch of attention to the U2A, but it looks like the differences are:
- it has a cooler beam (more bluish than the U2)
- slightly different beam pattern
- lower levels 1-5, with a similar level 6
- longer runtime (although I couldn't get an exact number)

I love my Lux V U2, but if I had a choice, I would default to the newer model. I don't mind cooler beams, and extra runtime would be appreciated. Also, for future upgrades, the Seoul emitter would probably be easier to find a direct replacement for than the Lux V.

If you keep it though, I'm sure you will love it!

Another option would be to keep your U2 as a wonderful lithium primary light, and explore rechargeable options in a SF 6P/9P/C2/C3 with a quality drop-in such as a Malkoff. The modular 'open' SureFires lend themselves much better to rechargeable battery setups and other customizations than the 'sealed-type' (my term) SF's. I've learned more about the possibilities this way than by buying lights that are rather more difficult to modify.

Just a _quick_ suggestion, since I don't want to take this OT anymore than I just did...:thinking:

My two cents, FWIW.

Oh, and +2 to mdocod's rechargeable battery guide,
https://www.candlepowerforums.com/threads/201375