# Test/Review of Keeppower 18650 3100mAh (Black)



## HKJ (Mar 31, 2012)

[size=+3]Keeppower 18650 3100mAh (Black)[/size]







Official specifications:

18650 3100mAh Protected Rechargeable Battery
Min Capacity: 2900mAh
Typical Capacity: 3100mAh
Normal Voltage: 3.6V
Quality Lithium Ion rechargeable cell
In Built Safety Circuitry
Maximum capacity and reliability
High Discharge Rate (Max 2C)
Protection Circuit (Against overcharge, over discharge, over current and short-circuit.)
4.2 volts max voltage and 3.6-3.7 volts nominal voltage






The cell used can be discharged down to 2.5 volt, in my test I only discharges to 2.8 volt, i.e. I do not measure the full capacity. But then, not all lights will be able to use the full capacity.



























Each chart has curves for two batteries, but these batteries are nearly identical in performance and the curves are on top of each other.

































[size=+3]Conclusion[/size]

This battery uses a good cell, this secures many things:

The batteries does match in capacity, i.e. they can be used in series.
The battery is very safe.
The battery has the specified capacity. 


All in all a very good battery.



[size=+3]Notes and links[/size]

Keeppower is a OEM manufacturer, i.e. many of the batteries they produce is sold with other names on them.

The batteries was supplied by Keeppower for review.

How is the test done and how to read the charts
How is a protected LiIon battery constructed
More about button top and flat top batteries


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## zer0ne (Apr 1, 2012)

Where do you find them in online retail?


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## HKJ (Apr 1, 2012)

zer0ne said:


> Where do you find them in online retail?



I do not know, but I believe that there is a reason I was asked to test their batteries, i.e. keep looking, something will probably pop up soon.


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## zer0ne (Apr 1, 2012)

HKJ said:


> I do not know, but I believe that there is a reason I was asked to test their batteries, i.e. keep looking, something will probably pop up soon.



They are OEM maker.....I don't think they are interested in small quantity for hobbyist.  Hopefully we can have more choices.


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## hellokitty[hk] (Apr 1, 2012)

Do you have plans to test the Orbtronic 3100mAh 18650? It looks like the cheapest 3100mAh battery at $13.00 and free shipping.


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## HKJ (Apr 1, 2012)

hellokitty[hk] said:


> Do you have plans to test the Orbtronic 3100mAh 18650? It looks like the cheapest 3100mAh battery at $13.00 and free shipping.



Yes, Orbtronic will send some batteries to me (or maybe they already has).


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## Changchung (Apr 2, 2012)

HKJ said:


> Yes, Orbtronic will send some batteries to me (or maybe they already has).



Please, post here when you make the review to the orbtronic. Thanks


SFMI4UT


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## GlassMan (Apr 4, 2012)

I am now using the Orbtronic 3100, still on the first charge. No way to do a test on my end thou.


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## HKJ (Apr 4, 2012)

Changchung said:


> Please, post here when you make the review to the orbtronic. Thanks



I cannot promise that I remember this. 
Check my summary or comparison, it will be included in the charts when I have tested it (Remember to press F5 to refresh the pictures).


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## zenbeam (Jun 6, 2012)

Thanks for the great review! I know many of us are in search of good pricing in batteries, but are fully prepared to pay the premium for "known quality and safety" and I don't disagree with that. But, these batteries seems like a great value and a contender with the known brands for quality and safety. Of course, being Panasonic based can't hurt. So I very recently ordered 2 pair of the Keeppower 3100mAh 18650's featured here. 

I googled them first and found another forum post stating that on ebay, find the seller asking $23 per pair (free shipping - but comes from China) and make offer of $21 per pair and the offer will be accepted. I did exactly that and am now just waiting. Should get mine between 6/12 and 6/18. That seller is doingoutdoor - is very high rated seller, so I don't feel like I took too much of a gamble.


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## tobrien (Jun 6, 2012)

zenbeam said:


> Thanks for the great review! I know many of us are in search of good pricing in batteries, but are fully prepared to pay the premium for "known quality and safety" and I don't disagree with that. But, these batteries seems like a great value and a contender with the known brands for quality and safety. Of course, being Panasonic based can't hurt. So I very recently ordered 2 pair of the Keeppower 3100mAh 18650's featured here.
> 
> I googled them first and found another forum post stating that on ebay, find the seller asking $23 per pair (free shipping - but comes from China) and make offer of $21 per pair and the offer will be accepted. I did exactly that and am now just waiting. Should get mine between 6/12 and 6/18. That seller is doingoutdoor - is very high rated seller, so I don't feel like I took too much of a gamble.


thanks for the info bud! i'll have to grab some


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## HighlanderNorth (Jun 6, 2012)

HKJ said:


> Yes, Orbtronic will send some batteries to me (or maybe they already has).




I bought 4 Orbtronics 2900mah 18650 batts per your review a few weeks ago, and I have not used them at all yet, as I already have other 18650's in my 18650 lights, but I assume they will be good.

I will eventually try these too.


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## Jedgar (Jun 6, 2012)

I just got 10 of these from the doingoutdoor seller on ebay I paid 85 But ended up having them send me a paypal invoice to get this price. 
They just got here this evening and I dont think you can beat the price for a heck of a deal on good batteries.
Just fyi 
Josh


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## tobrien (Jun 8, 2012)

Jedgar said:


> I just got 10 of these from the doingoutdoor seller on ebay I paid 85 But ended up having them send me a paypal invoice to get this price.
> They just got here this evening and I dont think you can beat the price for a heck of a deal on good batteries.
> Just fyi
> Josh


Very good deal. I snagged four for $40 total. Four cells that is, not pairs.


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## zenbeam (Jun 8, 2012)

tobrien said:


> Very good deal. I snagged four for $40 total. Four cells that is, not pairs.



I thought about offering 20 per pair but chickened out - didn't want to delay it any longer than necessary - considering it's already coming from China. So heed this notice for further orders folks - offer 20 per pair if ordering 2 pair.


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## tobrien (Jun 8, 2012)

zenbeam said:


> I thought about offering 20 per pair but chickened out - didn't want to delay it any longer than necessary - considering it's already coming from China. So heed this notice for further orders folks - offer 20 per pair if ordering 2 pair.



you raise a good point, but i don't need it insanely urgently lol


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## Dubois (Jun 8, 2012)

zenbeam said:


> I thought about offering 20 per pair but chickened out So heed this notice for further orders folks - offer 20 per pair if ordering 2 pair.



I made a slightly lower bid, but I was happy paying $42 for 4, and they arrived in the UK in 10 days, registered shipping.


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## zenbeam (Jun 10, 2012)

@ HKJ -

What are the dimensions of these batteries? 

I've never owned 3100mAh 18650's yet, but I've read that they might have a problem actually fitting certain lights?


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## Dubois (Jun 11, 2012)

zenbeam said:


> @ HKJ -
> 
> What are the dimensions of these batteries?



HKJ's table at the start of the Test/Review shows the size (69.7mm x 18.8mm).


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## zenbeam (Jun 11, 2012)

Dubois said:


> HKJ's table at the start of the Test/Review shows the size (69.7mm x 18.8mm).



Whoops! It sure does. Time for my next eye exam.


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## zenbeam (Jun 16, 2012)

Got my 2 pair of Keeppowers a few days ago and finally had time to complete the top off charge on one pair today. I don't recall my first volt reading, but I want to say they were at 3.68v upon arrival. I've only topped off one pair so far using an Xtar WP2 II. I had to interrupt the charge 2 or 3 times due to limited time and the need to snooze, etc. But I did check the voltage of the pair before resuming the charge each time and they were impressively exactly the same voltage as one another each time. 

When one battery completed the charge, the other was about 30 seconds behind when it completed. ***They both read at 4.22v. I was a little surprised that they actually went over 4.2 at all, but if I understand it correctly, a +/- .05v is still safe. And these are the first 3100mAh batteries I've had and figured it was due in part to their larger capacity. This was also the first time I used the Xtar WPA2 II charger on any 18650's - just bought it very recently. I used it to top off a 14500 and it reached 4.18v when the light turned green. 

I tried them out in my Crelant 7G5 V2 and man they performed just fine initially. I still opted to remove them from the light for tonight and then run a bit more juice out of them tomorrow and leave them in. 

Initial impressions - great price, the labeling and shrink wrap is very professional in appearance, they arrived in about 12 days from China... not too shabby shipped to the U.S., and they didn't warm up during charge and they worked great in a long throw light.
EDIT: And two of them fit just fine in my Crelant 7G5 V2. Have yet to test out fit in my 1x 18650 lights. 

***Only concern - should I be concerned about them being charged to 4.22v when the light turned green?


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## Shadowww (Jun 16, 2012)

zenbeam said:


> ***Only concern - should I be concerned about them being charged to 4.22v when the light turned green?


You should be more worried about your DMM (or charger, in case your DMM is calibrated/tested against some known reference), not the batteries themselves.


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## zenbeam (Jun 16, 2012)

Thanks Shadowww. It's a cheap DMM - so far I think things are in the realm of proper behavior, but I do keep a close eye out for any irregularities. 

I charged up the other pair today. They were at 3.62v out of the wrapping they came in (the others were probably at that too, I just didn't make particular note when I checked the first pair). I was able to top them off today uninterrupted on the Xtar WP2 II. When the lights turned green the batteries both measured at 4.21v right off the charger. 

This time I tested for fit in my ZL SC600 and Romisen RC-T601 II - no problem with fit what so ever. I haven't tried one yet in my Fenix TK21, but I about half expect it may not fit into that light because there have been so many reports of Fenix "T" series lights not accommodating 3100mAh 18650's (not sure if that applies to "TK" series). But heck, I'm happy they fit 3 of my 18650 lights! When I get around to checking the fit the Fenix TK21 I'll note the results here just for completionist kicks.


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## tobrien (Jun 17, 2012)

zenbeam, most 18650s i get based on those Panasonic 3100s come to me sitting at around 3.6v. i think that's how they leave the panasonic factory honestly.

my intl-outdoor ones came the same way and my orbtronics too 

nothing to worry about

also the 4.2x volt reading you got straight off the charger 'chills out' and lowers after a bit. what you're seeing is perfectly normal


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## zenbeam (Jun 17, 2012)

I like perfectly normal when dealing with these li-ions.


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## tobrien (Jun 19, 2012)

my four just arrived today and i don't know if it's purely coincidental, but *none of them had the label over the protection strip* (as in, the strip that goes from end to end was not under the sticker/label on any of the four)

this is real nice. it's a small thing, but i was pleasantly surprised. 

this should also maximize the fit on any lights i throw them in


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## zenbeam (Jun 20, 2012)

I finally tried one of these for fit with my Fenix TK21 - perfect! Not the least bit of issue with fit on any of my 18650 lights. Nice!

@ tobrien -
I looked at mine after reading about your protection strip and it seems mine is covered by the label. That is if it's what I think it is. There is a little raised strip maybe 1/8" wide (if that) that runs fully lengthwise - under my label. Can you take a photo of yours? 
Which way is it supposed to be anyway? I kind of assumed the label would cover everything?


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## HKJ (Jun 20, 2012)

zenbeam said:


> @ tobrien -
> I looked at mine after reading about your protection strip and it seems mine is covered by the label. That is if it's what I think it is. There is a little raised strip maybe 1/8" wide (if that) that runs fully lengthwise - under my label. Can you take a photo of yours?
> Which way is it supposed to be anyway? I kind of assumed the label would cover everything?



It does not really matter if the strip is under the label or on the opposite side, it will increase the thickness of the battery. It has to be just beside the label to reduce the impact on thickness.
You can see how the strip looks in my article about the battery construction.


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## zenbeam (Jun 20, 2012)

HKJ said:


> It does not really matter if the strip is under the label or on the opposite side, it will increase the thickness of the battery. It has to be just beside the label to reduce the impact on thickness.
> You can see how the strip looks in my article about the battery construction.



Okay - thanks. The "wire" is what I noticed then. So while it might be optimal to minimize battery thickness by having it _beside_ the label, as long as there are no issues with fit otherwise, the function of the protection remains the same (under, beside or on top of the label)?


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## HKJ (Jun 20, 2012)

zenbeam said:


> Okay - thanks. The "wire" is what I noticed then. So while it might be optimal to minimize battery thickness by having it _beside_ the label, as long as there are no issues with fit otherwise, the function of the protection remains the same (under, beside or on top of the label)?



Yes, the position only affects the thickness with maybe 0.1mm and does not have anything to do with the function of the protection circuit.


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## tobrien (Jun 20, 2012)

zenbeam said:


> I finally tried one of these for fit with my Fenix TK21 - perfect! Not the least bit of issue with fit on any of my 18650 lights. Nice!
> 
> @ tobrien -
> I looked at mine after reading about your protection strip and it seems mine is covered by the label. That is if it's what I think it is. There is a little raised strip maybe 1/8" wide (if that) that runs fully lengthwise - under my label. Can you take a photo of yours?
> Which way is it supposed to be anyway? I kind of assumed the label would cover everything?



yeah man, everything hkj said! 

i guess mine was luck of the draw then. i know Redilast/EDC+ has stated they do theirs so that the label is *never* over the wire/strip. it's a nice touch.


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## justanotherguy (Jul 31, 2012)

Jedgar said:


> I just got 10 of these from the doingoutdoor seller on ebay I paid 85 But ended up having them send me a paypal invoice to get this price.
> They just got here this evening and I dont think you can beat the price for a heck of a deal on good batteries.
> Just fyi
> Josh


So did you submit an offer, or send them a message negotiating this?? $8.50 a battery seems great!!
I am going to have to give this a try!!!

Tony


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## tobrien (Aug 1, 2012)

justanotherguy said:


> So did you submit an offer, or send them a message negotiating this?? $8.50 a battery seems great!!
> I am going to have to give this a try!!!
> 
> Tony


yeah you click the "Make Offer" button on the auction page and type whatever you want.


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## justanotherguy (Aug 1, 2012)

yea, I sent an offer, we'll see what he says..I should have gotten someone else in and upped my order to 20 batteries....




edit: Offer Rejected


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## justanotherguy (Aug 2, 2012)

offer accepted @$10 a cell , qty 10 though....


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## veedo (Aug 2, 2012)

Offer accepted $40 for 2 pairs. $10 a cell, not too shabby.


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## justanotherguy (Aug 3, 2012)

veedo said:


> Offer accepted $40 for 2 pairs. $10 a cell, not too shabby.



Ditto! But he told me 5 pairs for $100...I really budgeted $80..but whats a few more cells? I guess I just have to buy another light or two to put them in!
These look like great values even compared to AW's.I am phasing out the UF's
Tony


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## justanotherguy (Aug 9, 2012)

I am about to get the 10 in, but I figure I might have 2-4 left over, if there is anyone local to NE ILLinois who might want in @$10 each...
Tony


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## veedo (Aug 11, 2012)

cells showed up yesterday, 9 days, impressed!


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## hellokitty[hk] (Aug 12, 2012)

justanotherguy said:


> I am about to get the 10 in, but I figure I might have 2-4 left over, if there is anyone local to NE ILLinois who might want in @$10 each...
> Tony


Why don't you try starting a group buy? I'm sure that people may be interested if you can get them at $8.50 a cell.


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## CM2010 (Aug 12, 2012)

I just got 6 with tracking for $63.


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## justanotherguy (Aug 25, 2012)

veedo said:


> cells showed up yesterday, 9 days, impressed!



hmmm ...mine havent show up yet...I paid on 8/03 too....sigh


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## sidecross (Aug 25, 2012)

I bid on 5 pairs for $100 and it was accepted.

These look like very good batteries, but for owners of the NiteCore TM11 'Tiny Monster' be aware that these 69.7mm tall batteries will not fit. 

I plan to use my collection of Eagletac 18650 3100mAh batteries for the NiteCore TM11. These new KeepPower 3100mAh should fit all my other lights.

Thank you HKJ for all your information and help. :thumbsup:


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## sidness (Aug 26, 2012)

justanotherguy said:


> hmmm ...mine havent show up yet...I paid on 8/03 too....sigh



Mine took 5 weeks to arrive, but they are great batteries, worth the wait.


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## veedo (Aug 26, 2012)

wow, 5 weeks? i must have been lucky.


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## tobrien (Aug 27, 2012)

yeah I live in the southern USA and iirc i got them in less than 3 weeks I wanna say


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## sidecross (Aug 27, 2012)

I live on the west coast USA and I have tracked my new batteries and they left China a few hours ago; expeced by shipper to arrive by 9/12/12.


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## CM2010 (Aug 29, 2012)

Mine turned up today, 17 days from ordering.


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## sidecross (Sep 4, 2012)

My batteries from China arrived today 9/4/12!


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## justanotherguy (Sep 5, 2012)

hi
your batteries were returned to us yesterday , ( China post said that they don't ship parcels with battery)
we plan to ship them again via Singapore post with tracking number.
ok?
looking forward to your reply.
thanks

Best Regards! Bill


Got that today...I paid on 8-03....I hope to see them in less than 2 weeks. 
I hope.


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## justanotherguy (Sep 19, 2012)

Got them today....6 weeks later. They look great though, now for some testing....


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## Quest4fire (Sep 20, 2012)

Just had an offer accepted almost immediately for 2 pair, four cells total, of the *unprotected* Panasonic 3100 mAH for $16.00 a pair instead of $17.50. Add $2.00 shipping and that's $34.00 for four cells. Not bad!


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## tobrien (Sep 20, 2012)

Quest4fire said:


> Just had an offer accepted almost immediately for 2 pair, four cells total, of the unprotected Panasonic 3100 mAH for $16.00 a pair instead of $17.50. Add $2.00 shipping and that's $34.00 for four cells. Not bad!



that's awesome! i guess it's hit or miss on most of these offers lol


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## GehenSienachlinks (Sep 20, 2012)

I looked at HKJ's comparator and it looks like the sanyo 2600 red is one of the best batteries out there in terms if keeping a higher voltage for longer then the rest except for imr's ,panasonic 2250 and lg pink 3000 mah and 2800 at 4.30 votls . I have the xtar 18700 2600 mah which I think uses the sanyo 2600 mah and looking at the charts the sanyo 18650 out performs the xtar voltage wise .


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## Quest4fire (Sep 20, 2012)

GehenSienachlinks said:


> I looked at HKJ's comparator and it looks like the sanyo 2600 red is one of the best batteries out there in terms if keeping a higher voltage for longer then the rest except for imr's ,panasonic 2250 and lg pink 3000 mah and 2800 at 4.30 votls . I have the xtar 18700 2600 mah which I think uses the sanyo 2600 mah and looking at the charts the sanyo 18650 out performs the xtar voltage wise .



Yep! That's right. This ebay seller "doingoutdoor" is selling the red sanyo 2600's for $12.50 a *pair* plus two bucks shipping. If you could get them to accept a "Best offer" of say, $ 11.00 a pair you could get a *pair of sanyo 2600's for only $13.00 shipped!* Intl-outdoors couldn't compete against a price that low! Even the list price is a steal though. I wonder if folks realize that price is for a *pair* of cells. Better hurry though, the listing says "4 available / 10 sold".

****UPDATE*** *Just had an offer accepted for four sanyo 2600's at $11.00 a pair. With $2.00 shipping that works out to six bucks a cell. I'm liking this seller!


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## justanotherguy (Sep 21, 2012)

So after getting these I wanted to know the difference...between a new top rated cell and my used(unknown amount) Redilast 2900 and an ultrafire2600

I started an sc600 and sc600w this morning on the redilast 2900 and a KP3100. about 5:15 am on Medium: M1 *65*Lm (18hrs)
When I got home at 4:45 pm the redilast was already out, wife said it happened recently...I got home from dinner this evening and
now at 10:15 pm the KP3100 still has the sc600w lit.....

pretty nice , though I dont know if the cool vs warm tint makes a difference.......??
Dont have the UF2600 at home to play with. Doubt I want to really.
Tony

Runtimes are tested using Panasonic NCR18650 (2900mAH) batteries. Light output are out the front (OTF) values. All levels are current regulated.

Ok with 3100's I expect then 7% more energy/runtime? Another 1-1.25 hours.....? I wont be up then!


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## CM2010 (Sep 23, 2012)

Gutted, for some reason the guy on ebay won't ship to the UK anymore.


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## Quest4fire (Oct 2, 2012)

O.K. I'm officially impressed. Ebay seller doingoutdoor got my eight cells (Four Panasonic, four Sanyo) from China to my doorstep in the middle of the US in *11 days!* It will take a while to charge them up and discharge them for a capacity check, but they appear to be the real McCoy. I don't think there will be any surprises.

Quest out...


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## justanotherguy (Nov 26, 2012)

Now shipping has jacked up to $20.....!


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## justanotherguy (Jan 4, 2013)

Ebay seller Doingoutdoor is NARU on ebay...no longer a registered user....
argh


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## Dubois (Jan 4, 2013)

He's no longer on eBay, but is on aliexpress (with a limited range of cells and lights, and a few knoves) and will soon have his own website. PM me if you want the link for aliexpress, but he still won't ship batteries to the UK.


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