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Thread: CAUTION !! Misleading budget battery and lumen claims

  1. #31
    Flashaholic Epsilon's Avatar
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    Default Re: CAUTION !! Misleading budget battery and lumen claims

    @langham I disagree on a few points and will point out why
    Quote Originally Posted by langham View Post
    The curve for light output vs. current is useless above 3A and just reduces the life of the led dramatically. Why would you do that?
    This is just not true. With a good LED board you can go way past 3A.
    Source: http://www.candlepowerforums.com/vb/...t=#post4018726

    The extra 500lumen that a 6A drive deliveres, can be very useful. That you will not find it useful to do, is just your call.

    Quote Originally Posted by langham View Post
    The heat dissipation alone would be obscene and call for a light that was at least big enough to house 2*18650.
    For momentary use, almost any host is big enough. Even a 1*18650 P60 is big enough. A good host and thermal management will help a lot. I made a light that runs an XM-L @ 3.85A and can do this for extended times.
    Topic with temperature measurements

    Quote Originally Posted by langham View Post
    Now an SST-90 could be understandable, but even then the size of the head of a light that uses an SST-90 or multiple XML emitters would be large and bulky and in no way would you save anything by running the light on a single 18650.
    Multi XM-L and SST-90 with the dome is just not comparable with a single XM-L in terms of throw in the same host. The SST-90 is by the way a very difficult LED to direct drive of a single cell because of the relative high Vf. Very little cells go past 5A.

    Quote Originally Posted by langham View Post
    Beside all of that the smallest 5A driver I have ever seen is very large, much too large to use in any single 18650 host I have seen.
    True, but single cell operation are mostly limited to X*7135 drivers stacked. Those are small enough.

    Quote Originally Posted by langham View Post
    If you are talking about running a 4*XML with just 2 18650 cells I would say that is still unwise because in a light that is that bright you don't need to be able to carry it around as your EDC.
    Too bright? Every application needs a certain amount of light. When my eyes are full adjustment to darkness, the 4 lumen of the low setting of my quark 123 is even too bright. But that just doesn't cut it outside.

    There is no "Too bright", only too bright for a certain application. It is imho always desireable to have immense power in EDC size.

    Quote Originally Posted by langham View Post
    All in all, just get a multiple cell host and stop trying to spend way too much money on batteries they do wear out after a while no matter how expensive they are.
    This is for everyone to deside. I like high quality and want to pay for it on some occasions.
    Last edited by Epsilon; 10-27-2012 at 07:13 AM.

  2. #32
    Flashaholic langham's Avatar
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    Default Re: CAUTION !! Misleading budget battery and lumen claims

    You can not seriously think that this data is relative to this discussion of useful data in a real world application. I have 2 XML-T6 leds mounted on 16mm copper heat sinks and they are better than the aluminum heat sinks by a factor of almost 20% at removing the heat from the led. This point I agree on, but the simple fact is that in a single 18650 host the ultimate heat removal process is radiation heat transfer from the body of the light to the atmospheric environment. This test used a large cooler that was regulated at 20C throughout the testing which made the test invalid for any normal flashlight due to the fact that the heat sink used convection types of heat transfer to remove heat from the heat sink. This is completely irrelevant, to the discussion of single 18650 host. My light with a copper heat sink and driven at 3A gets warm to the touch after less than a minute of operation and hot to the touch after only a couple of minutes due to the simple fact of radiation heat transfer from the body to the environment is several times less efficient than the conduction heat transfer from the heat sink to the body. The best heat transfer would actually be obtained by a high carbon content diamond copper board and that would cause the external temperature of the light to go up within seconds to a temperature that was high enough above ambient temperature to make the difference in temperature enough to make up for the difference in efficiency. Another issue would be that the more surface area for heat transfer the light has the more it would be able to make up for the difference in efficiencies. The only thing that having a better material for the heat sink will do is allow you to store more energy per gram of material used prior to the heat being removed by the only real heat sink which is the ambient environment. As far as short term goes, yeah sure you can make a really bright camera flash if you want to but if you mess around and accidentally leave it on or let the wrong person use it you are going to have an expensive paper weight. There are numbers about the different materials used vs the amount of energy they can store, it is irrelevant as well though unless you can ultimately remove the heat externally, which can only be done by either choosing a cold ambient temperature, raising the surface area of the body of the light, making the body out of copper (or some other material that has better thermal properties than aluminum) or by adding some sort of additional flow between the body of the light ( the heat source) and the ambient environment (the heat sink). I guess you could also change the ambient environment to a different material ie: water or some sort of solid, but that would make the light a dive light. The amount of heat dissipation for a given body is set, you can not adjust it short of changing the body in some mechanical form like adding heat dissipation fins and as the amount of watts of heat vs light dramatically goes up after 3A of input current as seen on the provided efficiency chart I do not know how you would account for this factor. Their is 62% more heat being generated based on these charts at 6.5A input vs 3A and that would be an excessive amount considering the thermal capabilities of a single 18650 host.

  3. #33
    Flashaholic Epsilon's Avatar
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    Default Re: CAUTION !! Misleading budget battery and lumen claims

    The graph of the XM-L is just an example of an application, showing that there are XM-L's which can be driven at above 5A. There will always be a loss in efficiency but that can be acceptable. I could have picked a CBT-90 @ 13.5A, but that is not a realistic application.

    You are absolutely correct for long term use. But please, look at my topic with temperature measurements before talking about the dissipation of heat. In short term use, there is no need to dissipate the heat of the LED to the environment, that is the point. There is enough mass in the body to suck up the heat for at least 5 minutes in my example. Which means there is more than enough room to up the power even to 6.5A for short bursts. I decided not to, but it certainly is possible.

    Getting rid of the heat in long runs will always be problem in small hosts. The best transfer you can get, is by holding the light in your hand. But also this is limited, I tried to do this with a 9A powered SST-90 in a Mag-D and couldn't stop it to get to hot to hold. But again, this is only for long term use.

  4. #34
    Flashaholic* Poppy's Avatar
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    Default Re: CAUTION !! Misleading budget battery and lumen claims

    Quote Originally Posted by navarrma View Post
    Is there any demonstrable test that can be used to test the capacity of our new batteries to know whether or not they are reused or just falsely advertised junk?
    bump...
    I'd like to know too.

    I'd like to buy some 18650s and would like to find some good buys, but if I get one and don't know how to test its capacity, I wouldn't know if it was a good buy, or that I paid less to get less.

  5. #35
    Flashaholic langham's Avatar
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    Default Re: CAUTION !! Misleading budget battery and lumen claims

    It is relatively simple you can just get on the internet and get the power density for the material used and then weigh the battery, subtract a few grams for the case and protection. That and there are actual battery capacity meters, best bet is to get someone with experience to tell you. The DX SKU: 26248 are very good and relatively accurate in the claimed capacity. I have bought 10 or so and they have all been good. The batteries I currently like the most are the Panasonic NCR18650B or the NCR18650A because of the large capacity and low price.

  6. #36

    Default Re: CAUTION !! Misleading budget battery and lumen claims

    I have searched but I have not found any one that tested the 18650 TrustFire 4000mAh found on eBay.
    I assume the mAh is much less then claimed and will not match eachother in specs therfore would not be suitable for a series device. But I still would love to see all the charts done up on them. Or does curiosity always kill the cat.

  7. #37
    Flashaholic langham's Avatar
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    Default Re: CAUTION !! Misleading budget battery and lumen claims

    Series would be fine parallel is the time in DC that you would have to worry about the V matching. That link goes to a pair of Panasonic 18650s and they are an extremely good battery.

  8. #38
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    Default Re: CAUTION !! When a battery label becomes meaningless

    Not sure if this has been posted yet, but i thought it could find a nice home here in Misleading.

    A location called taobao, is one location selling your favorite brand battery Wrappers/Label (only) to be able to stuff any cell in about any label
    http://item.taobao.com/item.htm?spm=...id=10193523421&
    like here for example you can wrap your batts in a popular panasonic wrapper.
    http://item.taobao.com/item.htm?spm=...id=12670817495&

    Just at the one location, they have many different wrappers for turning trash into treasure :-) You can even cap it off with some fake protection.
    This just shows how easy has become for some ConArtist to try and rip people off.
    Li-Ion or even ni-mh cells.
    How does that cell test? better question, what even is it.

    When a label becomes meaningless , a reliable trustworthy seller/distributer is the only hope left.

  9. #39

    Default Re: CAUTION !! When a battery label becomes meaningless

    Vidpro: there are so many scam alerts in the reviews for cells being sold on Amazon right now that it isn't freaking funny.

    Langham: I like it when you post a big fat chunk of text. The bigger the better, the way you write. You sound like you've got a great grasp on heat transfer and dissapation.

    ...and seriously: if a 4x increase in lumens only means a doubling in perceived brightness, what's with all the splitting hairs concerning an extra 4%-15% in brightness from overdriving the crap out of your electrical system? Just curious. Please discuss and debate.

    disclaimer: I've got a few overdriven lights myself.

  10. #40
    Flashaholic langham's Avatar
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    Default Re: CAUTION !! When a battery label becomes meaningless

    I know it seems like splitting hairs, but indeed a 12% increase is all you get with the new XM-L2 and that was enough to release an entire new series of light for some manufacturers. The big deal seems like to me it is just in the fact that people want to be able to say that they have the newest and brightest light regardless of its useful functions. I have never over-driven a light, but I do have a plan to build a handheld light that is smaller than the SR-90 and has a force-cooled Cree model emitter and I would simply calculate my turbo mode based on the maximum amount that I could cool the led to maintain temperature less than 100C. I think that people always want to get the best out of what is available at the current time. I have a modified TN-31 that I got during the Christmas deal, and I wouldn't have gotten one otherwise, that stock did not even compare to a very cheap $30 DX light that I got and modified. First the thermal properties are terrible, they actually mounted the copper heat sink to the anodized finish. This is completely unacceptable as it basically acts as a thermal barrier between the copper of the heat-sink and the body of the light. I do not understand over-driven lights that take things past the point of possible heat dissipation, because when researching all of the thermal properties of the led you will notice that the higher the temperature the less efficient the led becomes and the lower the efficiency the higher the temperature will be. This is going to cause 2 things first the high current will need higher Vf and that will most likely cause you to need a Boost driver or a higher V by placing more batteries in series, and using a buck driver to get to the lower, normal operating modes. This would cause some issues, the higher the supply voltage is greater than Vf for the led the lower the driver efficiency will be and that kind of defeats the purpose of the lower more efficient modes. There are a couple of options, you could design a light that has the sole purpose of being an over-driven single mode light. The other things you could do is to use 2 separate drivers and switch, or you could use PWM and a capacitor that would allow you to compensate for the poor PF that you would have. Most people don't care though, every time I see a new SST-90 light my engineering spirit weeps for our community. The constant reminder that it is capable of almost 3000lm if over-driven is obscene. These are driven at 9.0A and a total of 34W with a current density of 1A/mm2 and at 25C they can get 2750lm. How hard would that be for 34W of led power and 22C/W of resistance between the emitter and the case? Therefore you can say that unless your ambient temperature is 3C you will never be able to achieve these numbers, regardless of your build design. The spread sheet has some stuff that would say that you can if you were able to achieve some seriously amazing thermal efficiency, but I have my doubts, as well as the SR-90 not being anywhere near those numbers. I guess I am just bitter, but the only way I would over-drive an emitter is if I had somehow improved the thermal efficiency of the light to compensate for the extra waist heat that was being formed.

    argleargle: I should be pretty good at therm o-dynamics as I got my training from the US Navy while training to be a nuclear operator, and I don't really like to participate in discussions that are just simple one line answers I like to think about the answers I give.

  11. #41
    Flashaholic* uk_caver's Avatar
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    Default Re: CAUTION !! When a battery label becomes meaningless

    Quote Originally Posted by langham View Post
    I know it seems like splitting hairs, but indeed a 12% increase is all you get with the new XM-L2 and that was enough to release an entire new series of light for some manufacturers. The big deal seems like to me it is just in the fact that people want to be able to say that they have the newest and brightest light regardless of its useful functions.
    Indeed - hardly anyone would be able to tell the difference between two lights which had 12% difference in output even in good comparison conditions.
    Personally I haven't upgraded my own homebuilt caving lights unless I could get at least 50% more output out of them, even when the only cost was new LEDs and a small amount of time.

    But if I'm selling something, being able to up the lumen output by 12% for the same runtime might make it more attractive to some people, especially if it pushes it past some arbitrary numeric threshold, because a lot of people seem to gravitate to raw lumen figures even when comparing two lights with significantly different beamshape options or user interfaces.

  12. #42
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    Default Re: CAUTION !! When a battery label becomes meaningless

    I unwrapped two of my Ultrafire 18650's (unused, due to their misleading specs: 4000mah! The site I bought them from two years ago when I wasn't familiar with this type of batteries now has some of these http://lanterne-profesionale.com/bat...-6800-mah.html )

    So what was inside:
    One of them a Panasonic 2200mah cell, probably from a laptop, the soldering marks still visible.
    And the other a 1100mah 3.2V cell.
    Both were selled as protected.




    So what could happen if you try to charge to 4,2V a battery that has a maximum charge voltage of 3,65V? Isn't it a potential bomb?
    Last edited by florinache; 02-17-2013 at 10:59 AM.

  13. #43

    Default Re: CAUTION !! When a battery label becomes meaningless

    Quote Originally Posted by argleargle View Post
    Vidpro: there are so many scam alerts in the reviews for cells being sold on Amazon right now that it isn't freaking funny.

    Langham: I like it when you post a big fat chunk of text. The bigger the better, the way you write. You sound like you've got a great grasp on heat transfer and dissapation.

    ...and seriously: if a 4x increase in lumens only means a doubling in perceived brightness, what's with all the splitting hairs concerning an extra 4%-15% in brightness from overdriving the crap out of your electrical system? Just curious. Please discuss and debate.

    disclaimer: I've got a few overdriven lights myself.
    I became interested in high powered LED lights and batteries due to having to hike in the dark with my dogs and found out the hard way on these Chinese knockoff brands, glad to see a warning posted at the top here. I bought several 18650 battery sets to power the lights I bought and on the 3x Cree T6 "3800 lumen" Trustfire (692x3= approx 2100 max according to Cree website @2A) got a 32 min runtime on high with "Ultrafire 3000mAh" battery set, 17mins with my "5000 mAh" blue batteries... less than acceptable for my 2hr+ hikes thats for certain, and worse, they started to degrade after recharging. I tried several purchases, and all had similar poor results. So, after doing some research I found the Orbtronic 3400mAh protected cells and bought those: what a world of difference! 1hr 21min for 2 3400 mAh vs 32min "3000 mAh" and 17 min "5000 mAh" garbage. With the above functionality, I can unscientifically but very much more accurately rate the "5000 mAh" China batteries as approx 710 mAh and "Ultrafire 3000 mAh" as approx 1340 mAh BEFORE they degraded further! Its hard to believe the extremely sub par quality and/or recycled crap from China that is now being sold on Amazon. I complained to a seller of the "5000 mAh" and of course only got the "thats what the factory labeled them" excuse, he offered me more free crappy "5000 mAh" (710 mAh) garbage and went right on with the listings. People should be rightly warned on any Chinese battery purchase beforehand!

  14. #44

    Default Re: CAUTION !! Misleading budget battery and lumen claims

    I ordered several 18650, 26oomAh batteries on line. They were shipped from Singapore. They say they are protected but when I removed the plastic jacket, all I saw was a metal can , no return strip. Could these still be a protected type? Thanks





    Quote Originally Posted by 51coronet View Post
    Budget 18650 batteries are usualy in the neighborhood of 2000mah give or take. Some are also reused rewrapped laptop batteries sold as new. This applies to ultrafire and trustfire branded batteries as well as some others. The 2 brands mentioned are the most likely to have false claims.

    Currently there is no commercialy available 18650 that is over 3100mah. The true 3100mah 18650 cells are pricey compared to their counterparts with false claims. (3100mah last time I checked)

    Cree is an LED manufacturer. Their LED's are installed in the most common budget flashlights you will see. Cree has datasheets available online for you to look at the real specs of the LED.

    The majority of current budget lights are installed with a cree XML-t6. This LED is rated at 1000 lumens when properly driven. When you see a flashlight seller that advertises more than 1000 lumens with a single XML-t6 you are being lied to. Also note this amount of light will not make it out the front lens of the flashlight. Consider heat, driver, budget battery, poorly designed host for heatsinking, budget lens.

    I hope this will help some people make an educated purchase on their next budget light. I like the budget lights but also believe you usualy get what you pay... not always.

  15. #45
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    Default Re: CAUTION !! Misleading budget battery and lumen claims

    Quote Originally Posted by chucka View Post
    I ordered several 18650, 26oomAh batteries on line. They were shipped from Singapore. They say they are protected but when I removed the plastic jacket, all I saw was a metal can , no return strip. Could these still be a protected type? Thanks
    There exist some 18650 where the protection is placed at the + pole, they will not have a strip.
    My website with battery and charger information: lygte-info.
    More than 1000 reviews of batteries, charges and other stuff.
    Compare 18650 LiIon batteries or smaller (RCR123, 16340, 14500, 10450) LiIon batteries.

  16. #46
    Flashaholic* xevious's Avatar
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    Default Re: CAUTION !! Misleading budget battery and lumen claims

    Given all of these glaring problems found with Ultrafire, Trustfire, and WhateverFire batteries that aim for the budget conscious battery buyer, I'm feeling like there should be a prominent warning on the top of this sub forum. Basically state something like this:

    "After numerous deliberate tests and consumer reported issues, it is becoming glaringly evident that the cheaper Chinese battery cells being sold under names like "Trustfire, Ultrafire, Spiderfire, etc." are often labeled with deceitful claims. For example, a 3100mAh labeled cell turning out to be 2200mAh or even less. In addition, they have been known to have extremely short lifespans and even protected cells have been known to fail, exploding during a charging cycle. Read on for specific instances of these issues..."

    I was seeing an above average number of positive reviews on the Ultrafire 3.7v 18650 3000mAh cells. But if a brand is so outright guilty of putting junk cells wrapped in plastic labeled with specs that basically lie, how can they be trusted for anything? How many people have posted positive reviews only from their first usage? One of the more prevalent negatives is that these budget Chinese cells don't last. If you tally up the cost on replacement and sub par performance, you end up spending more than you would with quality cells from the start.
    Last edited by xevious; 03-19-2013 at 01:24 PM.
    Lights in my rotation: Nitecore EA4 | Surefire U2 | Novatac EDC-120P | Olight M20 R5 | Fenix P3D-Q5, PD30. L0D-Q4 | Regal WT1 | Pila GL3/D26

  17. #47
    Flashaholic* PapaLumen's Avatar
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    Default Re: CAUTION !! Misleading budget battery and lumen claims

    OP might want to alter first post to mention top cells are now panny 3400mah.

  18. #48

    Grinser2 Re: CAUTION !! Misleading budget battery and lumen claims

    I've personally harvested quite a few 18650 type batteries from laptop battery packs to use for other purposes, and so far the highest listed capacity that I've found is from a Toshiba pack claiming 14.8 volts at 6450 mah. There are four battery groups in series with 3 batteries in parallel in each group which means that each battery should be 3.7V at 2150 mah. As I said, this is the highest milli-amp hour claim that I've found so far and have never seen a 3000 mah battery listed.

  19. #49
    Flashaholic langham's Avatar
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    Default Re: CAUTION !! Misleading budget battery and lumen claims

    I have never seen the 3400 mAh batteries in a laptop the largest I have seen is 2200 mAh cells, but I have seen them in 3 series 4 parallel arrangement that made the total capacity a lot higher.

  20. #50

    Default Re: CAUTION !! Misleading budget battery and lumen claims

    Now, I HAVE found that most laptop packs contain 12 cells of the 18650 type but vary widely in the amp hour claims. Some cells are stamped 18650A, some as 18650H, and others as 18650GR, so I suppose that there are a lot of 18650 types with different amp hour capacity. In looking at two packs right now, both have 12 cells, one with 18650A cells claims 6.0 amp hours and the other with 18650GR cells claims 6.45 amp hours. So far, I've found that the GR type has the highest amp hour rating claimed on the outer battery pack case.

  21. #51
    Flashaholic langham's Avatar
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    Default Re: CAUTION !! Misleading budget battery and lumen claims

    Typically you can look up the individual cell and find out who manufactured them and then get the data sheet for them. I had one that was LG and one that was Samsung, both 2200mAh and the LG was better as individual cells.

  22. #52

    Default Re: CAUTION !! Misleading budget battery and lumen claims

    Quote Originally Posted by xevious View Post
    One of the more prevalent negatives is that these budget Chinese cells don't last. If you tally up the cost on replacement and sub par performance, you end up spending more than you would with quality cells from the start.
    How long do they last ? Do you have data for each brand and their longevity?

  23. #53

    Default Re: CAUTION !! Misleading budget battery and lumen claims

    In regards to batteries, I saw the claim "you get what you pay for". Exactly what does this mean? Do we have a published list of "acceptable" prices? For example: On eBay, I saw a pair (2) for Panasonic NCR18650B (3400mAh) for around $20. The same vendor sold a "single" (1) Nitecore NL189 (also 3400mAh) for about $22. You can get a pair (2) of Trustfire "4000mAh" 18650 with charger for $8 on Amazon!! I understand the Trustfires are way out of range, but what about the others?

    A would like to see a list of "acceptable" prices for 14500's and RCR123's (including capacity).

    Bruce

  24. #54
    Flashaholic langham's Avatar
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    Default Re: CAUTION !! Misleading budget battery and lumen claims

    You have to use a reputable site to know the price range that they use, then you have to look at the cell that the other site is using and find out if it is what it claims to be. The reason that single 3400mAh cell is the same price as 2 of the effectively exact same cell is that one doesn't have a protection circuit built in. That means that you could kill a $10 cell by over charging/discharging. The Trustfire isn't worth $.10, any battery that clearly overstates the capacity is not worth your time. The way I did it is at first I bought some of the best batteries on the market (ie IMR 18650s) for $15 each. Then I bought some of the cheapest (get on DX and arrange all of the 18650 cells from cheapest to most expensive), and then I bought some that were halfway between. I found that the ones that were about $5 per cell were of the best quality for the price. As far as capacity per dollar goes, that is why this thread exists, because people are frustrated with cheap cells that claim more than they actually put out. The Panasonic NCR18650B should be around 10-11 dollars without protections and 15-20 with protection, I have seen that much range. I use the SKU: 26248 for all of my cheap 18650 flashlights and the Panasonic NCR18650B unprotected for all of my nice lights. I am not an normal user of the other cells. I got my Panasonic cells for 10.50 each, I hope this helps. I would be willing to help further with more specific questions if needed. If you have any complaints about specific cells be sure to post them.

  25. #55
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    Default Re: CAUTION !! Misleading budget battery and lumen claims

    What is the best 18650 for my Nitecore SRT7 ?
    Nitecore has a 3400mAH (189) which is made in China. Not cheap
    Orbtronic 3400mAH which is supposed to be a Panasonic made in Japan. Others??

    I would like to get a good reliable output and protected battery. Any ideas would be appreciated.

    I was also looking at a XTAR VP1 battery charger.
    What do you guys think?

    I need some help. This stuff gets confusing. Thanks
    Regards, Walt

  26. #56
    Flashaholic langham's Avatar
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    Default Re: CAUTION !! Misleading budget battery and lumen claims

    They virtually all have the same cell, it just depends on the circuitry. You should get an IMR cell for it.

  27. #57
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    Default Re: CAUTION !! Misleading budget battery and lumen claims

    As I am looking to purchase some 18650s with a charger, this thread has really made me reconsider my choices.
    There are lots of 3800 /4000/ 4200 /5000mah batteries out there!
    Help me! Are all these potential fakes?

    http://www.ebay.com/itm/2-X-UltraFir...item461575c8f4
    http://www.ebay.com/itm/111159029411...84.m1438.l2649
    http://www.ebay.com/itm/300903446482...84.m1438.l2649

  28. #58
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    Default Re: CAUTION !! Misleading budget battery and lumen claims

    What's an IMR cell. As you can see, I'm new at these 18650's.
    Thanks
    Regards, Walt

  29. #59
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    Default Re: CAUTION !! Misleading budget battery and lumen claims

    Quote Originally Posted by sav View Post
    There are lots of 3800 /4000/ 4200 /5000mah batteries out there!
    Help me! Are all these potential fakes?
    They're essentially guaranteed not to have the claimed capacity.

  30. #60
    Flashaholic langham's Avatar
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    Default Re: CAUTION !! Misleading budget battery and lumen claims

    IMR cells have lower than normal internal resistance which allows them to send more current and have higher efficiency than a normal cell. You will get more Vf for a given battery configuration because they do not have as large of a voltage drop across the cell. With a cheap cell I can get about 2A and with the same flashlight an IMR cell that is pretty old will give me 2.6A so as you can see, that is a large difference. Just do a google for IMR 18650, you could also look at 18700 batteries if they will fit in your light.

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