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  1. #1
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    Exploding Battery pack - CREE XM-LT6 LED Bicycle Light

    Bought a CREE XM-LT6 LED Bicycle Light on eBay from Hong Kong about a month back, used it about 6 times, i estimate i charged it 3 times, then on the 4th charge the Battery pack exploded, violently.

    It was being charged at the other end of my house in a spare room where i keep my biking gear. They had been on charge for about 2 hours when i heard 4 loud bangs, but to begin with I thought they were coming from outside. I then went through to the spare room to check and found that the Battery's had exploded all over the room causing dents in the wall, smashing the bar adaptor they were plugged into and causing burns all over the carpet. From the look of the carpet burns i was luck not to have had a serious house fire.

    As you will see from the pictures below there is very little left of the battery's or casing....

    I know these Cree lights are often sold under various names, and are fairly popular due to there decent brightness and low price, a friend has exactly the same pack but his is called the SSC P7 or something...


    Just thought i would give anyone else who has this pack or similar a heads-up..
    Attached Thumbnails Attached Thumbnails Exploding Battery pack - CREE XM-LT6 LED Bicycle Light-cree_xm-lt6_led_rechargeable_bicycle_light_and_headlight.jpg  

    Exploding Battery pack - CREE XM-LT6 LED Bicycle Light-photo-1-.jpg  

    Exploding Battery pack - CREE XM-LT6 LED Bicycle Light-photo-2-.jpg  

    Exploding Battery pack - CREE XM-LT6 LED Bicycle Light-photo-4-.jpg  


  2. #2
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    A lot of people are buying cheap clone light sets off of ebay. It's a well known fact that a lot of these batteries being sold are built with cells that were rejected by the more elite brand companies. Usually this means you just get a crap battery that has less capacity. Some of the rejected cells could have the dreaded "internal soft shorts". These are internal short-circuits within the cell material. If they are bad enough the battery can go into "thermal runaway". When this happens none of the protection devices built into the battery or external circuit protection can stop the cell from exploding. It only takes one cell to go bad. When that happens a chain reaction can occur as each cell gets exposed to the heat of the other bad cell.

    For the record an otherwise good cell could develop a "soft short" as well if the battery sustained a big enough impact. It could also happen if the charger malfunctioned and tried to charge the battery beyond it's designed limit.

    As it stands you probably don't know what really caused this to happen as it could have been any of the possibilities I mentioned. You should report the incidence to the Consumer Product Safety Commission. We need to get these "bad batteries" out of the market place. I'm not dissing Li-ion technology per say, I'm dissing people who are selling products that they know are using materials that have been previously known to be "UNSAFE".

    A poor product is one thing but the marketing of a dangerous product is something that needs to be stopped. A word of warning to anyone who bought an ebay bike light with battery....charge the battery in a safe place and preferably in a fire-proof container. Monitor the battery while being charged and make sure it is not over-heating. Never leave the battery unattended while charging. Remove from the charger when the battery is charged.

  3. #3
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    Caution;  Merge;  Workers Ahead!

    Holy Razor's Edge Batman what a close shave!
    I'm glad that no one got hurt & and damage was minimal.
    Thank God the pack wasn't strapped to your CF frame.

    Thanks for reporting this.
    It looks like most of the generic packs out there with the blue heat shrink jackets over the 18650. Hard to say what exactly caused the catastrophic malfunction. To be safe I'd discard the charger too.

    Like Cat-man-do recommends, I'm going to get a LiPo Fireproof bag for extra precaution.
    12 LiPo Guard Fireproof Bag - $5.95 : EP Buddy, We Power Your RC Hobbies!

    Be safe everyone.
    Last edited by spartacus001; 02-04-2013 at 04:53 AM.

  4. #4
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    Wow. Just jumping into this clone market have 3 Chinese batteries....that is scary stuff.
    Thanks for the link Sparacus.

    And these batteries.....can they explode like that while not on the charger? Say..I have the thing at the recommended middle capacity charge and am storing it? ( I don't use lights at all in the summer...just spring ,winter and fall.

    Also...what about charging these batteries outside in the cold? Any forseeable problem? Running an outlet strip outside for a few hours to charge means I don't have to worry about it.
    Last edited by the mayor; 02-04-2013 at 06:11 AM.

  5. #5
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    First i'd like to say i'm glad you and the other members of your household are ok, and that you all still have a house to sleep in tonight. I do have to say though that my only surprise is that we havent hered about another incident like this sooner with those cheep ebay systems. As the others mentioned, charge in a protective battery bag and dont leave unattended.

  6. #6
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    potentially scary stuff. Cat man's advice is sound. Luck of the draw with these batteries, with respect to safety. Glad no more damage was done to you, your home, or family. It is also pretty standard that the batteries included with these lights are just garbage, and don't live up to their specs at all.

    Having a background in r/c hobby, I decided to convert some of my LiPo's for use with the MTB lights. I feel they are safer as you know what you are buying, generally. In the process of disassembling the eBay battery packs and seeing the hodge-podge solder jobs, and other indications of very low quality and potentially dangerous materials, I am very wary of using any of those batteries any more. I remove and re-use the PCB, then store/throw away the ebay batteries safely.

    And, when charging the LiPo's I also use the LiPo bag and place the batteries on non-flammable surfaces, and away from flammable/explosive materials.

  7. #7
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    I had been charging them in the garage but I considered the potential damage to cars, people and risk of fire.

    I live up here in Canada so I didn't want to deal with the additional complication of sudden condensation when I transfer the batteries from the cold to a warm environment.

    Until my LiPo fire bags arrive I'll be charging my batteries a metal tool box in the basement.
    Last edited by spartacus001; 02-04-2013 at 11:56 AM.

  8. #8
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    Good thought on condensation.

    FYI.....I had a laptop battery explode about 10 years ago. HP took care of it very quickly.

    And yeah ...I guess it could POSSIBLY happen more with these cheap batteries.
    But there has to be a butt load of these out there.....and I'd think that every forum would be full of horror stories...even fake and over exaggerated....if there were problems. When the whole Geoman/ MS thing happened...I only saw 1 picture of a closet that had damage ( I may have missed more??)

  9. #9
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    Quote Originally Posted by the mayor View Post
    .....And yeah ...I guess it could POSSIBLY happen more with these cheap batteries.
    But there has to be a butt load of these out there.....and I'd think that every forum would be full of horror stories...even fake and over exaggerated....if there were problems. When the whole Geoman/ MS thing happened...I only saw 1 picture of a closet that had damage ( I may have missed more??)
    Considering the number of these batteries out there floating around it really is a wonder it doesn't happen more often.

    If you have a way to monitor the charging safely that would be the best thing you can do. I have thermal monitoring but the stuff I have doesn't include an alarm. Having a thermal alarm would warn you if the battery was going into thermal runaway.

    Keep in mind the catastrophic failure rate of Li-ion batteries is very low. That is because the better places that make batteries put the cells through serious quality control before using them to build battery packs. The problem is the discarded cells are picked up and used by people who have the idea that they can still be used in the construction of cheap power sources. They do this thinking that the "cheap consumer goods" market is off of every ones radar. Unfortunately this fact is what helps give Li-ion technology a "black eye"

  10. #10
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    I've been wondering when this would happen/get reported.

    Cheap batteries, and cheap chargers are a disaster waiting to happen.

    Glad you were home, no one was in the room, and nothing major happened.

  11. #11
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    Holy cow! After the Geoman battery recall, I bought some used metal ammo cans and store and charge my batteries in them. Never used a Lipo pouch, but they are supposed to work well. In one of my ammo cans I have 4 batteries in it though so if one goes up the others will likely be lost too, so I think I will pick up some Lipo bags to separate the batts from each other while they are all in one ammo can. That way if one goes up hopefully the others will not. Thanks for posting this chick0 as it reminds us to be safe when charging and storing our batteries.

  12. #12
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    sorry to see this happen and glad that you're ok!

    In case someone sees this post and it happens to them VENT THE ROOM AND LEAVE THE HOUSE FOR SEVERAL HOURS. Exploding li-ion batteries can release hydrogen fluoride gas which is incredibly nasty stuff and can cause permanent lung damage.

  13. #13
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    Quote Originally Posted by mattthemuppet View Post
    sorry to see this happen and glad that you're ok!

    In case someone sees this post and it happens to them VENT THE ROOM AND LEAVE THE HOUSE FOR SEVERAL HOURS. Exploding li-ion batteries can release hydrogen fluoride gas which is incredibly nasty stuff and can cause permanent lung damage.
    I can back Matthemuppet up on this, the spare room and in fact the whole house smelt horrendously bad for more then 2 days after, even with the rooms being continuously ventilated..

  14. #14
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    Quote Originally Posted by mattthemuppet View Post
    sorry to see this happen and glad that you're ok!

    In case someone sees this post and it happens to them VENT THE ROOM AND LEAVE THE HOUSE FOR SEVERAL HOURS. Exploding li-ion batteries can release hydrogen fluoride gas which is incredibly nasty stuff and can cause permanent lung damage.
    Glad you mentioned this Matt. Not the kind of thing one thinks about when something like this happens. Time for me to search out a thermal monitor with alarm. Maybe something like this...

  15. #15
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    How much does the temp of these things go up before they blow?

    And I asked about chargers before....but is there a charger available that shows details like current charge, etc...and may give details on possible problems? I have a Sears charger that claims to have a diagnostic mode that will not charge the battery if it thinks there is something wrong.

  16. #16
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    With the pack disassembled I've been charging the individual cells with a smart charger. I use a multimeter to record the history of all my cells.
    The guys over on CPF really like ver 4 of this smart charger.

    Here is an excellent review of the Nitecore Intellicharger from CPF:
    Sysmax/Nitecore/Jetbeam i4 Intellicharger Review (V2): current/voltage comparisons

  17. #17
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    Thanks for the info. But this won't change my current charging habits just like it didn't with the MagicShines several years ago.

    Lithium Ion batteries will always have the potential for this kind of problem. Do you think Boeing is using "discarded cells" on the new 787? Same battery type, same issues. Just use common sense and even then you could have an issue.

    Such is life.
    How can anyone who's been riding as long as I have, be so slow???

  18. #18
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    Cat pretty much hit the nail on the head. The Li-Ion batteries were most likely of lower quality. The internal soft short are a know issue where the cells have latent failures. If this was the root cause here you most likely will not know.

    Would try to replace the pack with a Lithium Polymer pack. The initial cost for a Li-po is a little higher but the total lifecycle cost is significantly lower.

  19. #19
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    Quote Originally Posted by Rock View Post
    Thanks for the info. But this won't change my current charging habits just like it didn't with the MagicShines several years ago.

    Lithium Ion batteries will always have the potential for this kind of problem. Do you think Boeing is using "discarded cells" on the new 787? Same battery type, same issues. Just use common sense and even then you could have an issue.

    Such is life.
    Yeah....I'm have to agree with you here.
    Time to take off the tin foil hat...and just use common sense.
    Like I said earlier....I had a new laptop battery blow years back.
    And I was going to buy a MS light when the whole battery FUBAR happened....so I held off. But looking back...I only saw 1 battery that caused the whole commotion.
    And with the butt load of clone batteries out there...this is the first I've seen that blew.

  20. #20
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    Quote Originally Posted by Rock View Post
    Thanks for the info. But this won't change my current charging habits just like it didn't with the MagicShines several years ago.

    Lithium Ion batteries will always have the potential for this kind of problem. Do you think Boeing is using "discarded cells" on the new 787? Same battery type, same issues. Just use common sense and even then you could have an issue.

    Such is life.
    Not Li-On in all cases, but it's my understand that many planes are designed so a run-away condition will melt through the bottom of a wing, and thus jettison the entire battery, before a disaster ... Ni-Cad's of the past = Almost always incorporated a melt the bottom out, into the aricraft design.

    The manufacturers of aircraft understand the problem, very well ... Once you reach the point, it's gonna blow.

  21. #21
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    Quote Originally Posted by the mayor View Post
    How much does the temp of these things go up before they blow?

    And I asked about chargers before....but is there a charger available that shows details like current charge, etc...and may give details on possible problems? I have a Sears charger that claims to have a diagnostic mode that will not charge the battery if it thinks there is something wrong.
    As far as how hot they get before they blow...I read about that somewhere but at the moment escapes me but I believe it is quite high.

    Li-ion batteries really don't get that hot when charging. If I was using a thermometer to monitor the battery during a charge I would start to worry if I began to see it go over 100F. If I see that happen I would immediately take the battery outside and then dispose of the battery properly.

    Sorry Mayor, I can't help with the fancy charger issue. Would be sweet though if a charger came with a built in thermal monitor. So we don't confuse people here, other battery chemistry can get quite warm when it charges but Li-ion is not one of them.

  22. #22
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    Exploding Battery pack - CREE XM-LT6 LED Bicycle Light

    It has been mentioned, I think in this thread and likely many others in the lights forum about using r/c hobby chargers. They aren't too expensive and offer all kinds of settings and info while charging. I use one for my r/c batts I've converted to bike light use, but have yet to hook one of these LI-ion batteries up to it. Not sure how it would work through the pcb circuit, probably fine, just wanted to research more before doing so. I have something like this... https://www.hobbyking.com/hobbyking/...ischarger.html

  23. #23
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    Crap. I bought a pair of these lights, and two of my friends each bought two sets.

    One of my friends owns a battery store. I'm gonna disassemble my stepson's packs and test his batteries and replace them if necessary with better quality cells.
    I like turtles

  24. #24
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    Glad the OP didn't have a fire.

    Had the same light. Too tempting when it claims 1200LM for $33.

    Died after one use. Sent it back. Amazon reviews were positive...

    Amazon.com: CREE XML XM-L T6 LED Bike Bicycle Light HeadLight HeadLamp 1200LM Red: Sports & Outdoors

  25. #25
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    Xtar has just released their newest VP1 smart charger featuring a digital display of the charging status.

    VP1

    Exploding Battery pack - CREE XM-LT6 LED Bicycle Light-vp1.jpg

    Quote Originally Posted by the mayor View Post
    How much does the temp of these things go up before they blow?

    And I asked about chargers before....but is there a charger available that shows details like current charge, etc...and may give details on possible problems? I have a Sears charger that claims to have a diagnostic mode that will not charge the battery if it thinks there is something wrong.
    Attached Thumbnails Attached Thumbnails Exploding Battery pack - CREE XM-LT6 LED Bicycle Light-53705055125506821952893.jpg  


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