# How dangerous are 18650 battery packs? (also how dangerous are ebay ones from China?)



## whitedragon101 (Mar 31, 2009)

I have been looking for a powerful bike light/ headlamp to light up the trail as much as possible. I found this 3800 lumen (probably produces less I know, hopefully 2800-3000) Cree XM-L T6 (x3) light for both on bike and on head use :

http://www.amazon.co.uk/Bicycle-Head...0852683&sr=1-1

It has good reviews and is sold all over the place to the UK market (from HK and China). However it says nothing about the batteries or charger other than 6000mah. (I have assumed its 4 or 6 18650 cells)

However I have just seen the stories of exploding lights and batteries (using multiple 18650 batteries) on the candlepower forum. I have also read the 18650 candlepower forum safety guide which recommends going to what I think are extreme lengths such as testing cells with a multimeter before and after every charge and charging cells inside a thick metal box. It says if you are not proficient in battery electronics and managing these 18650 li-ion cells then do not use them.

I would be most grateful if someone could take a stab at answering the following :
1)
How likely is it that this 18650 powerpack and light combo will catch fire or blow up on my back or head? Is it too risky?
2)
How great is the danger of 18650 battery packs? And how dangerous are these Chinese import ones as per my link? I don't want it blowing up on my head or in my face (or my friends who also want to buy it).

Many thanks


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## fahza29er (Jun 26, 2012)

Why even risk it? Just buy a decent set of lights and stop being so cheap, some things just are not worth saving money on. If I am bombing through the woods in the dark the last thing I want to cheap out on is my lights. If its 46 bucks while other are 300 for the same thing you got to ask yourself why? yeah some is markup but I havent heard of any top brands exploding or catching fire.
I am in the same boat looking for lights and I think I ma getting the serfas lights, gonig to cost me about 500 for bar and helmet lights but they are local, can have them tomorrow, warranty is taken care of here and the shop I deal with recomends them plus he uses them himself. Do what you like but its your skin,eyes face if it blows up or fails when you need it most and eat a tree.


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## mtbRevolution (Aug 10, 2012)

whitedragon101 said:


> 1) How likely is it that this 18650 powerpack and light combo will catch fire or blow up on my back or head? Is it too risky?


 Answer is 99.99% NO, but anything is possible. There is a video of an [alleged]iPhone catching fire in a back pocket in Finland. Was it an iPhone in the first place? Problem with social media is it's hard to disprove something that's posted online. People tend to believe what they see and read online even though there are no actual close up shots of these defective products turning pear shape on their own. My take on that video is, the phone was already overcharged before the driver got out of the van. The battery was well on thermal runaway. Product defect or done on purpose? YouTube is littered with overcharging Li-ion and LiPo including shootin 'em up with guns.



whitedragon101 said:


> 2) How great is the danger of 18650 battery packs? And how dangerous are these Chinese import ones as per my link? I don't want it blowing up on my head or in my face (or my friends who also want to buy it).


 Chances of it just blowing up is almost zero. One thing is certain. Majority are not tested in any way. With runtime results all over the dartboard except bullseye it would be interesting to read what's on the Material Safety Data Sheet (MSDS) before they were loaded onto a plane.

Battery University is a great resource. This article should answer your questions.

[Additional Info - most documented Lithium fires are from deliberate or faulty product during charging - more former than latter. In light of later comments I have to qualify - there IS an increased chance of fire and explosion to back and head if batteries are charged IN backpack strapped to your back - how and why would anyone risk that?]


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## JohnJ80 (Oct 10, 2008)

fahza29er said:


> Why even risk it? Just buy a decent set of lights and stop being so cheap, some things just are not worth saving money on. If I am bombing through the woods in the dark the last thing I want to cheap out on is my lights. If its 46 bucks while other are 300 for the same thing you got to ask yourself why? yeah some is markup but I havent heard of any top brands exploding or catching fire.
> I am in the same boat looking for lights and I think I ma getting the serfas lights, gonig to cost me about 500 for bar and helmet lights but they are local, can have them tomorrow, warranty is taken care of here and the shop I deal with recomends them plus he uses them himself. Do what you like but its your skin,eyes face if it blows up or fails when you need it most and eat a tree.


Pretty much what I'd say.

The marginal difference in cost when you've had an accident does not seem like much.

Here's the other guidance I'd give you - Chinese lights are notorious for having seriously overhyped lumen numbers - that's probably the theoretical output from the LEDs and not anywhere close to what comes out the front of the lens. There are no real free lunches in this and I'd use the light shoot out here on MTBR to figure out what you want.

Finally, the difference in battery packs is largely a function of (1) the quality of the battery, (2) the quality of the protection circuit (if there is even one), and (3) the quality of the charger.

On the cells, there are just several good battery manufacturers (Samsung, Sanyo have the majority market share at the top) and the rest are pretty much downscale and down quality from there meaning the longevity and purity of the cell (related to it's self discharge rate and it's long term reliability and lifetime). So, here again, you get what you pay for.

Some batteries have a protection circuit and some don't. When I used to sell this stuff in engineering applications, we spent a lot of time with the battery manufacturers coming up with a protection circuit that fit the application for discharge, safety and charging. There is a cost to this, obviously, and it matters given the flammability of Li-ion cells.

Finally the charger that is supplied is hugely important to the proper charging of the battery and getting the full capacity realized. THere are a LOT of chargers out there from really bad/marginally safe ones to some really good ones. Again, cost has a lot to do with it without going into a lot of detail.

I'd bet that those lights, for $46, are no where near 2000 lumens out and certainly not 3000. THere are not many 2000 lumen lights out that are any good and they all are pretty expensive and I think there is only one 3000 lumen light (Lupine Betty) but I could be wrong on that. THere are a lot more 1000 lumen lights out there and my bet is that this is where those lights come out (that or less) and more likely 800. At 1000 lumens, there is less heat and it's less of an issue to deal with but at 2000 lumens, it gets significant and if you don't want the light to self destruct, you pretty much wind up with control circuitry to manage the thermal characteristics. On the mechanical side, it takes some heat sinking to make it work right. If you don't do this stuff correctly, the reliability is going to be compromised.

So, I'd take that and evaluate where you are with this. Maybe it's worth the $46 to take a flyer at it. But it could just as easily be a waste of money if this stuff doesn't last. You also are probably not getting a 2000 lumen light out of it either and more likely a 1000 lumen light or less.

As for the chance for fire - probably low, but if it does catch fire, the potential for catastrophe is high. There was a highly thought of retailer here (geoman) who was an importer of Magicshine in the early days. There were several instances of batteries that caught fire charging resulting in even some damage to homes. Geoman then was pretty much wiped out by having to recall the batteries and replace them at their own expense since Magicshine wouldn't stand behind them. So, if you do have a problem, there is always the issue of getting right with the manufacturer.

J.


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## whitedragon101 (Mar 31, 2009)

How about a middle ground option? Something more expensive but not quite Lupine/ L&M expensive (love their lights). There seem to be two of these Chinese light makers who have pushed into the mainstream and become brands. These are :

Fluxient
Magicshine

Fluxient was tested here (video link below) by Mtbr and they said : "beautiful head unit", "I like it because the deeper the fins the more heat-sinking and the more air can pass through", they called the 3XM-L U2 "the big bad boy" and described the light output as "aaw yeah." The actual measured output by mtbr was 1500lumen. Only the big (and expensive) boys such as LM Seca and Lupine Wilma etc scored higher. The new version the 3XM-L2 U2 is 20% more powerful (cree XM-L2 LEDs have 20% more output per watt than XM-L and run 30% cooler which should increase output as output dropps with heat) so hopefully around 1900 lumens or so which equals the LM Seca for output.
2013 Fluxient Lights - YouTube

Magicshine seem to have history in the beginning of batteries going bang but now MBUK list the MJ-880 as light of the year.
https://magazine.bikeradar.com/files/2012/09/comp2.jpg

My preference is for the new Fluxient light the 3XM-L2 U2 
2014 3600 Lumen Fluxient 3x XM-L2 bike lightt -brightest on the market? | eBay

Not sure about either the Magicshine or the Fluxient batteries though. There just doesn't seem to be any info on them and they seem to be the dangerous part. But maybe as a backup I may see if I can buy the light only and use an OpenLightSystems battery. They are german made use panasonic cells (panasonic bought sanyo) and are tested for just about everything before they ship. Geoman seems to rate them very highly:
https://forums.mtbr.com/lights-night-riding/open-light-systems-688984.html
Open Light Systems Corporation | Lithium Ion Batteries and Accessories for Lupine, Sigma, MyTinySun, MagicShine, BikeRay, and DealExtreme Lamp Heads


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## Vancbiker (May 25, 2005)

A couple years ago when the dangers of charging Li-ion batteries was discussed quite extensively, I started a thread......

http://forums.mtbr.com/lights-diy-do-yourself/more-batteries-691248.html

Carry a cellphone in your pocket? Most have a Li-ion battery in them. Most are made in China. See where this is going? I'd be more concerned about the one in my pocket than the one strapped to my bike, or tucked in my hydration pack


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## JohnJ80 (Oct 10, 2008)

I don't often charge my cell phone in my pocket (although perhaps you may) and it's not likely to be a dead short when it's mounted in the phone. Cell phone mfgs also typically are not short on technical expertise either so they tend to get it right. Charging is the issue and the protection circuit in the battery both of which are more likely to be suspect on a cheapo Chinese product than with a cell phone. 


J.


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## Vancbiker (May 25, 2005)

As with the phone, few of us charge light batteries while in the pocket, hydration pack, or attached to the helmet while wearing it. Same exposure IMO. Differences in the quality of devices is almost a certainty. My position, based on the tiny number of documented bike light battery "incidents", is that charging them is no more hazardous than charging other Li-ion equipped devices. My linked post is simply a tongue-in-cheek attempt to illustrate my position.


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## fightnut (Jul 5, 2007)

I charge and store my batteries in fireproof bags.

I get them on ebay for about $5-6.


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## mtbRevolution (Aug 10, 2012)

A Lithium Ion or Lithium Polymer pack should never be warm during charging. If it's really warm to hot, disconnect from charger immediately. If the pack begins to bloat it may be on thermal runaway. If so venting and flaming will occur when current is still applied. There is a considerable time gap between bloating, venting and flaming. You may have time move it to an open space. If you own one of these suspect batteries you should charge them in an old cleaned out paint can with lid.

We can do away with these extra fire precautions with higher quality tested and approved batteries and chargers. Lithium batteries should be UL1642 certified. If a manufacturer does not specify the brand and model of lithium cells used in their packs it's probably because they not worth mentioning. A brand will have lower or higher end models so don't just judge it from the brand name.

Many disregard quality difference between mains chargers and protection circuits in batteries. Most countries have strict compliance regimes when it comes to chargers. These certifications may include CE, RoHS, AS/NZS, TÜV etc. Untested 50¢ electronic boards in generic chargers hooked to 110-240VAC mains power should concern us. This device is also used to charge a potentially flammable battery pack.


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## znomit (Dec 27, 2007)

mtbRevolution said:


> Many disregard quality difference between mains chargers and protection circuits in batteries. Most countries have strict compliance regimes when it comes to chargers. These certifications may include CE, RoHS, AS/NZS, TÜV etc. Untested 50¢ electronic boards in generic chargers hooked to 110-240VAC mains power should concern us. This device is also used to charge a potentially flammable battery pack.


Yeah I think the chargers are a bigger worry. My Magicshine 838 charger overheated and was pretty sketchy inside ... really poor solder connection to the mains pins. :madmax:

Resellers can purchase compliance stickers from china too. :nono:


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## mtbRevolution (Aug 10, 2012)

znomit said:


> Yeah I think the chargers are a bigger worry. My Magicshine 838 charger overheated and was pretty sketchy inside ... really poor solder connection to the mains pins. :madmax:
> 
> Resellers can purchase compliance stickers from china too. :nono:


MS chargers weren't compliant in AU and NZ over a year ago. They are now. We use other compliant chargers when the MS ones weren't back then. As you know AU and NZ have the same Trans-Tasman compliance regime called E3. Now, we are not talking about those stickers on cheap chargers that copy logos and official looking stamps. Chargers have to be bona fide compliant. They must be registered and listed. To get there they have been tested by accredited laboratories. In our instance chargers must be C-Tick approved, AS/NZS multiple parts and MEPS - energy efficiency approved. It is technically illegal to use unapproved chargers and using them may also affect insurance claims.


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## kingsqueak (Jul 21, 2013)

I have a pile of 18650 batts. I use them daily with an e-cig. I've had no troubles over the last 3+ yrs of daily use and charge cycles. That said, they have a lot more energy than most realize so if they do short out, it can be bad. 

A bit of common sense and caution are due. I make sure the chargers aren't sitting in a pile of clutter nearby. If I'm travelling I ensure the batts are not in the device and can't be shorted out by anything inside a backpack or pocket etc. 

This should apply to most any battery packs but LiIon have a very fast discharge rate thus the added attention.


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