Electric Danger of Lithium Ion 18650 - Battery Fires Exposed - Possible DIY Solution 

I'm an Electromechannical Engineering Technologist. I have designed many 18650 Lithium-ion Power packs for 6 years now. Did lots of research and tests on them.............and I have to tell you, I'M STILL SCARED OF THE DAMN THINGS!!!. I have seen the damage they have done to property, machines, People, laptops exploding at airports and business meetings...etc.

He talks about the dangers of 18650 batteries while taking a torch lighter to one.... great job buddy, really upping the safety factor there!

should have put the plastic ring back on there... Just saying...

Appreciate the informative nature of the video, although I'm sure you've heard this many times before this is NOT a design specific to the 18650. This is the design of almost all cylindrical cells for the last couple of decades. You can verify this by taking apart a standard household AA alkaline battery. It does seem kind of strange though with the lithium cells on the market now capable of delivering more than enough power to damage themselves and surrounding cells before discharging you'd think the design would have been improved by now.

Put one of these in the same pocket as your car keys and you may go to the emergency room or worse. Thanks for showing how easy it is to short out. I think disposing of the battery once the protection starts to wear away would be best for people using these in portable devices.

So glad someone else knows about this. I had a big Smok X Cube, which unfortunately uses 18650's and you need to get the fast discharge versions too. The big problem is that the X cube can't self charge, so you regularly have to remove the batteries and put them back in again. After 5 days of having one, I'd encountered what a big short was. The battery housing was so tight that it scraped off the protective ring of the battery and shorted them. This resulted in what I can only describe as a firework flying round my living room. I got burns to my hip which have left a scar and the living room needed to be redecorated. Back on real cigs again now. ahhhhh....much safer.

Good attempt at making the 18650 safer, but you should have re-installed the ring insulator before you used the heatshrink. Hopefully you can still accurately indentify the positive ends after you wrap them with shrink.

Great video. I thought the same thing about the entire barrel being negative. I am glad someone took the time to take one apart and show it. This video should be required viewing for anyone who is undertaking a DIY project using 18650's. Makes me rethink spring contact battery holders for these cells as well.

So now, how do you distinguish the positive and negative terminals? The scratching really isn't too much of an issue, the "dangerous" part is protected by the little plastic ring you removed. But I gotta say, the black does look a lot better :)

What got me is the title of the video claiming to make them safer, but in said video you dead short low-drain (probably ICR) to show the neg-pos thing. Even a quick dead short can cause venting. And, I think there is more danger potential with using a wrap that insulates the heat in the battery. If someone has enough know-how to make a battery pack, I am pretty sure they know about the positive and negative post and definitely know not to tamper with or remove the wrap. If the thicker heat shrink only fits *your* purpose, since you say you'll be using it in a go-kart with adequate airflow to keep them cool, I think the video should reflect that the wraps will work for situations like that, It's not making them safer for your audience if they're not using them in the same way.

So two main problems I saw with your video. the thick wire wrap you used does not properly let it dissipate heat. all batteries have a nominal operating temperature. different chemistries of batteries have different levels. if the battery stays at or above that threshold you risk permanently damaging the cell or it vents or catches fire. also you shouldn't have double wrapped it with your wrap and the original it came with. way more plastic to hold that heat. 2 you removed the plastic insulator ring. that ring is a thick piece of plastic designed that if the battery wrap were to be damaged, that thick tough ring should stop anything to lay across and short it out.

I was also naive thinking that the positive and negative were only on the opposing ends until just recently I noticed sparks when I plugged a 18650 with a worn coating on the positive end to my e-cig. The battery started leaking right away. I'm glad that I found out this without a more sevear accident! Great vid! I agree that the insulation on these is way too thin and prone to wear off with just normal plugging and unplugging of the battery!

great video and teaching on safety regarding the 18650 lithium-battery. Wow all you have to do to make them safer is to heat shrink (wrap) them.

Very informative, thanks for the advise. I got myself some good shrink tubes to wrap my batteries.

I don't understand all the dislikes as this video is very informative...

I saw your whole video and confirm its informative and "safe" , even without the added comments (which still are good addition). Your points are clear for the general audience so please ignore the senseless comments below.

You are placing a thicker, more insulating layer which prevents the batteries from cooling as efficiently. Heat dissipation in a battery, particularly Lithium, is important. While I agree that having the terminal so close is an odd design, battery designers, in general, are well aware of what they are doing... Laptop battery packs are generally well soldered and nowadays have a very low failure rate.

Just make a better end cap to protect the + and the edge of the -

It's an interesting peek into the anatomy of a battery and i really like the first part of the video. I would, however, advice against replicating the part where you roll your own insulation due to (as others are saying as well) changed heat dissipation characteristics and cell dimensions and it appears the custom isolation is not better than stock (remember that fairly thick plastic ring you removed?). I would also be nervous about using a torch on a li-ion cell, but as you say its not really heating the cell.

Lets work with flames on a battery, to make it safer. :D

Thanks for this video. I'll do it same way as you.

Did you consider the thermal properties of the original plastic coating vs. the shrink wrap you are replacing it with? The batteries need to have a way to release heat - might not be much, but with every degree they are warmer, they perform worse...

this very thing caused me to have very severe 3rd degree burns on both my legs that required skin grafts.. Those of you criticizing this man and have never been severely burned keep doing what your doing im sure you will see why he posted this sooner or later.

Thanks for this, really helpful!

So what your video has shown me is, Do not remove the plastic ring at top. Obviously it is there to prevent the bridge. Why would you possibly take it apart to show that? They are designed that way for a reason. Leave the ring, right?

The plastic ring and heat shrink are perfectly adequate. Unless you hold your soldering iron on for too long and melt it. Your dealing with 4.2v at the most,it's not going to jump the gap by any means and those with the new heat shrink wouldn't fit in a 18650 torch anymore.

Fear and Ignorance always a big seller.

i thought this was already known, thats why they make the insulating rings

Ha Ha you cant be serius ..... Removes the isolation ring that prevents short circuit and then heats the hole thing over an open flame xD

Wow that seems a little sketchy having positive and negative so close to together. I am glad I watched this. That's good to know. It looks like you could potentially short out a battery just by spilling a little water on the top of the battery.

Nice job on the video keep up the great work, at 10:00 how did you make that lighter that is made for grills and lighting candles how did you make it act like a blow torch?

Ahh, just like that time Gilligan rewired the professors beacon signal when they heard on the coconut radio that the air force would be testing in the area. Well done sir, well done.

this would increase internal resistance as head would now be an issue?

Question. Is that tubing designed to be a battery wrap? Also are you returning the insulator ring before heat shrinking it or?

The information is perfect, but the execution is dangerous. You never put heat on a lithium battery, and you also never short-circuit a lithium battery without protection.

Thanks for pointing out the design and construction flaws which apparently are not common knowledge for the general public. I'll be sure to be extra vigilant for any possible problems while working with these batteries.

When making videos about these batteries , I think a prior video should be shown of how dangerous these can be and what happens. Then people will think twice about relying on factory wrap.

Use the nylon washer you removed as its more durable than just your shrink tubing If you are building packs for motorized scooter or other high impact items use the plastic holders designed for them You can see a sample of these being used on the electric samba page

have 2 batteries that wrap has small tear along the negative body. Patched it with electrical tape. have been monitoring them for a week amd so far no overheating. is that safe though if its only along the long side?

Good explanation on the fire risk of 18650 battery. Shall take necessary preacuation.

Hi all! How to preserve a 18650 for a long time without using it? 80% charge once every 6 months, and store it in dry and room temperature, or fully charge it and leave it for a 1year, or 2? Thank you!

Perhaps the original covering was designed to permit the proper amount of thermal transfer as these batteries often have a high current draw and need to dissipate heat. Also you did not replace the plastic ring insulator. Batteries meant for flashlights and portable equipment should have the protection circuits built into them which will also prevent short circuits, over voltage and under voltage. Batteries out of a laptop power supply do not have protection circuits as this circuit is provided by the equipment. One thing to keep in mind though is that a lithium ion battery when permitted to discharge below (over time) it's safe low voltage level can catch fire as internally copper crystals can form a short circuit. Keep your lithium batteries charged and do not store long term without topping them up. When they are worn out - dispose of them properly. Lithium Ion batteries are wonderful for their large capacity but you do need to educate yourself in their use. As far as the negative and positive terminals being close - you can say the same thing about a typical 9 volt battery. Ever put one of those in your pocket with a handful of conductive coins ;) Why are my pants getting so hot?!!! ;)

6:50 I'm glad you discovered this too

Thanks for the post. You potentially saved me money before my batteries come. Thank you.

thanx, I did not know this about the negative body

I went back and watched your video again and you were right, I stand corrected.

may be protected from bouncing and shorting but it will retain heat like a s.o.b. manufacturers put specific coatings on certain products for a reason and this coating helps the battery vent

Andrew thank you very much for the informed video that you made and which many people who speak about this subject regarding 18650 lithium battery cells overlook. My questions happens to do with handling 18650 batteries coming from an old laptop/notebook battery that I took apart; Q. How does one discharge charged 18650 batteries that all currently fully or partial charged and since the batteries came in pairs how to I remove the metal connector on the positive and negative without arcing myself or causing them to explode? Also, these batteries I am experimenting with are for a power bank charger used on smartphone - Iphones, Android and I would like to know more about its handling safely and it is proper to use such batteries for this project?

You mentioned when you were getting sparks while opening laptop battery packs, generally if a lipo battery shorts out on itself it's done like dinner for good.

Hello Is it not better use, liquid tape with the plastic ring on the top? Regards Thomas

It's very interesting topic, and I'm glad that you came with this idea. I'm a user of an electronic cigarettes, so i have this batteries just in front of my face... How about 18650 batteries but with "pin" top, not the flat top, do you think they are safer or it's the same problem? PS: I didn't ripping of the plastic from the pinned one, so i don't know how it looks like inside.

I do a lot of these shrink wrapped batteries and yes it was silly to take off the protective plastic ring. Also you should have left the ring on when shrinking and if you have a lot to do it is so much easier to stick them under a grill and watch them all shrink together. These batteries will take some heat as they do get hot in extreme usage anyway.

Will they slide into a flashlight ? Once in light can they be removed ? Seems to me a tube designed for protection would be in order ? A battery carrier designed to carry multiple batteries perhaps?

you do not need to heat shrink the whole battery..just put on a half inch or so of heat shrink on the positive end...

Maybe it's only me, but please, people if you intend to modify those batteries in that way, make sure you do not cover the venting holes on + side.

Andrew I know exactly what your saying I was very concerned also so when I built my 147 ah pack for my solar power, I also wrapped all the cells inside a fire blanket, then added vents and sealed the whole lot up in Robnor Resin the fire retardant stuff semi flexible it has a texture similar to Rubber.

i would have made sure the positive end was lined up and shrank first correctly so all trimming and adjustment can happen on the safe negative terminal

why remove the protective ring what if sum conductive things slips through or sum conductive dust builds up there?

THANK YOU! this is very useful and vital information! that's just ridiculous to make a battery like that! they couldn't possibly make the production so that they include an insulator SOMEWHERE, literally ANYWHERE further away from RIGHT NEXT TO THE DAMN POSITIVE?? that's an absolutely terrible design. They need to include information along the lines of DO NOT USE IF THE WRAP ISN'T PERFECTLY INTACT.

At 1:34 of the video you briefly talk about the "little plastic cap on top". This is a ring insulator which is there to prevent the exact problem you are trying to solve against in the entire video. The insulator is thicker than the wrap which you are applying and I bet it does a better job at protecting against a short. In short, the battery design already accounts for the danger which you are highlighting and all needed components are in place to prevent the short from happening.

thats very r8 ...n nice informative vid... but last month with one of my projects i noticed that when iam connecting the negative part of the batteries near the positive(above the indented rim) iam getting different battery life and charge readings although when i connected the negative part of battery at the extreme end i got better battery life and more accurate battery charge readings...i got same result with 3 different setups.... cd not explain to myself why its happening as its a single complete negative shell.....just want to know if anyone else experienced the same or if anyone can explain it......

Nice video, trouble is manufactures use cheap heat shrink most batteries on the market are the same.

What's the size of the shrink wrap you used? 20mm?

thank you. a lot of people bitching about how dangerous litium ions are (and yes they sure can be) you are one of the few that expressed some of those concerns in a constructive way with education. next up someone needs to do a video on ir testing with a scope and signal gen. that might be me soon but im still building my lab. I was in a commercial space but the owner of the "electronics repair" store attempt knew nothing and didnt want to put any future profit sharing in writing even though he was using 5k worth of my equiptment every day. so my apt/flat is currently being converted which is a major pain in the ass. BTW get yourself a 50 usd adjustable temp heat gun on ebay "smd rework station"

Great Advice, Thank You!

thats how almost all cylindrical batteries are. only ones i've seen that arent are C cells made in the 1950s with cardboard middle pieces.

does 18650 requires an overcharge proyection and if yes then how to build that cutoff circuit

Hahahaha you take the protective ring off then claim it's unsafe.... I have about 16 of these 18650's and use them in a variety of dive torches, never had an issue.

With the heavier jacket will they fit in flash lite ?

Many if not most non original notebook battery replacement availabe in Brazil come from China and have this CJ cells. I actually bought a replacement pack for a Toshiba notebook that could power it but did not charge. I opened both the original Toshiba (Sanyo OEM) and the NoName (CJ cells??). There is a clearly visible quality difference, including in isolation and protection. Packs are 3S(2P) of those 18650 cells, with a tap from each of 4 serial voltage points to BMC board that holds protection and interface to the notebook. Original Toshiba has 2 thermal sensors, and replacement has 1. The most striking problem seen in the new NoName replacement is that the weld spotted metal holding a pair of parallel 18650 cells together would actually scratch the isolation, as the hypothesis of this video, and fire internally burning half of the metal shunting the cells and auto extinguishing before something worst happened! Clearly this isolation is not up to the task, and that lack of quality in both design and implementation put consumers at risk. Toshiba-Sanyo modules had extra sheets of insulating material to avoid frinction and contact. Those are UNPROTECTED cells that rely on the BMC board for protection. A short in a single 2P arrangement has absolutely no protection to avoid a fire or even an explosion. The pack has an UL inscription, but I would not be surprised if it ware a fake one.

Great video. Thank you for using "old english" demensions when cutting the shrink insulation. That insulation will disapate heat much better than the original. Come on over some time, we'll enjoy coupl'a liters of ale while chatting electrical science!

ALLL batteries have negative body. Well there is few mostly 9volts, but rest is always negative whole battery and i think everybody who uses batteries knows that :)

Great video! Would that piping fit a 18500 battery?

Good job !! have you got a link to the heatshrink are you using ?

What size heatshrink did you use?

Was wondering if replacing the coating with a heavier wrap would cause the battery to retain the small heat that they make under normal usage to actually over heat the battery and shorten its lifespan?

Do I need bms when I already have Mppt/pmw

so your afraid of shorting your battery and having it blow up but your not afraid of putting a torch to it, uuuukay seems pretty legit lmfao

It's NOT mylar that they wrap them with, it's merely a different kind of heatshrink tubing to the one you used. Used in the laptop industry since ever without problems. Those of us who use 18650s in torches, ecigs etc are used to rewrapping them in this way when the original heatshrinking becomes damaged, usually around the negative end of the can. The whole can being negative is, as far as i am aware, something that has been common in the battery industry for aeons. I can remember seeing it 25 years ago as a child.

As a fire sprinkler fitter 25 years the only actual sprinkler activation I've attended due to fire was caused by a laptop being charged on a carpet next to a couch. Nowadays anything I charge I do so on a flat non flammable surface. However in this case the enemy of lithium batteries is heat. This thick insulating material will not aid in cooling so I'd guess the batteries won't last as long.

How about a tight fitting vinyl cap to cover pos+ end of battery ?

Panasonic makes 18650A batteries. Is this the same for them or what is the difference?

I want to ask you, I have a fairly new 18650 battery, but earlier I dropped it and it spit out a liquid like water, I checked the voltage is still normal, is this not dangerous if I still use the battery?

Would it be safe to use insulation tape instead of the rubber tube?

very nice and helpful video ! next time could you please keep the camera a little further.

my battery casing scratched off a cheap 18650 like this one, and it was in my jeans pocket and rested next to my penknife and loose change. it began to get really hot in my pocket, i put my hand in and burnt myself and leg! nothing serious but I managed to get it out. my penknife was hot as hob on a cooker! and my loose change was to hot to handle.

You can use artist tape to isolate them.

I would say that all A, AA, AAA batteries has similar construction and even NiCd and NiMH will cause heat and burn if you shorten them out. No news, has been like this for 15-20 years at least..

what brand is the battery you start this with? I have this battery from a ecig mod I ordered and cant find what kind of battery it is?

thaks for the advice can u tell me please how can i charge them with out buying i charger ? or can i use i normal computer charger ? directly ? or any idea ^^ thanks

Just got deep into electronics for the first time. Reading 12 grade/college textbooks on DC, AC ohms law, learning how to read circut diagrams and got my first multimeter, (geeking out measuring stuff with it). I wan't to build my first lithium ion battery with 18650's. Maybe 40 amp hrs. With that many cells (can I balance them in parallel like LiFePO4 cells and get a good bluetooth BMS?) Do you need to harvest them sparingly, carefully? Only go with the best ones, and your ok. Assuming you have a temp sensor BMS with overheat auto shut down software on it, - can I go as high as 50 - 80 amp hr a 18650 celled battery and be safe from fires? The battery will be in a RU-vid Vanlife Van. Also where's the best place to harvest 18650's

Very informative, Thanks

great idea thank you!!!!

cool !! easier way to get the wire coating off wires is by using a lighter an just get it hot enough were you see it melt then take your finger nail an pull it right off or just cutter puller so you wont get burned do it quick enough with your fingers it wont hurt though iv done it hundreds of times works great for me an doesn't cut into the wire

The plastic ring on top made the battery safe, shorts along the negative side are usually towards grounded screws anyway so those are harmless.

But you will find this with all batteries, that's why they use the insulator around the body of the cell, how you configure them is up to you or the designer of the product. Often devices that use these types of battery use some kind of card separator to support the cell, and they have hot glue to hold them solid in place to minimise movement between the cells.

I did something similar for my 18650 that i use in my flashlights. But i didn't use shrink tube because is to thick and they didn't fit, i just used transparent duct tape to insulate them better.

what size heat shrink wray do i need ?

Good idea to wrap up the battery were can I get does black wrap around tanks let you know please contact me.

well worth the extra weight bro nice and simple gotta be a fella skip cheers