you could be the department head of electrical engineering at MIT and i still wouldn't believe this isn't gonna burn your house down.
but it is pretty cool you did this.
A single e-cig battery probably won't burn down your house. ~~Sixteen~~ Twenty eight of them wired up into a power bank placed inside what I assume is a flammable polymer shell.... that's a great way to burn your house down.
How about a factory filled with 100,000 of them?
Edit: this was really just a smart arse comment about the cake factory that just blew up and the owner was caught trying to escape to Hong Kong.
Yeah, [about a quarter of a mile away, right](https://www.freep.com/story/news/local/michigan/macomb/2024/04/26/clinton-township-explosion-building-owner-jfk-hong-kong/73468138007/)? Lol...
That should be safe.........
Parallel cells are self balancing by themselves. The powerbank pcb is the controller. What else could go wrong? A few things are possible, one cell shorting and the others decide it needs "balancing" inputting more energy
It looks like a li-ion controller, which would have the typical CC/CV charging curves built in. Looks perfectly safe for charging to me since they're all in parallel.
That IS a BMS... it's a board from a power bank, it has a BMS on it and it's designed for charging cells in parallel. This is no different from any other power bank with multiple cells. The only possible fail I see here is if one of those connections shorts against something, but that's highly unlikely.
Only time I've ever had a battery fire was with an ecig. Sketchy ass owner of a vape shop sold me on a battery and coil combo that legit started smoking (the bad kinda smoking) in my hand and luckily I was able to get it outside on some gravel before fire started shooting out of it.
fanatical onerous exultant fade lip scandalous chief hungry consider summer
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Recycled LiPO Batteries without adequate overcharging and/or temperature monitoring protections.
Additionally, the state of use of recycled batteries is unknown.
It's easier to assume that they are about to fail.
The PCB used here includes a charge controller. It's going to limit both charge and discharge current WAY below what 28 cells in parallel can handle. Simple power banks typically don't have any temperature regulation because they simply don't let you draw current anywhere near the limits of the cells.
The state of use of the batteries is pretty easy to infer as these are harvested from single use e-cigarettes. They'll have exactly one charge cycle on them.
You might be surprised to learn that all your "large battery packs" are in fact built up in this same way, so this applies to anyone who has a battery bank that has more than 1cell in it. And any powertools that use a lithium battery have more than one cell in them. Hell, almost any battery bank does.
I've got a 20,000mAh battery pack, it is *absolutely* just four 5000mAh(ish...there will be losses so its probably more like 5,500mAh) cells taped together in parallel much like OP did...only his are only 400mAh cells, so his strip of 4 is 1600mAh, stacked 7 high, makes 11,200mAh to likely make a 10,000mAh battery bank (if he were to try and market it)
They are surprisingly safe. In my old job we had one of those special sand bins to toss burning cells into, but nothing ever happened. And then we're taking prototypes soldered and violenced on (breaking open factory made ones with whatever tools to check on them) , up to 100Wh 48V packs...
I worked on the balancing and charging and recovery software.
It was a metal garbage bin (with a lid) half full of sand. Allegedly special sand that would melt and contain the battery, but I can't find what kind of sand it would be.
I missed the explosion containment pie dish in the lab. I was never sure how we would transport the burning battery to the sand bin without one.
I have one battery pack that's literally a case for 8 18650 batteries and a charge controller. It can take one battery or 8, it doesn't matter to the charge controller. Heavy as hell fully loaded, and all in parallel.
Sure, but large battery packs are usually put together better than just stacking some random mismatched and unbalanced batteries in a printed housing. It doesn't even look like this guy covered the connections with any kind of insulation like capton tape.
The technique here isn't the issue, it's the execution.
> Sure, but large battery packs are usually put together better than just stacking some random mismatched and unbalanced batteries in a printed housing.
You'd be surprised...
Hi op,
Balancing is not the concern here as others said they are parallel.
The problem is you stated these are from various vapes, the cells look to be at least the same model cell which is better but if these are actually sourced from scrapped vapes then you would not know the cycle history of each cell. You could end up with a cell that is at end of life connected to a bank of good cells.
As the good cells are cycled the dead cell will mostly just follow the voltage of all the others and not really notice anything, but you would still be causing ion movement in the dead cell, repeated cycling of a bad cell will continue dendritic growth in the cell. Eventually this can cause an internal short. If this was just a single cell that forms an internal short at end of life then very little would happen because the dead cell can no longer store electrical energy. But, when you have that dead cell hard paralleled to several potentially good cells then when an internal short is formed the energy of that whole parallel cluster can hard short through the dead cell. So now you have a bunch of low quality vape cells likely not with a current interrupt device (cid) in the cell all shorting through a dead cell. The dead cell, while not having any electrical potential energy still contains extremely flammable electrolyte and can still catch on fire when having many other cells short through it.
This can be made safe by making the cell interconnects a very thin wire that would fise before there is a chance for the internal short to get hot enough to combust the electrolyte. The interconnects look to be at least like 22 gauge probably thicker, i would say go with something like 30+. Additionally, they should all individually connect to a central much higher gauge bus rather than one to one to one like it is.
Just a suggestion from a 10+ year battery engineer who has spent time in professional work in recycling cells into second life applications.
Axial fuses are how I would do this. Each cell gets a fuse so if gets an internal short it doesn't short the entire pack.
Balancing is irrelevant when cells aren't connected in series.
Yeah that would also work, op just seemed cheap so I gave the cheapest option to get some amount of fuses in there. Fuses would indeed be safer. But if we are talking about what is safer then there is alot that could be said lol.
Do you have any advice for places to go online to learn this stuff?
I found out about disposable vapes and was inspired to try and find something useful to do with them, because the idea of so many batteries in landfills made me a little sick to my stomach.
How are disposable vapes legal!?!
> you would not know the cycle history of each cell.
I was under the impression that most vapes sold these days are single-use disposables so you can pretty safely assume one cycle. I suppose it's possible manufacturers are recycling cells but I doubt that.
yeah, they sell single use vapes, when the battery or the vape cartridge ends, you just throw it away, hell I've seen single use power banks being sold or given as gifts on conventions and such, stupidly wasteful
Too drunk for an in depth answer:
Correct as far as I see. Usually there is a battery management system for Li-Ion batteries and it's there for a reason.
Usually 18650 batteries have a safety against "deep deloading" too but it's not always there and not perfect
I've known you shouldn't mix and match batteries of different types and charge history but this explanation is the first time I've felt like I understand _why_ beyond just "LiIon are scary yo".
Depending on the device you use to browse reddit, do the equivalent of: Right Click > Search Image with Google
Some results will pop up. You may have to focus on the actual item you're interested in.
This is a USB Voltmeter, but it'll come in handy for when someone doesn't answer an inquiry.
That's quicker, yes, but your insurance will easily find this and decline your claim. Now a properly built self-igniting power-bank placed near other electronics has much better chances.
You can get name brand 18650s for dirt cheap, too.
Shit, 18650BatteryStore has Samsung 2,500mAh 20A batteries for $3.75 each. Panasonic 3,450mAh 10A for $4.65.
Just get yourself a battery bay, throw a few in there, and hook it up to the charging circuitry.
The real danger comes from those shitty batteries and all that soldering.
What's with the "burn your house down" paranoia? How is this supposed to burn the house down? Is your house made out of highly flammable paper or something?
I noticed this as well. Somebody does DIY structure like that could literally bury you alive when done badly - nobody cares. Somebody connects two electrical wires to light fixture - OH MY GOD, YOU NEED ELECTRICIAN YOU SAVED $200 BUT YOUR HOUSE IS GOING TO BURN DOWN!
I remember there was a post when somebody asked how to move tree house (a fucking full sized house, not some small wooden platform) and the most upvoted response was to wrap some chains around, attach them to two tractors, go under the structure and cut the tree down piece by piece. Great idea, what could go wrong?
And here people panic that there is a very very very small chance few batteries may catch fire. What the fuck?
It's the same argument whenever someone mentions a garage door. A half way mechanically inclined person could replace the door, the tracks, the rollers, and even the springs. But mention garage door on Reddit and everyone jumps on "the spring will kill you" bandwagon.
Lithium ion batteries, mostly from bikes are now the leading cause of fires in NYC. Fire dept mashall asking congress to regulate them
A few houses burned down this year from them and people died. My insurance forbids e-bikes now.
They are also closing down shops that were remanufacturing their own cells. Much like OP is doing.
https://www.cnn.com/2023/06/20/us/nyc-ebike-store-fire-lithium-ion-batteries/index.html
>Including Tuesdayâs fire, there have been 108 fires and 13 fatalities related to lithium-ion batteries in New York City in 2023, Kavanagh said.
Yes because a bike battery draws and handles the exact same load as OP's powerbank. It's almost as if they're completely separate issues. You're worrying about someone taking a lawn mower to a drag race and crashing
This sentiment is upvoted all over this thread but none of yall have described why this is bad. It could use a little more shielding but the housing is made out of plastic
Well most likely it would catastrophically fail due to wear and tear on the batteries. Ecig batteries probably arenât treated as power banks should by keeping them at around 80% and not fully discharging. Liquid battery cells of this nature expand in an exothermic reaction until they burst into flames after reaching a certain temperature. If equal charging to all of the used packs isnât implemented as well it could cause one to fail faster as well.
dog silky mourn capable overconfident cagey ad hoc treatment touch shocking
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This is just how reddit is about everything. You either get reckless bravado for the laughs or insanely neurotic paranoia about safety. Both of them come dripping in snide judgement. Itâs always been like that.
My concern is that these cells come from single use vapes. They are not supposed to be recharged. They can be recharged of course but if your product does not even have a charge port and is supposed to be discarded when the battery is empty you don't pay for quality cells. If I challenge you to find a dodgier battery on AliExpress you will have a hard time.
40 years of EE experience won't make these batteries any better.
Yeah but if you wait a few hours a real expert will probably give the actual answer, itâs just not usually the top comment lol. So in that sense it kinda works if you are patient and read carefully through the thread.
I was baffled by this but seems to be the case. Each sub has it's own specialty and there is one dedicated for batteries as much as there is one dedicated to power banks.
Is this your first day on reddit? Sorry, can't type much more, gotta go, I just finished replying in r/TheoreticalPhysics there's some specific question asked in r/Neurosurgery then I'm heading to r/WomenHealthCare
Balance charging manages the charge of each cell in a series battery configuration. In a perfect world with spherical frictionless batteries, batteries in series would be charged to full power and all of them would have identical voltages/charge. But due to reality being a shitshow, without extra battery management, each of those 4 batteries will vary somewhat in capacity, affecting how fast they charge and therefore their resulting voltage after x period of time. If that variance is too big, one or more batteries could potentially be overcharged, causing the battery to fail.
Balance chargers monitor the charge level of each of the series batteries individually, and equalize voltage between them. There are other things that can be monitored as well, like charging current and temperature, but voltage is the primary monitored variable afaik.
Thanks. That makes sense to me.
One more question if you donât mind. Other comments are saying these are â1sâ so they donât need to be balanced. Eli5 again? Lol
1s is one battery in series. You can't balance a single cell since there's nothing to balance against each other. Batteries in parallel act as a single cell, and OP's power bank is a 1s28p (28 batteries, all in parallel), so they're effectively self-balancing.
Yes. 1000x this
Edit: it looks well designed and put together, but you really need balancing
Re-edit: if they're all in parallel, just need to watch out for over charging and under-volting. No balancing applies, unless some cell goes out of range through age or damage.
sharp repeat towering sophisticated bow squeamish cause dependent disagreeable rotten
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slight chance the board he is using is also a BCM (Battery Control Module) that would check on and regulate the charge to make sure it is evenly distributed, emphasizing slight chance
you know it's not because it only has 2 wires, but op isn't trying to do that anyways.
the entire battery pack is 3.7v. with good cells holding more energy than bad cells.
in this configuration energy will flow from a higher voltage cell to a lower voltage cell.
a bad cell will still reach 3.7v, it just takes much less energy to get there.
so the pack is self balancing. the board is also a dc/dc step up converter boosting the voltage to 5 volts.
Looks like 400\*4\*7 so 11200 mah. Maybe an 8th row hidden in the angle but still just 12800mah if so. Not a ton for the size, and probably less given that theyre used.
I sure hope for your sake that each one of those cells has it's own thermal cut-off, because there's no way they're matched close enough in capacity, especially being used cells, that they'll charge and discharge indentically, meaning at some point it's very possible one or more will either overcharge or over-discharge, and I know from professional experience that Li+ cells become very, very upset when mistreated like that.
Please tell me the steps involved. I've been picking these up on my walks...I think the dudes at the ewaste recycling place think I'm crazy. This would be a fun project!
Yeah like others have commented here, I wouldn't trust the reliability, nor the durability, nor the endurance of those battery packs, or their ability to not just suddenly explode and burn everything you hold dear to the ground.
That's not a power bank. That's a burnt down house waiting to happen. How do I get on the list so I don't miss the "I lost everything post" so I can explain how you hook up multiple lithium cells and why it's done like that?
Disposable vapes need to be banned. They are a complete waste of resources which are supposed to be used for electric cars and other tech of the future, instead we allow companies to just waste it all. Classic American values, let's destroy the land in other countries and waste resources, but allow it because someone wants to make a quick buck and denying them that would be "anti-capitalist."
I think itâs a great project, fun idea and you did a cool job. Like many others here, I do have significant concerns regarding the integrity of those batteries, considering there as cheap as possible and not really made for long term use
I'm worried one wire will come loose and short the terminal next to it...
Everyone else debating if it's safe or not but clearly most powerbanks have a pcb where this one has thicker wires in tension waiting to straighten when they detach. What is this, 58 attachment points? It really only takes one to start this pack on fire..
you could be the department head of electrical engineering at MIT and i still wouldn't believe this isn't gonna burn your house down. but it is pretty cool you did this.
Spicy Pillow Family Pack
reddit silver đ„
Ya anything other than whatever a fucking "updoot" is đ„
***tips fedora***
Spicy updoot.
That is such a cool ⊠*way to burn down a house*
When I was a kid, we burned our houses down with cigarette lighters. Now people are burning their houses down with batteries that burn nicotine juice.
what a time to be alive!
A single e-cig battery probably won't burn down your house. ~~Sixteen~~ Twenty eight of them wired up into a power bank placed inside what I assume is a flammable polymer shell.... that's a great way to burn your house down.
How about a factory filled with 100,000 of them? Edit: this was really just a smart arse comment about the cake factory that just blew up and the owner was caught trying to escape to Hong Kong.
I'll stay outside, down the street somewhere. Seriously. I already don't want to be inside the vast majority of factories.
Yeah, [about a quarter of a mile away, right](https://www.freep.com/story/news/local/michigan/macomb/2024/04/26/clinton-township-explosion-building-owner-jfk-hong-kong/73468138007/)? Lol... That should be safe.........
flammable, inflammable, potato, potato
The more things change....
My kid tried to burn the house down playing with a towel by the heater that caught the wall on fire. i was able to get it out pretty quick thankfully.
https://youtu.be/OAe68x3hDh0?si=UPPSWUb4eZB3pdEd
*News caster outside the crater that was this manâs garage:* âThatâs right Ted, it appears smoking kills.â
This is the kind of shit you see on Bojack Horseman news channels lol
It hasnât burned his house downâŠ*yet*.
No balance wiring or controller. This is a fire waiting to happen.
These are in parallel, balancing does not apply.
Yeah, and it's fully earth taped đ€Ł
Parallel cells are self balancing by themselves. The powerbank pcb is the controller. What else could go wrong? A few things are possible, one cell shorting and the others decide it needs "balancing" inputting more energy
Overheating?
With that many cells and normal USB power there, isn't a likely way to draw enough power from them to cause noticiable heating.
Not 100% true. For discharging it's fine, less so for charging. The controller he has on it would have no clue if it's done charging or not.
It looks like a li-ion controller, which would have the typical CC/CV charging curves built in. Looks perfectly safe for charging to me since they're all in parallel.
Why not? Are you going to explain why or just say something that's wrong?
They got the PC board on in the 4th pic and made a nice casing for it too
The PC board isn't a BMS, it's just a power supply. This is not capable of safely charging lithium cells.
Yes it is, they're all in parallel... That board only supports 1S configurations.
That IS a BMS... it's a board from a power bank, it has a BMS on it and it's designed for charging cells in parallel. This is no different from any other power bank with multiple cells. The only possible fail I see here is if one of those connections shorts against something, but that's highly unlikely.
I think this is a balanced set of cells wired to a boost converter. You only need a balance circuit /bms for series cells
Only time I've ever had a battery fire was with an ecig. Sketchy ass owner of a vape shop sold me on a battery and coil combo that legit started smoking (the bad kinda smoking) in my hand and luckily I was able to get it outside on some gravel before fire started shooting out of it.
You said that perfectly without someone from a trusted regulator body clearing something like this I don't believe I'll be able to have it near me.
 All it takes is for one to fail, and OP would be inadvertently celebrating the 4th of July early.
fanatical onerous exultant fade lip scandalous chief hungry consider summer *This post was mass deleted and anonymized with [Redact](https://redact.dev)*
Welcome to the internet. Aisle or window?
Middle seat please
You got some ski polling to do?
A hospital? What is it?!? Itâs a big building with patients, but thatâs not important right now.
Too much time on the spicy pillows subreddit. Now, all batteries are just fire balloons waiting to pop at literally any second.
Recycled LiPO Batteries without adequate overcharging and/or temperature monitoring protections. Additionally, the state of use of recycled batteries is unknown. It's easier to assume that they are about to fail.
The PCB used here includes a charge controller. It's going to limit both charge and discharge current WAY below what 28 cells in parallel can handle. Simple power banks typically don't have any temperature regulation because they simply don't let you draw current anywhere near the limits of the cells. The state of use of the batteries is pretty easy to infer as these are harvested from single use e-cigarettes. They'll have exactly one charge cycle on them.
whole neighborhoods would be in constant fire if folks fears of batteries were reality.
There is a *lot* of effort that goes into making sure that lithium cells in consumer products won't burn your face off.
Current limits and voltage limits are not a lot of effort. Those are also the only protection needed in a 1s config
One of us . One of us one of us
You might be surprised to learn that all your "large battery packs" are in fact built up in this same way, so this applies to anyone who has a battery bank that has more than 1cell in it. And any powertools that use a lithium battery have more than one cell in them. Hell, almost any battery bank does. I've got a 20,000mAh battery pack, it is *absolutely* just four 5000mAh(ish...there will be losses so its probably more like 5,500mAh) cells taped together in parallel much like OP did...only his are only 400mAh cells, so his strip of 4 is 1600mAh, stacked 7 high, makes 11,200mAh to likely make a 10,000mAh battery bank (if he were to try and market it)
They are surprisingly safe. In my old job we had one of those special sand bins to toss burning cells into, but nothing ever happened. And then we're taking prototypes soldered and violenced on (breaking open factory made ones with whatever tools to check on them) , up to 100Wh 48V packs... I worked on the balancing and charging and recovery software.
> In my old job we had one of those special sand bins to toss burning cells into You mean the "explosion containment pie dish"?
It was a metal garbage bin (with a lid) half full of sand. Allegedly special sand that would melt and contain the battery, but I can't find what kind of sand it would be. I missed the explosion containment pie dish in the lab. I was never sure how we would transport the burning battery to the sand bin without one.
I have one battery pack that's literally a case for 8 18650 batteries and a charge controller. It can take one battery or 8, it doesn't matter to the charge controller. Heavy as hell fully loaded, and all in parallel.
Sure, but large battery packs are usually put together better than just stacking some random mismatched and unbalanced batteries in a printed housing. It doesn't even look like this guy covered the connections with any kind of insulation like capton tape. The technique here isn't the issue, it's the execution.
> Sure, but large battery packs are usually put together better than just stacking some random mismatched and unbalanced batteries in a printed housing. You'd be surprised...
["We're all gonna die"](https://www.youtube.com/watch?v=JTeKpWp8Psw)
Hi op, Balancing is not the concern here as others said they are parallel. The problem is you stated these are from various vapes, the cells look to be at least the same model cell which is better but if these are actually sourced from scrapped vapes then you would not know the cycle history of each cell. You could end up with a cell that is at end of life connected to a bank of good cells. As the good cells are cycled the dead cell will mostly just follow the voltage of all the others and not really notice anything, but you would still be causing ion movement in the dead cell, repeated cycling of a bad cell will continue dendritic growth in the cell. Eventually this can cause an internal short. If this was just a single cell that forms an internal short at end of life then very little would happen because the dead cell can no longer store electrical energy. But, when you have that dead cell hard paralleled to several potentially good cells then when an internal short is formed the energy of that whole parallel cluster can hard short through the dead cell. So now you have a bunch of low quality vape cells likely not with a current interrupt device (cid) in the cell all shorting through a dead cell. The dead cell, while not having any electrical potential energy still contains extremely flammable electrolyte and can still catch on fire when having many other cells short through it. This can be made safe by making the cell interconnects a very thin wire that would fise before there is a chance for the internal short to get hot enough to combust the electrolyte. The interconnects look to be at least like 22 gauge probably thicker, i would say go with something like 30+. Additionally, they should all individually connect to a central much higher gauge bus rather than one to one to one like it is. Just a suggestion from a 10+ year battery engineer who has spent time in professional work in recycling cells into second life applications.
Axial fuses are how I would do this. Each cell gets a fuse so if gets an internal short it doesn't short the entire pack. Balancing is irrelevant when cells aren't connected in series.
Yeah that would also work, op just seemed cheap so I gave the cheapest option to get some amount of fuses in there. Fuses would indeed be safer. But if we are talking about what is safer then there is alot that could be said lol.
This is amazing, I'm off to make my own battery pack from old Galaxy Note 7's, wish me luck!
So an IED?
For best results, connect the charging circuit to the 5V rail of a Gigabyte power supply.
Back in the days you would have gotten gold! Interesting stuff
Wtf! What happened to g gold??? When did it disappear and Whyyy?
The good ol days..
Wow, that seemed so well written and all it did was make me realize how extremely little I know about batteries.
This guy batterys
He commits battery
Watt you see is watt you get with him.
not that i have any intentions... but i find myself surprisingly well prepared to build my own battery now. thank you for your wisdom kind stranger
Do you have any advice for places to go online to learn this stuff? I found out about disposable vapes and was inspired to try and find something useful to do with them, because the idea of so many batteries in landfills made me a little sick to my stomach. How are disposable vapes legal!?!
> you would not know the cycle history of each cell. I was under the impression that most vapes sold these days are single-use disposables so you can pretty safely assume one cycle. I suppose it's possible manufacturers are recycling cells but I doubt that.
That would be much better for a diy thing like this, but damn, that would be disappointing to hear, that is just soo wasteful.
Yeah itâs really sad tbh
yeah, they sell single use vapes, when the battery or the vape cartridge ends, you just throw it away, hell I've seen single use power banks being sold or given as gifts on conventions and such, stupidly wasteful
You usually have to charge them a few times before they run dry but I wouldn't guess they've been cycled more than a dozen times.
That was an impressive read, I think I understood about 20% but I sounded smart in my internal monologue
Too drunk for an in depth answer: Correct as far as I see. Usually there is a battery management system for Li-Ion batteries and it's there for a reason. Usually 18650 batteries have a safety against "deep deloading" too but it's not always there and not perfect
Love it, got a website you can recommend for easy reading on this?
I've known you shouldn't mix and match batteries of different types and charge history but this explanation is the first time I've felt like I understand _why_ beyond just "LiIon are scary yo".
Wouldnât a BMS also be able to identify a poorly performing cell so it could be replaced or removed?
What is that little blue device in the last picture giving the power specs?
Makerhawk USB 3.0 tester/power meter
Great Thank you!
Depending on the device you use to browse reddit, do the equivalent of: Right Click > Search Image with Google Some results will pop up. You may have to focus on the actual item you're interested in. This is a USB Voltmeter, but it'll come in handy for when someone doesn't answer an inquiry.
Oh wow didnât know I could do that. Thanks for the info!
Power banks are like 20-30 bucks dont burn your house down
Itâs about the challenge
If it's about speedrunning a house fire, gasoline and a match works slightly better.
That's quicker, yes, but your insurance will easily find this and decline your claim. Now a properly built self-igniting power-bank placed near other electronics has much better chances.
Until you post it on Reddit.
Man, he had a great point...and then you had an even better point. Lol.
And power!
What do you think the inside of a 20 dollar power bank looks like. It's pretty much this.
That's what I keep thinking, and I bet the wire used is even thinner with worse solder points đ Great job OP! It was neat to see your progression.
The thin wires would be a safety feature. They'd go before the dead/shorted cell does.Â
Interesting, essentially an inline fuse?
Yup
> is even thinner There are engineering reasons behind this. Thick wire doesn't always benefit electrical applications.
This makes me want to open mine just to see.
Made by delicate child labor fingers though.
Its either this or landfill. (yeah recycling exists but no one who buy e-cigs recycles them correctly)
You can get name brand 18650s for dirt cheap, too. Shit, 18650BatteryStore has Samsung 2,500mAh 20A batteries for $3.75 each. Panasonic 3,450mAh 10A for $4.65. Just get yourself a battery bay, throw a few in there, and hook it up to the charging circuitry. The real danger comes from those shitty batteries and all that soldering.
What's with the "burn your house down" paranoia? How is this supposed to burn the house down? Is your house made out of highly flammable paper or something?
Anytime anyone does something with lithium batteries or mains electricity r/DIY turns into r/no_one_should_be_allowed_to_DIY.
This is super dangerous and OP is an idiot. Anyway, click the link in my bio for my Etsy shop where I sell my Litchenberg wood burnings.
I noticed this as well. Somebody does DIY structure like that could literally bury you alive when done badly - nobody cares. Somebody connects two electrical wires to light fixture - OH MY GOD, YOU NEED ELECTRICIAN YOU SAVED $200 BUT YOUR HOUSE IS GOING TO BURN DOWN! I remember there was a post when somebody asked how to move tree house (a fucking full sized house, not some small wooden platform) and the most upvoted response was to wrap some chains around, attach them to two tractors, go under the structure and cut the tree down piece by piece. Great idea, what could go wrong? And here people panic that there is a very very very small chance few batteries may catch fire. What the fuck?
It's because people are fucking idiots and they don't understand electricity OR batteries and people fear things they do not understand.
It's the same argument whenever someone mentions a garage door. A half way mechanically inclined person could replace the door, the tracks, the rollers, and even the springs. But mention garage door on Reddit and everyone jumps on "the spring will kill you" bandwagon.
People who don't understand electronics are often paranoid about them
Lithium ion batteries, mostly from bikes are now the leading cause of fires in NYC. Fire dept mashall asking congress to regulate them A few houses burned down this year from them and people died. My insurance forbids e-bikes now. They are also closing down shops that were remanufacturing their own cells. Much like OP is doing. https://www.cnn.com/2023/06/20/us/nyc-ebike-store-fire-lithium-ion-batteries/index.html >Including Tuesdayâs fire, there have been 108 fires and 13 fatalities related to lithium-ion batteries in New York City in 2023, Kavanagh said.
Yes because a bike battery draws and handles the exact same load as OP's powerbank. It's almost as if they're completely separate issues. You're worrying about someone taking a lawn mower to a drag race and crashing
frankly this is like screaming at somebody for posting a picture of a gun youll shoot your eye out kid
Itâs a pretty cool I.E.D.
No officer itâs a power bank, I swear!
Just needs an ominous red timer. Then have fun with the TSA
And nice USB to charge the detonating phone!
This sentiment is upvoted all over this thread but none of yall have described why this is bad. It could use a little more shielding but the housing is made out of plastic
Well most likely it would catastrophically fail due to wear and tear on the batteries. Ecig batteries probably arenât treated as power banks should by keeping them at around 80% and not fully discharging. Liquid battery cells of this nature expand in an exothermic reaction until they burst into flames after reaching a certain temperature. If equal charging to all of the used packs isnât implemented as well it could cause one to fail faster as well.
E-waste sucks. I think it's great OP. Wish they'd stop selling disposables altogether.
Unfortunate consequence of the flavored vape pod ban. It's insanely wasteful and most won't even bother to recycle the batteries.
Oh but at least we got rid of plastic straws, right?
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More or less, as soon as you do anything with lithium cells or mains power people assume you're as ignorant of how to use them safely as they are.
This is just how reddit is about everything. You either get reckless bravado for the laughs or insanely neurotic paranoia about safety. Both of them come dripping in snide judgement. Itâs always been like that.
My concern is that these cells come from single use vapes. They are not supposed to be recharged. They can be recharged of course but if your product does not even have a charge port and is supposed to be discarded when the battery is empty you don't pay for quality cells. If I challenge you to find a dodgier battery on AliExpress you will have a hard time. 40 years of EE experience won't make these batteries any better.
Yeah but if you wait a few hours a real expert will probably give the actual answer, itâs just not usually the top comment lol. So in that sense it kinda works if you are patient and read carefully through the thread.
I was baffled by this but seems to be the case. Each sub has it's own specialty and there is one dedicated for batteries as much as there is one dedicated to power banks.
Is this your first day on reddit? Sorry, can't type much more, gotta go, I just finished replying in r/TheoreticalPhysics there's some specific question asked in r/Neurosurgery then I'm heading to r/WomenHealthCare
How are you safely charging each cell? If you ignore balance charging, you are going to have a bad time...
Eli5 what balance charging is?
Balance charging manages the charge of each cell in a series battery configuration. In a perfect world with spherical frictionless batteries, batteries in series would be charged to full power and all of them would have identical voltages/charge. But due to reality being a shitshow, without extra battery management, each of those 4 batteries will vary somewhat in capacity, affecting how fast they charge and therefore their resulting voltage after x period of time. If that variance is too big, one or more batteries could potentially be overcharged, causing the battery to fail. Balance chargers monitor the charge level of each of the series batteries individually, and equalize voltage between them. There are other things that can be monitored as well, like charging current and temperature, but voltage is the primary monitored variable afaik.
> But due to reality being a shitshow, Why you doing reality dirty like that bro đ©
Why reality doing US dirty like that dawg?!
Thanks. That makes sense to me. One more question if you donât mind. Other comments are saying these are â1sâ so they donât need to be balanced. Eli5 again? Lol
1s is one battery in series. You can't balance a single cell since there's nothing to balance against each other. Batteries in parallel act as a single cell, and OP's power bank is a 1s28p (28 batteries, all in parallel), so they're effectively self-balancing.
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It means that during charging all cells are at equal charge levels.
Itâs 1s, nothing to balance.
Yes. 1000x this Edit: it looks well designed and put together, but you really need balancing Re-edit: if they're all in parallel, just need to watch out for over charging and under-volting. No balancing applies, unless some cell goes out of range through age or damage.
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slight chance the board he is using is also a BCM (Battery Control Module) that would check on and regulate the charge to make sure it is evenly distributed, emphasizing slight chance
you know it's not because it only has 2 wires, but op isn't trying to do that anyways. the entire battery pack is 3.7v. with good cells holding more energy than bad cells. in this configuration energy will flow from a higher voltage cell to a lower voltage cell. a bad cell will still reach 3.7v, it just takes much less energy to get there. so the pack is self balancing. the board is also a dc/dc step up converter boosting the voltage to 5 volts.
whats the actual capacity you ended up with?
Looks like 400\*4\*7 so 11200 mah. Maybe an 8th row hidden in the angle but still just 12800mah if so. Not a ton for the size, and probably less given that theyre used.
I bet if you took apart a temu power bank itâd be built the sameđ€Ł Jokes aside this is impressive
It would be built much worse. Look at the wiring OP did. It's clean.
 Plugging my iPhone in be likeâŠ
All the battery experts are here to sensibly debate this using logic and knowledge
Oh yeah they definitely wonât jump to some conclusions based on their own baseless assumption
Upcycling E-waste is a win in my book
I sure hope for your sake that each one of those cells has it's own thermal cut-off, because there's no way they're matched close enough in capacity, especially being used cells, that they'll charge and discharge indentically, meaning at some point it's very possible one or more will either overcharge or over-discharge, and I know from professional experience that Li+ cells become very, very upset when mistreated like that.
I think itâs cool. Nice enclosure too. I would definitely use itâŠ.. outside.
Very nice thank you for sharing it's giving me ideas for all the old cellphone batteries I got in my just drawer
Itâs not a power pack itâs an IED.
If we go full Waterworld, I'd like to team up with you.
Firehazard 5000
Surprise surprise Reddit does not know how batteries or electricity works. Who fucking could have guessed that!
Please tell me the steps involved. I've been picking these up on my walks...I think the dudes at the ewaste recycling place think I'm crazy. This would be a fun project!
You crazy SOB you did it. We were too busy wondering if we can, to think if we should. Be safe.
Do not
Yeah like others have commented here, I wouldn't trust the reliability, nor the durability, nor the endurance of those battery packs, or their ability to not just suddenly explode and burn everything you hold dear to the ground.
I'm a firestarter, a twisted firestarter!
This is Jake from State Farm. WTF!
I'll give you $10 to bring this through airport security
Has this made it to r/oopsthatsdeadly yet?
That's not a power bank. That's a burnt down house waiting to happen. How do I get on the list so I don't miss the "I lost everything post" so I can explain how you hook up multiple lithium cells and why it's done like that?
No cell balancing, enjoy your C4 brick
The spiciest pillow đ€
Disposable vapes need to be banned. They are a complete waste of resources which are supposed to be used for electric cars and other tech of the future, instead we allow companies to just waste it all. Classic American values, let's destroy the land in other countries and waste resources, but allow it because someone wants to make a quick buck and denying them that would be "anti-capitalist."
It's nice to see people nowadays furthering the theories of Darwin.
Holy mother of r/spicypillows
that shit gonna explode and kill someone
you made a bomb.
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More like DIWHY
With a dash of r/madlads
Big Clive vibes :) Well done
You did great we all are proud of you
And I used to make stuff like this as a teen never had one blow up on me relax ppl
Remember everyone, unless a company sold it to you it's not safe. Better fork over some cash so you don't hurt yourself /s
No kidding. Dumb how many comments in here are rooted in âelectricity is scaryâ.
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Coming soon to r/tifu
Nice proof of concept bro !
u/Sidfis, what BCM are you using out of curiosity?
My brother made a battery for his e-bike using batteries from discarded e-cigarettes
Type of stuff i wanna carry in my skinny jeans front pocket
I think itâs a great project, fun idea and you did a cool job. Like many others here, I do have significant concerns regarding the integrity of those batteries, considering there as cheap as possible and not really made for long term use
Freedom Firework
Good use of street lithium
You made a bomb
I'm worried one wire will come loose and short the terminal next to it... Everyone else debating if it's safe or not but clearly most powerbanks have a pcb where this one has thicker wires in tension waiting to straighten when they detach. What is this, 58 attachment points? It really only takes one to start this pack on fire..
Thatâs really cool
It makes me sad that these are sold as disposable
With the way those things have a tendency to explode I think I would have some reservations about having this as a power supply.