general questions about salvaging Lithium-Ions and Lipos,what do with them? - Page 1
Forum section: electronics / beginners

author: LECTERvsCHIGURH
author_rank: Newbie
timestamp: February 15, 2022, 11:53:22 pm
content: Hello Guise,my first post and greetings from Germany. I hope no one gets offendet if i skip the "introduction"So i am a owner of a stack of batteries now and id like to know e few things about safety and how to reuse them. Long story short, a neighbour gave me 2 large batteries from E-bikes because he knows im a guy that likes to work on stuff and build all kinds of things for fun that nobody needs. Few months ago i was asking for old batteries from laptops, powertool, ebikes, wanted to use them for lasers, pocketlights etc. Now ive been blessed with 60x 18650 cells and a huge lipo-stack that is build out of 20x 125x65x10mm batteries. Now ive never been uncomfortable with batteries, but with this huge pack of concentrated energy i deceided it might be a good idea to increase my knowledge (its very basic in electronics).I think i will just write down all of my questions with number and maybe if someone wants to answer for a few or one single question thatll also be great. Before i start, a few more things to the batteries and the condition: The 18650 were fixed and screwed in an array with 5 packs, each 12 cells. Theres was no BMS on it..i already dismantled it half way, cells look nice from the outside, theyre 3400maH cells from LG chem. Also theres a not-so-nice reminder that contains words like disfiguering and explosion XD. They obviously are not ment or wanted to be reused. The stacks had pretty different voltages, some cells had 4,17 volts, some had 1,6 volts and some where so discharged that i didnt even get a stable reading, was moving between 0 and 100mv i would guess.Now that lipo-stack is a little more delicate to me, i dont have much experience with them, i also never soldered or removed them from a BMS, i dont even see where the anode and cathode is to be honest. I tried to remove one from that..cable and probably wasnt careful enough, theres a little smell coming out of that lipo now. Only that single cell, seems i opened something. Deceided to store it not in my rooms.As for what i think today, i would like to use the batteries for DIY powerbanks and ebike. Build an ebike for cheap, would be nice if i already had a good quality battery. I already built a powerbank, it was an empty kit for 5 bucks from Ali-Express, i inserted 6 cells and it seems to work nice. I will however charge it in the cellar, at least the 1st time(Planing to buy the 16 cell-kit for 12eu)Now to my questions.1. Are these 18650 cells in any way more dangerous than "regular ones" that you can buy with a knob? I heard they miss some safety feature like OCP. What, besides of an overcharge, could lead to a drama?? shortcut, could even overdischarge cause a fire? (doesnt seem realistic to me) And is it safe to charge the ones that are down to almost zero volts?2. I used a dremel (mini-anglegrinder) to flex of the pointy rest from the point-welder to make the surface of the batteries smooth and even again, is that ok? Probably should have asked earlier.3.I was told only to use a good charger when charging them, i have a very cheap one from china that i used to charge my tiny 16340s for my laserpointer, all good so far but i wouldnt like to take any risks, if so, can someone give me a link for a charger that is safe and will never overcharge?4. what do u think about the safety of this 16 cells DIY Powerbank?https://de.aliexpress.com/item/1005002943359924.html?gatewayAdapt=glo2deu&spm=a2g0o.detail.1000060.1.32266490EJ1XnC&gps-id=pcDetailBottomMoreThisSeller&scm=1007.13339.169870.0&scm_id=1007.13339.169870.0&scm-url=1007.13339.169870.0&pvid=6ca842c6-f5ac-4000-8ff0-c4b08d18206a&_t=gps-id:pcDetailBottomMoreThisSeller,scm-url:1007.13339.169870.0,pvid:6ca842c6-f5ac-4000-8ff0-c4b08d18206a,tpp_buckets:668%232846%238116%232002&pdp_ext_f=%257B%2522sku_id%2522%253A%252212000022899519860%2522%252C%2522sceneId%2522%253A%25223339%2522%257D&pdp_pi=-1%253B10.79%253B-1%253B-1%2540salePrice%253BEUR%253Brecommend-recommend5. Now to the lipos, i dont know anything about these things, is there anything special about them that makes them more dangerous or unstable than the 18650s? Do you think its worth getting them off that cables? and then what can i do with it, can i solder them to a new BMS and use them as a bike battery? ATM i dont even know how to safely get them off, i guess it needs desoldering? Dont even know where to put my probes on that thing. Maybe somebody has a good video or post of how to assemble/disassemble Lipos?6. can someone take a guess about the capacity of the lipos? Theres nothing on them but a 5-digit number but it leads nowhere. I just know its about 125x65x10mm and weighs something between 100 and 120g. (the whole pack is nearly 2,5kg. Do you think its even worth for me, putting in the time and effort and new parts to build them into a bike battery or are they so cheap maybe that i just have to pay an additional 50eu to get the brandnew battery including BMS?answers are very appriciated.

author: Zipdox
author_rank: Regular Contributor
timestamp: February 16, 2022, 09:16:59 am
content: The cells alone have no protection at all. You need an external circuit for that. Lithium cells are pretty delicate, over-current, short circuit, and overcharge can cause them to swell, smoke or catch one fire. Slowly over-discharging them likely won't cause a fire, but it will kill them for sure. As for the ones that are below 3 volts, they are dead. Don't try to rescue them. They aren't as dangerous as charged batteries, because they contain very little residual energy. However, you should still handle them with care and dispose of them properly (your local recycling center will probably take them).That's not a smart thing to do, as the filings can cause a short circuit, and the cutting can heat them up. Don't do that again.You need to use a charger that is intended for charging lithium batteries. As for any other product, cheaping out can pose a risk. But as long as you buy something with a good reputation from a reputable reseller, and use it properly, you should be fine.Seems reasonable, but cramming so many cells into such a low power device seems like a weird thing to do. I advice making more smaller capacity banks instead. That decreases the severity of a possible failure. If you're willing to make your won enclosure you can use this board:https://www.aliexpress.com/item/4000574214602.htmlThe biggest problem with LiPos is that they don't have a hard casing, which makes them prone to physical damage. As such they require more care with handling. Other than that they're pretty similar to Li-Ion. As for what to do with them, I don't know in what configuration they are. I don't know if they're in series or parallel. What you want to do with them is up to you. You could try to separate them and create more USB power banks (by putting them in parallel if you want). If you want to keep them in series and create a higher voltage pack, it's important that you use a suitable BMS. Desoldering them is certainly possible, but you have to be careful not to short the cells when you do.No idea about the capacity. You can buy tools to measure the capacity in order to determine if it's worth saving them.

author: tunk
author_rank: Super Contributor
timestamp: February 16, 2022, 11:31:10 am
content: A simple USB-powered charger from Xtar or Nitecore should work fine.Some tests:https://lygte-info.dk/info/indexBatteriesAndChargers%20UK.htmlYou should also test the capacity, maybe something like this:https://www.ebay.com/itm/373735951380?hash=item5704660c14:g:ldkAAOSwmURhUXTiAnd self discharge: measure the voltage just after finished charging,then maybe once a day for week, and then every week for a few months.For battery packs, I think it's recommended to use cells with similarcapacity and selfdischarge.As for cells below 3V: test them and see.I've seen cells well below 3V turn out fine.

author: jerryk
author_rank: Regular Contributor
timestamp: February 17, 2022, 02:24:04 am
content: The pouch cells are tricky to separate. Cutting them out is not an option as you want that tab to stay intact. I have desoldered a few of them with a vacuum desoldering tool like the Rigol FR301 and a soldering station that can create a lot of heat. The tricky part is the speed it takes to melt the solder while trying not to transfer the heat down the tab into the pouch. I keep freeze spray handy.Tape adjacent cells connections and balance feeds with Kapton tape to prevent a short. Typically I will vacuum the solder off a connection first to see how the tabs are folded. Then take the iron from the solder station with the biggest thermal mass tip I can find and start with heat on a corner prying up the tab. I have some real fine prying tools that easily slip under the tab keeping the iron just in front of it moving down the tab till it's completely separated. It is a bit tricky and takes some technique. I also stabilize the pack in a wooden carpenters vise to the pack does not move during the process. A burn bucket and gloves are close by.I wish I had some photo's of the process but all I can find is a lifepo4 4S that I made from a combination of two packs that had a flat cell in each. Putting packs together is much more fun than taking them apart. Be careful.Jerry

author: LECTERvsCHIGURH
author_rank: Newbie
timestamp: February 17, 2022, 06:28:14 am
content: ok, ive had different answers now about trying to recharge the cells that have very low voltage. Ive read from people even reviving the ones that are almost zero allthough im not informed about the outcome. What if i try to recharge them in a safe enviroment? If they are 4,2v again after that, are they fine or do they carry some hidden risk?and about the lipos yes, i will at some point try desolder them while protecting the rest of the battery with some shielding. ill try to put a probe on the other side to measure the temps while soldering. These things are to huge for a powerbank, id use them for a bike battery if thats possible although i never made my own battery this big i guess ill have to search the right BMS for that.about the charger, isnt there a high-quality charger that can also read the capacity? So i dont have to buy 2 devices?

author: kjr18
author_rank: Regular Contributor
timestamp: February 17, 2022, 12:52:52 pm
content: BigClive had some thoughts about charging cells discharged to 0V and he thinks it's okay to use them (but ones that show reverse voltage are not). I think while you can use them, but keep in mind they might be faulty.And for testing and charging various things you can use something called analyzing charger or hobby charger.When testing li-ion's you need to take into account that some cells might have high self-discharge rate, high enough that it will interfere with charging. For example last week I disassembled notebook battery containing 3 18650 cells. One of them had lower voltage than other, while two of them had about 3.7V third one had around 3.1V. I tried testing them with analysing charger: charge-discharge with measurement-and charge once more. Two of them finished test with lowered capacity, but third one still was stuck on charging. High self-discharge was the problem.

author: ledtester
author_rank: Super Contributor
timestamp: February 17, 2022, 01:06:50 pm
content: Quote from: LECTERvsCHIGURH on February 17, 2022, 06:28:14 amMost chargers that have some sort of display can do this, for example:

author: LECTERvsCHIGURH
author_rank: Newbie
timestamp: February 17, 2022, 05:23:56 pm
content: ok ive never had a charger more than 4 or 5 dollars..im excited to get a real one with display

author: BILLPOD
author_rank: Frequent Contributor
timestamp: February 17, 2022, 07:54:03 pm
content: Good Morning LECTERvsCHIGURH,Here's a charger I have that 'does it all'. LOVE IT.https://www.skyrc.com/MC3000_Charger

author: tunk
author_rank: Super Contributor
timestamp: February 18, 2022, 10:39:12 pm
content: Quote from: LECTERvsCHIGURH on February 17, 2022, 06:28:14 amFor the cells themselves, probably not. But if they self-discharged below3.0V, they will not work, which could be a problem in a critical situation.If you get a better charger, maybe get one that can test internal resistanceas well. If you put together a battery pack, then you may not want to usecells with a large variation in internal resistances.

author: mosafet
author_rank: Contributor
timestamp: February 19, 2022, 12:08:58 am
content: "Li-ion" batteries as typically used in 18650 cells aren't that dangerous and the LiFe/LiFePO4 versions even less so. They can be dangerous but mostly when they break they just get hot. These can often be revived from extremely low voltages just watch the temperature when trying to charge them. One important thing to know with these cells is their voltage. Some are 3.3V (LiFe), some 3.6V (max charge 4.1V), and some 3.7V (max charge 4.2V). Best to look up the maximum charge voltage on whatever cell you're using. Often old 3.7 cells will only take 4.1V max, trying for 4.2V and they just get hot and never charge.Li-po's on the other hand catch fire pretty easily. If they're puffed/swollen at all then treat them with extreme care. They can often still be used but you never know when they might start smoking especially when trying to charge them. Once they start releasing internal gasses then they are not long for this world. Low voltages on these will nearly always damage the cell and puff them. I do not keep large quantities of these near each other and store them in fireproof containers. AFAIK all li-po's are 3.7V with a max voltage of 4.2V.Any lithium battery will have a longer life if you charge less than the maximum voltage but obviously you won't get as much energy out of them.All lithium cells are known for spontaneously combusting so should be treated with care. I discharge and throw away any batteries that won't take a charge or get hot. Unless I'm attached to them, Li-po's that are puffed also get discharged and thrown out (they won't last long anyway).Any type of lithium burning releases massive amounts of noxious gasses. If you keep them in your living space have a plan because you can't breath that stuff. Just cracking open a lithium cell will make your eyes/nose/throat burn, imagine a fire.Edit: Thought I would add some more info.