Beginner’s guide to building safe 18650 batteries

[@KyleBurrissTheMagnificent]

I have watched more battery-related videos than I care to count, and this has, by far, been the most resourceful.

[@ARepublicIfYouCanKeepIt]

Great video Michael. Three suggestions, if I may: 1. Even new, lithium batteries must be fully charged, either individually or in bulk as a parallel array. Once 100% state-of-charge (SoC) is achieved, cells must be assembled into their final arrangement, then top balanced (charged to 100% SoC using a BMS with balancing capability, or a balance charger). Regardless of even measured capacity, bringing all cells to 100% SoC in unison ensures the maximum capacity of the final pack. Otherwise, the cell group at the lowest SoC (regardless of voltage) compromises the entire pack. 2. Regarding charging and discharging, a universal rule of thumb to maximize the longevity of battery packs is to charge and discharge at 0.3C. To explain for your viewers, C stands for capacity. For example, a 2,500mAh cell's 1C rating is 2.5A. Therefore, 0.3C equals 0.75A, or 750mA. Charging and discharging at this rate ensures the safety of the battery pack, as well as it's longevity; easily extending its life by 3x to 5x. While it's acceptable to "push" a pack to the cell rating, it's best to do so infrequently and for only brief durations. So, assuming 2,000mAh nominal capacity for your 6S7P pack, (2A*0.3C)=0.6A*7P=4.2A without ever coming anywhere near your packs rating. Likewise, using these figures, your pack should be charged at 4.2A or less, recharging from 0% to 100% SoC in roughly 5 hours. So, 5 hours charging for 8 hours work. Not a bad bargain. 3. To maximize cell longevity, it's best to stay away from the "knees" of the power curve. There's only a negligible amount of capacity to be gained, either by discharging after the knee in the discharge curve, or by charging after the knee in the charge curve. Unfortunately, most low cost BMS boards will charge right up to the top and cut-off right at the bottom. So, to operate within an alternative band as I suggest, a programmable BMS is required. This is a no-brainer for larger packs. However, it just doesn't make financial sense for relatively small packs. As always, thanks for all the great content that you create and share.

[@seejjordan]

This is perhaps the greatest youtube reply I've ever seen. Honestly. The video answered just about every question I had with building a pack.. except the BMS! This covers that, as well as gives constructive crit all around. I'm literally copy/pasting this. thank you John Coloe, AND TEACHING TECH!

[@ARepublicIfYouCanKeepIt]

@@seejjordan Thanks Chris. It's good to hear that some of the learnings I've acquired through long experience benefits others. I only touched on BMS's in my comment. Honestly, it's a subject for its own video. Perhaps Michael will create and share covering this important topic. In the meantime, if I can ever be of any assistance, please don't hesitate to reach out. My e-mail address is my first.last at Google's e-mail system. It'd be my pleasure.

[@ElectricBikeLaboratory]

Fantastic info here !! Well done

[@jameslmorehead]

I was going to come down here in the comments to talk about this as well. It is of utmost importance that all batteries in series are charged to a storage voltage before being welded (3.5 or 3.7V choose one and charge everything to that voltage)). If they are not the exact same voltage, when you weld them in parallel, the higher voltage cell(s) will short out into the lower voltage cell(s). You run the risk of creating a thermal runaway. If you look at how most manufacturers assemble 18650 packs, they either cut the strips long where soldering is required, or they add a short strip specifically for soldering. The welded strip takes more time, but is the safest route as the welded joint has a much lower thermal conductivity than a solid strip does. But, a welded connection also does not have the current handling capacity that you get from leaving the strip solid. Which way you go really depends on the power requirements of the soldered connection. Using the previously described charge rate of 1-2C, a welded connection is more that sufficient for a balancing connection. However, the primary output of a pack drawing 10+ amps might be too much for a single welded joint. This is where leaving the tab where the final parallel stage is welded to the pack a bit long would be the better solution. Soldering to a tab like that would give you the lowest resistance to your pack. Personally, I can't wait for the 4080 LiIon cells to become more popular. They are the most exciting technological breakthrough in batteries since LiPo packs became popular. They get the capacity and discharge rate of a LiPo, but with the safety of a LiIon. It's the best of both worlds.

[@MrMikeyPayne]

Wow! Great video...now this great comment. I am hoping he will make a thorough video on charging/discharging if he has not yet. I agree with the commenter that stated: "This is perhaps the greatest youtube reply I've ever seen. Honestly."

[@zuluDhillon]

Sir, you get a thumbs up from me for reuploading with corrections.

[@TeachingTech]

I'd rather admit I stuffed up than leave the video like it was.

[@oleg146]

@@TeachingTech wow, this is a special kind of dedication to what you doing! I absolutely respect it! 👍👍👍

[@T3chWarrior]

@@TeachingTech thanks for the video, maybe soon also look in to lifepo4 cells and pouches. different voltage range from liion and lipo, but significantly more charge discharge cycles

[@42Hertzer]

Definitely one of the better video explaining how to make battery packs from 18650 batteries! Thanks!

[@bhikramseth]

Finally someone who makes sense. Of all the videos out there yours is the best hands down! Thank you.

[@CaliforniaBushman]

I'm 58. American in L.A. County. Who new nothing about Electrical last year. I thought I'd educate myself on 12th Grade electrical because we're now in the Electric Age. So, I went to the library & took out 'Physics Demystified'. Read the 4 chapters on D.C. then A.C. Current. I got it! A×V=W, or I×E=P. Ohms Law - A×R=V, or I×R=E. Even learned Sine Waves are looking at a pulley - edge on. Understood Trig and how it applies to all of it. I understand Phase Shift (say 120° for Alternators) and Inductance, now. But mostly, I can't wait to get a bread board and get hands on (that's what it takes for electrical) then make an 18650 battery pack to charge devices first (with a good Bluetooth BMS). Then build an Ebike pack . Or two or three, and build a custom Bike. Then a 1KW - 2KW solar system with a 3000W Inverter for my Vanlife Van. Complete with Isolator. There's a KZbinr - YehuGarcia here in SoCal (Legit Electrician) who sells big pallates of 100's of new 18650's at once for discounts. Thanks for the refresh on the Battery Pack Math!

[@StormBurnX]

Immensely useful video - I have like 5 salvaged electric scooters that all use massive packs of LG 18650 cells. Literally sitting on dozens of them and have no idea what to use them for or how to safely use them - this will be such a great vid to keep in mind.

[@beez1598]

Dang those were good salvage finds!!

[@StormBurnX]

@@beez1598 I used to do mechanic/charging work as a contractor for Bird and they "retired" (disabled/recalled) a certain problematic model in my division and required that we ship back any that we picked up so they could be destroyed but the cost of shipping a giant scooter was higher than the reimbursement we would receive so me and every other mechanic I know just scrapped them ourselves. The parts aren't usable cross-model and the scooter had it's folding hinge removed (and then riveted+welded into place) so they weren't even useful for refurbishing, plus the brains were removed and replaced with a Bird-made chipbox that was remotely locked out. Between myself and the other mechanics in our decision I have no idea how much electronic scrap we saved from landfills but I've got a few scooters' worth of hub motors, battery packs with built-in BMSes, and a bunch of probably useless aluminium frames, so at least I can use the batteries for something now :)

[@terrydaniels9573]

If you have enough, you might look into building your own "power wall" that charges either via solar, or charges via house power during non-peak times, it can then be used during peak time to save money on your electric bill. I'm not an expert on this, but plenty of people on KZbin are.

[@StormBurnX]

@@terrydaniels9573 I probably only have around 35-50 of the individually cells - not enough for a proper house power pack, BUT with that said there is a slim chance I'll end up in an RV/camper type living situation within the next 5 years so I would benefit greatly if I used them there :)

[@beez1598]

@@StormBurnX that’s really cool, thank you for sharing that! Thank you for taking the time to do this and at least take a few environmental hazards out of the system. I used to work In IT and would do the same with laptop batteries, and e waste . my manager wouldn’t pay to dispose of them proper so he would just throw them in the dumpster. I tried to sell him on having a salvage company come every month for free of course but he maintained it didn’t matter much since “a few hundred batteries a year aren’t going to make or break the environment.” Technically correct I suppose, but still a crappy take on the issue.

[@AerialWaviator]

Excellent video. One of the most informative and complete Li-Ion battery DYI building videos I've seen. Has most key points someone just learning need to know. Terms and sources so they know enough to search additional information. One point that might have been mentioned in more detail, when using reclaimed cells; is cells below 60% of new capacity should be avoided. They can't supply as much current and will reduce average cell capacity in the pack. Better to use cells as similar as possible. Best is all cells same (like if new from same manufactured batch), but this has substantial added cost. Before beginning to assemble cells together, a final check should be made that all cells are charged to nominal voltage (3.7V). Cells that are at different voltages will quickly try to self-balance, and this can cause them to emit excessive currents (aka sparks). Particularly joining in parallel (+..+, -..-). Once within ~0.1V of each order connecting together should go smooth. The K-weld is one of the best options. Being DYI kit, price is reasonable for a quality tool. Cheep (low priced) spot welders should be avoided as they do poor job of managing energy used in welds. When spot welding cells, it's better that they at nominal voltage (3.7V, or slightly lower, but above 3.0V) vs fully charged (4.2V). Should something go wrong, cells having much less energy will have lower potential to cause damage. A bucket of water nearby can act as safe zone/net (for just incase). If you first pack build, try a 3-6 cell (at most) pack to test and home your skills. Making a mistake on a smaller pack will have less risk (less energy). Still need to take all cautions mentioned. Just take you time and don't rush anything. :)

[@nicksmith8622]

Wonderful explanation of calculating current draw for custom-built battery packs

[@adrianrolfe3821]

This is hands down the best tech instructional video I've ever watched. Thanks!!! Comments are extremely informative as well! Cheers!!

[@MisterkeTube]

Just a thought: why not have the wires attached to short Ni strips before getting them close to the batteries (when heat from soldering is not a problem and even drilling some holes in the strips to have the leads go through would be an option) and then just spot-weld those strips to the battery-pack? Avoids getting dangerous actions close to the batteries.

[@Yosomy]

I've always wandered the same question, buy nobody does that, EVERYBODY does it like in this video and I really have no idea why..

[@22Tech]

ooo that's a good idea

[@StubbsRC]

13:37 seeing be battery wires jump from the current coming through 😳 nice video!

[@ISurLee]

I can only understand 50% of your contents, it look like my knowledge haven't reach the level of making my own lipo battery yet. Thanks for saving my day! If i made mistake on this project, i could end up wasting lot of money!

[@just_russ4633]

Best video of battery building I have seen. So informative. Thank you.

[@Dowent]

I'd love if you'd also do this in-depth video on various smart chargers and discharges, as well as the different kinds of BMSes, including ones with bypass, programmable, etc.

[@markrobinson9876]

Best video so far! As other videos just tell you what they are doing instead of explaining where everything goes....until 14.35. Then the rest was over my head! This was the bit I wanted to learn. Can do the parallel connections, but where does the series go? some gaps and not connected? Serial connections on 1 side, not the other? Where do the charging plugs connect? which wire goes where?

[@priezti]

After having an 18650 go thermal runaway on me, I applaud your courage to work with them, makes me uneasy just watching it, waiting for the isolator ring to fail..

[@blackwolfecc]

Timing on this is perfect! I’ll be doing something similar to this for a super racer that will be going into my rv. I don’t want it drawing power off my primaries, but I want to be able to charge it either when a generator is plugged in, solar, or the truck. Excellent video! As always :)

[@matthewweinberger7023]

Wow that was quick, thoroughly enjoyed and as usual oddly convenient timing

[@smellycat249]

Ditto

[@piotrpolska1666]

I really like your channel. You are going so deep into each topic. Great knowledge and skills.

[@replacesoundboard]

Thanks, you just convinced me that I cannot improvise myself as a technician on the go, even if the idea of making my own batteries sounded really neat. At least now I have a better understanding of how these things work.

[@olivercouch1651]

Great video, one big thing missing is how to deal with a battery fire - bucket of salt water. Also, do it somewhere that's ok to burn, and with plenty of ventilation. HF acid is nasty!

[@gideonlapidus8996]

Love your video, basic math, and lots of common sense

[@jsteph6965]

Thank you for explaining in such detail. Very well done. First time I donate on KZbin. Very impressed

[@nicksmith8622]

Thank you for helping us identify fake sells this is great

[@TheFilipFonky]

I loved the burning battery reminder

[@MrRickvanwinkle]

Your getting a big thumbs up from me buddy, that was such a great detailed comprehensive video. I learnt loads , cheers buddy

[@nigelholland24]

What a absolutely brilliant video learned so much as a just getting into 18650 batteries thank you

[@originaltrilogy1]

I've been wanting to make a battery to replace the one stolen from my e-bike. It's 18V, so this has been helpful.

[@louis-ericsimard7659]

Finally, clarity in explanations ! Thank you !

[@wolfrig2000]

Fun fact, the first time I picked up an 18650 I wanted to know what voltage it was, set my meter to 12V DC and touched the leads to both ends and immediately it got extremely hot and burned my fingers. That's when I went on Google to find out why and now I know much more about these batteries.

[@Kalvinjj]

Sounds like forgetting the leads in current mode, that's pretty much a dead short on the meter.

[@SharkyMoto]

another thing to consider is chenistry so for example if you take samsung inr25r (wich they use in hilti powertools) those are actually designed and tested to fail in a safe manner - meaning they short circuit them and they cant blow up, explode, burn or anything, they just remain as they are but are broken afterwards. on the other hand, many cheap noname cells are much more dangerous and actually can explode, so its important to know the chemistry of the cell you are building with too :) also there are very well cells that are optimized for both capacity and drain, like the LG INR HG2 wich has 20A continuous discharge while offering a serious 3000mah capacity. as a long term e cigarette user, i know a lot of 18650 cells and their capabilities :)

[@truetech4158]

Well said. Yes, if the goal is to not get her to run hot, then nickle should be placed on the knees of the connective points.

[@pulledtoworkout2833]

😢such low views and such an excellent way of deliveriing the information. AWESOME VIDEO ❤

[@RestoreTechnique]

Total battery newbie question; you say 22.2V is suitable for your 24V needs? So the printer will still work when the batteries discharge, and they're only providing ~20V? I want to make a 12V battery, as was wondering if i needed to make mine 3S or 4S 🤔

[@matthewadkins7973]

Depends but if ur trying to power sensitive electronics u should get a voltage regulator for 4s(boost converter for 3s) and wire ur battery to it then wire it to whatever

[@Mitch3D]

I built a backpack 3D printer with a small delta printer, I used a battery alarm so it would warn me of overdischarges but I didn't use a BMS. The best solution would be a BMS that could activate power recovery on the controller board before the voltage drops so you don't ruin your print and batteries on discharging.

[@izsakitt3711]

Great. Note, capacity (watt hour, Whr) increases for serially connected cells just the same as for paralleled cells. Doubling the voltage, doubles the capacity of a series connected pair relative to a single cell.

[@1queijocas]

that would be energy (Wh), capacity is different (Ah)

[@markoantesic4362]

At 3:31 its a bit misleading to say that no capacity is added. Each cell is cca 9 Wh. Look at it this way, adding another battery in series will make the mAh stay the same, but will boost the voltage form 3.6 to 7.2 V and P=I*V. Describing battery pack in Ah needs to die. Like all the ebike resellers say, we has a massive 10Ah battery pack (...at 12V) not like those other guys who have a tiny 5Ah pack (...at 24V) XD

[@T3chWarrior]

agreed, KWh along with the sustained and burst currents is what needs to be used

[@drabberfrog]

Yeah, the capacity is determined by the number of cells you have, not if those cells are in series of parallel.

[@GiddeonG]

13:36 There's enough power going through the battery leads to move from the magnetic field generated. Fun :)

[@gusty2333]

Thanks for making this guide, I was wondering about this for a while now

[@2010stoof]

If youre doing beginner series and havent yet (your first video ibe seen) please explain the body of them and the need tollfor the top area not to have shrink oack damaged. Always good to buy a combo oack of shrink wrap colored packs that comes with the top ring insilators. Also that when transporting them to use a case or something keeping thwm apart and away from other metallic object that can cause short circuit.

[@honahwikeepa2115]

Cool. I found some in a broken hover board. All good voltage. I was wondering what to do with them. Chur brother 👍🏾🇳🇿

[@guerriclc7659]

Thank you for your work ! Have an happy new year 2022 !

[@paulhack893]

Ah yeah. Hes got the kweld. The us reseller is a friend of mine. Real good dude

[@ericserafim7954]

Tons of information!

[@Marcin-fx6hz]

13:40 that electrodynamic force!

[@MooseKnuckleWarrior]

I wonder if this fella talks to his homies with the same 2 tone up to one tone down to finish each sentence 🤔 I would love to see a video of him telling an epic story to his bros while keeping the same tone as these videos 😆 That would be pretty great. Informative video anyhow. I done learnt me some good book learnin

[@TCHamilton56]

Thanks Michael - you've saved me / taught me so much - most grateful for your well thought-out video helps. Best of the season to you + thanks again😀

[@Mobile_Dom]

i would have loved to see you replace the 12v heated bed (which was woeful anyway) with a small circular 24v silicon one from keenovo

[@rockerpeller5346]

Just reminds me of all those vapes that explode when people make errors with the current draw. Battery Mooch is also a good place if you want to know capacities and limits from different 18650 manufacturers.

[@silver1fangs]

I think they weren't errors they just didnt care and used cheap cells

[@pgtips1199]

@@silver1fangs usually is those sub ohm vapers that make their own low ohm coils and the battery's wont take the load. Boom!

[@silver1fangs]

@@pgtips1199 I mean I've built hundreds and hundreds of coils never had a malfunction... I'm also very picky about my batteries... And a lityle common sense... if its hot put it down. My hardest build was a 0.08 on a single 25r.

[@rockerpeller5346]

@@silver1fangs Most didn't didn't their homework with ohms law. Went too low on the ohms for the cells they used. Gotta watch cell manufacturers. Mooch has proven some aren't up to their stated stats. And yes I have dabbled with rebuildables and stacked mechs. Just not as much as I used to. lol

[@silver1fangs]

@@rockerpeller5346 oh for sure I pretty much stuck with Samsung's or hohm life cells... I did end up building a lipo box and put my Colorado rda on it and vaped at 800 watts lmao it was ridiculous as it sounds

[@spacecraftbuildingservices]

Really really informative. You know your subject. Thanks

[@prawny12009]

When building a battery from salvaged cells is it necessary to match resistance and capacity to ensure all cells charge in a similar time? I've seen some cells take way longer to reach full charge than others using the same charge even though they started at a similar voltage. Edit: watched more of the video and saw you use vastly different capacity cells Is this not asking for trouble? If a cell set drops voltage quickly because it is very low capacity will it not trigger the safety shut off sooner than necessary? Or is that what the calculator you used does? Matching the cells to ensure each parallel set has a similar total capacity. It just doesn't seem sensible to me to have cells that vary as much as the ones I saw you using, some looked to have 1/3 the capacity of others.

[@auxlabs5228]

Great video, any possibility of releasing you cad files for the battery holder and printer base?

[@IVAN_ENT]

Nice edit so fast i was a little distracted watching the original haha I use both lipo and li-ion, currently building my first ebike atm with a custom aluminium box and a 14s5p pack with 21700s giving 52v 1.2kwh for a bbshd motor 😀

[@aborne]

Great video

[@sonyyoung1036]

Best video I have seen. Educational. Thanks

[@ChibiKeruchan]

16:06 for people out there.. this part is dangerous. see those green plastic around the battery terminals? those are the only thin sheet that insulate that part of the battery. if you solder the way he did.. you might end up melting those plastic and revealed the metal part behind it. and if you are unlucky enough it will short your battery if the head is a the positive part and the shell is the negative.

[@mister0ldschool]

Wow this was fantastic! Thank you!

[@judkins53]

Fantastic video! Thank you very much!

[@eidodoos]

thanks for sharing. need more videos about battery

[@leroy111007]

Thank you for creating this amazingly detailed video

[@DennisCrawfordJr]

Thanks. I'm looking to add a rechargeable battery for a led sign. Is that a good option?

[@Nevio_024]

Great video! Can you please share the STL for the Monoprice mini delta battery?

[@TeachingTech]

Here is the link to all my source CAD. you ca right click and export anything you want without an account: cad.onshape.com/documents/9f854275c67d8537da0d456f/w/109f792ba2c59fcde9545aaf/e/dca48bb26248603c97da2165?renderMode=0&uiState=6487b579b622966de0c31157

[@Nevio_024]

@@TeachingTech Thank you so much Michael!

[@PlopboxGOD]

thanks so much this helped a LOT with the project im working on great video

[@jpcme2002]

best video on this subject!!! thank you very much!!!!

[@MrMikeyPayne]

Awesome video! The only area I feel grey on after that is the overcharge and drain protection. I hope you will do a detailed video on that if you have not yet. I just liked/subscribed.

[@Aengus42]

Just what I needed. Nice one mate!

[@Enigma-Sapiens]

Great video and awesome information, thanks, Michael!

[@mrguppy1016]

OMG THIS GUY HAS AN OBSESSION WITH OLD EXPLODING LIPOS 😂😂😂😂🎉🎉🎉🎉🎉🎉🎉🎉

[@marcosramirez385]

Are you going to do an update to the Delta Mini? I’m planning to convert my delta mini to 24v, replace the hotend, replace the bed with a thicker plate, install a 24v bed heater, get rid of the bed leveling switches to replace with a probe, maybe magnetic klicky and enclose it to have a portable abs printer.

[@MrBaskins2010]

my bed leveling switch broke on one corner. you know what size would be the proper replacement?

[@PottedPork]

What was the point of switching the printer to 24V? Couldn't you have stayed at nominal 12V and run 3S (14.7V), or did the custom pack just work out better as a 6S?

[@nevilenobody606]

Great video thanks! Do you still recommend the Melbourne supplier you mentioned in the video? Their prices seem quite reasonable for bulk purchases of new cells.

[@oceanz55]

FANTASTIC Video! Thank you so much for this wealth of info!

[@officer_baitlyn]

i was watching the video from far away so 0:59 gave me darwin award vibes

[@ericokoth3218]

Thanks for this video. Applying immediately

[@kwk8363]

You are sure that your printer draws 2A? What was the voltage in this wire? Seems strange, very low wats if we assume 24v, 50W in total. I am no expert but 2A seems more reasonable with 110v or 230v that would mean 220w or 460w of power demand

[@friedrice5292]

Hello Michael. Thank you for sharing this awesome video. I learned alot from it. Quick question to ask. I am new to RC Car and I had acquired some 18650 used batteries a while back. I would like to use them (make some myself) on my RC car which currently came with a 2 cells batteries in series (7.4v 1200mAH). Question 1: Can I use the same charger that came with RC car to charge the 2 cells that I am going to make? Question 2: If not, what kind of charger I do need to buy to charge the new made batteries safely? Question 3: What your recommendation to do to use previous used 18650 batteries for the RC car? Thank you in advance. :) Jack

[@kurtXhecticXpl]

Great video. Thank you.

[@dogbog99]

Superb video, thank you. More content like this please 🙏

[@bruceatkinson5357]

Removed 3 18650 26A, 3.6v, 1300mA li batteries from dust buster. Do they have to be replaced with same battery, or are higher mA ok?

[@giovi727]

Thank You for sharing this knowledge!

[@TheRattleSnake3145]

Why did you show a lipo battery short circuiting instead of a Li-ion?

[@TeachingTech]

Far easier for me to do it safely. I would have needed to manufacture something to do the same shorting with 18650s without being right next to them.

[@NathanCroucher]

There very similar, they both make the same boom.

[@graealex]

@@NathanCroucher Actually they don't. And LiPo is usually considered safer. With Li-Ion it's harder to damage them due to their metal shell, but then again, that's basically a pressure vessel, so it releases more energy at once in the event of a catastrophic failure.

[@NathanCroucher]

@@graealex Actually actually the point is its not safe for either of them to short. Thats why they both need all that circuitry to charge and monitor. If he had of used a nimh/cd then yeah, poor comparison. Way to throw people off the issue suit man.

[@graealex]

@@NathanCroucher "had of"... At least "suit man" mastered the English language. If you want to get personal.

[@iteerrex8166]

I’d never make a battery powered printer, but a very nice video for making a costume battery 👍

[@norm1124]

Amazing Project ❤❤❤

[@i_Hally]

So clear and concise 👌🏼

[@GANGAN-z7y]

thanks, what abut LiitoKala Lii-M4 18650 Charger ? is it good?

[@serverguy007]

This is a very helpful video clip, Thank you so much! :)

[@TheMidnightSmith]

The part where you showed buy in bulk, I almost choked as you highlighted 500. That's like $2500 in batteries! But this is helpful, I might need a spot welder.

[@KieranShort]

That's why skin-only power tools are so cheap and the battery packs for them are sometimes the same price.

[@oofunstuff]

That charger you mentioned is no longer available on Amazon. Can you recommend another?

[@obie224]

i can completely understand why this video recommends using a spot welder - there are way too many people who can't follow simple instructions and will either damage or outright explode their 18650's using a soldering iron on them for too long. especially on a project like this where many connections have to be made. but for smaller jobs, a high heat iron used by someone who has experience with soldering is all that's really needed.

[@graealex]

Damaging is really easy. A while ago I had to do some field maintenance - a flat BIOS battery was preventing a CNC machine from working. It was only a simple CR2032, but one with a wire that was soldered to spot-welded tabs. I measured a new battery, and in the few seconds I spent soldering a wire to the prepped surface, the battery already lost a few hundred mVs from the heat. Obviously I replaced it later on when the actual replacement part showed up. Anyway, soldering on batteries is no bueno. Even if you're really really quick.

[@obie224]

@@graealex if you don't understand that soldering a tiny little button battery is nothing like soldering an 18650 that has about 1000% the the mass and can actually absorb the extra heat without damage, OR if you think it's a good idea to spot weld a button battery at all, you shouldn't be using any kind of soldering iron on anything. please get someone else to handle it.

[@graealex]

@@obie224 It's normal practice to spot weld button cells, as this was the manufacturer-provided solution anyway. And in an 18650, one of the poles will be in direct contact with a plastic part that isolates it from the rest of battery. It will have little thermal mass. How you even think that a battery is a big hunk of metal that will homogenously absorb the heat is beyond me - maybe you should leave those job to other people...

[@obie224]

@@graealex you have to be trolling me at this point. do you think that something has to be solid metal to have thermal mass to transfer heat ? do you think that an 18650 battery, which is composed or sheets of copper and graphite, two materials with EXTREMELY high coefficients of heat transfer, will somehow NOT transfer heat away from the solder point quickly ? but the BEST part of your comment.... please explain to me exactly how the electrical circuit is completed inside the battery if one of the poles is isolated from the rest of the battery with a plastic part ??? like i said, i can't really believe you're actually saying these things seriously...

[@graealex]

@@obie224 Look at how the negative pole of an Li-Ion cell looks, as it is a small metal disc connected to a small wire that touches a number of isolating plastic parts. For protected cells you also will see the wire broken up by the protection circuitry. It's not going to sink heat very well. And then again, manufacturers stress test their batteries up to 130°C and that means well below soldering temperature. It's simply not safe to solder Li-Ion cells. There's really no discussion here. Especially not with you.

[@matebarna7045]

Hello. Can you help me If I want to make 70Ah, 12V battery from 18650 battery what I need for it? I like to use for the electric boat engine which is 12V. Thx.

[@isaganivallesteros5149]

Is it safe to use my old BMS that runs 10s4p rated at 10Ah on a pack that will be rated at 14.4Ah? Note my old pack used 40pcs LG rated 2.5Ah. I am planning to replace them with 40pcs Panasonic rated 3.6Ah each. Thanks to or your patience and reply.

[@brians7613]

😊 thank you your video did make it easier for me to understand

[@avejst]

Great video as always Good walkthrough of the process Thanks for sharing your experiences with all of us :-)

[@johnclarke6647]

I am going to build a DeWalt 10 cell Samsung 30Q power supply. I think it is 5S5P, based upon your design specs. About how much capacity will it have in Amp Hours?

[@lafields86]

@teaching tech, any possibility you'll release or share your .stl files for the 3d printed additions so one may build off of what you started?

[@OneDollarNoHoller]

Excellent!

[@WinstonFanWin]

Hi there, thanks for the great video~! I saved it to my collection. Just 1 question: after we have the wires for balanced charging, where do I connect the terminal(which has the wires for balanced charging) to?

[@richardnixon5555]

They go to whatever BMS you're using. It was briefly mentioned in the video at kzbin.info/www/bejne/qnzKXp1_p9eSgKc and kzbin.info/www/bejne/qnzKXp1_p9eSgKc

[@jonnyrichards]

Ah, I thought they were li-ion not li-po, thanks for clearing that up.

[@VinnieVega76]

What was the brand of the 18650 balance charger? Also, should I use the drain cycle before a full charge?