BMS (Battery Management System) || DIY or Buy || Properly protecting Li-Ion/Li-Po Battery Packs
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- Опубликовано: 10 фев 2025
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In this episode of DIY or Buy we will be having a closer look at BMS or battery management systems. That means I will show you how a commercial BMS is built and how it functions. Afterwards I will then have a look at a DIY BMS project from Stuart Pittaway, build it and test it in order to find out whether you should stick to the commercial BMS or use a DIY one instead. Let's get started!
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Music:
2011 Lookalike by Bartlebeats
Killing Time, Kevin MacLeod
(incompetech.com)
![Seungmin "그렇게, 천천히, 우리(As we are)" | [Stray Kids : SKZ-PLAYER]](http://i.ytimg.com/vi/kAzmhLHePqU/mqdefault.jpg)
Your SMD soldering skill has become so much better than your previous one. Appropriate amount of flux was given. Louis Rossmann would be proud of you.
Thanks :-)
More flux
The bigger the blob the better the job
Why do people obsess over Louis rossmann
Don't delay, solder today
Just FYI, your videos got me through a seriously bad time in my life and I am thankful for you. This hobby saved me and God provided!
Thank you for taking a look at my BMS design. I have a new version 4 that I am currently working on which removes the higher current drain on the cells to less than 1mA, the software is also more flexible.
Sounds awesome. Let me know when it is done.
@@greatscottlab it's done
How can i get ur mail ID
Can i get ur email ID?
@@chiragrathod932 contact me via the forum at openenergymonitor
I am a biologist, but your videos have taught me so much about circuit design. Thank You!
There is article "how a biologist fix a radio " thats so interesting i suggests to read
Really pleased you got use out of my fork of the code and found the extra features of use. Thanks for featuring my channel and great video.
For smaller projects I still like using a TP4056 wired parallel on each cell or cells of the series pack so for a 2P 4S I have one TP4056 on each 2P = .500mAh each cell x4 Chips using 4 separate phone chargers for isolation and you can use the single cell protection strips for unprotected cells so they shut down before under voltage. Cheap and works.
Well that was unexpected! Great video as always. Thanks for featuring my channel.
Thanks for the feedback. I hope some viewers will have a look at your channel. It is linked in the video description :-)
GreatScott! I’ve seen it! Thank you for that.
Hey Adam, big fan!
Well deserved Adam, your channel is one of my favourites.
Hey Adam, you are doing a good work. I would like to do a power shed like yours.
I have been experimenting with these type 18650 packs for about a year now. I have built dozens. I use a fused nickel strip on most of mine now, all of them that have more than a few cells in parallel. I accidentally did short one while assembling it and all of the nickel fusable links glowed and melted, it was scary, but spectacular to watch, but it worked and potentially prevented a bigger problem. I just tested the cells and put new fused nickel strip on the top and it was good to go. I wish I had had a camera running. My point is that they are, in my opinion a worthwhile safety feature and insurance policy. For batteries in buildings, I have been building metal boxes for the batteries in case of fire. I do not have such charging and power draw as most of mine are working for small solar power collection and lighting backup. For me, heating of the batteries and thus needing to cool have not been issues. Every once in a while, if I have my thermal camera with me, I will look at them and see if any of them are heating, as they fail they get warmer when heating or cooling. I made some of my first packs from very old salvaged cells as those cells were very cheap to practice many of those cells were on deaths door, so I got to see failure modes. It is a pain in the neck to dissassemble a pack for a failing cell, so I try not to use cells that are too close to failure. I have taken to adding load disconnects and do not charge mine above 4 volts as I am dissatisfied with the BMS performance of the Ebanium and Amazonian varieties I have tried. I would like programmable LVD and HVD, but it seems that unless you build your own they are made out of unobtainium.
I like the way you present everything clearly.. Even a simple formula for all to understand.
Loved the extra balls of solder (04:04) on the commercial unit straight from the store!
So much for build quality control...
good catch!
The Power of zoom.
Its funny i was searching for these videos for the fist time about 12hours ago. and here you go making one basically as perfect a timing as you could.
Fantastic incredible job I love these diy or buy videos🙃
Samee:)
Hello
When Scott does something he does so that it just looks perfect and nice.
Duuude lets see this BMS in action! Make a charger for lithium ion batteries next! That'd be so dope
When making power bank from parallel batteries I would use Schottky diodes between the common junction and the battery positive to prevent weak battery from pulling down the strong one and thus exhausting / draining the overall power. This also provides protection against defective batteries. I would also use protection circuit (simple one) to prevent over charge and/or protection against accidental short.
@@mathieucaron4957 You are welcome.
Oh this was great. When you mentioned 1A of power, that rang with me and my project.
Scott, you are the best I ever seen about electronic modifies. I want to be great at understanding electronic devices like you.
It comes with high cholesterol/high blood pressure ...
You're videos are best of the best and provides much more knowledge. After watching one or two video I have just become your greatest fan. Keep it up always. ❣️
Perfect episode, I was trying to build my own BMS for quite some time, but everytime i failed. Thanks for the power od your chanel now I'm able to build one on my own :)
I needed this, and here you are. May you live long.
You're welcome :-)
I think it would be really great if you could order for example ten times the components you need for a project of yours and put them up for sale in kits consisting of everything you need except tools. Great job on all your hard work. I'm definitely enjoying the results.
Yes great work 💪 new to this BMS and Li batteries. If I use protected cells then a BMS is not required. Is this correct? If that is the case what type charger is recommended to charge a 48V 17.5A Li-Ion battery?
@@Ballindud BMS is always good, even if cells have internal BMS. Find a charger of the appropriate voltage but note that the higher the current, the faster the charging but it may harm your battery or decrease its life.
I have been using the diy bms project for a year now. The work Colin H has done is great. Tied right in to my grafana setup.
Commercial BMS : I'm simple and available.
DIY BMS. : it's complicated
More like:
Commercial BMS : I'm simple, readily available, and can be salvaged from laptop and tool battery packs.
DIY BMS : I'm over engineered, expensive, and might burn your house down.
@@Elfnetdesigns THIS haha
Always Love your handwriting skills and of course your knowledge base
Great Scott! this fellow is left handed.. I always knew he was brilliant!
I'm left handed and I didn't understand any of what I just watched 🤔
@@ksrnate it takes awhile to catch on.. Being left handed myself I understand..
@@tinkmarshino How long?? I'm 40 this year 😖
@@ksrnate 68 this year.. last may..
@@tinkmarshino Ah that's good then. I thought my left handed powers would never come! I'll just wait longer 👍
So some of the BMS you find that look like yours and are sold on several platforms (amazon, ebay, or aliexpress) do not actually do as they claim. I bought one almost identical to your only 3s version... it almost ruined my pack. I have a nearly perfectly balanced pack (50mAh variance out of 30 000 mAh total). The issue is that is somehow managed to make 2 of my cell banks (3s16p battery) were discharged to 0 volts and one was at 4.3 volts... Not good. None of my cells had any measurable self discharge before this happened, and I have been attempting to find out what is now causing the self-discharge, whether it's the BMS or if the cells now have a self discharge. I didn't even get one charge out of the pack. Only the initial charge was usable (I charged each cell to full to test for self-discharge and so they'd all be the same SoC for assembly).
I saved the pack with a small active balancer, and thankfully the over charge and over discharge protections all worked on the BMS or it would have started my pack on fire.
Maybe mine is defective, but I'll have it investigate later. In any case I would recommend an active balancer on any large pack. They actively balance at any voltage so they can be used even you limit the charge to between 20% and 80% to extend cycle life... and they're a LOT faster than bleeding off the cells since every amp you drain from the highest cells goes to the lowest cells so it's almost like balancing twice as fast... while making less heat. Though some of them have low current so I just get one that has low drain ( less than a miliamp) and leave it connected so it can just always balance and I never have to worry about it. Realistically, the DIY BMS with the 1 amp bleeder resistors is faster than cheap active balancers because of that giant 1 amp of current... the bleeder resistors in most commercial BMS boards are way way smaller and are thus going to be slower than active balancers and are only going ot activate at a set voltage which is set by the BMS circuit rather than programmable software.
currently working on my own arduino based system. Don't have a main control board yet, but I have working cell modules, and they only draw 0.11 uA when idle and 2-7 mA when transmitting.
Great! Publish it all. And don't forget documentation :D
Yes ... I'm very interested to see your design when it's finished!
I bought my 14s 52v bms from ebay 1 year ago and used it on my ebike battery. To anybody thinking bms's don't work, you probably didn't buy one. I made my own battery pack and spot welded the batteries together. One day the battery died on me really quick and i couldn't understand why. Two of the spot welds were disconnected and the bms tried to compensate so it shut the whole battery down which in fact saved my ebike battery. 30$ well worth it
Thanks to greatscott,Im now great at soldering!!
That ad spot in the middle was probably the smoothest segue to one I've ever seen! :P
redpheonix1000 Support me please
Thank you dear Awsome!
This comment is under-apreciated
THANK YOU KEEP US TRYING
I believe the DIY is the best option especially if you are hoping to making a product for future use. Once you fully understand the commercial vs the DIY, you will be able to fully appreciate a potentially better design for future use. Thank you, for your excellent presentation. By the way, Series is not the same as Serious (ha!). Thank you again
You should do video about reflow ovens! You do so much surface mount soldering, it might be worth doing a DIY or Buy. Nice video by the way.
I can put it on my to do list
"Draws quite a bit more current". Of course! What were you expecting? Wi-Fi isn't exactly low power. And that's an extra in comparison to the commercial BMS, which can be removed to make them comparable, and save 3 €. In fact, you could also try NRF24s or other low-power solutions, combined with an ESP gateway, in order to make it better.
It’s better to buy only, because cost will be less 👍🏼
Stealing tends to work out pretty expensive once you factor in the time served and lawyer fees 😁
Support me please
youcan buy it cheaper, this project is encouraging students and hobbiest, to getting knowledge.you must appreciate this type youtube video.
spot on with DIY BMS being for powerwalls and such. It seems to have better front end functionality than most of the cheap to midrange BMS units, which are mostly focused on providing BMS functions more than front end features, so you can end up blind on how your batteries are actually doing with most purchased BMS units - which isn't ideal for something that you want to closely and carefully monitor. Meanwhile anything that's portable, you may not care as much about what individual cells are doing, and just need a relatively simple (in terms of features) BMS to keep the cells relatively healthy, and shut down the current flow in the event of something dangerous happening (which you can later check into on a bench). Good stuff, very interesting.
I am hoping to see something eventually come out that is nearly as comprehensive as a Batrium system but more adoptable for smaller projects. One specific need though is for higher current output through any of these BMS solutions at the small side. With the attractive nature of building high capacity portable battery packs, the ability to push a lot of amps is a must have if you also plan to feed the power into an inverter, especially if it is only a 12v inverter.
I am starting my first project and have some of the 4s 40 amp BMSs on the way and a dedicated charger like what they sell on Vruzend. Should be sufficient for what I am up to but I am watching and looking at things a lot. Still not seeing that magic solution yet...
You are so clear in your explanation! Perfect!
So DIY for powerwall, and commercial for small packs...
I just got my DIYBMS pcbs yesterday! Still waiting on some components from china, but I will be making a 12s version to balance chevy volt modules.
where did you get design of PCB??
@@Curious_pi the link is in the video description, its the Stewart pittaway git hub one
@@JankyShack ok cool thank you
Wow , Holy Scott ,…… nicely explained project,…….
Please do some 4S BMS ´, Lifepo when possible ,.
Don't you just hate when you accidentally build a lipo battery pack🤣👌
Happens to me all the time......
Wow! Very creative indeed dude. Your video tutorial (electronics) is the best i watched so far. Every information of the components, schematics, mathematics, technics are all there making it a stop learning experience. Some words i might miss due to accent but its not a problem. You are imperfectly perfect. Thanks and stay creative.😀
I always BUY mine. I aint got the...
Stark: what? Time?
Me: The patience.
Fungineers for a 7s or 14s which would you pick?
Depends on the application really. A 7s would run a 24-30V application and a 12/13/s would run a 48V application.
Fungineers but for a bms which would you pick.
Oh, Ok. If I understand your question right this time, you are asking whether to pick DIY or BUY? For such a small pack, definitely buy. Mainly because the fairly priced BMSs from China are surprisingly quite reliable (at least from my experience). If you are doing a high voltage application, like a powerwall as Scott said, I would definitely build the DIY BMS to monitor the voltages anywhere in the world over wifi. This way I wouldnt have to open up the enclosure every few days and inspect the batteries.
@@Fungineers just asking what you buy. Batrium or Chinese brand or some other well known.
This is the best series from great scott
Maybe compare DIY high capacity powerbank with commercial product ? Cause I want to build one in future. Also try to salvage lithium cells from old notebook battery
can you do a video on how to test a BMS to verify it functions properly (completely disconnected from batteries)
Sponsored by the pink markers ! :p
Awsome video, like always
Great Scott is becoming... "Greater and Greater" Scott. Awesome videos
will you make some projects on audio electronics and please make a video on how to make a NPN common emitter power amplifier.
I learn so much from watching your channel, thank-you!
Great vid. Scott!!!-This is a passive balance/power bleeder-How about active balancing so not to waste power?
Active balancing is quite complicated to implement and drives the cost up significantly. That's why 99.9% of BMS don't have it, including top of the line options such as Batrium. Also if the cells are properly matched, then there should be very little balancing needed so there is little benefit to active balancing.
I've wanted to experiment with using that waste power for something useful, like put all the resistors in one place to create a heater. Or use LEDs instead as a light source.
If the cells are charged from solar, then the nearly full battery needed to trigger the BMS balance means soon all the power will be un-used.
Deligreen has an active balancer.
Those commercial units are becoming better and better, as well as cheaper.
The DIY BMS by Stuart is a great project but I just can't help think it is very specific for larger applications/powerwalls, especially those set up with quite large parallel packs ...
For GreatScoots examples ... his 4 PCB boards are all just to balance his 4s2p pack ... literally, 8 Li-Ion cells need the 4 PCB's and the ESP board. The BMS is as big as his pack.
Anyway, would love to see something more compact yet as effective, I'm sure it's possible.
good explanation, Thanks for sharing.
i was planning to use it to charge my drone batteries.
But ended up buying 4ch 4s charger for 60eur.
Im glad i did, at the end.
Well i think this is a good alternative for some projects but this doesn't provide balance discharging....It can only be used for balance charging ..
Can you please also guide for balance discharging from the same bms..
Technically all it would take is new code/software to implement that feature
Do BMSs balance cells during discharging? As far as i know, the balance function is only for charging
@@muhammadwaqar3406 Balancing the cells at the end of charge ensures all cells have 100% state of charge, but this still limits the entire pack to the capacity of the weakest cell. Active balancing during discharging allows the full capacity of the battery pack to be used, but is more complex.
Balance discharging is kinda a waste off time. Once a cell/cells have hit the min limit, all other cells will be close to their limit too. Say 1% away. Assuming all the cells are same spec and condition, not a mis match of random salvaged junk. Charge balancing is plenty good to stop the ballance drifting out of hand, and will discharge a tiny bit off ballance and the corrected the next charge.
@@UberAlphaSirus +1 for that. Balance discharging is unnecessary in the vast majority of cases.
From research to practical applications is a long way. Technology is like that ! It is not easy
Well, you did not test nor compare the "cheapo" BMS as a comparison. which is what feels missing to me...
You are always Great MR.Scott......
Awesome video 👍👍
To make BMS can we use TP4056 charging modules for each cell and then solder them on one PCB followed by connecting input wires?
*Will it work fine?* If yes, this will be the cheapest and easiest way to do that.....
Plz reply??????
@Stefan Brückner thanks for your reply.
I simple words i want to say connect each cell individually with each TP4056 charging module (say 1 module for 1 cell). Now power them all by soldering their input pins together on PCB.
not a good idea, if you have a lot of cells
@@matrixdexter270 thanks for your reply.
But i think i will more Cheapest and easiest way to do that then to make Or buy BMS. I want to know is it good technically.......😊
@@pr2207A
Short answer: No.
Long answer: It is possible if you have a dedicated and separate ground isolated power supply for each TP4056 and isolate the chargers properly. Another way is to disconnect/take apart your battery pack into single cell modules and charge them separately.
A separate isolated power supply for each TP4056 module is absolutely essential if you do this, otherwise you will create a short-circuit right across most of the cells via the common ground.
Best BMS explaination on youtube yet ..... Thanks scott
Interesting....🤔 Thank you for the information and keep it up!!!
Wow! I've just discovered your channel: I wish I'd found it before. Excellent in-depth stuff, well filmed and explained. Thanks.
long story short: unless you have a microscope for smd sodlering and chirurgical precision, go for plug&play commercial BMS :D
Thanks! All the things I've forgotten since basic electronics class.
Love me some lithium ion battery panks
Prince Alabi Support me please
I haven't watched the video yet but YESSSSS this video came just in the right time!!
18 $ shipping, nice)
It is 18$ for shipping because, he choose a shipping through an DHL, if you choose standart shipping, then it is cheaper.
Muhteşem bir çalışma olmuş hocam. Batarya yönetim sistemleri önemli bir konu. Yazılım ile de çok verimli batarya yönetim sistemleri yapabiliyor ki en büyük örnek Tesla bataryaları.
Great video! What is the maximum amount of cells you can use in series with this system?
as many as your power source can feed, so if you put a 1,000,000 V configuration, share it on RUclips and wait to be news ;)
Well, if I understand what he did properly, each of his boards monitors two cells in series for a total of six monitored cells consisting of two chemical cells in parallel on his battery pack.
The arduino is then performing data analysis across those boards which mostly seems to be a fancy feature rather than one critical to the role of battery management. In which case, the theoretical upper bound is unlimited for the bms boards and the data metrics have an upper bound of the combination of I/O pins and sampling methods/frequency along with any supporting hardware for I/O multiplexing.
I suppose you could then double up on arduino boards and handle the collation of data metrics on the computer application side of things. Which would then push your theoretical limit up into the range of IP addresses your router can handle and this likely exceeds the physical means of most people. You would be well into the multi-kilovolt range by that point and the highest voltage you probably want to work with is 1.2 kilovolts, natively, as that is where most silicon carbide devices start needing to be stacked in series to deal with that. There's very little practical use for home power projects above 1 kilovolt on a power delivery bus. It would actually be rather eccentric by industrial standards as you usually only see voltages above 480 in special equipment and the mains stepped down from the power plant.
@@Aim54Delta I wouldn't put these boards in more than a 100v system, the isolation on the i2c bus is pretty much non-existent and you'll pretty much put the entire pack at risk. Even if he actually paid attention to the isolation on the board, the i2c isolator is only rated for ~500v continuous
You just taught me bMS design! Awesome! 👍🏻
Hey you should do a diy or buy wireless Qi charger
When I see Great Scott, I already know the video will be great .. as Scott.
Aren't there simpler DIY BMS's available? No need for all those fancy-pancy super features for a simple home made battery bank.
like 80% of the features are making sure it won't damage the cells or whatever its hooked up to and the new DIY features aren't all that useful
Looking into a project that will require a 128s BMS, great info!
Watching this video after got burned by a lipo battery pack.. 😂
go to hospital
Nice explanation on the "Buy" options... one point I'd make is, that the DW01 works in tandem with MOSFETs, not "simple" Transistors. Yes, I know, MOSFETs technically are transistors, but you did make a distinction, when talking about the big Power MOSFETs... so... just my two pennies on the matter.
8:46 "as well as the female headers" - solders male headers :D
Great video and I agree that diy and buy are the winners
This is a mismatch, its like a go pro vs dslr both useful cameras with different application, what could have been the comparison should be that BUY vs DIY (of the same build of the buy).
Ya buying is obviously easier so the question is mute.
who watches these videos just to watch the perfect penmanship?
Hmm I just made a lithium ion battery _and_ I have no idea how I did this 😂 guess I'll watch the other video.
You are best teacher. I always wait for your Video.
Thanks :-)
Shame you haven't actualny explain HOW do design a BMS
It's on GitHub but yad he didn't do it by himself
Because the other channels did in depth videos about it already
He referenced pittaway and chickey. Did you watch the video ? He even put links to them in the description.
Thanks!
Thanks for the support :-)
next up: "DIY or Buy: BMX"
Been so curious about BMS's lately. Thanks for a great vid
Can you please say in a future vid:
2 cells in a series relationship, you could say, are married.
Plzzzzzz
I think you're the man, that's what I think!
What's your college or university background? And most of all I think you should shoot a video telling people why you chose it and why you love (and understand) it so much!
Congratulations!
Is it possible to build a BMS for LIPO, that only load to 4V/Cell? The Idea is to charge the battery not to 100% and keep it good longer.
I like the way you hold the pen. :)
Wow. My brain just exploded. Nice job, man!
Thanks for the video. I am planning on building my own 18650 battery pack and I have a lot of questions about the BMS part of the build. I was thinking about a DIY BMS, but thanks to this video, I know that is not an option.
This channel is AWESOME
Dispensing solder paste by hand or with a stencil, placing the components, and putting in a little toaster oven will save you a lot of time. Use your soldering iron only when really needed.
is there any programming involved to tell it the battery voltage/type of battery etc or does it just know somehow?
nice work mate, but i just want to say ive bought loads of cheap bms from china/ebay and ive never had one fail
I think they're reliable enough. I've never heard a report of those Chinese BMS boards failing. The DIY BMS is certainly much nicer with the WiFi blings, but if I just want a battery pack that works safely I'd go for the Chinese modules.
Your channel is one of two channels that are on whitelist in my ADblock ;]
Hi, thanks for your great Videos! I like them and learned a lot from them. But I would like to comment on two things ins this videos.
1. Your SMD soldering is good but I would recommend you to get some very fine tipped tweezer. When you soldered those bigger packages onto the smaller footprints you need to grab them tight and guided the into the solder. That way you can get a better solder joint and be faster. It looked kind of funny when you tried to poke the in the right direction.
2. Bootloader: A bootloader doesn't program fuses only. (That part I also don't know) But he programs a certain firmware in a special sector of the µC which tells him how to act on certain signals on his pins and where he needs to put this data.
Keep up the great work and your great videos! (BTW: I love your handwriting and your drawing skills!)
Love the aggressive highlighting!!! 😁
Congratulations for 1 million subscribers 🍻