How to build a safe and better lithium battery WITHOUT a BMS. 

The eloquence, the fine humor and people dare to say RU-vid has no good content. Not that you need my compliment, but you're good! I learned a lot.

Thanks for letting us in on this. I just went out and tried to see if my ego hedger would work with just 56v without its bms and it did. This will save me lots of money. Thank you Rocket Man

I rarely comment on videos but I had to this round. This was an outstanding and informative video with a very good option to an aggravating issue. I see this solution 10 fold better than pretty much all standard styles and 95% of any non-standard ideas for doing this. Love it and for sure recommend.

Thank you very much sir. I'm glad that there are people like you in this harsh world we live in. I wouldn't have ever known this if it wasn't for you.

this may be the most informative lithium charging video I've come across so far. thank you

Hey Shawn, thanks for the awesome vid. Making all my packs with this info now and it's making a huge difference! Thanks again Shawn!

Thanks for this Shawn I've explained this to many after watching your video a good while ago. I'll be creating 4x29V packs @26AH. Connecting 2 in series & then paralleling. creating a 58.8V @52AH With cell logging like yours & also adding foldable solar panels to the bike. I have a 48V 1000W rear hub on a dual suspension, 300+ new cells. I'm just waiting for my spot welder to arrive which should be pretty soon! Excellent video.

Your explanation of the whole charging issue was awesome and I understand much more then I did! Thanks

Hey Shawn. Excellent video! Your approach sits really well with this retired instrument engineer with a serious DIY inclination. I can't wait to build my first battery pack and put your approach into action.

On behalf of everyone involved in 18650 cells THANK YOU sir

Man I've been thinking about this way for a while, just came across your video, THANK YOU.

Ok you've made a believer out of me and have made the most straight forward to the point video I have ever witnessed! Thank you battery guru thank you!!

Good video. I've found that battery packs last better when cells are in parallel as the cells keep each other balanced. I use 3x 4S4P in series for a 12S 20Ah pack without a BMS. I can split them at anytime for hobby charging but prefer to bulk charge using a constant current 10A LED driver with Max voltage set so that cells do not exceed ~4.1v. I occasionally balance each 4S4P pack separately using hobby balancer. The 4P setup keeps them very well balanced.

Thanks Shawn for this great video! I'm now convinced to use a hobby charger to charge my ebike and no longer rely on a BMS. The only small "issue" I see is with the cell logger: this thing will be powered from a single cell and so it could slightly drain that cell compared to the others, thus generating imbalance... Is that a problem in practice? Or are there any cheap cell loggers that are powered from each cell one at a time? Thanks!

Thank you for taking the time to put together such a non BS video. anytime I am told I have to use something I ask why and if I don't get a satisfactory answer I usually find it is a lawyer insurance company or Corporation.

sir, you have no idear how much knowledge you have, please share it with the world, we thank you for.

Agree 100%. Your battery is only as good as its lowest capacity block. Once it is full, charging should stop. There is no point in putting more charge into any other block, its just a waste. My Idea is to monitor and display each block voltage and auto disconnect the charger when any block reaches 4.2 volts. Less if you only want to charge to 80%, to lengthen battery life as with Tesla. Likewise turn of the load when any block is down to around 3 volts. To really balance a pack it is best to make sure each pack has the same Ah capacity.

I watched your video 10 times and I rephrased my question again. 1. I'm planning to build my first battery pack and convert to ebike, and you convinced me to spend more on good smart charger. I looked up iCharger 1010B+ but max output V 40 with 7 A, so by charging not to 42V but 40 V , I will extend my battery life. Please confirm that 1010B+ charger will be good for 36V 15 amp pack. What power supply would you recommend for this charger? I found Junsi 350 - Outputting 350W at 23A/15V. Will it be good? 2. If I get 10S charger but cell logger can only take up to 8s, can I connect 2 loggers 5 s+ 5s (not physically splitting the battery?????) and have extra port with JST-XH 10s for my 10s charger so I can charger my my 10s5p battery as one? 3. Mr. Jehugarcia, talks about bottom levering batteries, should I then go up on the charger and get PowerLab 8 to do both smart charging and bottom levering of the batteries?? Thank you a lot!

Completely agree with this approach, needs a wider audience.

You are just dripping with the goods around here. Thanks for stoking the fire to the next level!

Hey Shawn, great to see someone accurately describe those Battery Murdering Systems! One thing I would suggest though...you can reduce the effort involved in bulk + balance charging like this by just using a balance tap only charger like the BC168. Yes the balance leads/plugs are somewhat limited in current carrying capacity, but if you limit the charge rate to something reasonable it can and does work. I've been doing it like this for over 4 years now. Cheers

Sacrilege, you mean low quality chinese made BMS should not be trusted to manage your expensive batteries? thats not what the internet told me

Thanks Shawn. Coming from an rc background I didn't like the sound of these BMS units. You verified my thoughts and I will be using your charging method on my diy batteries. Full control and monitoring of the charge is the way to go. Hobby chargers have gotten so inexpensive too. Cheers

Thank you for this video. Good monitoring is much better than bad management.

Hey Shawn, this is the BEST anti-BMS video I have watched so far!!! I don't use BMS myself for the same reason as you, there's no feedback and I don't know what that little cheap and nasty PCB is doing. Most batteries (to not say all batteries) I repair have a problem related to a faulty BMS. The cheap ones don't balance the cells at all they actually KILL cells.. last thing you want is "a device that will unbalance and kill your battery". BMS also makes things unnecessarily a LOT more complex, that doesn't encourage people to make their own batteries! I made a pack with Panasonic PF back in 2014 and last time I balanced was almost a year ago, I run it hard 1500w every single day, guess what, almost one year later the pack still balanced. On the other hand I have many videos showing "how to install BMS" because from a bike shop perspective, most ebike users have absolutely no clue about electronics so in this case the BMS is more reliable than some humans. Congrats for this video, I will recommend to many people here when replying comments in my channel =]

What about if i use different brand cells in 16s10+p pack ? still dont need a bms ?

As an Electronics Technician, with many years of field experience (yeah, old schooled in TVs, who also keeps up to date on tech) I can vouch for this excellent presentation. I began watching the video and had to smile when you came to the point that BMSs do not provide any feedback of the state of the individual cells, therefore makes no sense to use them, specially when one cell goes whacky and the BMS shuts down everything. Thanks for putting it together and to the people who gave negatives to the video, you guys don't know squat about LiIon batteries and basic electronics.

That is really a great video. Very good Information. I wish I could learn this battery stuff. Thanks for posting.

can I buy a 24volt 30 amp + battery from you? how much would it cost?

Ok, so just to be sure: you can ''bulk charge both at the same time'' meaning you use the balance charger in another setting in order to charge? And then, when you want to balance charge, you separate the 2 packs and then charge them one at a time (assuming you have only 1 charger)? Thumbs up perhaps so people can see.

This is exactly what I am looking for. Thanks for the video. Subscribed :)

Hey man THANK YOU! exactly what i was wondering! Cant wait to check out your channel

Please excuse my ignorance, I don't understand how the charger or logger can see individual "cells" when everything is connected together in series. Does it do the math for you and work it's way out along the chain? Could you do the same with a multi meter manually? Sorry for the dumb question, this is all new to me. Is that batter pack both parallel and series combined? 14 long in series, and 5 wide in parallel? How does the charger target specific batteries? Does it bring everything down to the low water mark, and then charge from there hoping that everything will be even afterwards?

4.0v saturated cells are 80% charged. If that is not enough range then better to add more cells than to charge to 4.2v which stresses the cells and saturation cutoff is critical.

enlightening! Thank you. I like your POV

Thank you for the video my eyes are starting to open up no BS LOL have a great day Dennis

when you adjusted the voltage your hand covered it, any way you can re-record it with a better view please.

"tripple the life of a pack with a bms" this assumes all bms use the same balancing methods... they dont. "a better battery pack with out a bms" False. If you take the time to select the right components for your build ..and go down the path of an active balancing/charge redistributing bms... it will be better in any objective measurement of "betterness" you wish for two packs to be compared.

Shawn - this is far and away the best video I've seen on setting up on 18650 battery pack. I can't tell you how many times I've paused your video, taken notes and implemented into my pack. I decided to build a single pack broken out into 2 (non-mechanically). Specifically the harness to connect the two in series and the cell-logger wiring - great stuff ( I even bought the same balance charger but the 8 not the 10). The only aspect of the video which confuses me is the 8 pin Deutsch at the end (I paused and tried to count the holes in the plug). I have to believe this is an adapter for the 8 pin balance lead, in which the adapter connects the "sensor wires" (assuming you are referencing the cell logger wires) together to something else. I'm just not sure about that last part, understanding that the XT90 is the power lead. 16:30 of your video. Any illumination on that last bit would help.

A brilliant video! everyone thinking of going the diy route should watch this before doing a build. Hobby chargers a the way to go, its a no brainer!

This is an interesting concept! I learned a bunch from your video - Do you think this would work on something like my build on my page? Thanks -Kage

Watching this in 2019. Now you can get BMS with bluetooth and monitor cells(ebay and aliexpress from china) I'm going to assume that the BMS intended for 300 amp charge/discharge is going to have enough balancing capacity to handle an ebike no problem. There is stil the issue of the BMS cutting power mid-ride if it finds low voltage. Price is around 120 USD from china. I am waiting for mine to arrive. I hope it works well. They come with a flat aluminum plate as head sink on both sides of circuit because there are mosfets to pass current on both sides of the board. I will be mounting finned aluminum heatsinks using thermal conducting tape to both sides to keep the board cool. Solves a lot of complication, hopefully it works well and reliably. Thanks for reading.

Legendary video, have watched it several times.

Glad I stumbled upon this. As a “newbie” to this stuff, I couldn’t understand why BMS’ are held in such high regard when 90% of the reclaimed cells I have so far are good cells and bad BMS’ (it seems). My logical brain said “wait! what about safety!” But when I heard the little alarm go off? A little alarm went off in my head. I want to be in control, not a nameless, faceless (silent) BMS. Visions of exploding LiOns ...umm..exploded lol. Bravo! As I tell my customers, “ I like my smart devices to be smart when I want them to be...and very dumb when I want them to be. “ Your approach seems logical. Great stuff and pretty funny too lol.

FYI, BMS = Bristol-Meyers Squibb. Oh, wait, it is Benicia Middle School. Perhaps Blue Mountain State?

As someone with a electronics and communications degree Please do not and i repeat DO NOT make one of these on anything bigger then a 4 blade drone. The issues and DANGERS are very real on any none BMS pack after a certain size.

sir, you are a legend. keep up the work. so funny to watch you fiddle around. indeed hd quality vids has no chance on you

great vid ...just built a bms free pack took me hours but that fine it works great tnx

Took me a while to find a "cell logger". For anyone else like me they're called Lipo Voltage Monitor.

Battery Murder System

I've been looking forward to making a battery pack for an ebike conversion and I was initially going to try to find a high quality bms, but since I already have a hobby charger I thought I might as well use that and save some money. I'll be building a 12s 3p pack split into two 6s 3p so I can use my 6s charger.

Thank you, this is exactly what I was looking for. I suspected that the tiny resistors on a BMS were not capable of applying enough drain to actually balance the batteries. There's a reason the hobby chargers need fans to stay cool, and that's because they're dissipating off more energy as heat to actually balance the packs. I also really appreciate you showing how you wire the batteries to split them for charging as 2x 7S instead of one 14S. Hopefully now with EVs becoming more common, larger and better chargers will become available for charging 12S - 16S packs used in EV setups.

your I-charger cost more than the battery.

"Stay within a 100drths of a volt whether you have a BMS or not"..COMPLETELY untru. As a matter of fact the higher amperage you draw the more they will vary in voltage as they are discharged. "If your battery is perfect you dont need a BMS"..lol..what?..I make battery packs and use Panasonic NCR18650PF cells and I can tell you that after drawing 50 amps of discharge (burst) and an average of 25 amps continuous, they ABSOLUTELY do vary in their voltage and without a BMS the weaker ones in Parallel would hit 4.2 volts first and then get overcharged. Here's a hint; not all cells even quality ones are created equal!!. Of course the problem with using a hobby charger for balancing is that on the discharge side, the weaker cells will hit 3 volts first while others are at 3.3 or higher, and if you think that doesnt happen, then you have NO real experience working with these cells, and in my opinion this video is very dangerous.

Great video Shawn, I made an ebike last year using 10 x 6S 5Ah lipos to make a 48V 12S 26Ah pack and don't use a BMS. I charge using a Turnigy Reaktor 300W 6S charger in two sessions, and as often as possible from 300 W of home made portable solar panels, that weigh about 6 lbs, fit in a backpack and can be laid out anywhere. The pack is capable of giving 12kW of power, though I "only" use about 1.5kW, and that is plenty! I just made a couple of extra cells using 16 18650s per cell (~36Ah each) so it can cope with 30A and 50A burst regen, and now gives me 14S, though regen doesn't work until the voltage drops 1/2 an S, as I found out when I needed to brake the first time I tested it! Yes, I know the chemistries are different, but I charge them individually and make sure voltages are always within spec. (Just a note about XT60s / XT90s - lipos use the female type, so I'd recommend following that convention for compatibility). (I put a video up showing my pack, charger and solar panels on my channel if you're interested)

I can't say for certain, but I seem to remember some BMS units that have Bluetooth and/or WiFi commo that can do what the "loggers" do, and send the real-time data to your smartphone as you ride. They also had an alarm feature in their "app" that provided both audible and visual cues from the phone to the rider. ...and here I am talking about using an "app" when I have always warned about relying on any tech that REQUIRES an "app" to work for you...the fact there is no guaranty the "app" will be around next week and could be unilaterally removed from your phone at any moment without warning (company goes out of business, stops supporting it, to continue working it requires you replace your phone with one that has a newer version of Android/iOS, etc).

LOL i use to want to build an ebike but all this catty bullshit just made realize I'd rather die a man who still rode his fucking bike

I've noticed that people who smoke a lot of dope all act the same.

Really glad I found this video before I build my pack. I've gone BMSless and have no regrets so far (300 miles of riding so far, and ZERO Balancing needed using 280 used laptop 18650s). I'm waiting for a little 8s voltage display that cycles through the voltages of each series, it cost me a $1, that's the kind of feedback I want.

Awesome video It answered so many of my questions as I discover ebike batteries thanks heaps.

Super shawn, the concept is easy and you got at very reasonable costs a perfect picture of the state of your battery packs. I ll order some low voltage buzzers and this Icharger (for 6S) and will refer the results happily when finished. Thanks a lot. I was about to buy an expensive BMS 12S ... but know I ll go for your genial solution of the charging problem.

Shawn, I have a 400 amp x 12v Li battery in my motor home and its playing up, you gave me the idea of opening it up and seeing if that is the problem, thanks mate

You are the berries! I love the presentation! Thanks!

i've been thinking about this for most of the day today. it must be possible without the BMS. ZACK! now I have seen you....many thanks and greetings from germany

I learned a lot in this video. Thank you so much. Very well done. Ron

Thank you. A very helpful reply.. I feel much better now I know I don't need to rebuild

Exceptional info. Thanks !

Many thanks you saved me from a costly mistake.

Thanks Shawn , very good video , logical and well explained .

Great thoughts on this! Thank you sir..

Very comical but great info. I know Jehu doesn't use a BMS on his EV van so neat to confirm when you can charge responsibly without a BMS. Thank you kindly for sharing even though it was a couple years ago - just seeing it now :D

Well sir, you got my attension. Cheers and have a good one :)

great vid. Helped me better understand a few different concepts I was kinda grey on before

This is the best battery pack video I have ever seen and I have these chargers anyway god bless your common sense

So glad I found this Video. Working on a Chinese 100w scooter and swapping the Lead Acid battery with 18650's. This was really helpful because I had the same thought. I wanna know what my cells are doing and not just let happen till it fails. So thank you for this detailed explanation why not to use a BMS and what alternatives there are.

Thanks for sharing your knowledge & experience.

Really good information!

1st class info , thanx Shawn

Thanks mate, great explanations.

Awesome video thank you. I am new to the e bike world am working on my first build now. I'm a bigger guy and live in a town thats ALL hills so I want to make sure there is enough power to get around without over taxing the system. It first I just wanted low range (around 30 miles) but seeing what these 18650's are capable of I'm not thinking I want to be able to tow a small cart with additional batteries for a long distance trip this summer. I like that you monitor each group and you can turn them off to not draw wasted power. I dont have any experience so my concern is not knowing when to check them. can I run a bulk monitor to measure overall voltage or could I just leave these on all the time without too much of a net effect?

Thanks for reminding me to think from first principles.

I have been using this method since 2017 on all my battery packs on all my ebikes. Thanks Shawn. I've seen some comments about a newer type of BMS that replaces the need for this method of charging. If you are one of those persons please point me to a BMS that can limit a charge to 80% and balance at 80% as well. Ive seen bluetooth BMSs and have had one in the past but couldn't see how i could limit the charge to 80% and have it balance all at the same time. Thanks for any replies or links.

I like the way you think about modularity. The great cost for DIY EVs is the battery pack that gets luxuriously expensive when it gets bigger. The smaller packs are produced in quantity and get cheap. It's important to keep it safe though. You sound like you know what you're doing and I just wanted to reinforce to random viewers to know the risks and what to do exactly before attempting this. It looks like good BMSs talk RS232 and other protocols to communicate the monitored values (individual cell voltage and more) or even be programmed/setup. One could use that to talk to a microcontroller and display whatever is needed. These days there's Arduino enabling this for most people with time to spend on it. Not OOTB, I agree. Or just hookup the "trouble bit" to a dash LED and have the microcontroller/laptop setup at home for debugging. Not better or worse than the "Engine light" + OBD devices on gas cars. I like the hobby charger approach as it's pretty safe but I'm at 16S and it already got somewhat cumbersome to manage daily charges. I made a 16 Ah pack out of Multistar 4S bricks. Currently charging on a unbalanced charger for the whole pack, no BMS but only because the pack is new and I monitored close per cell voltage in the first 5 cycles. I'm installing a higher end BMS in the next month or 2, so when they age the BMS will shutdown if something abnormal happens and I can connect to it and see what's wrong (or check the pack manually). I made my pack removable exactly to make this sort of maintenance easy. But yeah, not too surprising that the cheap BMSs do a bad job -- we get what we pay for.

Thank you for posting this, very informative!!!

Excellent video, thanks!

Totally agree I had a battery that didnt have capacity. The problem was it become unbalanced, and after I balanced it, the battery was good again. Thank you alot

EXCELLENT VIDEO !!! I HAVE ELECTRIFIED MORE THEN 30 BIKES AND I AGREE 100% WHAT YOU SAY !!! THANKS FROM ITALY !!!

6 yrs later and this is still a good idea

Epic video, this same I do with used 18650 cells

I spoke of using step down modules that i can use to charge each cell individually rather than use a balance charger but thats a lot of plugs to connect when you have a 16S pack. However you don't need to balance charge each time. I usually balance charge every 3 or 4 discharges. Otherwise i charge at full voltage of all of the cells in series. Then it's only one connector to plug in.

I'm happy I ran across this. I was looking at new drill batteries, and wondered if harbor freight's battery chargers had the bms, instead of the batteries based on the amount of connections on the charger. It would make the batteries cheaper too.

I confirmed your conclusions the hard way. After failed bms after another, was heading back to the Imax. I will be splitting my 10s packs into 2-5s. Thanks!

I like it! Thanks for the informative video, Shawn. What model are those battery loggers? How many charges do you typical find you go between balancing sessions? And lastly, is there any reason one can't bulk charge a pack with a standard lab/benchtop power supply (eg a 14s7p pack with the supply set to 57V (~4.1V/cell) and current-limited to 2-3A). I have plenty of power supplies at work capable of that. It seems like it'd be fine, if I'm sticking to 4-4.1V. I'd likely charge at home with a normal charger, balance as needed (monthly?) and charge at work with the power supply. Sound sane?

Enjoyed the video! How would you set up a 60 Volt pack? Split it into 3 - 20V sections or 2- 30V sections?

Awesome stuff bro...my battery tipped over and hit the concrete, I couldn't fault any cells so bypassed the bms...better power now and I just keep an eye on the cells after every 5 rides

awesome... thanks for sharing :)

Cant wait to try this

I would put money down this guy is right, you don't NEED a BMS, but I am cringing thinking about the number of wires on any of his bikes. A quality BMS could be used with one of the battery log devices to keep the feedback loop. Absolutely deserves a thumbs up for the video and for leaving an email address! Nice work, great video!

Great info. Thank you.

It's a very nice setup. I also chose this solution for my ebike ( 20ah / 72V ). The only problem I experienced is that when you parallel balance leads toghether you lose track of each single cell. I had a bad cell and I didn't recognize it right away so I ended up screwing all parallel cells on that pack.