Does a BMS charge my Batteries? (MEHS) Episode 57

[@chrisharvie-smith486]

3S cells all see the same current. 1 Amp is not divided by three for each cell. Volts are but not Amps !

[@michaelsstuff4402]

OMG I just realised what I said. I really was having a bad day. Yes of course you are correct. I will add a correction or maybe take the video down. Thanks.

[@youradvertisehere]

@@michaelsstuff4402 even though it is still not exactly constant current, would you consider this circuit to be a usable charger for cells with 1-1.8ah?

[@michaelsstuff4402]

@@youradvertisehere - Hi. These BMS will allow current to flow to the cells but they really only stop over voltage and current. The cells will receive charge but it won't be peak and it won't help the cells last a long time. If the cells are cheap and your not too worried about costs and lifespan then it will work. If you wanted to do it better in a 3S or 4S configuration I would put a MAX745 in the mix as the dedicated charger. If you're using 1S or 2S then the TP4056 or TP5100 boards are a better option. Cheers.

[@rosekreuze]

how about the batteries in parallel, 3s 2p in exact. does the amp divided on each battery? also a follow up question, i have alot of 18650s i tested around 4 to 6 wh (1000-1500 mah) when i discharge them with constant 0.3 amps each they're good and able to retain the same readings last time i tested. but when i discharge them 1 amp or more they instantly shuts down at 3.6v. if i rest the batteries less than a minute before plugging them back to my charger they're back at 4.0v. are these bad batteries?

[@michaelsstuff4402]

@@rosekreuze - Yes I would say your cells are bad or are very low capacity. A good cell will easily deliver a constant 1A. I have quality cells that delivery 4A each without issue.

[@parsipax6337]

been really looking for such an educational video for this bms, lack of which disappointed me, happy to find your video, awesome!

[@ratbler]

EXCELLENT work! I've seen too many KZbin "experts" who aren't. MEHS clearly has technical mastery of his subject and presents the information in a clear, understandable delivery.

[@michaelsstuff4402]

- Thanks Bruce. Very kind. Cheers.

[@ratbler]

Dear MEHS, I've built a charger that works for a 6-cell 18650 battery pack to run my Makita cordless drill (3 pairs in parallel, the whole set in series to get the 12 volts). I charge each parallel pair with TWO TP 4056's in parallel. I can't seem to send you the schematic here, but my question is this: The setup seems to give a full charge to the Li ion batteries, but I don't have undervoltage protection when using the drill. The video you did for Episode 57 mentions that, though the board does NOT give a full charge to the batteries, it DOES provide undervoltage protection. Is there a way I could use the board featured in Episode 57 to provide undervoltage protection and use my circuit to provide full charge? Thanks for any thoughts you might wish to share. Bruce Ratcliffe, self-taught electronics teacher, Edison High School, Fresno, California

[@michaelsstuff4402]

- Hi. This can get tricky as you need to watch out for the common ground problem when connecting multiple tp4056's together to something. The grounds become common and one tp4056 ends up doing all the work and overloads. That aside you have 2 options. There is a version of the TP4056 that has a BMS built in. Its a little longer than the plain version but it has under and over voltage protection on each board, good option. The 2nd option is to connect each 2 cell pack to a 3S bms. Again watch out for common grounds but you could get the 3 packs connected to a single 3S BMS with 20-100 amp rating and end up with a single 12V pack as you described. If your not charging while the pack in connected in this 3S configuration then you might be fine with the common ground problem as its normally only an issue when charging through the tp4056 boards. Cheers.

[@IRONMANMETALBILLDANKANIS]

This is the video I've been looking for. Thank you.

[@AdminTuber]

1. if you measured the current from your PS - then 1A goes to all of them - each get 1A - it does not split (the voltage does) . 2. getting the optimal charge has nothing to do with what you say .. you must wait until the charge is complete and the current deops to zero (not close to zero but zero) - to each cell . then discharge and check how much capacity they got ... I guess I will just need to do the test once I get my BMSs.

[@michaelsstuff4402]

- Hi. Yes I noted the mistake a while ago regarding the current to each cell. I think my point is valid for the charge going to each cell mostly because this board is a battery protection board and not a battery charger. It does not have a proper charging IC. The charge going to the cells through this board is a rough charge much like charging a lead acid battery. Cheers.

[@sachinmehrafitnessworkouts5282]

Hi can you pls tell me do i need charge controller..if i am using BMS on 3s3p lithium ion battery...and do BMS comes woth PWM

[@ehtcom]

The current is the same for all three cells, the voltage is divided. (Learn ohms law) So 1 amp for each cell (not 330ma)with the voltage slowly ramping up to 4.2 volts across each cell (12.6v across the three cells).

[@theopendoor3716]

I agree. This is correct and the video needs revision accordingly.

[@jaspanackal]

Can you provide a proper charging module eg ( XL4015 ) ?

[@andykay479]

The problem with charging a Li-Ion battery pack the way that this particular board invites you to do is that it doesn't guarantee that each of the cells receives an equal amount of charge. So even if you limit the charging voltage to 12.6V (3x4.2 since exceeding 4.2V is a fire hazard), you may be charging one cell to 4.0V, one to 4.2V, and one cell to 4.4V (fire hazard!). To put it another way, this board does not BALANCE the cells. Some boards claim to balance the cells but I bought a 7S board that cuts off the charging current when the first cell reaches 4.3V (a little high for my comfort but not excessively so), leaving all the rest of the cells below 4.3V, and so does NOT balance the battery. The only problem this gives is that the full capacity of the battery is never realised, but I wonder how many people have bought this particular board and take it on faith that it performs the claimed balancing function. The moral of the story is never take the seller's claims on faith... always test.

[@michaelsstuff4402]

Andy Kay - Test always, agree. The only difference here is that the potential over voltage problem you mentioned is mostly mitigated as this board does cut off the voltage at each cell if the individual cell voltage goes above 4.25v. It's abrupt but it does work. Cheers.

[@andykay479]

Sounds a lot like the 7S board I bought and tested then, except that with mine the advert claimed a balancing function (which it clearly doesn't have if it stops charging the battery pack when the first cell reaches the over-charge cut-off voltage). Incidentally, this arrangement would make it an ideal board if you prefer to bottom-balance your cells and then leave the rest to the BMS.

[@squee222]

Generally BMS ballances on discharge by shunting the excess voltage battery to either a resistor or to charge the lowest voltage battery - this is called "bottom ballancing" and is far cheaper to implement and safer than balancing on a charger. As such - yes you never reach the full potential of the pack, but the battery pack will last many more cycles on an 80% charge than a 100% charge.

[@andykay479]

As I understand it, a BMS balances on the Charging cycle by discharging any overcharged cells through resistors -- this is called "top balancing". "Bottom balancing" entails Discharging all cells to the same low voltage and then charging the entire pack (rather than the individual cells as a BMS would). Bottom balancing ensures that all cells reach the same low voltage at the same time during the discharge cycle, preventing the rest of the pack pushing charge through a cell that has switched into a mode where it needs recharging (this would be bad because at the point the cell wants to go into the charge cycle, forced continued discharge would destroy it).

[@volodumurkalunyak4651]

Top or bottom ballance, you still are limited to cell with the lowest capasity. BMS should cut off if ANY cell is over- or under-voltage. Top ballancing has a 2 advantages - 4.2V charge voltage per cell (with even proper CV phaze in multi-cell battery) and slightly higher total Watt-hour capasity (1mAh at 99% SOC is more than 1mAh at 1% SOC). In cabe of bottom ballace if the charger does NOT maintain CC-CV at highest cell, end result will be skipping the CV phaze, losing from 10% to 20% capasity alltogether.

[@DescubreAntigua]

I have one of those, it "works". It charges the batteries quite fast (diff brands tried) but never reach full 4.2V, mine gets them to 4.11. In full detail: measuring each cell independently it goes up to 4.23 but when charging is cut, the batteries are only 4.11, so the previous reading is not just the battery. It works fast, I like that, but after many tests I know it doesn't get them at 100% of charge. It's fair to say there are different brands and PCB colors for this same circuit, so not all of them will behave exactly the same. I read comments regarding the input charging voltage but in my case it made no difference using 12V and up. It's not a full charging circuit. Yes it will cut the charging and discharging but there is no way to know if the batteries are charging unless you plug your meter. A one or two color LED would be a great addition but there is none. The only reasons I'm keeping it is because it charges fast, faster than my other 18650 chargers, but I know IF I want 100% charge I have to move the batteries to the classic chargers, this one will never reach the 4.2V, it doesn't matter new or used batteries, or brands. But as said, that's mine, yours might work differently.

[@mutthunaveen]

Thanks for sharing man... Is there any resistor to tweak and correct it?

[@irapashunnur8237]

I made a circuit, with (3 Batteries + 10A BMS & XL6009) - working fine. Buit, the battery voltage is dropping automatically even if the input voltage is ON and is 12V. Why the battery voltage should drop ?? Where could be the problem ??

[@sk.sourov]

Finally a video with the answers that I was looking.

[@parsipax6337]

could you also test the balancing capabilities too? will they be balanced if each battery was at a significantly different voltage?

[@parsipax6337]

what do you think about a ptc to limit current on these 18650s or any polymer battery, is it a good idea?

[@lua-nya]

What made you think the intensity is being spread when they are in series? You're not doing any parallel, are you?

[@renmaru4485]

This is the video i was searcing for. Thank you so much

[@michaelsstuff4402]

- Thanks for the feedback. Don't forget to take a look at the other BMS videos I did for more detailed information. Cheers.

[@stephensomersify]

I'm not clear from the outset whether 3x cells are series or parallel (I reckon parallel) I was looking for info / guidance on how to charge 3x in series - at 12V supply

[@MrCharlieCom]

I think your thinking is flawed on this one. 12 volts x 1 amp = 12 watts of charging power total. But your three batteries are charging at basically 4 volts. So that's 4 volts x 1 amp per battery = 4 watts of charging power per battery. 4 watts x 3 batteries also equals 12 watts of charging power. So then your batteries are charging at 1 amp per battery not 1 amp divided by three batteries. You should've put the amp meter between a battery and the BMS circuit board to find the charge current for that one battery.

[@ca5ualm3dia]

so what are these used for, how do people charge their battery packs , i need a bms where do i get one ?

[@CarolinaCowboys]

What if you use a CC CV step up instead of a laptop power supply?

[@john-sw1nu]

Do you know if I were to build up multiple 3s battery packs using the BMS you are reviewing 2:31 mark could I wire them in parallel to my load to get a longer battery life?

[@u201120966]

then how can a lithium battery pack behind a bms be charged? i am new to this

[@airrondelacruz]

Hi. Ive been working on many 12.6v battery packs for my speaker maker customer. He complained about after a week of use, the battery pack suddenly not charging. We're using 12.6v charger power wall directed to the charge input of the bms. But they suddenly not charging. I've been seeking a solution for this in a long time. But i dont see any. Please help me

[@pault6533]

Thanks for the information. @4:36 Why are you dividing the current in three? I understand energy should be conserved, not amperes. If you supply 12V 1A (12W) then each 4V cell would get 4V 1A (4Wx3) at 100% efficiency and equal charging. I generally agree with what you did, but I think to be accurate you would need to monitor each cell. If 5A was actually supplied, your cells would likely get very hot! Depending on the cell size, it might be necessary to control the input current.

[@skullandbadbones]

You’ve only hooked up to cross current charging circuit. That circuit is only used for load leveling it is only supposed to run at low amperage. You didn’t hook up the main leads. You’re using the BMS incorrectly. The charge circuit would take all 5A if you did.

[@JayCras]

I'm not sure this is correct. Certainly your brick be it 5 or 50 Amps is only going to deliver the amount of current the BMS draws. As to voltage no charger external or using the BMS is going to take a dead battery at 3.2 volts and instantly have it raise up to 4.2v correct me if I'm wrong? As to the maximum charge per cell versus what your seeing (Lower but still ramping current down as the voltage is kept the same) I think instead of concerns of fire you really only have to consider the time to charge. If I use your BMS to charge with a Lab Supply on a 3S battery I see it taking 2.x amps for the strong part of the charge curve (Where you have charged up the battery to 80 something percent then the charge drawn from the supply goes down just as it should until the battery is topped off and then charge current is as near zero as I can measure. What do you normally do to charge? Are you using an external charger like a Wissblue LCD-4? Note that on this charger you may select 0.5, 1 or 2 Amps of charge current so I'm pretty sure it not only safe but probably extends the battery life. If your removing the individual cells to put them into a commercial charger whats to be done with people spot welding say a 4 S(eries) pack to the BMS which I think is the norm.

[@christophertilley4297]

Alright. I'm convinced this video needs to come down. Too much conflicting information to be useful or even safe.

[@johnhoeppner1569]

These types of BMS protection boards don't actually charge Lithium batteries, they prevent charge over-voltage by disconnecting the charger from the batteries when any battery in the pack exceeds a preset max voltage (approx 4.2V). Because the BMS board doesn't control charging current, your external charger should be a constant current source or at least current limited to less than the maximum charge rate of the Lithium battery type connected. And because the charger and the load are connected to the same point, it can get tricky if the charger must power the load and charge the batteries at the same time. The charger output current should be greater than the load requirement but less than the load current plus the maximum charge current for the specific battery used. Another issue: when the circuit senses over-voltage and disconnects the charger your load voltage can suddenly change. This might be OK but could cause problems in some applications.

[@valleynomad]

BMS by definition doesn't control the charge current and voltage. It only monitors the status of batteries and take action for protection when something goes wrong. So question is not whether a BMS charges the battery. Rather, it should be whether a given BMS works well with a specific battery charger...

[@MilesPrower1992]

so if i had a bms and i just hooked it up to 12vdc and i controlled the current , it would keep the cells balanced and wouldnt let them overcharge?

[@rafailpeikos2070]

I wanna charge a Park 12A2 Li-ion battery (18650P 3×3,6V BSB connected) with an AEG charger AL1214G. The manual of AEG charger refers charge times for Li-ion too, the voltage when charging the old 12V Ni-cd (10cells of 1.2V) was at least 14.2V. Can i charge the Park 12 A2 battery with AEG 1214G charger? Can BSB handle the 14+volts without damaging the batteries?

[@michaelsstuff4402]

Hi. It might work for a short time but that charger does not charge in the way lithium cells need to be charged. I would say use that charger as an emergency only to put a little charge into your cells, otherwise avoid that charger. Research how lithium cells need to be charged (battery university) and start there. Cheers.

[@rafailpeikos2070]

Thank you very much for your reply. I studied the problem in depth and it's more complicated than i thought. The Parkside charger is at 12,68V while the AEG charger at 14,4V. I don't know if the BMS can tolerate the extra voltage and moreover the Parkside charger uses a C- pole instead of the - pole when charges the battery...It's risky and dangerous to do it, so i won't try it.

[@viswanathanramakrishnan7613]

I saw your this video. I am now planning to replace the nickel cadmium cells which were put in series ( no BMS is added in the circuit) and after 2 years the charging couldn't hold which makes me to charge again and again frequently; hence I thought of going in for replacing with lithium ion batteries of 3.7v/2000mAh capacity in 3s/4p ( 3 in series and 4 in parallel) for which I have 3s/20amp BMS board. The rated capacity of the drill is 12v/48 watts please suggest me the charger specifications for this set up. The charger came alongwith the drill is having 13.1 volt/1 amp. Shall I use this for charging after constructing the battery pack as 3s and 4 p setup? Your answer will help me in saving lots of pains to me before starting to do it. Also kindly let me know the parameters to be observed before designing a PS for the drills and other equipments which are sold with nickel cadmium cells.

[@_.trappedinpixels._]

Hay I used a 12v power supply to charge the battery pack (with BMS) but the power supply bursted after an hour. Can I please know how can I avoid it?

[@prakashsuryawanshi6211]

2s8A. BMS 2 battery Can I charge by TP 4056 module, if yes please show me wiring diagram This 2battery's pack use for cordless drill machine 7.4volt Please give me some suggestions

[@allinthefamiliy3122]

I have a question: what component determent the Charge current on a BMS. If I want to charge with 2A can I change that on the BMS or is that a BMS Control chip specific parameter. hope someone can telle me.

[@parsipax6337]

I can't tell a man with that much equipment he's wrong, but there's three batteries in series and it's given 12 full volts, so isn't that 1A going to each cell, and no split (0.3 amps each)? just asking

[@nlo114]

Thanks for the vid, it provides the info that I was looking for. I realised your error on the current-sharing bollocks at an early stage, so turned the sound off and watched the meters. Apart from the initial current-surge, the bulk charge is within spec +/- 10-15%, so for a commercially available cheapo it is great for hobby-use. Might be worth re-doing the test from flat to full. Also watch out for fake 'ultrafire' batteries, there are a lot about.

[@charlschuck6]

That sucks to know and I was about to do a project, I wanted to use or more like make a solar 3s just for a super small led for night usage I’m currently using acid batteries , but they suck at taking fast charge only .5- .7 amps per hour and battery is 4AH -12volts . Where I have used lithium with no bms and they take their 1c rating like nothing well and I have smart charger they work perfectly with out bms but when it comes to charge them without that bms in solar panels you can’t it’s not ideal, and you can’t really use a bms board and at the same charge it some bms won’t let you do that . Where in an acid you can charge it and use that battery . Any ideas what can I do ?

[@haerospace2475]

There must be some 2v or 3V difference between Max BMS voltage and charging Voltage. For example my system is 62V~64V- solar panels connected directly to a 14s BMS, and it works perfectly as a charge controller because the Panels have always a slightly higher voltage than the full charged battery-58.6V.

[@shmuelnaarai677]

Thanks for the coaching Sir. What would you recommend for a 5s(18.5v) powertool battery pack? I need to replace 2 packs which aren't available aftermarket. Each pack has 5 x 18650 @2700mah each. The power tool is rated for 18.5 volts. thanks and Regards. Shmuel.

[@skidkev6421]

So does this means I need to use a charging module along with the bms?

[@DheerajKumar-dk747]

What difference between BMS vs TP4056 and which one is better to use with 18650 lipo batteries?

[@michaelsstuff4402]

Hi. A TP4056 standard is a charging IC for a single cell. A BMS is a protection circuit for any number of cells that doesn't actually have a real charging circuit. A TP4056 with a protection circuit will charge and protect 1 cell. A 3S BMS will protect 3 cells connected to the BMS in series but doesn't actually charge. Cheers.

[@eva2k0]

What do you recommend for charging larger lithium ion packs like 12S5P. I'm building one for an electric skateboard and was planning to use a BMS. Would it be better to just plunk down the money for a proper lithium ion balance charger? Do some BMS work better than the one you're using?

[@michaelsstuff4402]

- Hi. Heaps better to spend intelligent money on a quality battery charger. Considering the cost of good batteries and the number you're suggesting I would suggest a good charger over a BMS every time. You may still need a BMS if you don't use protected cells in order to catch the low voltage point of the cells during use (the BMS will stop draining the batteries at the 2.9-2.5volt mark) which is desirable.

[@PunakiviAddikti]

I bought a BMS for li-ion packs that is designed for also balance charging the pack. In fact, it looks almost identical to that one, but the PCB is green. If I disconnect the BMS and recharge the pack and then reconnect it, the BMS won't re-engage until a voltage is applied to the output wires. It seems to be the only way to recharge the pack by design, you can't disconnect and recharge the pack manually.

[@bibibiskouaz5867]

Your conclusion is that a BMS prevents over charging, over discharging (so avoids the worst) but do not charge correctly the batteries to used it full potential. Based on this, if your 4s pack of batteries is going to remain inside the equipment, can you have a 4s BMS inside the equipment (for controlling the discharge (V and A), possibly controlling the charging (even though it does not do it correctly when connected to a basic power supply) and have a set of 5 wires going outside (with standard 5 pin connector) for a clean external charging via a more sophisticated charger? To put it another way, is there a risk that a BMS interferes with an external Lithium Ion Batterie charger.

[@michaelsstuff4402]

- Hi. What you're describing is possible. It would depend on how everything is connected. Say you had a BMS and the 4 cells were connected to that BMS. Most BMS (I can't say all) would not care that you are bypassing the BMS and applying charge to each cell individually. In this configuration the BMS probably won't give any protection but that should be fine if you're using the sophisticated charger as you mentioned. The only possible complication I can see is if the BMS is active because the pack is being drained by the load (the project is turned on) and the BMS IC doens't function as expected because of a common ground issue or false signals because of the external connections. if you're external charger is not connected to the project (or cells) when the BMS is in operation (because the projects is turned on), then I think you will be fine. You should always do testing on a project like this to make sure everything works as expected and is safe. Cheers.

[@bibibiskouaz5867]

Yes it makes sense. I will do some trials. Many thanks for your quick and kind answer. And thanks for your nice videos.

[@christhorney]

i know this is old, but when your charging in series, a 1a load is 1a per cell, if you were charging in parellel then yes yeah bank of series would be getting 0.33a per cell, but because your charging in series at the total pack voltage, 12v to make it easy, at 1a your charging at 12w, if you were to charge a single cell 4v at 1 amp thats 4w, 4w x 3 cells is 12w, so they are each seeing 1 amp my dude

[@noweare1]

This was an interesting video. I wished you time lapsed the video until the current started dropping. Like you found out the 1 amp was charging the 3 cells so there was still a lot of charing going on. At some point the cells would of reached 4.2 and the current would drop off dramatically (if the bms worked as such). Then you could say that the bms although not perfect is pretty close to what a charger designed for Li-Ion batteries would do. In your video about the bms you kept mentioning it as a charging board also which is mis-leading. I am glad you made this video and set things straight.

[@robzetxnoname9785]

Do I need to add balance wires and plug in my imax b6 mini then charging my 3s bat.pack useing that bms?

[@michaelsstuff4402]

- Hi. Yes. For the B6 to work correctly it will require access to each cell directly, not through the BMS. Cheers.

[@RoyAndrews82]

It guides and monitors the charging. The charging is done via voltage and current.

[@jj-jo6wr]

what the input voltage? does any input voltage affect the output at all?

[@bryantull7596]

So what kinda of board could I use to charge a 4S Li-Ion pack without the stand alone charger used in hobby type applications? Would there be any way to get enough amps/volts from the USB 3.1 protocol of 5V, 2.1 A?

[@bryantull7596]

Would it just be easier to get 4 of the TP boards and wire the power supply in parallel to each board. Allowing one board, one cell. The 5V from the USB would be shared to each board and the 2.1 amps divided to each giving a charge rate of 500ma

[@michaelsstuff4402]

- Hi. You must have peeked at my next video as it looks at a very good lithium charger that can do 1-4 cells in series. Coming very soon. No you won't get enough total power out of a USB C or 3 / 3.1 port.

[@michaelsstuff4402]

- Hi. No you can't use multiple TP4056 boards unless you have complete isolation which would mean independent power supplies for each TP and a way to isolate the ground from each when you connect the cells in series for your combined power output. Very tricky especially with 3 or more cells. Take a look at my latest video on BMS and lithium cells to see what I'm talking about. Cheers.

[@TheFoxranger]

I'm a bit confused. Will a BMS + constant voltage constant current power supply balance charge my battery ?

[@michaelsstuff4402]

Hi. To get a balanced charge to each cell in the battery you would need to use a balanced BMS. Many, like this small blue one don't have balancing. Physically a larger board. Cheers.

[@TheFoxranger]

@@michaelsstuff4402 I was wondering if it exists. Thanks a lot for the information ☺️

[@akisakis9397]

hello i want to make battery pack 18650 6s 22.2v my battery its 5.6A so its better to buy bms balance 8A or another 60A ? the A of bms what use it ? for battery or brushless motor because i make a electric skateboard

[@michaelsstuff4402]

- Hi. The A stands for AMPS and you will likely need the 60A version. Cheers.

[@Sam-hj5ok]

What if it's 16 cells in parallel( so a 3.7v output)

[@zyghom]

@4:26 - I think you made a mistake: it is NOT shared current as all batteries are in series so current is equal for all of them - unless, BMS really splits and maintains INDIVIDUAL current for each of the cells - in that case mea culpa ;-) We don't see the Power Supply voltage but considering it is constant 12.5V with 1A it will be 12.5W consumption (and dropping with the time). So it cannot be 300mA per battery, why? Battery has 4V now, with current 0.3A it is 1.2W consumption per battery, times 3 = 3.6W for all 3 of them. So how is 12.5W consumed by the entire system (12.5V + 1A) versus 3.6W (as you said: each battery is third of this 1A)? I bet you made a mistake but I am wondering ;-)

[@1112223333111]

so wheres the constant voltage part with 150ma?? big waste of my time here

[@jwb3034]

My BMS stop providing a flow of current after voltage down from 28 v to 23 v with a battery pack of total 28 cells. I am planning to drain all cells out and do recharging to the full again but BMS doesn't allow me to do that. Upset but don't know how I could do that. Any help? I like your videos, they are great.

[@michaelsstuff4402]

Hi. 28 cells? Do you mean 28 volts? Remember each lithium ion cell is 3.7v nominal, 4.2v fully charged and a BMS should stop the discharge between 2.8 and 3v per cell. Cheers.

[@PupettaZoccola]

i've tryed to upgrade a ridgid's battery pack by 2200mah to about 6700mah 18650 panasonic ncr18650, (2 pair for 5 in series), when i started to use a brushless drill i've had no problem when tryed a brushed tools the same battery pack stopped to work. To enable the battery i insert into owner charger and all back like before, what i have to think bms problem with the brushed tool Thank you vey much

[@Ziplock9000]

I've just done some tests on this board. If I have 3 cells, 4.1v, 3.33v, 4.18v and start charging, as soon as one of the cells (the last one) hits ~4.26ish it cuts off charging for ALL of them. While I understand this is not a balance BMS, I thought the behaviour was that it only cut off the charging on the individual cells that are already at max and continues with the ones that are not (the 3.33v one)? Is this the experience you're having?

[@budmartin3344]

I have the same result too, I guess I need to get one with Balancer function too.

[@Ziplock9000]

@@budmartin3344 I did quite a lot of testing here and found the board to be completely useless for anything really: facebook.com/pg/StockysElectronicsProject

[@DrZipZwan]

Even with a balacing BMS it is ging to be close to the same result!! Likemost people, I though I could plug 3 x 18650 to those BMS type and get a 12v pack, and then when it is empty plug a 12v charger and then it will charge. It is more complexe than! There is 2 option here: Option 1- Get a special wall charger for 18650 battery, they usually are rated to work with the BMS you installed in you project. If you used a 3S BMS, so you need the 12v version. Those wall adapter got an small led on them, and they are kind of smart, they cut ff once the BMS is charged at the other side. Or Option 2- Get a charger Board for 2S or 3S, and add it to your project, ad then plug a normal 12v charger. Explanation: 3x 18650 connected to BMS >> Charger Board >> 12v. If you do some reading you ll learn that a BMS is just a protection board for the 18650 batteries, not a charging board!! Electronic words have been made very banal , as result people are confusing everything...

[@projectnemesi5950]

I know its been a while, but adding an active balancer will eliminate this problem. The charging will slow down somewhat, but it will be way faster than a balancing bms. People have added an active balancer to a passively balancing bms without much issues. Some people turn off the balancing functions in more advanced bms, but a basic resistor based balancer should have an insignificant affect.

[@squee222]

where did you get the 25-30% number? Any calculations or did you just make that up?

[@michaelsstuff4402]

- Hi. Rough calcs based on initial observation from a couple of run throughs. It does not consider the possibility of a bad cell throwing out the results as was the case here. The average result was that the cells charged through the BMS were very well charged but not properly meaning they had a good runtime per charge but won't last as long (replacement cycle) as properly charged cells. Hope that helps. Cheers.

[@FullSendPrecision]

Maybe because those ultrafire cells are only good for about 500mah's in the first place?

[@gigiogigi5148]

I have a question: if use BMS can I change mu Pbgel 12v 9Ah battery on my UPS with li-ion 18650 pack?

[@michaelsstuff4402]

- Hi. That would be nice but no you can't. The BMS will tie the cells together but the UPS charges the lead acid battery differently to what we need to do for the lithium cells. In this example it may work for a while but the charge method would shorten the life of the cells considerably. Lead acid batteries are much more forgiving and can be trickle charged which is why they are still used in UPS. Cheers.

[@gigiogigi5148]

Thank you very much.

[@michaelsstuff4402]

- Hi. Yes that's a nice build. It's worth noting that he didn't just use a BMS. The main addition that makes it work is the lithium charger running at 12.6V and probably following the correct charging methodology. The lithium charger feeds power to the BMS which supplies power to the cells. In that instance the UPS build is working just like a laptop with an integrated battery. When external power is available the UPS battery is charged (correctly) and the rest of the power is being relayed to the inverter and the (nice) printer he was using. When external power is unavailable the relay switches back to the UPS as the power source. Again, the key is the additional of a proper lithium charger charging CC then CV at a max of 12.6V for the 3S pack used in conjunction with a BMS. Cheers.

[@PrajwithUllal]

I hope a buck boost converter connected between power supply & 3S BMS by setting it's CC (1A) & CV(12.6) can charge these battery safely. What u ppl think?

[@IamPrakashRanjan]

Can charging be done while a Load (live/active/running) is connected?

[@michaelsstuff4402]

Hi. Yes if your power supply has sufficient power to run the project and spare capacity to provide power to the cells without them being drained. It will depend on your project wiring too. Also, its not ideal as cells can become stressed which shortens their life expectancy. Cheers.

[@arn_abs8882]

A very informative demonstration. I think we need to apply a little more than 12.6 V to charge the single cells to 4.2. Hopefully the BMS has a cut off mechanism, if voltage of single cell is over 4.2V.

[@michaelsstuff4402]

- Hi. Yes the BMS has a cutoff and yes you are correct, there will be a slight loss through the circuit meaning the cells might only receive 4.18V each (as an example). Cheers.

[@neogator26]

Great explanation!

[@sudipdhara8752]

Tell me one thing. You are using 12V power supply to charge, right? Whereas the full charge voltage would be 4.2x3 which is 12.6V. How do you expect the batteries to get fully charged?

[@michaelsstuff4402]

- Hi. Yes good point. I set my power supply to deliver 12.6V so I can get a full charge but a basic 12V supply will still deliver 4V to each cell and that is satisfactory as that still gives about a 75% charge. The cells last much longer that way too. Cheers.

[@kumardeepam]

Hi Sudip, I have built a 3 battery pack with a BMS. It's working great so far. My worry is I have no clue how to charge the pack once it runs out of charge. Would you be able to help me?

[@codebeat4192]

Weird conclusion because when I use a TP4056 board, current drops when near to complete charging, cannot spot a difference. When the consumed amps is nearby zero, the battery is fully charged. I think that is pretty normal, as it should.

[@MarshallSmith27]

I didn't realize I've been charging my batteries wrong this whole time. does anyone have a link to what I should be charging my 4S 16.8v packs with? I'm totally lost now

[@michaelsstuff4402]

- Hi. If you take a look at some of the other BMS videos I introduce the MAX745 IC on a ready-to-go board. It is capable of correctly charging 1 to 4 cells through a BMS. That is probably what you're looking for. Cheers.

[@mohamadmisto8909]

can i know how to voltage balance before charging those batteries directly after getting them out the laptop battery ? placiing them in parallel for a night would do the job ? thankyou

[@michaelsstuff4402]

- Hi. Yes you are right. Placing them in parallel with a decent low resistance connection (thick wire) will do the job. Cheers.

[@mohamadmisto8909]

1 more question pls, can i charge those batteries(after being sure they're not dead) 1 by 1 by the tp4056 chip(cant afford more than 1 tbh it costs 5.7$ for each here and even its the old version) and then use the bms circuit for 4 of them and use them as a portable battery pack ? would that be enough ? thanks in advance again

[@michaelsstuff4402]

Hi. Yes that would work fine. Basically make yourself a single cell charger using the TP4056 board and charge each cell up individually, then add the charged cells to your battery bank. Cheers.

[@FSHerrante]

Now you can buy equilibration modules (balance boards) to attach to this BMS board and get this function without an specific charger.The only problem is that this attachment have a small margin of balance by cycle.

[@redscorpion133]

and how to charge my 6s bms corectly and cheap ?

[@2049bits]

Great: you might review Ohms Law V=R*I. The R is Internal Resistance that varies during charging. Then Watts exchanged=V*I-losses. You have the Volts and I current so far!

[@justsoyouknow1196]

I dont understand why only 60% charge. Wouldnt you get 100% eventually but it would take lo ger because of the lower current?

[@michaelsstuff4402]

- Hi. I did get some low readings because of a bad cell, but basically you won't get a great result unless you are charging the pack with a proper charger such as a MAX745 that will charge up to 12.6V and charges via constant current and then constant voltage. I have some more videos on the BMS and the MAX745 board that may help you. Cheers.

[@berndhachmeister4357]

Other BMS could potentially do that better? Or is your statement a general statement that BMS are not good for charging?

[@michaelsstuff4402]

Bernd Hachmeister - Hi. Generally not good for charging. They allow some charge to go into the batteries and they do control some unwanted situations such as over voltage but they don't charge the batteries correctly and there are risks such as trickle charging that a BMS doesn't manage. I would rather avoid such risks and get 90% out of my batteries rather than est 30%. Cheers

[@michaelsstuff4402]

Oh, and I haven't yet seen a BMS that is any better that the one I tested or one that has a dedicated charging IC on board. Cheers.

[@thecombatengineer7069]

@ Bernd Hachmeister there are several boards that will protect your cells. Please don't believe this is a blanket statement. He is also using the worst cells known to exist for this test. I have several videos available on this topic.

[@tuxnoel]

Those are protection boards not balance charging BMS. They claim to be the same.

[@roopesh1988]

Then what is the ideal way of charging 18650.. do you have a video

[@michaelsstuff4402]

- Hi. Yes. Just scan through my videos and you will find ones that discuss the MAX745 board. Cheers.

[@luischacon7960]

Hi friend how are you ? What voltage have the charger for load to 100% the 3S array?

[@michaelsstuff4402]

Luis Chacón - Hello. 12.6v is the max voltage you should give a 3s pack. Cheers.

[@justintakayasu9414]

@@michaelsstuff4402 so you had a 12v power supply hooked up to the bms? and it was drawing voltage from ~3.6 to ~4volts?

[@fookutube501]

If i put a bms on my battery pack ,do i still need to put a balance cable on it as well to connect to my balance charger ? ?

[@michaelsstuff4402]

Hi. If you are connecting and charging using a balance charger then yes you need separate connections. Cheers.

[@fookutube501]

Thank you for the reply...Ok so,do i put the balance cable on the bms or do i just put it on the battery like normal

[@michaelsstuff4402]

- It depends on your charger but it would be safe to say you should connect the balance charger to the cells as you would normally and not to the in out of the BMS.

[@fookutube501]

Awesome reply,you understood what i was saying .Again thank you...Awesome

[@BeetleJuice1980]

Where did you sir buy that rubber multimeter case? I got the same unit but no case..

[@michaelsstuff4402]

- Hi. No idea, i am pretty sure it came with the meter. Sorry cant help. Cheers.

[@kylecarrington8989]

It feels better without the rubber. What!?! THAT'S WHAT SHE SAID!

[@BeetleJuice1980]

lol

[@jj-jo6wr]

what if i charge with 19v power adapter.. will that charge?

[@michaelsstuff4402]

- Hi. It will sort of but you will be causing the BMS to heat up a lot as the circuit on the BMS will cut in and out each time it detects total voltage over 12.6V (for a 3s setup). In your case this will be most of the time. Not great. You should feed it 12.2 to 12.6V, not 19. If you must use 19, use a MAX745 board that will charge the cells properly through the BSM and it will take up to 20v as the input voltage. Cheers.

[@fklotaloi]

Uploader, I am very interested to know how much is th discharge "cut off voltage" of yr BMS u used? is it 2.3 or 2.5v or whatever ? I alys wonder, why ths BMS manufacturers make ths discharge "cut off" voltage way below 3 volt, coz as we know draining a lithium ion cell below 3 volt reduces its life span. Can u explain pls? Thanks a lot.

[@michaelsstuff4402]

- Hi. This BMS has a cut of voltage of 2.9v. I have seen some that go down to 2.5 but most are 2.8 or 2.9. If someone is using a 2.1v cut off then I would say that is too low unless it was set by the actual manufacturer of the cell. Cheers.

[@fklotaloi]

Uploader, In yr video I did not find link of th BMS u used. I will like to buy that if its discharge "cut off " voltage is 2.9. Wow thts better for th health of expensive lithium cells. Wld u pls gv me th link. Thanks.

[@michaelsstuff4402]

- Hi. The seller I used doesn't sell them anymore but I found many like the link below (same board). www.ebay.com/itm/10A-BMS-Charger-Protection-Board-Pack-of-3-18650-Li-ion-lithium-Battery-Cell-SA-/322385705714?hash=item4b0faf7af2

[@fklotaloi]

Hello, I checked it, bt it says: Over-discharge detection voltage: 2.3-3.0V±0.05V So, how did u say 2.9volt it cuts off th load circuit? I hv hooked up a 3 cell BMS & saw in multimeter, as soon as th load voltages reaches 2.34volt , it cuts th circuit . I ws wishing 2.90 volt :-( :-(

[@fklotaloi]

To rise the cut off voltage is possible by any means? Thanks.

[@jackassrulez88]

At the end, which is the best way to charge a 3s battery pack? i'm building a portable display for a gopro and I want to include the pack into the box and the intent is to charge it with an external charger by micro usb o something similar. I found the TP4056 but I read that only support 1 cell and I need 12volt! Thanks in advance!

[@michaelsstuff4402]

- Hi. You say you need 12v? What for? 12V at how many amps? Your best solution might be to run a 3.7v pack and use the handy TP4056 board but get the 12v through a 12v boost reg. Cheers.

[@jackassrulez88]

Hi. yes 12v for a lcd controller board (from an old netbook). It uses a power adapter that give 12v and 4A. I would like to make it portable to use it with a go pro. so i was thinking to use 3s2p battery pack. but it is difficult for me to undestadn how to make chargeable with an external power adapter!

[@michaelsstuff4402]

- Ah I see. Do yourself a favour and test the LCD and controller board and see if they run from 5V, many do. If they do you will be able to run a 5V setup which is way way easier to deal with. You will be able to run one or two cells in parallel a 5v reg and just a phone charger and a single TP4056 and the job is done.

[@jackassrulez88]

I'm sorry, but my knowledge it isn't enough to check what you advice; i found this on the specifics of the board POWER Requirement 12V DC/12V(built)/12V,5V(built in)/12V,5V,5VSB(built in) To Panel 3.3V/5V/12V Management Standby Power Consumption < 0.5W(Board Only)

[@michaelsstuff4402]

- All you need to do is run 5v through the board and see if the LCD powers up. If it does you can get away with an all 5v system which is great. Send me an email with your project diagram and maybe i can help more. [e-mail]

[@TejKiran]

Hi, if I use this BMS in combination with max 745, will it become a balance charger?

[@michaelsstuff4402]

- Hi. No it won't although passive balancing happens anyway. Most of the time (many applications) you don't need a balance charger. A lot of BMS say "balancing" because passive balancing happens anyway, they are not active balancing. If you're using say 3 cells in series (3S) then the BMS will evenly distribute the power to each of the cells so at the end of the day they are all the same voltage. If you connect cells in parallel then they balance each other out unless they are very different batches and are not equal. Cheers.

[@TejKiran]

Hi, Thanks you sooooo much for the information!!.. lipo charging is the biggest problem for diy projects especially in robotics (high currents..).. if possible can you pleeease.. kindly make a video on proper and reliable way to integrate lipo batteries, bms and chargers into diy projects... without those bulky chargers.. thanks again!!! :)

[@michaelsstuff4402]

- Hi. Sure can. Will be making such a video soon. cheers.

[@TejKiran]

Thank you very much:)) will be waiting for it. :)))

[@Ziplock9000]

@@michaelsstuff4402 "3 cells in series (3S) then the BMS will evenly distribute the power to each of the cells so at the end of the day they are all the same voltage." Are you saying that if one of the 2 cells is fully charged and the other 2 are not, further power to the BMS will only go to those that are not with this particular BMS? or does it shut off power going to the whole battery?

[@lurkingcorsa10]

++My Electronics & Hacking Show - does bms protection save thecurrent too..?

[@michaelsstuff4402]

- Hi. Yes a BMS can have over and under current protection but you need to look at the specifications of the BMS you're considering as not all do. Cheers.

[@lurkingcorsa10]

sorry.. I mean, save about eonomical, not save of protection ! thnks... cheers too. :)

[@lynnfredwoods1]

Thankyou for your great work. I have a query here.What charger system would you use for to charge the batteries properly when using the BMS board. I am building a unit in an old laptop shell which has 19v transfiormer in. I need 12v for the screen and for some audio preamps etc that are being used with a raspberry pi with internal plug in sound card with audio recording in and dac output. So I would need a healthy amount of 5volt power as well. The ability to leave the batteries connected wen the external power is working. I willlet you know what is being used for if you are interested. Lynn Woods (mr.)

[@milvolts1]

Would solar charging the battery packs be out of the question or what.

[@michaelsstuff4402]

- Hi. No not at all. You do have to consider a couple of issues but solar is a real option. The main issue is that solar panels output ranges from 10v to 19v. If you fed that voltage into the BMS it would likely lock out the input. This is not ideal. All you need to do is run a voltage regulator between the solar panel and the BMS. A SEPIC style reg would be good as they boost low voltages and reduce high voltages and give a smooth 12v supply. If you used the MAX745 charging IC then they accept voltages up to 20v so that would work well with a solar panel. The only issue there is that the MAX745 charger will only charge the cells through the BMS when the input voltage is 3V higher that the battery pack voltage, say 12.6V. That means a 3S pack at a nominal voltage of 12.6V would only receive charge from the MAX745 when the solar panel is producing 15.6V. You're missing out on some of the solar panel output range but it would work. Cheers.

[@highspeedshipbuilding8318]

i want to use 3s2p 20amp bms for charging 3x3.6V 6 cell which i will use in motorcycle. and motorcycles regular charging system will be used to charge and drain the battery pack [3s2px3.6]. is it possible successfully? -regards. -mamun2a

[@michaelsstuff4402]

- Hi. Yes and No. You can easily find a BMS that will handle 3S at 20A so that part is easy. The harder part is charging the pack as the BMS will handle input voltage peaks and troughs but it doesn't correctly charge the cells. Your bike will just dump 12-15v into the pack and the BMS will try to reject anything outside the safe limits of a 3S pack. This will put power back into the cells but they aren't being charged correctly. You should connect a charging circuit to the pack so the charging circuit takes the power from the bike alternator and provides a correct charge to the pack. This is tricky as the charging will be interrupted each time you stop the bike. This is not ideal for lithium cells, hence why its not common to do it. Without the charging board, you will get it to work but the life of the cells is unpredictable. Cheers.

[@highspeedshipbuilding8318]

then using an additional charging circuit next to regulator will work, what u think? DC-DC Buck circuit helps or else to use for charging??@@michaelsstuff4402

[@michaelsstuff4402]

- Hi. Even if you add a charging circuit you still have the problem of the charge being interrupted every time the bike stops. A full charge typically takes 4hrs or more and is not supposed to be interrupted. @@highspeedshipbuilding8318

[@highspeedshipbuilding8318]

Thanks for reply. now a days quick charger available for mobile, if i use them, what then?? @@michaelsstuff4402

[@highspeedshipbuilding8318]

sorry for late, if i use quick charger for charge it?? i.e. 2 ampere mobile charger as charging unit?? @@michaelsstuff4402

[@Dr.Stein99]

Thanks for tutorial. Have you discovered a BMS board that does what it should? I also like to find one with separate charge and output lines, so I can use it like a backup battery. Run my load off the battery that constantly charges.

[@michaelsstuff4402]

- Hi. BMS are trial and error but pair a decent one with a MAX745 and you have a drain and charge battery pack as long as you drain at less than 1.5A. Cheers.

[@freetrailer4poor]

I gave your video a thumbs down as you should of had a voltage meter on each cell and the optimal voltage for long life is 3.92V (lowest $/kwh). It is a 3S1P charger so it is charging at 1 amp even though 5 amps are available. If 4.2 are available then if the maximum is 3.98V then that is good but too high. But you never allowed the voltage to end or the current to drop to zero.

[@michaelsstuff4402]

- Hi. I would prefer a thumbs-up but I always appreciate detailed feedback. I just did a quick re-watch and yes I know what you are saying. I recall I ran out of time in a big way during this video and it had impact on the details and the overall quality. Fair points. It would have been much more instructive to see what was happening to each cell etc. Cheers.

[@denilpt2020]

Thanks for the information

[@pijushdutta7432]

can i use one TP4056 for parallel charging of two LI ion batteries??

[@michaelsstuff4402]

Pijush Dutta - Yes you can. To keep the cells at peak health and efficiency you should cycle them through a dedicated battery charger but a tp4056 will work. Cheers.

[@pijushdutta7432]

thnk you sir..cheers

[@greekdecibel108]

So i can use the bms and the tp4056 together without any problems?

[@michaelsstuff4402]

- Hi. No. The BMS in this and other videos is for 3 cells connected in series. A TP4056 is for one cell or two cells if connected in parallel which works like one cell. A TP4056 only works with voltages for one cell. You can get a version of the TP4056 that has a BMS built in which works well with single cells that don't have an integrated protection circuit. Cheers.

[@greekdecibel108]

I have 3 tp4056 with overcharge, discharge protection etc. The board has also battery outputs...is it possible connecting all 3 tp4056 outputs and have an output of 12.6v?

[@pleasecho2]

I found that some work better than others and some don't work at all. Another thing to look at is how much current you can get out of a BMS enabled pack compared to not using one

[@michaelsstuff4402]

Agree, some are better than others. The BMS is there to provide limits so you will get more current from a pack without a BMS but potentially do damage to the cells if you ask too much from them. That's why you use a BMS. Cheers.

[@pleasecho2]

@@michaelsstuff4402 This is where I see a difference: Drills and other high draw tools seem to take full advantage of the total available power with monitoring cell integrity in the background. I have not seen this type of performance from any off the shelf Chinese BMS

[@benjaminbuljevic7977]

very useful information! thank you.

[@michaelsstuff4402]

- Thanks.

[@azeemtics6613]

I use think multiple battery Bms didn't make sense

[@Giblet535]

So, it's not *really* a BMS. A genuine BMS should manage power switchover and charging primarily, and safety limits secondarily. Most good batteries e.g., Samsung, have protection built into the cell itself. A diode should be added between the power source and this BMS to prevent battery power from going back through the power source when the power source is off.

[@michaelsstuff4402]

- mmm yes I see your point but I think we can still call this a BMS. It's not feature rich and doesn't contain a proper charging IC or other features you mentioned so you wouldn't say this a $100+ BMS solution for a mini power wall or anything but it still ties together multiple cells and gives the basic protection for the pack. Cheers.

[@ddthames]

Thanks for making the video. it was helpful to me as I am just starting to mess around with building battery packs and Lithium Ion charging. I built a 3 cell pack with the same BMS board and a balance cable connector. In use 2 of the cells seem to have less capacity than the third and result in an out of balance condition after discharge. So I was interested to see if the BMS board would do any balancing if the pack was raw charged. I connected it to a very low power and unregulated wall-wart. The open circuit voltage is about 18 and the battery pack pulled down the voltage and it was charging at about 270 mA. I plugged in one of those 2 dollar LED digital battery monitors to the balance connector. The two lesser cells started their voltage climb and I was very interested in what the better cell would do. It appears that the BMS tries to shunt some of the current around the higher cell(s) to allow the lower voltage cells to catch up. What I am observing is that the higher cell voltage will be (in this instance of time) 4.08....4.01....4.02....4.08....4.05....4.02...repeating up and down, with a cycle time of 10s of seconds. I think the shunting can only take so much power/heat so it is done off and on. Anyway, that is what I have observed. So while it is not managing the charge, it appears to be trying to balance, within some limits.I can charge on this low current charge until the voltage at the pack terminals is 12.70 and then I stop it. If I then put in on my good charger, it will only add about 20-30 mAH and say it is full.

[@michaelsstuff4402]

- Thanks for that. Good additional info. I have seen a similar board that has an inbuilt balance function that might be worth testing too. Also, I've just posted another video on this subject you might find interesting. Cheers.

[@Ziplock9000]

So can you confirm that the HX-3S-01 does perform at least some limited form of balancing when charging? What about when discharging?

[@GoodWolfWonRocky]

⚠️ WARNING!!! ANCHEER WILL NOT HONOR ITS WARRANTIES!!! IF YOU INVEST IN THIS COMPANY YOU ARE ON YOUR!! WARNING!!! ⚠️

[@jonathanbryandechavez7460]

Can i make a 3s2p for this bms 3s 10a?

[@michaelsstuff4402]

- Hi. Yes you can add cells in parallel as the BMS only cares if the load exceeds its current handling, say 10A. So you would only have issues if you wanted to recharge at more than 10A or wanted to draw more than 10A through the BMS. Cheers.

[@amshamil1991]

Will my 18650s drain faster, If I use a 3S 10A BMS as a power source where only 12v 3A is needed? or else is it better to use a appropriate one like 3S 3A BMS?

[@soc6729]

Shamil Aiyubkhan no it will drain normally. Buy

[@stereojos86]

The tp4056 is better for charge?

[@michaelsstuff4402]

- Hi. Yes, significantly. Cheers.

[@michaelsstuff4402]

But the TP4056 is only for 1 cell, no more.

[@joaopaulolawrencedasilva9498]

Awesome Video!! I just bought this protection board. I Just want to know if I can charge with a regular power supply of 12 V 1A. Thank you for your attention!

[@michaelsstuff4402]

- Hi. Take a look at follow up videos I've done and the numerous comments on this video for more info. Basically you can pump 12v at 1A into the BMS and you will end up with some charge in the cells. It won't be ideal as each cell wants 4.2v so you should provide 12.6v as the supply but 12v would work giving up to 4v per cells. This is not ideal as a 4v charge is under capacity so you will miss out on some capacity but the main problem is the charging method. A basic power supply will just pump power into the cells. To properly charge lithium cells you should charge CC then CV. You can do this with a dedicated IC or charger but you can also do this with a basic power supply if you take some care. I would suggest watching a few more of my videos on BMS and also take a look at EEVBLOG who did a video on using a bench power supply to charge lithium cells manually. Cheers.

[@svankervej]

Hi there, im doin almost the same as Joao says, using a 12,5V 1,5A powersupply for a router connected directly to a 3S bms with batteries attached. It seems like the current is just limited by router powersupply's max current protection? It charges up the battery fine

[@christophertilley4297]

@@michaelsstuff4402 Are you saying we should design a dedicated charging port in our packs that bypass the bms? What happens when you hook a proper Liion charger to the P+ and P- discharging/charging pads? Does the pack still only charge to 60%?

[@FIFTYmil]

Awesome video, well done. I was under the assumption that the BMS can handle charge & balance. Your video, however, tells me that a dedicated lithium balance charger is still needed to this day. Recently motorcycle manufacturers have begun adopting lithium batteries into their motorcycles to save weight and increase cranking amps. The engine's stator directly charges the "oem" lithium iron phosphate batteries via a voltage regulator. Alternatively, they suggest maintaining the battery with a battery tender as long as it doesn't have desulfation mode and it doesn't exceed 14.9V. It is assumed the BMS on board will handle everything and there's no need for a dedicated balance charger. My question is: What would be the long term effects of charging a Lithium iron phosphate battery via the BMS and if there are any negative effects, why is this acceptable for oem motorcycle/industrial standards? Thanks!!

[@michaelsstuff4402]

- Hi. Big question. Basically LIPH cells are more tolerant of overcharge and can be held at full charge for longer. Also a batch of these cells with the nominal voltage of 3.2V and a full charge of 3.6V works nicely when replacing a 12v lead acid batt which is normally charged to 14.2v. There are still issues as they are still lithium and are not as forgiving a lead acid batts. Since we are talking having the cells in series, the BMS would need to be LIPH specific but if it was decent it would do the job. Passive balancing would be dealt with by the BMS. The car or bike would need a proper charging IC or device otherwise (eventually) the cells would deteriorate faster that if they were managed by a dedicated balance charger. How long they would last is a good question. I have seen many commercial devices and home made projects that just have a BMS managing the cells with raw power going through the BMS to the cells (no proper charging IC, just a straight voltage reg) and they can last quite a while. Not as long as doing it properly but I can't say what the real world difference would be. Maybe I should build a rig and test it. Hope that helps. Cheers.

[@FIFTYmil]

Wow thank you very much for the detailed answer. Sorry I am getting off topic, when you mentioned that the "bike would need a proper charging IC or device" - Is it found inside the battery or perhaps onboard the motorcycle ecu? What purpose does the IC/Device actually serve (eg. regulate voltage? Cutoff from overcharging?) or is this IC/Device equivalent to a balancer? Yet, the said lithium battery only has a positive and negative terminal no different from a lead acid (and no additional ports for balancing) Reason I ask is because the same model motorcycle uses the same voltage regulator and stator after confirming the same part numbers. However, while a higher trim model would be equipped with the lithium battery, the lower trim level uses a lead acid. Is it possible there exist an additional ic/device on the higher trim model?

[@michaelsstuff4402]

- Unfortunately both are possible. The battery could house a charging IC or the bike could have it in the ECU. The other possibility is that the BMS is doing all the work and there is no proper charging IC. OK, the IC is just a chip that correctly charges lithium cells, just like the TP4056 single cell charging IC. It follows the constant current then constant voltage charging methodology. This is more detailed than just allowing a correct voltage to go to the cells. Just a good voltage will charge the cells but the CC then CV method is what you are supposed to use when charging lithium cells. The IC just provides that CC then CV stages and sometimes has a timer to cut off the charge if it goes too long. The BMS does the under / over voltage and current work. Cheers.

[@FIFTYmil]

Thank you for enlightening me! It seems like the IC can replace the need for a cell balancer charger completely and the former case (ie. battery housing a charging IC) seems to be the more logical way for manufacturers to adopt lithium technology. Regardless thank you very much for taking the time to explain this to me. Keep up the great work!

[@_munkeymunk]

I've been searching for a long while now trying to see if a BMS can be a sufficient "charger". I'm wanting to hook up my motorcycles rectified AC current (which sits around 14.8v DC) and see if a BMS will effectively charge and balance a 4s or 3s pack through its over and under charge functions. I cant really find a clear answer so I'm starting to dig into the schematics and components of the BMS IC to get to the bottom of how the BMS behaves under constant voltage, overvoltage, undervoltage. etc!! If you happened make a video or built a rig showing things like this I'd really be stoked...otherwise someone's gotta make it cause I'm seeing these question arise now and again in the world of BMS.

[@jesuishalil]

Aww, i thought this was a nice magical replacement for simple 12v packs and charging them, had ordered a few and waiting, thanks for the video though!

[@michaelsstuff4402]

- Well its a start and if you add a 3S charging module ($3 ish on Ebay) and feed the charging module the right voltage and current you will get your 12v pack. I'm doing a project (Next vid probably) with 2 high powered LED panels with, remotes, adjustable brightness and battery backup power and in them I will use either the BMS with 3S board or an array of TP4056 boards. Maybe do one of each. Might be something you find interesting. Cheers.

[@floxflux]

any recommendation for the charging module?

[@jesuishalil]

A 3S lithium ion charger for RC vehicles would be good,but then you also need to solder on the appropriate headers and attach the charger(relatively big) to every time you wish to charge it, which is something i hoped to avoid with this solution.

[@floxflux]

thanks, but wouldn't a decent rc battery charger replace the need for the bms altogether? (charging wise)

[@jesuishalil]

If you attach the battery to, say, an electric bike, then the battery could get damage by over-discharge.