This project made me rethink my setup with an Adafruit solar charger. For my timemachine project to run longer using an Arduino Pro at 3.3v. I placed two Lipo Batteries in Parallel to have the same output of 3.7v with a larger running time or capacity when the sun was gone. I noticed the second battery drained more than the second battery once I place them in a commercial charger. Seeing your animations and showing single and multiple charging methods I now feel better about learning what are my mistakes. Thank You for sharing and keeping up on all the great content. Not everything is applicable but as makers we must learn from each other to share our project. Awesome overview and great tips. You are always setting the bar higher and higher for all makers.
Great Video! I've been subscribed for the longest of time, but every now and then, you just publish more and more explanatory and informational videos that go briefly into the problems were are trying to solve step by step, stage by stage. Thank you so much! 6/5 Starts
I read A LOT of explanations about BMS and to really understand it well, this is really the best. I let it rest overnight, asked myself questions, and looked at it again. Really, very very very best explanation out here!!
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I've watched a few bms videos before this. I have to compliment on how well you explain how this works and how to build your own. You are very underrated and deserve more recognition. 5 stars!
If you put in a cell charged to 4.2v, but circuit was tuned to 4v or lower, wouldn’t it completely short out the cell? (at least till it reached 4v or lower)
A very nice BMS circuit for smaller LiPo, Li-Ion oder LiFePO batteries. The advantage of the circuit is, that you can easily cascade the circuit for your desired s-number and you can charge it with a power supply which delivers enough current and a few volts more than required. The disadvantage is the power loss, but for smaller Cells it is quite useful.
Error: The output of R2, R1, R10 voltage divider at 5:00 is supposed to feed into the Ref pin of the TL431 with Anode to negative and cathode to the BD140. If you just swap the AN/REF labelled pins on the schematic you should be right.
Yeah bro, I also saw there is a mistake, after i fix that issue it almost works fine, but i recommend others to use 22k and 1k resistors for that voltage divider connected to tl 431 ref pin cause the ref input voltage is higher when you use two of 20k resistors.
Nice build! I am looking to build a BMS for a huge build with 1000 or more 18650s I have on hand. This circuit does have quite a few important limitations though: No under voltage protection No over temperature protection No over current protection. The DIY project could be massively improved with the use of a low power microcontroller for each cell monitoring the voltage and using galvanically isolated (optocouplers) in a token ring or CAN network to transmit data back to a more powerful MCU that manages the series string. Active balancing is harder for sure. I have one idea involving using lots of gate drive transformers and implementing small basic forward converters for each cell to dump energy into a shared AC square wave bus, but have yet to get it to work right in LTspice.
This is the CHARGING "half" of a BMS. This does not have the LOAD "half" of a BMS ( load over-current & under-voltage ). He made that very clear at the beginning of the video.
Mmm.. LM317 old school, that always works and is tested for decades.. 👍 431 references is used even in cheap BMS modules for batteries and ultracap's from China.. Great video!
But they all charge to 4.2v, which is sub-optimal for battery life. This circuit is great for battery packs you don’t use much, and would otherwise just zero out eventually
I am sorry if this was mentioned before but the datasheet for LM317 has an application specifically for battery charger. You can put the current limiting resistor at the output before the voltage divider that sets the output voltage... and since the current limiter will be pretty much >2 orders of magnitude less than the resistors in the divider, it shouldn't affect the output voltage. You save 1 LM317 this way :)
@@SocialPerspective101 on what? I don't think links are accepted in YT comments (unless they're made to your own video) ... but I can try if you tell me which part you want me to elaborate on.
@@SocialPerspective101 I believe it's easier to try and link you to the application. The LM317 datasheet has at chapter 9.3.6 the battery charger application I am talking about. There's the voltage divider that sets the CV part and the series current limiting resistor (Rs) that will set the max value for the charging current to your CC desired value. The CC part will not really be CC, but the current being drawn will not drop significantly during this time (it will drop with (Vbat - 1.25)/R1 and Vbat increases as the battery is charged). The CV part will stop the battery voltage from rising above the desired (usually 4.2V) value. Rs is more than 2 orders of magnitude (or 100 times) less than R1 or R2... and as such it will not significantly decrease the desired output voltage set by the divider (R1 and R2). If it's close to R1 and R2 than you're either limiting the current a lot or wasting it through the voltage divider... or both and you're setting yourself up for a hard calculation and less than optimal result. I hope this is more clear :)
Hi sir very good video and explanation I understood whole video except 1 part and that is why you have connected 5 resistors of 10 ohms in series ?? [PLZ REPLAY 🙏 ]
Good Day is there any problem with the circuit? Can i ask since we are having trouble adjusting the potentiometer. Is there any corrected schematic and instruction on how to adjust the potentiomer? Do i need to adjust the potmeter without connecting the lm317?
Hi thank you it was very clear and very nicely explanatory. However I have still have a question. Is this homemade BMS protects cells from short circuit ? As far as I understand, we saw only the "charging" side of the BMS, nothing related to the "discharge", when the battery is connected to the load. Am I wrong ? If so, it would be nice to have some info about that topic as well. Thank you so much.
Nice project! The point you dont need to use 2 LM317 to limit U and I. I faced to this case as well. There is a scheme that allows to do this with one LM317. The scheme is mentioned as Load Regulation in the datasheet. Anв as usuall you need to use addшtional transistor for hight current.
I have constructed this circuit and i have found just a few issues, but the circuit does work pretty good. My battery was 280mAh battery, datasheet called for a standard of 58mA charge, or max charge of 280mA.. i chose 58mA.. estimated charge time ~ (280/58mA) = 4.8 hours Because I have a power supply i figured I would skip the lm317 voltage regulation and simply use only one lm317 for CC and just use 4.2V from power supply for the input.. the issue with the lm317 in current mode is you can't use 4.2V input supply because the output will not provide CC at the given 4.2V output.. it states on datasheet of headroom around 3V or soo.. So i decided to use both lm317 for voltage and current.. like the circuit diagram shows but only CC comes first then Voltage regulation.. IMPORTANT you must have power supply 3 volts above battery level.. so for a 4.2V lipo i put a supply of 7.5V into the CC lm317 input and connected the output into the input of a lm317 in voltage mode.. with an output of 4.2V.. only needed 60mA.. P=(7.5-4.2V)(60mA)=200mW.. lm317 isn't even hot I could have used only one lm317 in both constant voltage and current.. but would have been bigger headache in calculations because of output impedance Also Iref into the tl431 is too low.. around 8mA is recommended.. for the voltage divider i used resistor values of 212.2 ohms for R1 and 313.5 ohms for R2.. this will provide more stable reference of exactly 4.2V I monitored my batteries voltage and current throughout the whole charging process.. the current started at my selected max current limit of 60 mA.. the battery voltage slowly rised.. once i hit around 4.19V the current slowly slowed down to 0 amps.. then the transistor opened and the battery stopped charging.. so the circuit does provide CC charging and CV charging.. the closer the battery gets charged to the supply voltage then obviously a trickle charge to 0 amps will occur.. Overall was a great learning circuit.. learned alot about tl431 and also lm317...
I bought a Daly BMS a long time ago and I can't say I'm happy with it cause it makes one battery go over voltage I got lifepo4 will your BMS work for me . I'm using the batteries for a solar system on my house
Hey man . I got 60v li-ion battery pack for my powerful electric scooter and i got charger that seems to be overcharging the battery pack to 64v plus and it doesnet stop . Wheni asked the seller he said i can charge it all the way to 72v 😐which i think its hazard high alert 😬so tell me what is the maximum recharge voltage please ? Thank you
thanks, one question, would this work if one mix cells with different ah ???, and please stay healthy !!! and continue with your work in lithium battery cells !!!
I have a question/suggestion for a video idea... I saw a video from someone showing how to use a 2.7volt 500F super capacitor for a spot welder for LiPo batteries.. But they never explained how to properly charge the cap without going over it's rated voltage. Can you do a video showing how to make it the right way?? A proper Super Cap charging circuit... to be used as a spot welder. Thanks!
Hi, good stuff. But you make one mistake in your schematics. Current limit must go first, after that voltage regulation. If voltage regulation have to give 4.2V, then you need to add another 2V for LM317, then you need to add another 1.25V + 2V, which means power supply must be at least 4.2 + 5.25 = 9.45V or more.
all voltage regulators have a voltage drop ( eg. 0.7 V for SI semiconductor jonction ), for LM317 is safe to use Vin-Vout at least 3V so no way to use 5V for one lithium cell that requires 4.2V.
Высококачественные видео, у этого гениального парня! и почему то , так мало лайков? Ау люди проснитесь, ваш лайк - это уважение автору видео , за его труд.
Sir i want to sometimes use it for 2s battery charge and sometimes for 3s battery charge so can I use the same circuit for 2s and 3s battery charge ?? PLEASE REPLY SIR 🙏🙏🙏🙏😇
Pay attention, there are several quite similar 431. The TL 431 pinout is Ref Anode Cathode, while the LM431 is Cathode Anode Ref or Cathode Ref Anode It's a mess ...
How can i know the accurate resistivity value for limiting charging voltage? Because i wanna use static value resist instead of potentiometer. And thanks for helpful video
Really enjoyed the explanation. Thanks. Love to see a more efficient example (for minimal heat dissipation). BTW: has anyone seen a protection, balancing and charging solution for four 3.7V 500mAh LiPo batteries in "parallel" and in circuit? Protection, balancing and charging, without removing the batteries. Every battery management IC manufacturer offers 1S and multiple series solutions, in circuit and out, but I can't find one offering an "in parallel in circuit" solution. What gives?
Nice explanation, but i was wonder how its possible in my case i make a 3s2p bms circuit? i'm having a lot of doubts about this topic, one of them is how i will make this kind of circuit and why only bms are sells with 3s, 4s, 5s options instead of 3s2p, 4s2p and soo on...
I have a question.i have some lipo here that no matter how long they charge they never reach 4.20/4.25 volts. I was wondering how to make a circuit to show the battery is not charging properly. Maybe use some circuitry based on time lapse. Do you have a. Idea? Just one more question: how to add a temperature control based?
How would you design a 144V battery BMS. Not sure you can simply add more batteries and listed components? Some of the components would require different component types to be able to work with potentially 185Vdc in a 120Vac standard system. Thanx again for your presentation. Learned lots from it.
Hola buenas, muy buena idea y video, quisiera saber si puedo utilizar el LM336 en lugar del TL431 y que modificación tendría que hacer?Desde ya muchas gracias!
Cool video but with this circuit you can only charge your batteries not discharge them in a load after they are fully charged, its more a li-ion charger than a real BMS with which you can also control the maximum output current and undervoltage ... but still this video is great, keep going man
this looks interesting, can we replace the BJT with P-ch mosfet? also is the ref pin supposed to connect to negative of batt or its just a error on the diagram?
for lm 317.. just make sure you have at least 3v headroom for vin - vout, or less you will not be able to delivered the current , even only for charging a single battery..btw the circuit works well.. tq
If we use a 5s bms we need a constant current source? Bms has protections but it's not a charger so I guess we must use a constant current power supply to every bms?
Hi, I need to know that how important are the 20k resistors an 20k trimpot? Can I use 10k resistors and a 10k pot instead? Also, what can I use a resistor instead of the 4 diodes? If yes, what value? TIA
The nominal voltage of most lithium cells is actually 3.7V and not 3.8V. The latter is called "HV". The higher ones go up to 4.35V and not 4.2V. But there are also some older cells that are only 3.6V nominal and they end at 4.1V. So be careful and check the writing on the actual cell. If there is no nominal voltage written on it, then check the part number or don't charge higher than 4.1V if in doubt. Better safe than sorry with lithium batteries.
Lithium batteries charge at constant voltage constant current. When battery reaches the 4.2volts, it continues to charge by reducing current flow and storing capacity. The switch off indicator-circuit must be triggered when current is off, and not when a voltage of 4.2v is reached. A battery can stay at 4.2v and keep changing for sime time(depending on its capacity) until current is not flowing. When 4.2v is reached and no current is flowing then battery is Fully charged. In any other case all you get is an undercharged battery with a voltage of 4.2v and no capacity.
I have a question, how do you get sponsored by jlcpcb or pcbWay (they contact you or you contact them and how), and how the sponsorship works (payments, contract ecc...)? Thanks! 👍
Will this work for Lithium Ion batteries? I have hundreds of 18650 cells and want to build a 72v 20ah battery pack for an ebike so it needs to be able to handle a lot of power.
This project made me rethink my setup with an Adafruit solar charger. For my timemachine project to run longer using an Arduino Pro at 3.3v. I placed two Lipo Batteries in Parallel to have the same output of 3.7v with a larger running time or capacity when the sun was gone. I noticed the second battery drained more than the second battery once I place them in a commercial charger. Seeing your animations and showing single and multiple charging methods I now feel better about learning what are my mistakes. Thank You for sharing and keeping up on all the great content. Not everything is applicable but as makers we must learn from each other to share our project. Awesome overview and great tips. You are always setting the bar higher and higher for all makers.
Great Video! I've been subscribed for the longest of time, but every now and then, you just publish more and more explanatory and informational videos that go briefly into the problems were are trying to solve step by step, stage by stage. Thank you so much! 6/5 Starts
Probably one of the best videos I've ever saw with explanation of BMS!
Thank you!
I read A LOT of explanations about BMS and to really understand it well, this is really the best. I let it rest overnight, asked myself questions, and looked at it again. Really, very very very best explanation out here!!
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I've watched a few bms videos before this. I have to compliment on how well you explain how this works and how to build your own. You are very underrated and deserve more recognition. 5 stars!
Thank you very much!
If you put in a cell charged to 4.2v, but circuit was tuned to 4v or lower, wouldn’t it completely short out the cell? (at least till it reached 4v or lower)
What an easiest way to explain the difficult concepts. Amazing.
True, this is honestly why i stopped electric builds years ago
A very nice BMS circuit for smaller LiPo, Li-Ion oder LiFePO batteries. The advantage of the circuit is, that you can easily cascade the circuit for your desired s-number and you can charge it with a power supply which delivers enough current and a few volts more than required. The disadvantage is the power loss, but for smaller Cells it is quite useful.
Error: The output of R2, R1, R10 voltage divider at 5:00 is supposed to feed into the Ref pin of the TL431 with Anode to negative and cathode to the BD140. If you just swap the AN/REF labelled pins on the schematic you should be right.
bro have you tested your circuit please tell me it'll be a great help
So the reference pin of tl431 must be between R1 and R2 resistor?
Yeah bro, I also saw there is a mistake, after i fix that issue it almost works fine, but i recommend others to use 22k and 1k resistors for that voltage divider connected to tl 431 ref pin cause the ref input voltage is higher when you use two of 20k resistors.
I also found that out after struggling setting the TL431. Good observation
Hi, would you be so kind as to share the corrected plan, with the values of each component, thanks
I've watched quit a few of your videos and I just decided to subscribe. I've seen a lot of the things you make that might come in handy in the future.
I understood it well. Thanks for the simple explanation and animations. Loved it. ❤️
Nice build! I am looking to build a BMS for a huge build with 1000 or more 18650s I have on hand. This circuit does have quite a few important limitations though:
No under voltage protection
No over temperature protection
No over current protection.
The DIY project could be massively improved with the use of a low power microcontroller for each cell monitoring the voltage and using galvanically isolated (optocouplers) in a token ring or CAN network to transmit data back to a more powerful MCU that manages the series string.
Active balancing is harder for sure. I have one idea involving using lots of gate drive transformers and implementing small basic forward converters for each cell to dump energy into a shared AC square wave bus, but have yet to get it to work right in LTspice.
This is the CHARGING "half" of a BMS. This does not have the LOAD "half" of a BMS ( load over-current & under-voltage ). He made that very clear at the beginning of the video.
Look at Adam Welch's channel ruclips.net/user/AdamWelchUKvideos and search for 'diyBMS'.
Can I get the circuit
Mmm.. LM317 old school, that always works and is tested for decades.. 👍
431 references is used even in cheap BMS modules for batteries and ultracap's from China..
Great video!
Nice for understanding the concept of charging but there are very low-cost chips to the same thing with much more effencency.
right
But they all charge to 4.2v, which is sub-optimal for battery life. This circuit is great for battery packs you don’t use much, and would otherwise just zero out eventually
I am sorry if this was mentioned before but the datasheet for LM317 has an application specifically for battery charger. You can put the current limiting resistor at the output before the voltage divider that sets the output voltage... and since the current limiter will be pretty much >2 orders of magnitude less than the resistors in the divider, it shouldn't affect the output voltage. You save 1 LM317 this way :)
Great Idea ! Or use a Buck Converter with adjustable voltage and current regulation built-in
Can you elaborate on this?
@@SocialPerspective101 on what? I don't think links are accepted in YT comments (unless they're made to your own video) ... but I can try if you tell me which part you want me to elaborate on.
@@VrumsAdventures current limiter will be > 2 orders magnitude... I did not get this part
@@SocialPerspective101 I believe it's easier to try and link you to the application. The LM317 datasheet has at chapter 9.3.6 the battery charger application I am talking about. There's the voltage divider that sets the CV part and the series current limiting resistor (Rs) that will set the max value for the charging current to your CC desired value. The CC part will not really be CC, but the current being drawn will not drop significantly during this time (it will drop with (Vbat - 1.25)/R1 and Vbat increases as the battery is charged). The CV part will stop the battery voltage from rising above the desired (usually 4.2V) value. Rs is more than 2 orders of magnitude (or 100 times) less than R1 or R2... and as such it will not significantly decrease the desired output voltage set by the divider (R1 and R2). If it's close to R1 and R2 than you're either limiting the current a lot or wasting it through the voltage divider... or both and you're setting yourself up for a hard calculation and less than optimal result.
I hope this is more clear :)
I had to build this circuit.
Good working . Thanks a lot for your sharing of experience.
May I know how can we replace the loads from the diode to the motor in this circuit, can just replace all diodes with single 12V motor for 3s bms?
Hi sir very good video and explanation I understood whole video except 1 part and that is why you have connected 5 resistors of 10 ohms in series ?? [PLZ REPLAY 🙏 ]
Thank you. I have benefited from your explanation, but I have a question: why 4 diodes and not one?
Good Day is there any problem with the circuit? Can i ask since we are having trouble adjusting the potentiometer. Is there any corrected schematic and instruction on how to adjust the potentiomer? Do i need to adjust the potmeter without connecting the lm317?
Hi thank you it was very clear and very nicely explanatory. However I have still have a question. Is this homemade BMS protects cells from short circuit ? As far as I understand, we saw only the "charging" side of the BMS, nothing related to the "discharge", when the battery is connected to the load. Am I wrong ? If so, it would be nice to have some info about that topic as well. Thank you so much.
Nice project! The point you dont need to use 2 LM317 to limit U and I. I faced to this case as well. There is a scheme that allows to do this with one LM317. The scheme is mentioned as Load Regulation in the datasheet. Anв as usuall you need to use addшtional transistor for hight current.
I have constructed this circuit and i have found just a few issues, but the circuit does work pretty good.
My battery was 280mAh battery, datasheet called for a standard of 58mA charge, or max charge of 280mA.. i chose 58mA.. estimated charge time ~ (280/58mA) = 4.8 hours
Because I have a power supply i figured I would skip the lm317 voltage regulation and simply use only one lm317 for CC and just use 4.2V from power supply for the input.. the issue with the lm317 in current mode is you can't use 4.2V input supply because the output will not provide CC at the given 4.2V output.. it states on datasheet of headroom around 3V or soo..
So i decided to use both lm317 for voltage and current.. like the circuit diagram shows but only CC comes first then Voltage regulation.. IMPORTANT you must have power supply 3 volts above battery level.. so for a 4.2V lipo i put a supply of 7.5V into the CC lm317 input and connected the output into the input of a lm317 in voltage mode.. with an output of 4.2V.. only needed 60mA.. P=(7.5-4.2V)(60mA)=200mW.. lm317 isn't even hot
I could have used only one lm317 in both constant voltage and current.. but would have been bigger headache in calculations because of output impedance
Also Iref into the tl431 is too low.. around 8mA is recommended.. for the voltage divider i used resistor values of 212.2 ohms for R1 and 313.5 ohms for R2.. this will provide more stable reference of exactly 4.2V
I monitored my batteries voltage and current throughout the whole charging process.. the current started at my selected max current limit of 60 mA.. the battery voltage slowly rised.. once i hit around 4.19V the current slowly slowed down to 0 amps.. then the transistor opened and the battery stopped charging.. so the circuit does provide CC charging and CV charging.. the closer the battery gets charged to the supply voltage then obviously a trickle charge to 0 amps will occur..
Overall was a great learning circuit.. learned alot about tl431 and also lm317...
idk, I'm gonna take another 5 year break of electronics
How about the scenario where max input voltage is limited to 14.7 volts?
What an awesome circuit and I actually have all the components except the battery box but I could just print one
I bought a Daly BMS a long time ago and I can't say I'm happy with it cause it makes one battery go over voltage I got lifepo4 will your BMS work for me . I'm using the batteries for a solar system on my house
Very informative content. Dispelled many confusions. Thanks.
Excellent! Bravo bravo, great presentation!!
Nice video! What benefit is there to using this circuit over just putting the diodes in parallel with the battery?
Finally another great video to watch
Thanks so much for this video Sir.
Please I am working with a 5s battery setup, what are the changes I will have to make for an efficient charging.
Hey man . I got 60v li-ion battery pack for my powerful electric scooter and i got charger that seems to be overcharging the battery pack to 64v plus and it doesnet stop . Wheni asked the seller he said i can charge it all the way to 72v 😐which i think its hazard high alert 😬so tell me what is the maximum recharge voltage please ? Thank you
Your intro is great.
Faz tempo que estava procurando um circuito como esse. Muito bom. Interessantes explicações. Congratulações!
thanks, one question, would this work if one mix cells with different ah ???, and please stay healthy !!! and continue with your work in lithium battery cells !!!
Amigo, que buen proyecto!!!! muchas gracias!!!! saludos desde Argentina GENIO
Why use diodes as a load instead of just a high power resistor?
I have a question/suggestion for a video idea... I saw a video from someone showing how to use a 2.7volt 500F super capacitor for a spot welder for LiPo batteries..
But they never explained how to properly charge the cap without going over it's rated voltage.
Can you do a video showing how to make it the right way??
A proper Super Cap charging circuit... to be used as a spot welder.
Thanks!
Good teacher! Please I need the full picture and diagram for two or more cells.
The explanation is perfect!
Thanks
God bless you
Thanks. Built a 5S version and works well.
Good job... But suppose I want to have the solar panel supply an the input voltage from 12 to 18v and want a 12 volts output
Thank you. May the force be with you :)
Hi, good stuff. But you make one mistake in your schematics. Current limit must go first, after that voltage regulation.
If voltage regulation have to give 4.2V, then you need to add another 2V for LM317, then you need to add another 1.25V + 2V, which means power supply must be at least 4.2 + 5.25 = 9.45V or more.
Can you please explain why the additional voltage is required?
all voltage regulators have a voltage drop ( eg. 0.7 V for SI semiconductor jonction ), for LM317 is safe to use Vin-Vout at least 3V so no way to use 5V for one lithium cell that requires 4.2V.
I ment Linear Voltage Regulator as LM317 is.
Высококачественные видео, у этого гениального парня! и почему то , так мало лайков? Ау люди проснитесь, ваш лайк - это уважение автору видео , за его труд.
Excelente proyecto! Muchas gracias desde Cuba
Instead of using LM317, why don't we use a buck or boost converter to stabilize the voltage?
Sir i want to sometimes use it for 2s battery charge and sometimes for 3s battery charge so can I use the same circuit for 2s and 3s battery charge ?? PLEASE REPLY SIR 🙏🙏🙏🙏😇
Yes, I believe that a 3S Charger will work with only two (2) Cells installed, with the third bay empty.
Thank you so much for this. What about for Parallel cells?
Pay attention, there are several quite similar 431.
The TL 431 pinout is Ref Anode Cathode, while the LM431 is Cathode Anode Ref or Cathode Ref Anode
It's a mess ...
How can i know the accurate resistivity value for limiting charging voltage? Because i wanna use static value resist instead of potentiometer. And thanks for helpful video
It's good. Not highly efficient but works in a jiffy.
This is awesome sir. Is it possible to build such a circuit with 12v batteries in mind and how would the components change accordingly? Thank you.
excellent ! concise ,informative and articulate !
Very understandable. Bit what aboit parallel battery configuration?
can it use for lifepo4 batteries? Should I use by adjusting to 3,6v the zener diode?
Really enjoyed the explanation. Thanks. Love to see a more efficient example (for minimal heat dissipation).
BTW: has anyone seen a protection, balancing and charging solution for four 3.7V 500mAh LiPo batteries in "parallel" and in circuit? Protection, balancing and charging, without removing the batteries. Every battery management IC manufacturer offers 1S and multiple series solutions, in circuit and out, but I can't find one offering an "in parallel in circuit" solution. What gives?
The positive for charging and loading must be different in your circuit an must have two diodes for reverse current flow.
Thanks so much for the idea.
Have we seen how the upper threshold is limited (4.2 V), but haven't we seen how the lower threshold is limited (3.2 V) ?
Do you know a place where you can buy parts for a BMS ? I would buy too!
Excellent BMS explanation, congrats!. I only have NPN transistors, how will the circuit be? Thanks a lot.
I know that keysight dmm is over a decade old but it's timeless. I love it. It must be 4.5 digit is it?
This is an example of a passive balancer right? cheap, but power wasteful? good video btw!
commercial bms also has over discharge protection and balance discharge features.
It's really good.
If i want charge 5 cell. What i change in this circuit
Nice explanation, but i was wonder how its possible in my case i make a 3s2p bms circuit? i'm having a lot of doubts about this topic, one of them is how i will make this kind of circuit and why only bms are sells with 3s, 4s, 5s options instead of 3s2p, 4s2p and soo on...
Great explanation, but undervoltage protection is missing.
This project is very good!
This is great explanation!
How can you put in parallel to the battery a 4.2 V voltage regulator if the transistor closes at 4.2V?
I have a question.i have some lipo here that no matter how long they charge they never reach 4.20/4.25 volts. I was wondering how to make a circuit to show the battery is not charging properly. Maybe use some circuitry based on time lapse. Do you have a. Idea?
Just one more question: how to add a temperature control based?
hey great vid mad props. can this that lead battery charger?
Very interesting, does this mean that if i want my cells to stop charging at 3,9 or 4v, that i can just adjust the potentiometers?
Yes
How would you design a 144V battery BMS. Not sure you can simply add more batteries and listed components? Some of the components would require different component types to be able to work with potentially 185Vdc in a 120Vac standard system. Thanx again for your presentation. Learned lots from it.
Inductive loads might not work.
what can you recommend for it to work on 48 volts system 200 ah life04 battery with balancing current up to 6 amps? thanks and great video.
input output same connecter???? VERY INTERESTING......HOW WILL LM117 AND LM317 OUTPUT ???? CAN YOU EXPLAIN
Hola buenas, muy buena idea y video, quisiera saber si puedo utilizar el LM336 en lugar del TL431 y que modificación tendría que hacer?Desde ya muchas gracias!
Cool video but with this circuit you can only charge your batteries not discharge them in a load after they are fully charged, its more a li-ion charger than a real BMS with which you can also control the maximum output current and undervoltage ... but still this video is great, keep going man
Yes disconnect feature if any cell goes below threshold is missing.
Excellent bro .what a valuable circuit. Like it .
Great video my friend👉❤️
this looks interesting, can we replace the BJT with P-ch mosfet?
also is the ref pin supposed to connect to negative of batt or its just a error on the diagram?
for lm 317.. just make sure you have at least 3v headroom for vin - vout, or less you will not be able to delivered the current , even only for charging a single battery..btw the circuit works well.. tq
where is the balancing and discharging circuit?, i dont get that point. Do we need add extra passive balancing circuit to this circuit?
If we use a 5s bms we need a constant current source? Bms has protections but it's not a charger so I guess we must use a constant current power supply to every bms?
Awesome content,
Thanks bro :)
Sam 🎵✌🏻
SIR can it work with 9 volt as input power ❓❓❓❓ PLS REPLY🙏🙏🙏🙏
Each LM317 requires an additional 3 volts, above the (1S, 2S, 3S) Battery Pack voltage.
@@vtorsi610 Then will it work ?? with 9volt 🙏🙏
@@sohamgaud7120 Can you compute this formula? Minimum Input Voltage = 3v + 3v + ( #cells x 4.2 volts )
I wonder if there is a video on a much more efficient charger?
Hi, I need to know that how important are the 20k resistors an 20k trimpot? Can I use 10k resistors and a 10k pot instead? Also, what can I use a resistor instead of the 4 diodes? If yes, what value? TIA
now need one with thermo control! gj!
Good 1. Thanks for sharing the knowledge.
Can you do a video with lifepo4 battery packs in 2s?
Can we measure air core inductor(lower value for rf projects) by a cheap 15$ lcr meter(4070lcr meter)? Please answer me.
Maybe you could improve by using an opamp to compare total output voltage to input and cut the charge
The nominal voltage of most lithium cells is actually 3.7V and not 3.8V. The latter is called "HV". The higher ones go up to 4.35V and not 4.2V. But there are also some older cells that are only 3.6V nominal and they end at 4.1V. So be careful and check the writing on the actual cell. If there is no nominal voltage written on it, then check the part number or don't charge higher than 4.1V if in doubt. Better safe than sorry with lithium batteries.
Very interesting again!
Lithium batteries charge at constant voltage constant current.
When battery reaches the 4.2volts, it continues to charge by reducing current flow and storing capacity. The switch off indicator-circuit must be triggered when current is off, and not when a voltage of 4.2v is reached.
A battery can stay at 4.2v and keep changing for sime time(depending on its capacity) until current is not flowing. When 4.2v is reached and no current is flowing then battery is Fully charged. In any other case all you get is an undercharged battery with a voltage of 4.2v and no capacity.
Does LFP batteries behave the same way too?
@@SocialPerspective101 All batteries behave the same way. When no current can flow, the battery is fully charged.
Hola. Hasta cargador de cuántos amperios soporta. La teoría está muy buena para extender a un BMS de bicicleta pero q cambios tendría q hacer.
All bms regulate cells to 4.2v… with this setup I could charge to 80% and double the life cycle
I'm not a electric engineer in getting the bill done do you have a site where I can try it out
And also can I change the value to a lower voltage
My battery is 3.7 v .is it workable
@@jehirulislam3047 yes. That's its nominal voltage. He explained in the video that the output voltage will drop to 3.7v. All lipo cells are 3.7v.
Diagram?
7:02 What is that blue element in the circuit ? I wonder what it does in the circuit.
I have a question, how do you get sponsored by jlcpcb or pcbWay (they contact you or you contact them and how), and how the sponsorship works (payments, contract ecc...)? Thanks! 👍
Can I charge 100 amp 3.2v lithium phosphate battery
Could you make a second video with a design that improve yield and energy consumption ?
Nice Video.
So can I suggest a video that you can make.
Can you make a DIY Ossliscope. Or how to measure waves at least with an Arduino. Thanks!!!!
Will this work for Lithium Ion batteries? I have hundreds of 18650 cells and want to build a 72v 20ah battery pack for an ebike so it needs to be able to handle a lot of power.