Calculating the State of Charge of a Lithium Ion Battery System using a Battery Management System

[@oliverheeg3908]

In you example 50% SOCe corresponds to 58% SOCc, doesn't it?...I think you mixed it up as you plotted over Ah discharged and not over SOCc initially.

[@tonymunn]

At the 5:00 min. point, doesn't that point actually represent a greater than 50% SOCcapacity or is that 42% capacity used at that point? I think I understand. It seems that the 42% is more Depth of Discharge????

[@staflsystems]

You are correct. The 42% figure should be Depth of Discharge (DOD) or 58% SOC. This is an error on our part.

[@0786RICARDO]

@@staflsystems i was wondering the same. Thanks for the clarification

[@apurvawatekar6720]

Thank you for your videos. So simply explained. Your videos helped me to prepare for my interviews.

[@johnnyflanker8509]

Excellent explanation ! Glad I found your you. Will continue listening to all your videos prior to asking a question. Thanks !!

[@joechi7979]

Thanks for the introduction. I really learn something.

[@ChuckJ1944]

GREAT ONE!!!! The calculas everyone needs!

[@bharathik.2911]

Very nice explanation!!

[@erfquake1]

These videos are brilliant, Mr. Stafl, thank you, very easy to follow along. One gets into the noble field of lithium battery technology for environmental concerns, tries to brain-up on lithium battery characteristics and electrical fundamentals, and invariably gets stuck between principles and real-world application. Me for example. A coulomb meter out of the box needs initial settings ...specific to that battery config that it's monitoring... like capacity, full voltage "empty" voltage, and drift. A lithium battery pack's stated Ah may be, say, 40Ah, but is it the kind of parameter that ought to be tested for? And if it's "72v," obviously the range is going to be a few volts above (for full) and a bit above. (for depleted) But these are rules-of-thumb, and sort of nebulous to the amateur. To get specifics, should I test the voltage a.) immediately after charging, or after a day or two, and b.) idle or under load? In the interests of mitigating range anxiety, I'd like to make sure my settings are as specific/accurate as possible. You've got several videos. Is there one that may address these real-world scenarios best? Thank you.

[@cangudem]

Thanks for the explanation. You save my life

[@smde1]

I would really like to see a LiFePO4 BMS among your product offerings .

[@avatr7109]

I couldn't find the Video about Calculating SoC for various things like SoC for Energy etc .

[@peppi0304]

Informative video of what i exactly didnt understand about how you know what nn% charged means of a battery. I would ve appreciated if you defined the first SOC you wrote right away as SOC_c and in two different graphs you once mention Ah-discharged and DOD. Could have made them the same aswell.

[@stevecoscia]

Very informative video. Thank you for this. I just bought a 100Ah lithium battery and this explanation helps in understanding the app's SOC metric.

[@writerconnect1596]

Excellent job. Clearly explained . Very eloquent !!!

[@KeshavKumar20]

Brilliant presentation!

[@dhadumia]

Thank you very much for such a great video!

[@edsonferraz1]

OK, excellent information. Do you have a SoC code using C++?

[@JSGregg]

Excellent video! Very helpful. One question, so does the BMS use voltage to determine the starting point for monitoring SOCe?

[@energyeve2152]

Clear and concise. Thanks for sharing!

[@FINwithFAME]

Your explanation beats what my professor has covered.

[@MuhammadQasim-92]

Excellently explained sir

[@srinivasponnaluri5800]

Isn't no load voltage for a given charge level is a function of temperature of the battery?

[@rajivmallipudi2679]

Hi Stafl...A very good explanation

[@HugforYou]

Very good explanation. Thank you!

[@mohamedzain8628]

Thanks a lot, good explanation, keep going.

[@serhatpolat4956]

Hello, what is the internal resistance of the 4S lipo battery or what is it? I have a 5200mah 50C battery and the internal resistors are showing 7 ohms. Do you think these values ​​are normal?

[@dannybalisi6744]

very nice tutorial sir, in my set up sir im using 2 pcs 24v 100ah lifepo4 batt. in parallel connection. my question is why is it that in my volt meter, display of my scc and in my inverter was 100% and when i scroll down in my scc srne 60a mppt the soc was 54% what is the defirence betwen them? thank you sir i hope i'ved got an answer sir. thank

[@vishva8kumara]

If we have a function approximation for voltage / SOCc curve, it would be easier to normalize SOCe from voltage than a lookup table. I would like to model that. Wonder if there would be use to that.

[@plkh9602]

modeling a Voltage/SOC and measuring SOC based on voltage curve could be easier, but don't forget to consider the voltage drops on the battery itself due to internal resistance and the variation in voltage when charging.

[@sohailansariadvocate]

great information provided thanks

[@sunpiljang2334]

I enjoyed the video. I want to learn more about BMS. Is there any institution or certification you can recommend?

[@laurabarnes3295]

So please was the right voltage to charge a 11.1v System

[@vikaspandey3537]

at 6:45, how can I calculate that area. can you please help me in this ?. I have a device from that, I have a graph of Amps and voltage over the time and now I want to calculate total wh. how can I do this ?

[@DennisMathias]

Great presentation! I knew there were nonlinearities in monitoring SOC and wondered how they did that. So now I know.

[@snehal4582]

Very helpful . Could you please explain calculation about charge or discharge Ah required for individual module depends upon min and maximum of cell voltage

[@avinashpaulfernandes3932]

Hi! I have a small clarification. It was said that energy distribution is imbalanced. We know that energy is Voltage times Ah discharged. Even though the voltage is high in the first part the X axis is at a low value. Will it not be compensated? Thanks in advance for correcting me and clarifying it to me :)

[@mohamedamr6228]

The x-axis is the Ah discharged from the beginning of discharge not the instantaneous Ah

[@johnnyzee383]

" In general"..should be the name of this little video...

[@faradayera]

Very nice Information sir 👍

[@navnithrajsn1705]

Excellent presentation bro

[@juliushazzart9985]

Thanks for the clarity and simplicity

[@armanazote321]

If the battery is design only to take 80 mWh but test result it can be overcharged up to 90 mWh is that a normal Reading? thanks you.

[@wisalahmad1867]

My solar station software show SOC 3% and gradually increase but the voltage is above 12 so than why 3, or 5 or 7. It’s mean battery is too low . I am using Phoenix 230amp flooded

[@SeniorDonCarlo]

I’m impressed 👏🏼

[@richpetrelli2783]

Excellent info. My question may seem elementary but I understand quite a bit of what was discussed from my EE background. That said, I find one thing confusing. Is SOC and DOD the same with two 100ah lifepo4’s in parallel as one 100AH standalone lifepo4? I realize that I am getting 200AH with the parallel config and only 100AH with the standalone battery. With 2 in parallel, I would think that it should take twice as long to reach the 50% SOC level with the parallel config than in the single battery config, of course assuming the same load on both configs.

[@staflsystems]

Hi Rich - thank you for your question. SOC and DOD are expressed in percentages, so they would be normalized to the size of the pack itself. For example, if you've discharged 25% capacity from a fully charged state, the SOC would be 75% and DOD would be 25%, regardless of if it is a 100Ah or 200 Ah pack. So if you have a constant load of say 25A, it would take you 1 hour to get to 75% SOC with a 100 Ah pack and 2 hours to get to 75% SOC on a 200 Ah pack.

[@Doctorbasss]

WATT-HOUR is the real term that define remaining range/energy. Capacity is voltage dependent and each Ah at the end of charge worth less than the first Ah. So the REAL SOC is Watt-hour defined and not Capacity (Ah)

[@ashujoshi1632]

what is TCU error,While charging EV?

[@jihanas-syabani7889]

Awesome explanation! However, I just want to make sure if I get it right: 1. DoD can be calculated through current measurement and time graph.? 2. The battery capacity is calculated by comparing its measured voltage to its Voltage-DoD graph?

[@yangjingxi179]

The capacity is measured by coulomb counting. Capacity equal to integration of current by time.

[@yangjingxi179]

from current and time get SOC, from SOC get DOD

[@surenbono6063]

Does 0% start from 2.5/3 voltage in phones batteries...?

[@avisengineering8952]

Mr. Stafl.. great videos Can you pl make more videos

[@johnmeyer77]

So what voltage corresponds to 50% SOC? That seems like a very critical piece of information that you didn't provide because, if you are trying to estimate either the mAh or total energy remaining, the simplest thing is to measure the voltage and use that as a proxy. I watched this video hoping to learn these voltages, but was disappointed when you didn't provide them. And yes, I do realize that Coulomb Counting is the more accurate method, but that doesn't help you if you simply "come upon" a loose 18650 and want to know how much capacity it currently might offer.

[@Predato0000]

Very clear and brilliant presentation. Thanks a lot!

[@heshanmahela7789]

Thank you very much very informative.

[@garthlane4070]

Well done.

[@aed-smbenv7190]

Good larning sir

[@sergeymarshall3173]

Спасибо бро!

[@jimmytvglobal]

Very good explaination

[@junctek1802]

Fortunately to see your popular science video, we made a battery monitor KG140F, which can check the remaining capacity and current voltage of the battery, and can export the discharge curve, I think you should be able to use it, we want to send Give you a test.

[@nileshparmar4246]

Nice explanation!

[@Nic7320]

It would be better to define SOC(energy) as "SOE" or "State of Energy" and leave SOC for the lowly job of coulomb counting.

[@jimmytvglobal]

Great presentation

[@dahappychappy]

But Amp.hours is a measure of energy. You mean the peak power available, potential to do work goes down over time because the voltage drops? I am confused.

[@SpeakerKevin]

@Nick Keller Yes, amps x volts = watts. The same 100 watt light bulb will draw more amps as the sos drops.

[@swananddate6277]

if the battery is connected to load , How we gonna measure open circuit voltage in practical application ??

[@NawtieBoy96]

you cant , you will need to use some other estimation methods

[@DennisMathias]

My hypothesis would be that when the car is off or sleeping that that measurement is done. That's why when you park your car with 33% that when you get back in it might be 35%. Or 30%. It's possible it is more dynamic than that. It may do an instantaneous measurement during load reduction and calculate the delta from that.

[@electroumit]

Thank you. You are awesome.

[@Warpreacher]

Yes, you bloody legend

[@nishpendumondal9338]

Is it possible Calculate Cell Or Battery Pack Capacity if Amp's don't Known? PlZ Ans Me

[@yangjingxi179]

Yes, but complicated.

[@rizqizulqornain2539]

Well presented

[@Thecrow999]

Thank you!

[@a0cdhd]

Quite so Mr. Stafl

[@januaryonenineteenseventy4195]

Love the video.

[@Drillmechanic]

Power * hour is the actual capacity measured in W*h

[@LalthlenglianaKhawlhring]

Thank you 💐

[@r.e.tchoas5057]

I got thrown off at the first 30 seconds no one got the misspelled word?

[@ioandragan3729]

You look like PM.Justin Trudummy , or are you brothers??

[@RogerRumbu]

Great

[@aspboss1973]

How do you the remained capacity"70ah"?

[@yangjingxi179]

For example, you have a battery with 100Ah capacity. And you discharge the battery with 30A for one hour, there will be 70Ah capacity left in the battery.

[@aspboss1973]

@@yangjingxi179 thank you

[@Ksklithium]

Interesting

[@underdog5004]

"Remaing"

[@rayvanokeizer2354]

Vak man!

[@Cosme422]

From a professional video editor, there should never be any kind of music during any explanation videos ever

[@ericseidel4940]

I totally dislike your BMS system because it can handle the ODD number of 12 cells, are you aware that most of the batteries in storage applicatins are 16 cells LiFePo4 ? Then the total cost of just the BMS is way overpriced at 700+280+280=1260$ with the last monitor only half populated. Totaly ou of the residential storage market!

[@jeebusk]

I think this presenter is mostly presenting his own confusion, there's no actual distinction between capacity and energy.

[@4G12]

That's only true if internal resistance and voltage discharge curves are non existent.

[@sonicspring6448]

Capacity is charge (Amp hours) and Energy is Joules (Watt hours), so the voltage profile is important.

[@thedolphin5428]

Simplistic, theoretical nonsense, not corresponding to the reality of any particular LiFePo4. Have you ever bench tested dozens of batteries? Not one of them ever follows the maths or the graphs. New vs old; quality internal chemistry vs recycled lithium; hourly/daily/seasonal temperature variations; balance between cells; number of cycles; all conspire to make the only real SOC a specific measure of currents in and out from a daily top balanced cell reference point compared to the maximum actual battery SOH (State of Health). I have never, within real life situations, found a SOC figure to be any better than about +/- 8%. The only true SOC is

[@batteriesforeverything7112]

Not impressed

[@vishnoor]

Wonderfully done. Explained in very simple manner. So I guess one needs the charts for a battery pack to implement the socc soce and dod.