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  • #46
    Originally posted by santaclaws View Post
    PS: You're perfectly right, those string equivalent resistances are dynamically changing but, at the end of the day (so to speak), no string will be discharged bellow bank voltage, no matter what.
    Right. The string will still die.

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    • #47
      Originally posted by santaclaws View Post
      Btw, the load current (during discharging) will be mostly supplied by the strings with the higher SOC (which have higher EMF voltages and lower internal resistances), not by the "abused" (aka lower SOC, lower EMF voltage and higher internal resistance) string.
      Now you've got it! It will not be charged or discharged as strongly as the others. It will simply sit at a partial state of charge and sulfate. This is why we get so many "I have a big 1000ah battery bank but it seems to act like a 250ah battery! What's going on?" questions. Answer - only one of the four strings is still "alive."
      (that's part of the self-ballancing process, too)
      Again, that's part of the self-UNBALANCING process.

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      • #48
        Originally posted by jflorey2 View Post
        Right. The string will still die.
        You should have added dies from from Sulphate crystals and resulting in high internal resistance that prevents the battery from taking or giving a charge. He thinks parallel strings act like a single battery and does not realize each is its own Node independent of the others. He is hopeless and clueless.

        He should go to Batt Con and do a comedy act between lectures and demonstrations. If he hangs around, he might learn something.

        Santafraud you now have 5 engineers telling you do not understand. Two of us hold PE with a combined 80 years of battery experience It is time for you to give it up. You do not know what you are talking about. You have lost all credibility here and just embarrassing yourself.

        To start your battery equivalent circuit is way off and leading you to the wrong conclusions. You have not even scratched the surface of complexity. For a FLA battery we use a Randles Circuit to study Pb battery modeling.

        Last edited by Sunking; 02-16-2017, 09:00 PM.
        MSEE, PE

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        • #49
          Originally posted by foo1bar View Post
          I understand you may be reluctant to listen to a poster who is arrogant and antagonistic and IMO generally an *ss.

          You have to repeat that more often. Curios enough, you're the only person who has actually dared to say it (many thanks). I see that none of the moderators do anything to stop those every-single-post-insults against me. I know what are they're after though: they want me to react the way that "poster" does to actually put me on jail. Man, I feel like being in Russia (not that I like to talk about politics): "if you're not with us, you're against us".


          Originally posted by Sunking View Post
          I suppose you need to talk to about 64 engineers that make up IEEE Battery committee. It is composed by 1/2 from battery manufactures engineers and scientist

          I'd be ashamed to be part of that "commitee" (and YOU were talking about fraud)?! What's that "commitee" doing? Taking notes from the Volta experiments two hundred years ago??

          The "battery" commitee is the next best conspiration board after the "petrol & gas" one. They keep the world from moving on by perpetuating these pathetic technologies with no progress whatsoever.

          Look around, we're overwhelmed by the top notch technology.. then look under your car's hood: a prehistoric stone-like of "energy storage". We better use frog legs (as Galvani has experimented two hundred years ago) to generate electrical power and I bet they will be easier to maintain and last longer.

          If I were you, I'd stay away from humanity knowing what "techonology" I'm advertising. For that matter, please stop using "commitee" as an explanation when I'm asking you techical (electronics related) questions.

          I have a proposal for you though: tell that "commitee" to donate me eight of the highest quality 12V batteries available then I'll run a test of this S2P4 configuration (they could do the same test with series only configuration). Meet you over 10 years to check my batteries for any damage.

          Btw, you don't want to know what junk batteries I'm actually using. Their plates are thin like a paper sheet and misshaped (they're actually advertised as truck batteries, but they are the worse ones for sure). But they have "survived" for 2 years and a half in this "unreal" configuration. Actually, just one of them has died (shorted), the rest of them are perfectly fine.

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          • #50
            Originally posted by jflorey2 View Post
            Originally posted by santaclaws
            "Btw, the load current (during discharging) will be mostly supplied by the strings with the higher SOC (which have higher EMF voltages and lower internal resistances), not by the "abused" (aka lower SOC, lower EMF voltage and higher internal resistance) string."


            Now you've got it! It will not be charged or discharged as strongly as the others. It will simply sit at a partial state of charge and sulfate.
            You still don't get it. Those things are dynamically happen. The higher SOC strings will deliver most of the load current initially; when their SOC decrease (reaching the "abused" string SOC level), their output current will be ballanced hence all the strings will output about the same current.

            Once again: this is not an ON/OFF operation. Things are going smooth, depending of your load, SOC and so on.

            So let's get back to Kirchhoff:

            No matter what the equivalent resistance of the strings is, the current passing (in/out) the string will be:

            I = (Voc - Vbank) / R

            where Voc is the total EMF voltage of that string and R is the equivalent resistance (including everything in the current path: connectors, wires, plates, electrolyte and so on).

            Now, if Voc is greater than the Vbank, the current will flow away from the battery (it is discharging). If the Voc is lower than Vbank, the cells of that string will be charged (sucking energy from their higher SOC neighbours).

            That's how self-regulating works, really. It does not matter what temperature differences, internal resistance variation and so on. That above formula will stand no matter what.

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            • #51
              Originally posted by santaclaws View Post


              Btw, you don't want to know what junk batteries I'm actually using. Their plates are thin like a paper sheet and misshaped (they're actually advertised as truck batteries, but they are the worse ones for sure). But they have "survived" for 2 years and a half in this "unreal" configuration. Actually, just one of them has died (shorted), the rest of them are perfectly fine.
              Unfortunately as good as your knowledge is concerning the subject and your battery system you have run afoul of the simple reason not to wire multiple cells in parallel. That killed your one battery and there is no chance of bringing it back to life. If you believe the problem was a manufacturing defect and not a wiring issue then we are wrong and you are right.

              If you are right then go add a new battery to replace the bad one and tell us how long it lasts. IMO 2 1/'2 years is no where near what it should have and is way short of what a lot of off grid people would like to see since they are fixed on having a system that lasts 10 years.

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              • #52
                Now let's be honest, how many of the off-griders (heavy cycling) are using cheap & junky truck (starter) batteries and are expecting more than one year of service?!

                FWIW, I've just checked the batteries voltages (manually, I just didn't believe the remote data I was seeing): all the 6 batteries left in service (2S3P) have a very closer voltage indication (they were under a moderate load of ~300W, so that's not the true EMF though), in the range of 12.95-12:91V.

                Anyway, that's a reasonable indication of a pretty ballanced system, don't you think?

                ==

                Look, I'm not in the mood of arguing anymore. I thought we could have changed legit & technical oppinions about this subject but I was only getting insults and threatenings.

                Beside, the subject of this thread was completely different (what's actually happening when a battery is forced to boil, as a chemistry/physics approach).

                From my point of view, there's nothing left to say (on neither of the two subjects). I feel very uncomfortable being forced to accept those insults just to be allowed to express my oppinion.

                I feel like living in North Korea and that's not the ultimate goal of my life.
                Last edited by santaclaws; 02-17-2017, 10:28 AM.

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                • #53
                  Originally posted by santaclaws View Post
                  Now let's be honest, how many of the off-griders (heavy cycling) are using cheap & junky truck (starter) batteries and are expecting more than one year of service?!

                  FWIW, I've just checked the batteries voltages (manually, I just didn't believe the remote data I was seeing): all the 6 batteries left in service (2S3P) have a very closer voltage indication (they were under a moderate load of ~300W, so that's not the true EMF though), in the range of 12.95-12:91V.

                  Anyway, that's a reasonable indication of a pretty ballanced system, don't you think?

                  ==

                  Look, I'm not in the mood of arguing anymore. I thought we could have changed legit & technical oppinions about this subject but I was only getting insults and threatenings.

                  Beside, the subject of this thread was completely different (what's actually happening when a battery is forced to boil, as a chemistry/physics approach).

                  From my point of view, there's nothing left to say (on neither of the two subjects). I feel very uncomfortable being forced to accept those insults just to be allowed to express my oppinion.

                  I feel like living in North Korea and that's not the ultimate goal of my life.
                  You would be surprised at the number of people wanting to go off grid using car batteries only to find out how short a lifespan they have.

                  Unlike you most newbies do not understand the technology or logistics of electrical systems, solar equipment, batteries, circuit protection, etc. They just want to purchase a "kit" with everything plug and play to get into solar with no idea what they will use or how they plan on installing the system. Those are the people that we have to yank back from the edge of failure and help them keep from wasting their money.

                  We also come across some people that believe they are "experts" in the field of solar/battery and it becomes a heated discussion trying to get them to think about what they are trying to do in the physical world instead of the theoretical world. Trust me when I say after getting my EE degree I found there was a much different approach to designing a power distribution system then what I had learned from the books. Reality sometimes sucks and the truth can hurt ones ego if you let it.

                  So while I don't condone abuse of anyone I also understand that being very polite does not get my point across to some people so the 2 x 4 approach is necessary.

                  So instead of arguing the point any longer I will say it is your money and your understanding of the problem you can do what you want. But I will ask that you at least keep an open mind to what some of the others have posted concerning a parallel wired battery system.

                  Comment


                  • #54
                    Originally posted by SunEagle View Post
                    So while I don't condone abuse of anyone I also understand that being very polite does not get my point across to some people so the 2 x 4 approach is necessary.
                    I strongly disagree that the abusive and antagonistic behavior on these boards is conducive to getting a point across.
                    As you can see from this discussion it actually makes it so that the person is *less* willing to listen.

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                    • #55
                      Originally posted by foo1bar View Post

                      I strongly disagree that the abusive and antagonistic behavior on these boards is conducive to getting a point across.
                      As you can see from this discussion it actually makes it so that the person is *less* willing to listen.
                      It can have that affect also. What would you suggest as a action plan to get past someone that is too stubborn for their own good and help them save money or not get hurt?

                      Unfortunately there is not one way to do it for everyone. We each have our own set of feelings which can be affected by different stimuli. What works for one will be totally opposite for someone else.

                      Maybe a 5th grade teacher can jump in and provide some idea how to teach someone without hurting their feelings.

                      Comment


                      • #56
                        Originally posted by santaclaws View Post
                        The "battery" commitee is the next best conspiration board after the "petrol & gas" one. They keep the world from moving on by perpetuating these pathetic technologies with no progress whatsoever.
                        There's an electric car out there that can go 300 miles on a single charge, get an 80% charge in 40 minutes and can beat almost anything else on the road from 0-60. We have 76 gigawatts of solar out there and that number is doubling every 2 years. We've got grid scale battery storage and batteries in medical implants that last 20 years. I'd say that the world is "moving on" when it comes to battery technology, based in part by work by the IEEE.
                        I have a proposal for you though: tell that "commitee" to donate me eight of the highest quality 12V batteries available then I'll run a test of this S2P4 configuration (they could do the same test with series only configuration). Meet you over 10 years to check my batteries for any damage.
                        I'm a member of IEEE and I'd rather my dues go to organizing important research, rather than providing you with basic battery education.

                        But I have a better idea. Get an 8S 48V battery and a 2S4P 12V battery and connect them to similar inverters. Should cost you around $1600 for the batteries. Use them for five years. Then test each one and see which configuration gives you the best residual capacity.

                        Btw, you don't want to know what junk batteries I'm actually using. Their plates are thin like a paper sheet and misshaped (they're actually advertised as truck batteries, but they are the worse ones for sure). But they have "survived" for 2 years and a half in this "unreal" configuration. Actually, just one of them has died (shorted)) . . . .
                        So you are misusing batteries and one just failed after 2 years. This isn't helping with your claims that you know what you're doing.

                        Comment


                        • #57
                          Originally posted by SunEagle View Post
                          It can have that affect also. What would you suggest as a action plan to get past someone that is too stubborn for their own good and help them save money or not get hurt?
                          Well, how about just give good advice, and if they don't want to take it, give up? Easier and more efficient. And in the end it's their money and their safety.

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                          • #58
                            Originally posted by jflorey2 View Post
                            Well, how about just give good advice, and if they don't want to take it, give up? Easier and more efficient. And in the end it's their money and their safety.
                            I think that's a good note to close this thread with.
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