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  • Batteries connection

    i am new in this forum
    and i did not really now where to post this

    so my question is
    if i have 4 batteries and i want to connect them in series and in parallel so i increase both the volts and the amps

    which configuration is best
    2s2p or 2p2s???

    connect the batteries in series and then in parallel or
    first connect the batteries parallel and the parallel batteries in series?

    both setups seems to be giving the same results
    but from battery perspective is 1 design better?


    as i see it in case 1 battery fails
    2s2p case 1 battery fails so you loose the other battery so you are left with the 2 batteries trying to
    power you so they get both double the normal amp to push
    n case of 2p2s you loose 1 battery but then you have only 1 battery trying to push the double amount of normal amp

    so i see that the design 2p2s has some advantages over 2s2p


    second question

    if you have a number f batteries lets say 5 for the argument
    what will be better
    put them all in parallel and just draw more amps from the pack
    or put them in series and draw fewer amps???

    so from battery perspective which setups is better for the batteries
    parallel or series?

    i have done some dyi in electronics and i know that in electric circuits
    some designs may seem identical but electrical there is a huge difference
    the order you put some components


    thank you all for the replies

  • #2
    Originally posted by ANIKHTOS View Post
    i am new in this forum
    and i did not really now where to post this

    so my question is
    if i have 4 batteries and i want to connect them in series and in parallel so i increase both the volts and the amps

    which configuration is best
    2s2p or 2p2s???

    connect the batteries in series and then in parallel or
    first connect the batteries parallel and the parallel batteries in series?

    both setups seems to be giving the same results
    but from battery perspective is 1 design better?


    as i see it in case 1 battery fails
    2s2p case 1 battery fails so you loose the other battery so you are left with the 2 batteries trying to
    power you so they get both double the normal amp to push
    n case of 2p2s you loose 1 battery but then you have only 1 battery trying to push the double amount of normal amp

    so i see that the design 2p2s has some advantages over 2s2p


    second question

    if you have a number f batteries lets say 5 for the argument
    what will be better
    put them all in parallel and just draw more amps from the pack
    or put them in series and draw fewer amps???

    so from battery perspective which setups is better for the batteries
    parallel or series?

    i have done some dyi in electronics and i know that in electric circuits
    some designs may seem identical but electrical there is a huge difference
    the order you put some components


    thank you all for the replies
    The best wiring arrangement for multiple batteries is all in series.

    The chances of finding 5 batteries at a voltage that adds up to 12, 24, or 48 is pretty slim. Most batteries are in the 2, 4, 6, 8 & 12volt range will allow you to set up a series string using an even number that add up to your desired system voltage.

    As for your first question. Neither (2p2s nor 2s2p ) is better than the other. Losing 1 in a 4 battery system will hurt the entire bank.

    Comment


    • #3
      Originally posted by ANIKHTOS View Post
      which configuration is best
      2s2p or 2p2s???

      connect the batteries in series and then in parallel or
      first connect the batteries parallel and the parallel batteries in series?
      Yes.

      With Solar or Stationary applications you should not parallel any batteries unless necessary, and it is never necessary unless you need more than 4000 AH. You are correct if you use a Ladder Connection of parallel cells, you do have some redundancy if one string should fail. Typically it is just a single cell or battery that fails. This is one reason EV's use Ladder Connections, so they can get home or to a garage if a string fails and not leave them stranded on thee road.

      But there is a catch. An EV has a very sophisticated Battery Management System monitoring every cells and all strings. The operator is immediately altered of a problem. Additionally EV use Lithium batteries and solar uses Pb. Unless you have a BMS monitoring every cell/battery, you will not know you have a dead or open string immediately. In fact unless you monitor and inspect your batteries weekly with a hydrometer, you may never know until your good string has now been worked to death. So now instead of a dead cell/battery in a string, you now have a completely dead and useless battery system you have to replace. So instead of replacing a single bad battery, you now have to replace every battery. Had it been a single string, you would have caught it immediately, and no thave to replace every battery.
      MSEE, PE

      Comment


      • #4
        hello

        Originally posted by Sunking View Post
        Yes.

        With Solar or Stationary applications you should not parallel any batteries unless necessary, and it is never necessary unless you need more than 4000 AH. You are correct if you use a Ladder Connection of parallel cells, you do have some redundancy if one string should fail. Typically it is just a single cell or battery that fails. This is one reason EV's use Ladder Connections, so they can get home or to a garage if a string fails and not leave them stranded on thee road.

        But there is a catch. An EV has a very sophisticated Battery Management System monitoring every cells and all strings. The operator is immediately altered of a problem. Additionally EV use Lithium batteries and solar uses Pb. Unless you have a BMS monitoring every cell/battery, you will not know you have a dead or open string immediately. In fact unless you monitor and inspect your batteries weekly with a hydrometer, you may never know until your good string has now been worked to death. So now instead of a dead cell/battery in a string, you now have a completely dead and useless battery system you have to replace. So instead of replacing a single bad battery, you now have to replace every battery. Had it been a single string, you would have caught it immediately, and no thave to replace every battery.
        Ladder Connection of parallel cells what is this connection?? i am new so i do not know the terminology

        the second question about parallel or serial the batteries was asked from the aspect of life of batteries
        better way to manage them

        so not considering the other aspects of the electrical consumption

        having all batteries in parallel or all in series makes a difference??

        in complexity of charging? managing the batteries? life expendency of the batteries?


        sorry for this but i am new and still learning the terminology

        so the yes was to 2p2s or 2s2p??' i did not understand

        thank you very much for your time and your effort to explain things

        Comment


        • #5
          Originally posted by ANIKHTOS View Post
          Ladder Connection of parallel cells what is this connection?? i am new so i do not know the terminology

          the second question about parallel or serial the batteries was asked from the aspect of life of batteries
          better way to manage them

          so not considering the other aspects of the electrical consumption

          having all batteries in parallel or all in series makes a difference??

          in complexity of charging? managing the batteries? life expendency of the batteries?


          sorry for this but i am new and still learning the terminology

          so the yes was to 2p2s or 2s2p??' i did not understand

          thank you very much for your time and your effort to explain things
          Wiring batteries in parallel ends up getting uneven charging and discharging. When you get uneven you will shorten battery life. Sort of the weakest link will fail first and take down the rest.

          A series wired system does not introduce uneven charging or discharging so it is better then any type of parallel.

          Here is a site that explains different parallel wiring and what the issues are.

          http://www.smartgauge.co.uk/batt_con.html
          Last edited by SunEagle; 09-21-2015, 02:24 PM. Reason: spelling

          Comment


          • #6
            Originally posted by ANIKHTOS View Post
            Ladder Connection of parallel cells what is this connection?? i am new so i do not know the terminology
            That is what you call your 2p2s. It is the[B] Alternative[/B] Connection shown below.




            Originally posted by ANIKHTOS View Post
            the second question about parallel or serial the batteries was asked from the aspect of life of batteries
            better way to manage them

            so not considering the other aspects of the electrical consumption

            having all batteries in parallel or all in series makes a difference??
            Already covered this, Connect batteries in Series and avoid parallel strings unless neessecary. Reason is simple you cannot BALANCE the Battery internal resistance or distribution resistances to keep all currents equal in parallel arrangements. That means there is always one string doing most of the work wearing itself out prematurely. Professional installations can parallel batteries with great success, but you CANNOT because you do not have the money, knowledge, or resources. Pro's use engineered solid copper buses arranged in such a fashion that equalizes circuit resistance so all strings charge charge and load equally. If you must Parallel to obtain the desired capacity limit it to just only 2 parallel strings, or use a Ladder Connection, but with Ladder you need a way to monitor every battery including Specific Gravity.

            If you find yourself using parallel is most likely ignorance. What we see a lot of is folks stuck inside a nasty 12 volt box. All they know is car batteries, and batteries are 12 volts right? Wrong, they are 2 volts, and if you need 12 volts at say 400 AH, there is no such thing as a 12 volt 400 AH battery, as you could not lift it up easily. Largest 12 volt you will likely find is 100 AH forcing you to use 4 of them in parallel. Each weighing around 80 pounds or a total of 320 pounds is what a 12 volt 400 AH battery weighs. The right solution is to use either 3-4 volt 400 AH batteries or 2-6 Volt 400 AH batteries wired in series. Or you could even use 6-2 Volt 400 Ah batteries if the 4 or 6 volts is too heavy for you. [B]Are you one of those stuck inside a 12 Volt Box? [/B]

            Ever hear of 24 and 48 volt systems. 12 volts is for toys and RV's. 12 volts is not capable of delivering larger amounts of power and extremely expensive and inefficient. So if you are stuck inside that 12 volt box, get out of it it. Theere is a much better world outside the 12 volt box you are trapped in.

            On paper a 12 volt 400 AH battery = a 48 volt 100 AH battery. But in practice the 48 volt system is initially lees expensive to install. more efficient, delivers more usable power, and a lot less less expensive to maintain with less frequent battery replacement. Not to mention a whole lot SAFER like 400% safe.
            MSEE, PE

            Comment


            • #7
              Originally posted by Sunking View Post
              That is what you call your 2p2s. It is the[B] Alternative[/B] Connection shown below.






              Already covered this, Connect batteries in Series and avoid parallel strings unless neessecary. Reason is simple you cannot BALANCE the Battery internal resistance or distribution resistances to keep all currents equal in parallel arrangements. That means there is always one string doing most of the work wearing itself out prematurely. Professional installations can parallel batteries with great success, but you CANNOT because you do not have the money, knowledge, or resources. Pro's use engineered solid copper buses arranged in such a fashion that equalizes circuit resistance so all strings charge charge and load equally. If you must Parallel to obtain the desired capacity limit it to just only 2 parallel strings, or use a Ladder Connection, but with Ladder you need a way to monitor every battery including Specific Gravity.
              Just to avoid potential confusion among other readers of the thread, the illustrated connections are 3S2P and 2P3S respectively. The OP was looking for a four battery configuration, but adapting the diagrams given (by removing two batteries from each) should not be to intellectually challenging.

              One of the problems with a ladder connection is that the two batteries in each "rung" of the ladder must be well matched in charge before the connection is made.
              With the series first connection that is still an issue, but it is equally important to match the SOC of each of the batteries in the series string before making the initial connection. Otherwise you will end up doing much more initial equalization than necessary, stressing the batteries which started with a high SOC.
              SunnyBoy 3000 US, 18 BP Solar 175B panels.

              Comment


              • #8
                thank you all for the info now all are clear

                i am doing baby steps

                first step was buy dc power supply for computer
                actually bought 3 of them
                then bought an atom board so i can build a low power pc and a battery
                and i run the computer from the batter successful

                then i bought leds just the led and i build the lamb myself
                so i need a dc converter to use
                second phase a battery 12 volt and a dc dc converter

                and start replacing lights at home

                ultimate goal to go off grid

                i start by changing things inside the house one by one lowering the power drain and switching everything in dc

                so now i am looking for the batteries
                technologies connections capacities

                i have a friend that went off grid but because of money problems
                his solutions was the best i can do with the money i do not have
                so his pack is different batteries manufacturer age and capacities making his pack
                a solution of the desperate

                i do not have the money to go off grid now
                but i like to get informed and i am doing small steps towards it

                Comment


                • #9
                  For lifepo4, it is pretty simple if you have multiple cells:

                  PARALLEL the individual cells to build up your desired capacity first.

                  The SERIES connect these "groups" of paralleled cells to get your desired nominal voltage. You now have a "battery" of cells.

                  This helps to keep them in balance, once they are charged properly to do so. Follow guidelines as mentioned above about not doing simple "ladder" connections for charge / discharge, but do the "diagonal" or other such configuration to avoid charging / discharging solely from the end of the bank.

                  Comment


                  • #10
                    Originally posted by ANIKHTOS View Post
                    ultimate goal to go off grid.....
                    i have a friend that went off grid but because of money problems
                    That would be extremely foolish. Why do you want to pay 5 to 10 more for power than buying it from the POCO for the rest of your life? Answer that question..

                    Just in battery cost alone, not counting anything else, you are looking at around 60-cents per Kwh. A good 5 year battery will cost you around $1100 to $1200 for each Kwh of usable power a day. 10-cents worth. In 5 years it needs replaced at even higher cost. In 5 years you get 1825 Kwh out of the battery. That means in battery cost alone you are paying $1100/1825 Kwh = $0.6027/Kwh. That is roughly 600% more then you can buy it from the POCO.

                    Your friend was a fool, don't follow him over the cliff.
                    MSEE, PE

                    Comment


                    • #11
                      Originally posted by ANIKHTOS View Post
                      thank you all for the info now all are clear


                      i have a friend that went off grid but because of money problems
                      his solutions was the best i can do with the money i do not have
                      so his pack is different batteries manufacturer age and capacities making his pack
                      a solution of the desperate

                      i do not have the money to go off grid now
                      but i like to get informed and i am doing small steps towards it
                      The cost of generating your own power with batteries is many times what it would cost you for the same amount of electricity purchased from the Utility.

                      The only way your friend could save money by going off grid was to not use about 95% of the electricity he was paying for. That usually requires a major change in the way you live because there will be next to no electrical appliances.

                      Comment


                      • #12
                        Originally posted by Sunking View Post
                        That would be extremely foolish. Why do you want to pay 5 to 10 more for power than buying it from the POCO for the rest of your life? Answer that question..

                        Just in battery cost alone, not counting anything else, you are looking at around 60-cents per Kwh. A good 5 year battery will cost you around $1100 to $1200 for each Kwh of usable power a day. 10-cents worth. In 5 years it needs replaced at even higher cost. In 5 years you get 1825 Kwh out of the battery. That means in battery cost alone you are paying $1100/1825 Kwh = $0.6027/Kwh. That is roughly 600% more then you can buy it from the POCO.

                        Your friend was a fool, don't follow him over the cliff.
                        because in my country
                        with the bill we have to buy 2 3 times more in other fees
                        so it makes real sense to go off grid

                        so all this in mind per kw in my country is sold 0.3 euro or more

                        so can i ask why something i can buy today and cost x amount of money 5 years latter will cost more?
                        if you say inflation then i will also say that most probably the salaries will also go up
                        and also lifepo4 batteries go down in price
                        i bought a few small ones to play around with the new technology and i used them in custom flash lights with leds

                        now both leds and the batteries cost less
                        so why the battery cost will be worse??

                        also my friend has no option he is unemployed
                        so he used his last money to go off grid
                        if not done that the power company would cut the power anyway because he would not be able to pay the bill

                        so i do not think him as a fool
                        at list now
                        he has light to see in the night
                        he can watch television
                        he can use his computer to try to find a job
                        he can charge his telephone

                        if he had not done it what??
                        he was going to be like his sister living in an apartment without electricity?

                        his life is not the same as on grid
                        but at least he has not return to stone age
                        in my country because of the prices the crisis 2 million houses are cut off from the poco
                        and many more will follow

                        so depending your situation off grid maybe is the only choice that makes sense to do
                        also form a financial point

                        and you know i love maths
                        and i won maths competitions when i was in school
                        so all the time i am with a calculator calculating things in a ridiculous extend and detail

                        because of my personality i always want to have the max out of a situation

                        so no worries i have done the maths and i know the cost
                        2nd i know that i will not be able to build a system to have a life as when in grid
                        but at least i will have minimum level of quality that i will not go bellow

                        thats why the led testing the experiments with low voltage computers

                        most probably i will have money to buy only 2 solar panels and build a small pack to start with

                        but at least i will be able to be on Internet and talk here and there and have people telling me that i am stupid
                        and i should have stayed with poco
                        i prefer to be called idiot because at least i will have the possibility to be online so i can be called like that
                        so calculations say 5 years to break even with current prices
                        calculations were 1 year ago so maybe now it will break even faster
                        panels are cheaper batteries are cheaper

                        Comment


                        • #13
                          Originally posted by ANIKHTOS View Post
                          so all this in mind per kw in my country is sold 0.3 euro or more
                          That means batteries will be just that much more expensive. You will still be paying many times more than buying it.

                          Originally posted by ANIKHTOS View Post
                          so can i ask why something i can buy today and cost x amount of money 5 years latter will cost more?
                          You are joking right? Batteries are a very mature product. It is called inflation. Anything you buy today will cost more 5 years from now.

                          Batteries are a product of energy. You cannot make a battery without a whole lot of energy. It takes a lot more energy to make a battery that it will ever be able yield over its lifetime. That simply means a battery like Hydrogen and many other carries of energy will always be a multiple of the SOURCE FUEL. In a Pb battery at best it takes 1.5 units of energy to make a battery that can only deliver 1 unit over its life time. So to just make the battery it cost 1.5 times in just energy. That does not count labor, materials, equipment cost, taxes, liability, insurance, delivery, and profit. One you add all that up you you are a 5 to 6 time looser. That means you can never obtain a ROI or EROI. It means you are throwing money and resources away. The world would be better off if you stayed on the grid. Go off the grid and both you and earth are loosers.

                          I will help you, but all your reasons going off grid is FALSE. Now that you know, I will help if you decide to throw money away. Hell I might profit from it. I have no problem taking your money from you. Do you?

                          I also have no problem and prefer to help you make smart decisions and keep your money in your pocket.
                          MSEE, PE

                          Comment


                          • #14
                            If your total cost of grid power is upwards of $1-$2 per kWh, then it justifies doing a careful evaluation of the economics of battery stored PV power.
                            Right now there is nowhere in the US that has that high a cost, even Hawaii and Alaska.
                            (In some cases of remote areas where the "grid" power is provided by a cooperative using diesel powered generators, the cost can be above $.50.)

                            Less cost than that, it only might make sense if you also need to provide daily backup for an unreliable grid.
                            Last edited by inetdog; 09-22-2015, 01:36 PM.
                            SunnyBoy 3000 US, 18 BP Solar 175B panels.

                            Comment


                            • #15
                              Originally posted by inetdog View Post
                              If your total cost of grid power is upwards of $1-$2 per kWh, then it justifies doing a careful evaluation of the economics of battery stored PV power.
                              Right now there is nowhere in the US that has that high a cost, even Hawaii and Alaska.
                              (In some cases of remote areas where the "grid" power is provided by a cooperative using diesel powered generators, the cost can be above $.50.)

                              Less cost than that, it only might make sense if you also need to provide daily backup for an unreliable grid.
                              i do not live in usa
                              i live in Greece
                              and the country now is in mess

                              it is bankrupt
                              people without jobs
                              jobs with lousy money if you are lucky to have one
                              there is no social security in greece
                              you loose your job you get no support

                              and as i said we end up paying 30 cent euro per kw
                              because of all the extras we have to pay with the electric bill

                              i do not know the mentality in the usa or how much you consume but i am around 900kw per month or less
                              with the old fridge consuming around 1kw per day in winter time
                              so i need a new fridge to cut down the consumption

                              now for lights thank you led consumption is very low
                              low power computer helped to go down in consumption

                              so know i have to deal with fridge
                              then the cooking
                              and then i pull the plug off grid

                              are you know serious of how much energy takes to make a battery???
                              a 12 volt 200 ah battery takes how much energy?
                              which you are going to use for 5 years
                              lets say you use 40 ah per day that 480 watt per day thats 876kw in end of life

                              so according to you the battery will cost us 1314kw to make?????'

                              Comment

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