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Please Help ! Connection 12v Inverter to 24v system ?

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  • #16
    Oh ! Damn...

    Originally posted by Sunking View Post
    Maybe not so good.

    What is the Vmp of your panels. Unless it is at least 36 volts or higher, there is no configuration you can use the panels on a 24 volt battery system with a PWM controller. You made a huge mistake buying a PWM controller.

    Even if the panels are 36 volts wired in parallel (only possible way to configure them). You just turned your 500 watts of panels into 330 watts. If you wired them in series 115 watts.
    Ooops...
    How can I improve my system now ?
    I can sell PWM controller and buy MPPT ? or something else ?

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    • #17
      Originally posted by myselfsbs1 View Post
      I can't do above as my panels are 24v and charger is fixed at 24v too !
      Sorry to hear that. That's a common result of the "buy first design later" method of solar power installation.
      One idea that I was reading somewhere was to use a MPPT charge controller ? Can MPPT controller charge 12v batteries in parallel with 24v panel ?
      An MPPT charge controller can take a higher voltage panel and drop the power for a 12 volt battery, yes.
      So, if I buy a MPPT 24v, 20 amp charge controller and then connect my batteries in parallel (to make it 12v) and then connect inverter to batteries...
      Does that appear to be a quick workaround ?
      Yes, with the following caveats:
      -Paralleling several batteries to increase capacity doesn't work that well; expect a more rapid end of life of the batteries if you do that.
      -Technically you need a 12V (system voltage) MPPT, not a 24 volt.

      The Tristar 30 would work for you (12 volt out, up to 150 volt in, 30 amps) and runs around $350.

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      • #18
        Originally posted by myselfsbs1 View Post
        Ooops...
        How can I improve my system now ?
        I can sell PWM controller and buy MPPT ? or something else ?
        Get rid of the PWM controller and buy a quality MPPT controller. If you insist on using 12 volt Inverter. (bad idea), Get a MPPT controller and reconfigure your batteries for 12 volts. At 500 panel watts on 12 volts requires a 40 amp MPPT controller.
        MSEE, PE

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        • #19
          Originally posted by Wy_White_Wolf View Post

          It'll unbalance the batteries. One battery will remain at full charge voltage 12.8 while the other will drop. Let's say you drop it down to 12.4V. Now your string voltage is 25.2V. The charge controller sees that it needs charged. It (the charging process) assumes both batteries are of the same voltage. That would be 12.6 V. so it's trying to overcharge one battery while the discharged will never achieve full charge. The more you use the system the worse the imbalance becomes.

          You really have only 2 options.
          1. Get a 24V inverter
          2. Get an MPPT charge controller and reconfigure into a 12V battery bank.

          WWW
          i have forget my system and discharged one battery badly and this happen one battery at 13vdc other 14vdc i tried to dishcrge the higher voltage one but no use as soon as connect batteries to charge controoler one goes high and oother stay same as it was

          what to do now? how to solve it?

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          • #20
            Originally posted by gendil View Post
            i have forget my system and discharged one battery badly and this happen one battery at 13vdc other 14vdc i tried to dishcrge the higher voltage one but no use as soon as connect batteries to charge controoler one goes high and oother stay same as it was. what to do now? how to solve it?
            Sounds like you need new batteries. It is nearly impossible to "fix" a battery bank with one bad battery.

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            • #21
              Originally posted by jflorey2 View Post
              Sounds like you need new batteries. It is nearly impossible to "fix" a battery bank with one bad battery.


              not that bad man ... i have done this mistake many times and get away with it the main problem is that i own a 24vdc system and from time to time used to get 12vdc inverter to operate on one of the batteries


              while one get dischraged i quickly try to discharge the other and eventually get the balance again

              however this time i forget the system after i used it and went on in trip for 2 days



              the pwm start charging one at 14 and other at 12.9 or so


              still i am struggling getting them in balance i am connecting them in parallael as some one indicates should be restored with 3 days of paralled operation


              remember on note they are agm for if not agm they wont withstand harsh charging ,,,,,if they were gel i would have tossed them away far before i make this post

              Comment


              • #22
                Originally posted by gendil View Post



                not that bad man ... i have done this mistake many times and get away with it the main problem is that i own a 24vdc system and from time to time used to get 12vdc inverter to operate on one of the batteries


                while one get dischraged i quickly try to discharge the other and eventually get the balance again

                however this time i forget the system after i used it and went on in trip for 2 days



                the pwm start charging one at 14 and other at 12.9 or so


                still i am struggling getting them in balance i am connecting them in parallael as some one indicates should be restored with 3 days of paralled operation


                remember on note they are agm for if not agm they wont withstand harsh charging ,,,,,if they were gel i would have tossed them away far before i make this post
                Stop trying charge them in the same circuit. Split them up and charge each 12v battery seperately or just throw them away and start all over again but this time don't try to discharge one 12v unit in a 24v system. Stop being stupid.

                Comment


                • #23
                  Originally posted by SunEagle View Post

                  Stop trying charge them in the same circuit. Split them up and charge each 12v battery seperately or just throw them away and start all over again but this time don't try to discharge one 12v unit in a 24v system. Stop being stupid.
                  never assume that a moderator will answer a novice stupid this is not polite at all i have done this many time and get away with it i hope i get away with it now at least

                  with out the help of the insulters!
                  Last edited by gendil; 08-10-2018, 01:02 PM.

                  Comment


                  • #24
                    Originally posted by gendil View Post
                    not that bad man ... i have done this mistake many times and get away with it the main problem is that i own a 24vdc system and from time to time used to get 12vdc inverter to operate on one of the batteries. while one get dischraged i quickly try to discharge the other and eventually get the balance again. however this time i forget the system after i used it and went on in trip for 2 days.
                    The worst thing you can do to a lead acid battery is discharge it completely and leave it there. It destroys the battery very quickly. It is very likely that that battery is unrecoverable.

                    If you want to try, charge both batteries SEPARATELY. That's SEPARATELY. Don't parallel them, don't try to rebalance them while in series. Use the manufacturer's recommendations for absorb voltage, then float them for a day. Then discharge them and measure the discharge to some point (say 2.05 volts per cell.) If they both give you about the same amp-hours, then great. Charge them again and reconnect them.

                    If they give wildly different amp-hour numbers, or one has a much lower discharge voltage or a much higher internal resistance, then you'll need new batteries.

                    Comment


                    • #25
                      Originally posted by gendil View Post
                      i have forget my system and discharged one battery badly and this happen one battery at 13vdc other 14vdc i tried to dishcrge the higher voltage one but no use as soon as connect batteries to charge controoler one goes high and oother stay same as it was

                      what to do now? how to solve it?
                      Good morning, gendil. It would be great if you could replace the batteries with a new pair to insure that you're starting out with a system of equal capacity. Also, please purchase a 24V inverter also, to ensure that the batteries share the load equally. I hope this helps, have a great day.

                      Comment


                      • #26
                        Originally posted by gendil View Post

                        never assume that a moderator will answer a novice stupid this is not polite at all i have done this many time and get away with it i hope i get away with it now at least

                        with out the help of the insulters!
                        My apologies. I am having a bad day and while I wanted to get your attention I should have not insulted you..

                        Comment


                        • #27
                          never mind man i really have to pay for my forgetfulness i just forgot to charge them to flaot both i slept and sun take over pwm charged one more than the other and for my

                          worest luck i was escorted by 2 of my friends

                          to trip at the very morning that ii have no chance to fix the situation


                          they service me for 3 years or more and i have done this and get a way with it by discharging the one with extra voltaage and charge the low on to its flaot and leave it there at flaot
                          for day or 2 then reconnect them they catch each other


                          i will try use what you say guys and back to you with answers

                          thanks all

                          Comment


                          • #28
                            Originally posted by gendil View Post
                            never assume that a moderator will answer a novice stupid this is not polite at all i have done this many time and get away with it i hope i get away with it now at least

                            with out the help of the insulters!
                            You keep making the seam mistake and keep repeating it.
                            MSEE, PE

                            Comment


                            • #29
                              Originally posted by gendil View Post
                              never mind man i really have to pay for my forgetfulness i just forgot to charge them to flaot both i slept and sun take over pwm charged one more than the other and for my

                              worest luck i was escorted by 2 of my friends

                              to trip at the very morning that ii have no chance to fix the situation


                              they service me for 3 years or more and i have done this and get a way with it by discharging the one with extra voltaage and charge the low on to its flaot and leave it there at flaot
                              for day or 2 then reconnect them they catch each other


                              i will try use what you say guys and back to you with answers

                              thanks all
                              look you got away with it for way longer than you should have... get over it and fix the system.

                              You have a few choices now that you need new batteries.

                              cheapest is to set the entire system up 12V. assuming you have sufficient wire capacity...
                              OutBack FP1 w/ CS6P-250P http://bit.ly/1Sg5VNH

                              Comment


                              • #30
                                How do i post my own question? I have 2 60v 240 w panels and a 30a mppt controller and 2 12v deep cycle batteries. Is that going to work?? Can i charge 12v batteries with 60v panels? Mppt charger 30a

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