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  • #61
    Originally posted by Mike90250 View Post
    MPPT only is active while the battery/loads demand full charging power.

    That would always be BULK, and sometimes in the ABSORB stage, but FLOAT would be PWM, until loads are applied to demand more power than PWM can provide. Then a good controller can switch to MPPT to provide enough power to keep the battery & loads at the proper float voltage. I watch this happen all the time with my Morningstar and Classic
    It's probably my cheap Outback equipment the display may say Absorb, but the shunts say it's still in Bulk and the amps haven't started to drop, so yeah there could be some difference. There is probably some saturation and equalization time as the voltage stops rising and the current starts to drop. How about a new term, Declining Current Phase is in PWM. My Re-bulk is pretty high, so maybe I never go back into bulk.

    Comment


    • #62
      Originally posted by lkruper View Post
      Lets see if I understand. Does the 20 amp MPPT controller take the 37v 8a output of the panel and convert it to 12v and 25a (20)?
      You tell me. 300 watts / 12 volts = ????

      20 amps x 12 volts = ???? Watts

      25 amps x 12 volts = ???? Watts

      a 20 amp MPPT controller can only convert to 20 amps at battery voltage.

      Answer your own questions and you will understand a lot battery. I am giving you the tools you need.

      Watts = Volts x Amps = Current x Current x Resistance
      Watt Hours = Watts x Hours = Battery Voltage x Amp Hours
      Voltage = Current x Resistance = Power / Current

      MPPT Output Current = Panel Wattage / Battery Voltage

      Put it all together and you have Ohm's Law.

      MSEE, PE

      Comment


      • #63
        Originally posted by Mike90250 View Post
        Sunking, factual corrections are fine, catching things mods miss is fine, 1st grade name calling stops
        No problem Mike. When someone claims to be a Pro and is not, or gives unsafe poor advice, I will let it go. A professional site like MH bans the OP immediately without question or notification. The owners of the site can can be sued and held liable. I have no problem with the site being sued. Do you? How about the owners? I suppose they have no problem with being sued either or held responsible?

        Me i have no control. I just speak loudly to warn people, and hopefully embarrass the offender so much they just leave in shame. But i will comply with your request. Ban me if you like, I do not care, but I take what I have contributed with me. You get stuck with Willy's as a replacement.
        MSEE, PE

        Comment


        • #64
          Originally posted by Mike90250 View Post
          Willy T.
          YOU brought up the first mention of 4/O cable

          ya'all are now warned.


          LKruper - with your lister gensets,
          with the older diesels , you have to be cautious of "Wet Stacking" if you run less than 60% load. Newer gensets don't have that much of a problem lightly loaded.

          Your ST heads, are they internally wired in parallel for 120VAC, or for 240VAC ? They are sensitive to load imbalance if wired for 240, and you only load one side, the windings really growl and groan. You may want to consider 2, 120VAC chargers, one on each leg of the generator, to keep loads balanced.
          see http://www.utterpower.com/genhead.htm for the mod
          http://cgg1.com/index_htm_files/ST%20Manual-42013.pdf for the manual

          I run a CS-6 with a ST-5 head @ 240VAC and use it to both run loads and the integral charger in my inverter (XW-6048) which also does load balancing for me too. Because of loading limits, I limit my charging to 30A to prevent overloading my engine.
          30A @ 60V =1800w plus my base loads, and I'm at 1,400' elevation.
          Thanks for getting back. That overloading issue was a major concern. Thats why I asked allot of questions about the 40 amp vs the 25 amp IOTA, What I have is both gen sets are wired to feed 240v to a 3KVA Square D, "Sorgle" isolation transformer. #1 and or #2 gen set can be selected with a transfer switch. There will be another transfer switch for the selected gen set or inverter power. Then it goes to the six circuit transfer switch in the house. So with the transformer I don't have an issue with "balancing" I was hopping to be able to run the charger with the small Lister 4&1/4 HP. Running time with the gen sets is not a problem. so if charging takes longer no big deal as long as Its not harming the batteries not being able to pump 40 amps in.

          Comment


          • #65
            Originally posted by Sunking View Post
            You tell me. 300 watts / 12 volts = ????

            20 amps x 12 volts = ???? Watts

            25 amps x 12 volts = ???? Watts

            a 20 amp MPPT controller can only convert to 20 amps at battery voltage.

            Answer your own questions and you will understand a lot battery. I am giving you the tools you need.

            Watts = Volts x Amps = Current x Current x Resistance
            Watt Hours = Watts x Hours = Battery Voltage x Amp Hours
            Voltage = Current x Resistance = Power / Current

            MPPT Output Current = Panel Wattage / Battery Voltage

            Put it all together and you have Ohm's Law.

            Thanks, I could not have done it without you! Thanks for giving me enough hints without just giving me the answer.... I will remember it better.

            Comment


            • #66
              Originally posted by lkruper View Post
              Thanks, I could not have done it without you! Thanks for giving me enough hints without just giving me the answer.... I will remember it better.
              You are welcome. That is why I gave you the tools to figure it out yourself.

              I had one good instructor in college I really liked. He said don't ask me questions, figure it out yourself. He said he was not paid to be an answer man or teacher, I am here to instruct you how to figure it out yourself. He went on to say: If you want answers and ideology, go see a professor who has never done anything, that is why they teach and preach. I never forgot that and try to live by it. Even one year I taught musheads students in Jr College. It separated the students from the slackers. You passed the test.
              MSEE, PE

              Comment


              • #67
                Originally posted by Sunking View Post
                Let's get some simple math out of the way and help you understand. It is 5th grade math and super easy

                Starting with Amp Hours = Amps x Hours. Told you it was hard.

                From that equation then you know:

                Amps = Amp Hours / Hours
                Hours = Amp Hours / Amps

                Using simple numbers let's say you have a 100 AH battery. You want to discharge it at 10 amps. How many hours does it take to discharge it. 100 AH / 10 A = 10 Hours.

                Want to charge that battery from completely discharged with a 10 amp charger. How many hours will it take. 100 AH / 10 A = 10 Hours.

                How many Amps can that same battery last with a 5 Hours discharge rate? 100 AH / 5 H = 20 Amps

                Unfortunately life is not that simple. Batteries are not 100% efficient and Mr Peukert Law gets in the way. Not to worry what is above gets you the idea.

                Next problem you run into is batteries have minimum and maximum charge rates. A FLA battery minimum is C/12 and maximum is C/8 generically. C = the battery AH capacity at the 20 Hour discharge rate. So those 225 AH batteries need at least a 225 AH / 12 H = 18.75 amps. Just call it 15 is close enough. The maximum is 225 AH / 8 H = 28.125 amps. Just call it 30 amps is close enough. So you now know you need something in the 15 to 30 amps. But there is a Gotcha. It you go with 15 and want to use power while charging, you are robbing the battery of charge current. If your load is 30 amps and you have a 15 amp charger, you are still discharging your battery at 15 amps. Gotcha!

                On the Flip Side Batteries have a Maximum Discharge current they can provide otherwise their voltage will sag to far and cause unnecessary Low Voltage Disconnect built into all Inverters. For standard FLA battery that is about C/8 or 30 amps on a 225 AH battery. So if your limit is 30 amps limits how large of an Inverter you can run. So you want to run 24 volts x 30 amps = 720 watts. Not a good match for a 1000 watt Inverter.

                Don't cuss there is a work around. Use a hybrid FLA or a more expensive AGM battery. Buy Golf Cart FLA batteries, as they are Hybrids. A Golf Cart battery can handle C/4 Discharge currents so a 225 AH battery can supply up to 225 / 4 = 56.25 amps, just call it 60 amps. At 24 volts x 60 amps can handle a 1500 watt Inverter so a 1000 watt 24 volt Inverter is no problem.

                This brings us back to a battery charger issue again. You do not need a 3-Stage Battery Charger for Emergency Back Up. You do not even want one for that application. You want a FLOAT CHARGER of the appropriate Amperage Capacity. You will leave it plugged into commercial AC keeping the batteries fully charged waiting to be used. You want it to be as large as a standard 120 VAC wall socket can supply and your generator. a 120 VAC circuit in your home can supply 1500 watts continuously. So for a 24 volt battery charger you are looking at a 60 Amp 24 volt charger.

                Now just go over what we just did and look at how the pieces fit together in harmony.

                You are looking at needing a:

                1800 watt genny. check
                24 volt 60 amps FLOAT CHARGER. Check
                4- 6 volt 225 AH Golf Cart Batteries wired in series. Check
                1000 Watt TSW Inverter. Check

                Fits like a custom tailored shirt made with Warm Fuzzy.
                I am getting ready to look at the second stage of my backup. In reading this, I note something new to me. I don't recall Golf batteries being able to take a C/4 charge rate. This is interesting and useful. I just want to make sure I am correct in this, as the 60 amp charger is being used for a 225AH bank.

                Is it always true that the charge rate and discharge rate are the same?

                Comment


                • #68
                  Originally posted by lkruper View Post
                  Is it always true that the charge rate and discharge rate are the same?
                  No Sir. There are just general rules. Golf Cart batteries are not what you would really call Deep Cycle Batteries. Close but slightly different different in construction and application. Great example is the Trojan T-105 and T-105RE. The 105 is a pure Golf Cart battery of 6 volts @ 225 AH in a GC2 case. The 105RE is a pure Deep Cycle 6 volt @ 225 AH in the exact same GC2 case. Side by Side you cannot tell the difference. When you go to pick up the T- 105RE you will know the difference because it is 10% heavier than the T-105. It has more lead in it. ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ The T-105 is recommended to be charged the same as the 105RE of 10 to 13% of C which is 22 to 30 amps. However the Golf Cart version has lower internal resistance, and thus can be discharged at higher rates with Less voltage loss. You can discharge them both at say C2 or 110 amps for an hour until discharged. The difference is the T-105 will deliver the 100 amps at a higher voltage of say 4 volts while the RE would be down to 3 volts. -------------------------------------------------------------------------------------------------------------------------------- You can charge any lead acid battery at any charge rate you want. On the high end as much current as the battery will accept without going above the gassing voltage of around 2.4 vpc. The higher the internal resistance of the battery, the lower current is going to be.
                  MSEE, PE

                  Comment


                  • #69
                    Originally posted by Sunking View Post
                    No Sir. There are just general rules. Golf Cart batteries are not what you would really call Deep Cycle Batteries. Close but slightly different different in construction and application. Great example is the Trojan T-105 and T-105RE. The 105 is a pure Golf Cart battery of 6 volts @ 225 AH in a GC2 case. The 105RE is a pure Deep Cycle 6 volt @ 225 AH in the exact same GC2 case. Side by Side you cannot tell the difference. When you go to pick up the T- 105RE you will know the difference because it is 10% heavier than the T-105. It has more lead in it. ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ The T-105 is recommended to be charged the same as the 105RE of 10 to 13% of C which is 22 to 30 amps. However the Golf Cart version has lower internal resistance, and thus can be discharged at higher rates with Less voltage loss. You can discharge them both at say C2 or 110 amps for an hour until discharged. The difference is the T-105 will deliver the 100 amps at a higher voltage of say 4 volts while the RE would be down to 3 volts. -------------------------------------------------------------------------------------------------------------------------------- You can charge any lead acid battery at any charge rate you want. On the high end as much current as the battery will accept without going above the gassing voltage of around 2.4 vpc. The higher the internal resistance of the battery, the lower current is going to be.
                    Thanks, Sunking. I am starting to understand the 14.4 v limit on batteries better. I don't think I was ready for this kind of advanced information before, and now a little at a time I am able to add to knowledge that I hope I can retain.

                    Here is my situation. I just had my Reliance 10-circuit transfer switch installed and am in the process of testing my Generac ix 2000 inverter generator. If it handles the surge of my Energy Star 14.5 Frigidaire and my small Suppenton 3.2 then I don't need anything else, but if it does not run all my loads plus the surge then here is plan b:

                    Power Normal: Grid -> Charger -> Batteries -> PSW Inverter (Off)
                    Power Out: Generator -> Charger -> Batteries -> PSW Inverter (On) -> Transfer Switch -> max 177 w/h load + surges

                    I am hoping that the batteries will handle the surge if my generator cannot, that I can also run the generator in Eco mode to save gas and also that the generator can both charge the batteries and run my loads at the same time. (I am considering 2 Golf Cart batteries, Progressive Dynamics 12v 70 Amp charger and Samlex 1000 (2000 surge) pure sine wave inverter). This system will only be used if the power goes out and we are at the cabin or when I test the system to exercise the generator and/or test the batteries. I estimate that my batteries will carry my load for about 5 hours if I do not conserve(eg turn off one fridge) and keep the TV on 16 hours per day and might last the night if I do conserve. One goal is to not have to listen to the generator at night.

                    One thing I am also wondering is what effect does the fact that this charger apparently does not have temperature correction have on the life of the battery? Is this less important when the batteries spend most of their time in float?

                    Comment


                    • #70
                      Originally posted by lkruper View Post
                      One thing I am also wondering is what effect does the fact that this charger apparently does not have temperature correction have on the life of the battery? Is this less important when the batteries spend most of their time in float?
                      Not something to worry about while charging on generator or really any charger in Bulk and Absorb modes. Temp compensation is something used in Float Mode Stand-By service applications where the batteries could set there for years doing nothing and remain on Float Charge. Solar Off-Grid is a daily cycle operation and a rare event you will see FLOAT MODE. Even if you do is not till late in the day, so you never spend any real time in Float. Only thing where you really use temperature is when you measure Specific Gravity so you can make the Correction to read your SOC. 99% of the time, your Specific Gravity is going to be low. If you Specific Gravity is low all the time means it makes no difference what voltage you set your controllers too because you will never get fully charged up unless you use a generator.--------------------------------------------------------------------------------------------- Sounds like your system is grossly undersized. If that is a true statement, then voltage set points is a moot point for you because you can never get there. ------------------------------------------------------------------Kind of like being a parent with a 5 year old kid. You notice one day the kid jumping up and down and ask what he is doing. He answers trying to jump over the moon. You just turn away and let them jump. Eventually they will get tired and quit, and going no where fast.
                      MSEE, PE

                      Comment


                      • #71
                        Originally posted by Sunking View Post
                        Not something to worry about while charging on generator or really any charger in Bulk and Absorb modes. Temp compensation is something used in Float Mode Stand-By service applications where the batteries could set there for years doing nothing and remain on Float Charge. Solar Off-Grid is a daily cycle operation and a rare event you will see FLOAT MODE. Even if you do is not till late in the day, so you never spend any real time in Float. Only thing where you really use temperature is when you measure Specific Gravity so you can make the Correction to read your SOC. 99% of the time, your Specific Gravity is going to be low. If you Specific Gravity is low all the time means it makes no difference what voltage you set your controllers too because you will never get fully charged up unless you use a generator.--------------------------------------------------------------------------------------------- Sounds like your system is grossly undersized. If that is a true statement, then voltage set points is a moot point for you because you can never get there. ------------------------------------------------------------------Kind of like being a parent with a 5 year old kid. You notice one day the kid jumping up and down and ask what he is doing. He answers trying to jump over the moon. You just turn away and let them jump. Eventually they will get tired and quit, and going no where fast.
                        I am grid connected and my batteries will spend most of their lifetime in float. It is for emergency only and the only action the system will see other than this is when I exercise my generator or test the batteries. I did have an 8 hour power outage two weeks ago because of a transformer and I think El Nino might wreak havoc with our grid this winter, but other than that, it will be float. We do not live at the cabin full time.

                        The battery system is undersized because all I want from it is to provide surge capabilities for the fridge (if I find it is necessary with my generator) and to allow for a few hours of sleep time at night without listening to the generator.

                        At this time I don't have any plans for solar. That would be phase III, and the only purpose would be to prepare for an emergency that lasts long enough to exhaust my gasoline supplies (1-2 weeks).

                        Comment


                        • #72
                          Originally posted by lkruper View Post
                          I am grid connected and my batteries will spend most of their lifetime in float.
                          OK here is my take. You need temp compensation on whatever charger the batteries are normally charged from. In a solar system that would be the Solar Charge Controller. --------------------------------------------------------------------------------------------------------------------------------------------------------------------- However when charged from a genny, you do not need expensive 3-stage chargers with temp comp. Complete waste of money and only slows things down. When you charge on a generator, there is only a couple of good reasons to do so. 1. woul dbe you have gone a couple of days without Sun. 2. Monthly EQ maintenance. ----------------------------------------------------------------------------------------------------------------------- Either way you are looking to get to fully charged as quick as possible. Last thing you want is a long Absorb aka Float saturation charge. You want to set your charger to a high voltage to fore it into Constant Current until the cell voltage is near 2.5 to 2.6 volts per cell, then terminate the charge. This is known as Fast Charge. --------------------------------------------------------------------------------------------------------------------------------- Fast Charge is a Constant Current until you hit a target voltage, and then terminate. So when shopping for a charger to be used on a generator there are a few things you are looking for. Power Factor Correction, CC/CV mode of operation. Adjustable set voltage of 2.65 vpc or 16 volts on a 12 volt battery, and as high as a current as your batteries and genny can handle. That higher voltage and current is going to be the most effective at dissolving the soft lead sulfate crystals on the plates and minimize charge time. Remember Pb batteries live on a knife edge to fall off of. One side is Sulfation (too low of voltage), the other is Corrosion (too high of a voltage) . You want to live on the Corrosion side of town for cycle applications. For Float Service you want to do the Balance act on the knife edge using temp comp. Maintenance is always on the Corrosion side.
                          MSEE, PE

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