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Can I just built a simple battery charge with a setdown transformer and rectifier?

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  • #16
    Great, we can highjack this over to power supplies, which are cool. Perhaps my first
    DC supply used a 6AL5, about 1953. 100V @ 0.011A; no big silicon rectifiers back then.

    Bruce Roe

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    • #17
      Originally posted by Sunking View Post
      There has go to be more to this story. Why would you carry it on a plane from Jamaica my friend.
      Not From Jamaica. is other way round.
      What I try to say is I would buy one of those old time Charger on two wheels because they don't just die like the new light and small type. But it is so heavy and big I don't think I can carry it from the USA to Jamaica VIA airline and Cargo is cost too much and duty etc.

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      • #18
        Originally posted by Sunny Solar View Post
        Great stupid reply as it has nothing to do with your ridiculous post ..."""""Paul the transformer part is the easy part. For every 12 volts DC requires 18 volts of AC. So armed with that you are looking for a AC voltage roughly 96 to 100 volts. But for a battery charger the voltage has to be tightly regulated and requires more than just a rectifier to do that."""""

        If he need a charger for a 48v battery pack he does NOT need 96 to 100v AC.. That is just nutz. he only needs about 42v AC to give about 58v DC,..

        Having built thousands of audio amplifiers,sound mixers, lighting controllers I have I think a reasonable knowledge of what AC is needed to get a desired DC voltage..
        Time to change your username again JohnP and Sunny Solar. Try something like Owatagoosiam. Call manufactures and tell them they do not know what they are doing. Here are some schematics from manufactures.



        Here is one for a 13.8 volt high power used for car Audio amps.



        Sure you can use a 12 VAC RMS transformer if you want 12.2 volt DC output. A 12 VAc RMS transformer output roughly 14.4 volts. After a bridge rectifier dropping roughly 2 volts you get roughly 12.2 volts output. But for batteries you need a minimum 13.8 volts output which requires a minimum 15 VAC RMS transformer to overcome the voltage losses of the rectifiers and regulators. You want a 48 volt battery charger with EQ to deliver 64 volts? You had better be looking at a 68 to 70 VAC RMS minimum transformer. You can go higher with good heat management and tighter voltage regulation at full power.
        MSEE, PE

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        • #19
          Sunkin Your first ps is a std as used by millions . but whats its relavence to anything the the orig poster could use .??he is NOT looking for a split regulated at max about 3a 12v supply. and why you even showing one ??no one has asked for any info about one..?? Your second supply is just over designed and it would not be well ballanced. and is unregulated ..it shows 18v + and- split suply... But you say its for a 13.8v high power car radio?? huh????? Im as yet to see a commercially available car radio/amplifier that can connect to a split supply.. ALL only connect to the usual pos ,neg 12 v battery ..You have a special magic method to make the connection successful???

          To prove how crazy you telling the original poster he needed a AC aupply of 96 to 100 to be able to charge a 48v battery pack .. I said he only needs about 42v AC..
          Attached is a simple toroid transformer output 36.4vac and DC at rectifier filter caps is 44.9vDC Now if you scale up the answer is clear 48v AC will give 58vDC The required charging voltage for 48v is 56vdc.
          Attached Files

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          • #20
            Originally posted by Sunny Solar View Post
            Sunkin Your first ps is a std as used by millions . but whats its relavence to anything the the orig poster could use .??he is NOT looking for a split regulated at max about 3a 12v supply. and why you even showing one ??no one has asked for any info about one..??
            You are right, it is standard which is my point. It is relevant because the OP asked about getting a transformer wound and making hi sown charger to EQ batteries. Does not matter if you use center tapped transformers or not. It is the RMS voltage that matters, and it takes a minimum 14 to 15 volts for a 12 volt DC power supply. The voltage does not matter if it is 12 or 48 volts. To get to 48 volts is just a matter of scaling up in multiples.


            Originally posted by Sunny Solar View Post
            To prove how crazy you telling the original poster he needed a AC aupply of 96 to 100 to be able to charge a 48v battery pack .. I said he only needs about 42v AC..
            Attached is a simple toroid transformer output 36.4vac and DC at rectifier filter caps is 44.9vDC Now if you scale up the answer is clear 48v AC will give 58vDC The required charging voltage for 48v is 56vdc.
            Proves nothing John except we were both wrong. I made an error when I said 96 to 100 volts. That came from late night math in my head of 64 x 1.414. I forgot one step. It can certainly be done at 100 volts, just a lot of waste heat.

            Answer me this. What is the formula to convert RMS voltage to Full Wave Rectified DC? Just the rectifier and filter cap, no regulation.

            First thing we have to know is the Vpeak of the AC RMS voltage. Vpeak = RMS x 1.414. DC Out = Vpeak x .637 all day long in any country. Lets use your imaginary 48 volt RMS number. A 48 volt RMS Vpeak = 48 x 1.414 = 67.9 volts. Full Wave rectified DC Out = Vpeak x .637 = 67.9 volts x .637 = 43.25 volts DC from a 48 volt RMS transformer. Wont work. Your second error is it takes 62 to 64 volts of tightly regulated DC voltage to EQ a 48 volt battery, not 58 you stated. If one were going to use a transformer to provide unregulated 64 volts one needs a minimum 70 volt RMS transformer. Want tightly regulated voltage with that? You need a few more volts. Do the math:

            Step 1. 70 volts RMS x 1.414 = 99 Vpeak. (That is where I stopped earlier and did not perform the second step, my bad)
            Step 2. 99 Vpeak x .637 = 63 volts DC output from rectifier/caps.

            As a designer you would be looking for around a 75 volt RMS transformer to build a battery charger with EQ capability..... But for JohnP and DIY's without design experience we can dumb it down KISS (keep it simple stupid) approach. Maximum DC output voltage x 1.2 = Transformer RMS Voltage. First formula I used at age 14 to design a power supply for my radios.
            MSEE, PE

            Comment


            • #21
              Originally posted by Sunking View Post
              You are right, it is standard which is my point. It is relevant because the OP asked about getting a transformer wound and making hi sown charger to EQ batteries. Does not matter if you use center tapped transformers or not. It is the RMS voltage that matters, and it takes a minimum 14 to 15 volts for a 12 volt DC power supply. The voltage does not matter if it is 12 or 48 volts. To get to 48 volts is just a matter of scaling up in multiples.




              Proves nothing John except we were both wrong. I made an error when I said 96 to 100 volts. That came from late night math in my head of 64 x 1.414. I forgot one step. It can certainly be done at 100 volts, just a lot of waste heat.

              Answer me this. What is the formula to convert RMS voltage to Full Wave Rectified DC? Just the rectifier and filter cap, no regulation.

              First thing we have to know is the Vpeak of the AC RMS voltage. Vpeak = RMS x 1.414. DC Out = Vpeak x .637 all day long in any country. Lets use your imaginary 48 volt RMS number. A 48 volt RMS Vpeak = 48 x 1.414 = 67.9 volts. Full Wave rectified DC Out = Vpeak x .637 = 67.9 volts x .637 = 43.25 volts DC from a 48 volt RMS transformer. Wont work. Your second error is it takes 62 to 64 volts of tightly regulated DC voltage to EQ a 48 volt battery, not 58 you stated. If one were going to use a transformer to provide unregulated 64 volts one needs a minimum 70 volt RMS transformer. Want tightly regulated voltage with that? You need a few more volts. Do the math:

              Step 1. 70 volts RMS x 1.414 = 99 Vpeak. (That is where I stopped earlier and did not perform the second step, my bad)
              Step 2. 99 Vpeak x .637 = 63 volts DC output from rectifier/caps.

              As a designer you would be looking for around a 75 volt RMS transformer to build a battery charger with EQ capability..... But for JohnP and DIY's without design experience we can dumb it down KISS (keep it simple stupid) approach. Maximum DC output voltage x 1.2 = Transformer RMS Voltage. First formula I used at age 14 to design a power supply for my radios.
              Dereck,

              A diode bridge feeding a capacitor input filter with a low impedance AC supply (good sized transformer) will produce a DC output close to the peak value of the the AC waveform, not a fraction of the RMS value. So a nominal 12V AC secondary on a transformer will produce a Vpeak of 16.9V, and a lightly loaded capacitor input rectifier/filter will easily produce at least 16V DC (although maybe with a lot of ripple.)
              A choke input filter, more common for high current DC supplies that are not asked to supply good load regulation without downstream regulators will produce a lower voltage.
              To be precise, for very large inductance the output voltage will be 2/pi times Vpeak (not Vrms). That is .636 times Vpeak, or .9 Vrms. Which is exactly the value that you get for 63VDC from 70V RMS AC.
              But, and here is the rub, you say that is the output for a rectifier and capacitor only "from rectifier/caps", leaving out the series choke.

              It is credible that a heavy duty battery charger would be designed with a choke input filter, but that would have the adverse side effect of letting the output voltage rise all the way to Vpeak when lower current is drawn (such as the tail end of Absorb or in Float.)
              The alternative of a capacitor input filter requires some very big capacitors and rectifier diodes designed for high peak currents, but it is workable. It is the type of circuit used every day in large industrial VFDs (at higher voltages and lower currents.)

              A choke input filter is at its best when the design load is predictable and fairly constant, as it would be in many electronic circuits. And to deal to some extent with the very poor load voltage regulation over a current range the "swinging choke" was developed by early radio enthusiasts. It is an inductor deliberately designed to gradually saturate so that the inductance value is greater at low currents than it is at high current levels.

              My grandmother had a tube type radio and record player in which the speaker did not use a permanent magnet. Instead there was a voice coil and a magnetizing coil. The magnetizing coil doubled as the choke for the power supply. Fortunately the speaker had close to zero output at 120 Hz because of its mechanical design.
              And, synergetically, the more current the amplifier drew, the higher the "gain" of the speaker's electrical to mechanical power conversion.
              SunnyBoy 3000 US, 18 BP Solar 175B panels.

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              • #22
                Originally posted by inetdog View Post
                My grandmother had a tube type radio and record player in which the speaker did not use a permanent magnet. Instead there was a voice coil and a magnetizing coil. The magnetizing coil doubled as the choke for the power supply. Fortunately the speaker had close to zero output at 120 Hz because of its mechanical design.
                And, synergetically, the more current the amplifier drew, the higher the "gain" of the speaker's electrical to mechanical power conversion.
                You are preaching to the choir. I rebuild antique radios. Here is my latest pride and joy project. Respectively submitted Back when Motorola made real radios.

                MSEE, PE

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                • #23
                  Originally posted by inetdog View Post
                  Which is exactly the value that you get for 63VDC from 70V RMS AC.
                  But, and here is the rub, you say that is the output for a rectifier and capacitor only "from rectifier/caps", leaving out the series choke.
                  I know and understand pi filters, but they are not used when you use a voltage regulator as they serve no purpose other than to add weight and expense. Al of it is kind of a moot point because very few manufactures still use conventional transformers for DC power supplies. Ham radio operators are about the only user group I can think that still use them because they have far less noise than which mode power supplies. Astron is the only one I can think of that still make high current DC supplies in 12 and 24 volts. Here is their most popular version, but if you look at all their others and th eonly difference is size of the tranformers and more/less 2N3055 output transistors for the rated current output. The transformer is a 30 volt ct 35 amp secondary and output is 13.8 volts @ 35 amps. It is a great Brute Force tank of a power supply. No pi filter required. Just brute force caps. The whole point is Paul thought about having a transformer wound to use as a battery EQ charger which it takes a lot more than just a transformer and a rectifier to pull off. Then John jumped in to start trouble.

                  MSEE, PE

                  Comment


                  • #24
                    Thanks guys,

                    Back to my original question, What I was thinking is impossible or don't make economical sense.

                    I have spent two days and one night try to EQ the S530 bank, all the cells come close to 1.250 reading on the SG meter, The bank still feel weaker than the S460 bank as the S460 has less capacity and it take and push out more current than the S530 bank.

                    Do I still need a charger with EQ capacity if I do weekly mini EQ? I try to full charge the batteries every week with grid power and the voltage the inverter can provide is 62.2 volts. no higher, if it in the morning the classic 150 CC can provide 64 volts and up to 40 amps when the sun is shinning. When I charge the batteries with the grid I set the absorb voltage to 64 volts but only reach 62.2 volt, that will do charge the battery and provide a short EQ.
                    Would that prevent the sulfation on the batteries?

                    Thanks again.

                    Comment


                    • #25
                      Originally posted by Sunking
                      You are preaching to the choir. I rebuild antique radios. Here is my latest
                      pride and joy project. Respectively submitted Back when Motorola made real radios.

                      Nice radio; like to hear more about it. That was the kind of stuff I had to work with in
                      the 1950s. Still have selected items from the 30s and 40s. Nice CHANALYST with 4 magic
                      eye tubes, 1938.

                      As for the field coil in the speaker doubling as power choke. Those units always had a
                      "hum buck" coil. A few turns next to the field winding picked up hum, then it was wired
                      in series with the voice coil to mostly cancel the hum.
                      Attached Files

                      Comment


                      • #26
                        Originally posted by Sunking View Post
                        You are preaching to the choir. I rebuild antique radios. Here is my latest pride and joy project. Respectively submitted Back when Motorola made real radios.

                        Nice radio. Sounds like a fun hobby if you can still find the parts for those radios. Some tubes are just not being manufactured any more but you may still find them at a Field Day auction or I guess now on eBay.

                        Comment


                        • #27
                          Guys,
                          think a minute before clicking the Reply button. Is it on topic ? Does it help the original poster ?

                          Small side trips to electronic restoration land are OK, but You Fool, You Idiot, You Bigger Fool, You Bigger Idiot yammering, really does detract from the forums.

                          You can LIKE a better way, things can be Code Violations. These conservations end up in my living room.

                          Moderator.
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                          || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
                          || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

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                          • #28
                            Originally posted by Mike90250 View Post
                            Guys,
                            think a minute before clicking the Reply button. Is it on topic ? Does it help the original poster ?

                            Small side trips to electronic restoration land are OK, but You Fool, You Idiot, You Bigger Fool, You Bigger Idiot yammering, really does detract from the forums.

                            You can LIKE a better way, things can be Code Violations. These conservations end up in my living room.

                            Moderator.
                            Thank you.

                            I usually skip reading what I consider the rude, selfish, self absorbed, borderline abusive, bullying and otherwise childish behavior from a few posters and also wonder what it has to do with the sign over the door that says "Solar Panel Talk".

                            It may be that the repeat offenders (IMO) also have a sense of entitlement to carry on that way due to what is their exhibited and acknowledged experience and technical knowledge.

                            FWIW, as an engineering manager (ret.), I've corrected less obnoxious and non productive behavior from people who were probably equally knowledgeable in their fields. Even the substantial contributions of those folks wasn't worth the cost in morale or the loss of productivity to my organization(s) caused by their disruptive behavior.

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                            • #29
                              JPM you are right.
                              MSEE, PE

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                              • #30
                                Originally posted by Sunking View Post
                                JPM you are right.
                                Opinions vary.

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