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Backpacking PV: looking for MPPT with energy buffer build-in?

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  • #16
    Originally posted by PNPmacnab View Post
    Any cheap buck converter can be turned into a MPPC controller with only a couple parts.
    Please show us your 2 part conversion plan. Bruce Roe


    • #17
      I'm sure you have seen this before. The buck or boost is faked into thinking the output voltage is too high and pulls back. The TL431 can even be replaced with an old power FET if you can accept a little temp drift. The 431 can only saturate to about 2V and you really shouldn't use it below 2.5V. The diodes and LED provide an offset voltage. At least one diode must be used in any circuit to prevent pulling down the sense voltage divider. .Many one chip buck modules with an inhibit/shutdown pin. That pin can be lifted up from the board common and with a pull down resistor can be used to turn the regulator on and off. These pins are quite fast. Any simple comparator circuit can be used. Use a couple diodes for a reference and you will have temperature tracking.
      Attached Files


      • #18
        You are creating a Linear Current Booster? What is an MPPC? Bruce Roe


        • #19
          MPPC (constant) is a fixed panel voltage. It can be made to track with temperature.

          For those interested in the various methods used with solar panels this is pretty good. Teaching methods haven't improved in 40 years.
          Last edited by PNPmacnab; 07-15-2019, 12:13 PM.


          • #20

            (the PV output voltage) it varies just a little. Temperature changes output voltage slightly
            Sorry@jflorey2 but it varies not just a little! Either you and bruce never got a so small panel, or you do not consider all environments: Where I am - setting my panel right now - I will have changes in Voltages from 0 to 24V multiple times per minute and it is not up to me but the availability of photons.

            Choose a panel or a range of panels. Decide if you want the PV voltage to be higher than or lower than the battery voltage. Choose a controller accordingly.
            There is no decision between higher or lower that target voltage - you annoy me with repeating your opinion again.

            This is not about your opinions.
            It is about to get a device that does the job I want.

            @Mod: Can someone regulate this stuff?
            Since 2 pages this thread gets spammed with stuff not belonging here.

            I have to laugh any time I see these MPPT schematics. It isn't only ebay that plays with the truth. That first link is to a MPPC controller.
            Sad your response is only focusing for one link, because if seems like you are good with electronics?
            So, if you would have read all the rest -and maybe stumbled across stuff like the LTC3870, or my spec list I look for - maybe you would be up saying something like "hey kid, I can help you creating some layout for a device you are looking for"?
            I consider even paying for it so I get rid of this "proposed solutions" that do not fulfill the spec sheet.



            • #21
              Originally posted by letmefreak View Post

              This is not about your opinions.
              It is about to get a device that does the job I want.

              @Mod: Can someone regulate this stuff?......
              This thread is closed. Many experts have voiced their opinions and stated facts. I even suggested another forum that has a lot of folks on it, and you are encouraged to ask them for help, as we are out of ideas for you.

              Powerfab top of pole PV mount (2) | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
              || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
              || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A



              • #22
                Originally posted by letmefreak View Post
                @Mod: Can someone regulate this stuff?
                No problem, I'll take care of it. See you in three days,