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  • Controlling Amps

    Attention everyone. Noob question alert.
    First day so take it easy on me.

    I am the proud owner of 2 solar panels although my electronics knowledge isn't spectactular.
    I know I can control volts with a voltage regulator, but how do I control amps.

    I know that there's a formula of V=RxI. My confusion is if the sun varies in strength will the amps change as well, or does that depend on what is plugged in.


    thanks in advance

  • #2
    Originally posted by PrestonNorthEnd View Post
    Attention everyone. Noob question alert.
    First day so take it easy on me.

    I am the proud owner of 2 solar panels although my electronics knowledge isn't spectactular.
    I know I can control volts with a voltage regulator, but how do I control amps.

    I know that there's a formula of V=RxI. My confusion is if the sun varies in strength will the amps change as well, or does that depend on what is plugged in.


    thanks in advance
    yes and no

    amps out will be more of a function of how strong the sun is. Too much load and the voltage will crash.
    NABCEP certified Technical Sales Professional

    [URL="http://www.solarpaneltalk.com/showthread.php?5334-Solar-Off-Grid-Battery-Design"]http://www.solarpaneltalk.com/showth...Battery-Design[/URL]

    [URL]http://www.calculator.net/voltage-drop-calculator.html[/URL] (Voltage drop Calculator among others)

    [URL="http://www.gaisma.com"]www.gaisma.com[/URL]

    Comment


    • #3
      So if I use an iphone as an example.

      The iphone takes 5 volts and 1 amp to charge.
      If I have a solar panel getting 12 volts and put a 5v regulator in between what happens if the sun gets hotter. Does that mean higher voltage with same resistance = higher amps which means a fried iphone?

      Comment


      • #4
        Originally posted by PrestonNorthEnd View Post
        So if I use an iphone as an example.

        The iphone takes 5 volts and 1 amp to charge.
        If I have a solar panel getting 12 volts and put a 5v regulator in between what happens if the sun gets hotter. Does that mean higher voltage with same resistance = higher amps which means a fried iphone?
        The Iphone charger will limit amps to the Iphone excess amps will just be wasted. Think about when you plug something into the wall The potential there is 120V and 15 or 20 amps depending on the size of the circuit breaker.

        To charge the Iphone you will need a 12v battery to buffer and reduce the voltage from the panel and a charge controller to keep the battery from overcharging assuming the panel is large enough to overcharge the battery.
        NABCEP certified Technical Sales Professional

        [URL="http://www.solarpaneltalk.com/showthread.php?5334-Solar-Off-Grid-Battery-Design"]http://www.solarpaneltalk.com/showth...Battery-Design[/URL]

        [URL]http://www.calculator.net/voltage-drop-calculator.html[/URL] (Voltage drop Calculator among others)

        [URL="http://www.gaisma.com"]www.gaisma.com[/URL]

        Comment


        • #5
          What if I remove all batteries, solar charge contollers and inverters. Is it still possible to do?

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          • #6
            also remove the iphone charger

            Comment


            • #7
              Originally posted by PrestonNorthEnd View Post
              What if I remove all batteries, solar charge contollers and inverters. Is it still possible to do? . . . .also remove the iphone charger
              Then you'd have an exciting few seconds. Then you'd need a new iphone.

              Comment


              • #8
                Originally posted by billvon View Post
                Then you'd have an exciting few seconds. Then you'd need a new iphone.
                But not nearly as exciting as plugging the phone cord directly into 120VAC household outlet
                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

                solar: http://tinyurl.com/LMR-Solar
                gen: http://tinyurl.com/LMR-Lister

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                • #9
                  Have someone shoot a video when you try that - might be a big hit on youtube!
                  [SIGPIC][/SIGPIC]

                  Comment


                  • #10
                    Controlling amps, you need a current limiter, and many 3 terminal regulators have in the application data sheets, a schematic for a current limit configuration.

                    But it's much simpler and conventional to peovide the proper voltage, and you won't have to worry about over voltage, if your device power draw, reduces, as when the battery is full.
                    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

                    solar: http://tinyurl.com/LMR-Solar
                    gen: http://tinyurl.com/LMR-Lister

                    Comment


                    • #11
                      you need a solar charge controller

                      Hello ...
                      First the solar panels will produce energy that you can use in anytime only if you first save it in a battery(or batteries).

                      So if your solar panels are both at 12VDC nominal ( if they are under 150Wp they are), you can connect them in parallel ( + to +, and - to -), and connect a PWM 12 Vdc charge controller, the output of this Charge controller will be connected to the 12Vdc battery. Then this 12VDC battery you can connect a phone charger that U use in your car, and you can recharge your celular phone , 12VDC LED bulb lights.

                      BR

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                      • #12
                        Hi, I'm new here too.
                        The current is drawn by the load of the circuit. No load, no current. Don't worry about it. Just regulate the voltage.
                        Hope this helps you.

                        John Smith
                        John Smith
                        Southern California....

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