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  • Using a solar regulator with a laptop power supply

    Hi there,

    I have one of those CMP12 solar regulators (12V 10A version) and it’s connected to a 12V 7AH SLA battery.

    For the load, I have a 12V amplifier hooked up, which I use in the backyard for playing background music (and for parties).

    Since it’s all sitting in the garage now, I thought I’d disconnect the solar panel from the regulator, and in its place, connect a DC power supply from a laptop (15V 4.5A) in order to charge the battery . No problem. After connecting the laptop power supply, the charging indicator began to flash and the battery was being charged.

    Later on, I disconnected the laptop power supply, but this time, I plugged it in again while I had the amplifier (i.e. the load) already switched on and playing music. As soon as I connected the laptop power supply, the amplifier stopped playing music. I measured the voltage at the regulator’s load terminals and it showed only 1 or 2 volts from memory. As soon as I disconnected the laptop power supply from the regulator, the amplifier instantly kicked in again and started playing music.

    I’m now wondering why this set up isn’t working. Could it be the laptop power supply is causing too much current to flow through the regulator (while the amplifier is drawing current at the same time)? If so, I would have thought the regulator being rated at 10A would be sufficient for this.

    I then connected a universal power supply that lets you choose voltage from 12V up to 24V. The only voltage that worked was 12V. As soon as I bumped it up to 15V, the regulator would instantly cut off power to the load (i.e. the amplifier playing music).

    Any ideas?

    BTW, not sure if this would have any impact, but I have a cigarette lighter socket connected in parallel with the load (although there is no device plugged into it). Also, in parallel with the battery, I have a momentary switch connected to a voltmeter, so I can push that switch button to see the battery's voltage at any given moment.

    Thanks!
    Pete

  • #2
    Originally posted by pete_melb View Post
    Hi there,

    I have one of those CMP12 solar regulators (12V 10A version) and it’s connected to a 12V 7AH SLA battery.

    For the load, I have a 12V amplifier hooked up, which I use in the backyard for playing background music (and for parties).

    Since it’s all sitting in the garage now, I thought I’d disconnect the solar panel from the regulator, and in its place, connect a DC power supply from a laptop (15V 4.5A) in order to charge the battery . No problem. After connecting the laptop power supply, the charging indicator began to flash and the battery was being charged.

    Later on, I disconnected the laptop power supply, but this time, I plugged it in again while I had the amplifier (i.e. the load) already switched on and playing music. As soon as I connected the laptop power supply, the amplifier stopped playing music. I measured the voltage at the regulator’s load terminals and it showed only 1 or 2 volts from memory. As soon as I disconnected the laptop power supply from the regulator, the amplifier instantly kicked in again and started playing music.

    I’m now wondering why this set up isn’t working. Could it be the laptop power supply is causing too much current to flow through the regulator (while the amplifier is drawing current at the same time)? If so, I would have thought the regulator being rated at 10A would be sufficient for this.

    I then connected a universal power supply that lets you choose voltage from 12V up to 24V. The only voltage that worked was 12V. As soon as I bumped it up to 15V, the regulator would instantly cut off power to the load (i.e. the amplifier playing music).

    Any ideas?
    When you plug in the computer DC power supply, there is an inrush of current to charge the capacitors inside the supply. That, combined with the load to the amplifier, caused the solar regulator (or the DC power supply) to go into current limiting (foldback) mode. In that condition the voltage is dropped to a level where the current will not go over the set limit no matter how much the loads try to draw. The computer power supply will react to a lower input voltage by trying to draw more current. So the only way to get it working again is to disconnect and start over.

    The "regulator" apparently also has a provision for cutting off the charging (and power to the load) if the voltage goes too high.

    There is a lot that you have left out of your information, like just what terminals on the controller you have connected everything to, and what brand and model it is.

    It will probably not work if you do not have a battery connected, and the amp and computer supply should be connected to the battery terminals, not to the Load output of the controller. Just make sure you do not pull the battery voltage down too low.
    SunnyBoy 3000 US, 18 BP Solar 175B panels.

    Comment


    • #3
      Originally posted by pete_melb View Post
      Any ideas?
      Can you upload a drawing/photo of how you have connected everything together?
      Also, let us know what the specifications (wattage, operating voltage, etc) are of the load, and of any other items that you are using (eg power supply, etc).

      Comment


      • #4
        Hi there,

        Thanks for your replies, and for the explanation.

        I've included some photos below, so let me know if you think more would be useful.

        The way I've connected everything is as follows:

        The regulator's SOLAR terminal is connected to the power input jack (this is where I plug in the solar panel, or the laptop power supply).

        The regulator's BATTERY terminal is connected to the on/off power toggle switch, which in turn, connects to the 12V SLA battery. There is also a momentary switch wired in parallel to light up the voltmeter.

        The regulator's LOAD terminal is connected to a fuse, which in turn, connects to the amplifier. There is also a cigarette lighter socket wired in parallel (this is where I plug in the iPhone or MP3 player for charging).

        The load is a TA2020 amplifier, that runs on 12V and draws up to 2 or 3 amps. I only listened to it at low volumes, and still had the problem occur (i.e. the regulator cut off power to the LOAD terminal when I plugged in the laptop power supply).

        Just to recap, the problem I encountered was that plugging in the laptop power supply (while everything was connected, and music playing) causes the regulator to cut off power to the LOAD terminal. As soon as I unplug the laptop adapter, power to the LOAD terminal is restored, and the amp immediately kicks in again and starts playing music. I would have expected the regulator to cope with this scenario (it's rated at 10A).

        I also tried switching the amp off, and then on again (while the laptop adapter was still connected), but that didn't change anything.

        BTW, I tried with two different power supplies, as you can see in the photos. One is a 16V laptop power supply, and the other is the type that allows you to select different voltages. I had it set to 19V. The same scenario occurred with both of these power supplies. The photos show the specs of each of them.

        Daz, you said "the amp and computer supply should be connected to the battery terminals, not to the Load output of the controller". I wonder if this is the cause, since I have connected the amp to the LOAD terminal of the regulator. I thought the LOAD terminal would be the correct place to connect the amp???

        Let me know if you need any more information, or if you have any suggestions on what I could try.

        Thanks!
        Pete

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        Comment


        • #5
          Try connecting all loads to the battery terminals and not to the load terminals on the controller.
          That will work and fix the problem
          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


          • #6
            Originally posted by Naptown View Post
            Try connecting all loads to the battery terminals and not to the load terminals on the controller.
            That will work and fix the problem
            Hi Rich,

            By connecting all loads directly to the battery terminals, doesn't that negate the management capabilities of the controller (i.e. it will then not be able to cut off power to the load to prevent the battery from over discharging)? I was under the impression that the load always gets connected to the load terminals, so that the regulator can control the conditions under which the load receives (or does not receive) power.

            Can you maybe explain your suggestion, as I'm still just a newbie when it comes to electronics, etc.

            Thanks,
            Pete

            Comment


            • #7
              Have you tried disconnecting the battery in order to get the CC to reset? I have one of those CCs and I remember having to disconnect the battery after I did something stupid (I don't remember what it was) in order to get it to reset.

              Comment


              • #8
                Hi Green,

                I have a toggle switch that allows me connect / disconnect the battery from the entire circuit. I flipped it over a few times, but that didn't help.

                One thing I forgot to mention... Before I even assembled all the components in the toolbox, I initially had all the bits and pieces lying around on the garage floor, connected to each other via thin jumper wires. The amp was actually able to play music while the battery was being charged via the laptop power supply. I connected the cigarette lighter socket, and was able to charge my iPhone at the same time as playing music. I also connected the voltmeter and associated momentary switch, and everything was working.

                When I modified that toolbox and fitted all the components inside, I wasn't expecting any issues since it all worked OK during the 'dry fit' stage.

                After assembling all the parts in the toolbox, that's when I first encountered this issue of the load (amp) being cut off by the charge controller. I was stumped. After checking all connections, solder joints, etc. I though the actual wire thickness may be the cause. Instead of using the relatively thin jumper wire I had originally used, I replaced it with thicker lamp cord wire. That proved to be successful. After doing that, I was able to get the amp to remain switched on and playing music, even after plugging in the laptop power supply.

                For some reason, the original problem returned after a few days, and that's where I am now. No idea how the problem re-emerged. Maybe somehow related the battery's charge which had increased gradually over a few days of being charged by the laptop power supply.

                Cheers,
                Pete

                Comment


                • #9
                  Just did some more tests...

                  I tried connecting the load to the battery terminals... same problem. Amplifier gets cut off as soon as I connect the 16V laptop power supply.

                  I measured the voltage at the LOAD terminals of the controller. With no laptop power supply connected, it read around 13V. With the laptop power supply connected, it read 14.5V.

                  It then dawned on me that maybe the amplifier was going into its own protection mode due to overvoltage. The more I think about it, the more this seems to make sense. I guess my original voltage measurements were somehow wrong, as I remember measuring only 1 or 2V across the LOAD terminals.

                  In any case, I connected the other power supply, that allows you to select the voltage. When I set it to 12V, everything worked fine. Amplifier did not get cut off. As soon as I bumped up to the next voltage (15V), the amp immediately cut off.

                  From what I know about these T-amps, around 14.5V is their absolute maximum, so I guess that explains it. The reason why it worked earlier on is maybe because the SLA battery wasn't fully charged, and probably caused the resultant voltage to be under 14.V (with the laptop power supply connected at the same time).

                  I bumped up the voltage a few more times until I reached 20V. In all cases, the maximum voltage across the LOAD terminals was 14.5V.

                  So, at the end of the day, it looks like the combination of battery and laptop power supply both connected at the same time produces too much voltage for the amp to handle.

                  Assuming that's the case, is there any easy way to address this? Is 14.5V the 'official' maximum voltage for the CMP12 charge controller?

                  Would the solution be to somehow limit the voltage at the LOAD terminal to keep it under 14V?

                  Thanks,
                  Pete

                  Comment


                  • #10
                    Originally posted by pete_melb View Post
                    So, at the end of the day, it looks like the combination of battery and laptop power supply both connected at the same time produces too much voltage for the amp to handle.
                    Glad to hear that you found the problem!


                    Originally posted by pete_melb View Post
                    Assuming that's the case, is there any easy way to address this? Is 14.5V the 'official' maximum voltage for the CMP12 charge controller?
                    From the little "manual" that comes with it (I have used these before), 14.5V is it....there isn't any option to change the voltage.


                    Originally posted by pete_melb View Post
                    Would the solution be to somehow limit the voltage at the LOAD terminal to keep it under 14V?
                    There are a few options that you could try, depending on what complexity you decide to go. The easiest may be to just use 2 power diodes (eg 1N4004 etc) in series for about a 1.4V drop (connected via a switch). Then when you operate just off the battery without the solar panel connected, you can disconnect the diodes (via the switch). There are many other ways...but the diodes are the easiest!

                    Comment


                    • #11
                      Thanks daz.

                      All good now. I simply connected a single diode between the charge controller's + LOAD terminal and the amplifier. The amp is now getting 13.8V instead 14.5V and all is working. No more cut outs.

                      Thanks to all for your suggestions. Sometimes the answer is obvious, and thinking out aloud (i.e. posting on the forum) goes along way to solving the problem (and realising the obvious .

                      Cheers,
                      Pete

                      Comment


                      • #12
                        Hi again,

                        Things have been working well using the 12V 7AH SLA battery. Recently, I replaced that battery with a smaller one, a 12V 2A battery. When I then connected the 19V laptop power supply to the charge controller, the charge controller immediately cut off power to the load and then I started hearing sizzling sounds coming from the battery. I immediately disconnected the battery to be safe.

                        Any idea why the charge controller is behaving differently, when the only difference is that one battery is rated at 7AH and the other at 2AH? It seems like the charge controller is passing way too much current over to the SLA battery. Is that what that sizzling sound could be?

                        I'm wondering whether it might be worth trying to limit the 19V laptop power supply to a maximum of around 1A.

                        Cheers,
                        Pete

                        Comment


                        • #13
                          Originally posted by pete_melb View Post
                          Hi again,

                          Things have been working well using the 12V 7AH SLA battery. Recently, I replaced that battery with a smaller one, a 12V 2A battery. When I then connected the 19V laptop power supply to the charge controller, the charge controller immediately cut off power to the load and then I started hearing sizzling sounds coming from the battery. I immediately disconnected the battery to be safe.
                          What wattage is the panel? a 12 volt 2 A battery cannot handle more than a 15 to 25 watt panel. The sound you heard was your battery cooking from way too much charge current.
                          MSEE, PE

                          Comment


                          • #14
                            Originally posted by Sunking View Post
                            What wattage is the panel? a 12 volt 2 A battery cannot handle more than a 15 to 25 watt panel. The sound you heard was your battery cooking from way too much charge current.
                            Hi Sunking.

                            I have a 20W panel, and that works fine with the 2A battery.

                            It's when I swap the 20W solar panel with a 19V laptop power supply that the battery starts to cook.

                            Is the regulator supposed to limit the amount of current that reaches the battery?

                            Cheers,
                            Pete

                            Comment


                            • #15
                              A charge controller is intended to take power from a CURRENT source like a solar panel, not a VOLTAGE source like a laptop supply. If you intend to continue to use a powersupply, you need a true MPPT controller, Morningstar makes some that are allowed to use voltage sources.
                              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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