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  • Do I need isolation?

    I have a set of solar panels connected to a charge controller which is connected to my camper batteries. The camper has an on board charger which runs off 120 VAC and supplies 12 VDC to the camper and charges the batteries. The first time I connected the "solar system" to the batteries all was fine everything went as expected. However I had a need for 120 VAC and ran a generator for a bit.The next afternoon I noticed that the solar charge controller has emitting a loud buzz, like an alert tone. The LED's on the charge controller appeared to be functioning correctly just the loud tone.
    Without the solar panels connected I still got the noise from the charge controller when connected to the batteries.
    The charge controller retailer had no information on what the problem could be and gladly replaced the charge controller no charge (pardon the pun).
    This brings me to my question: Do I need to put a properly sized diode between the charge controller and the batteries to prevent the on board charger from back feeding into the charge controller?

  • #2
    Originally posted by dkrece View Post
    I have a set of solar panels connected to a charge controller which is connected to my camper batteries. The camper has an on board charger which runs off 120 VAC and supplies 12 VDC to the camper and charges the batteries. The first time I connected the "solar system" to the batteries all was fine everything went as expected. However I had a need for 120 VAC and ran a generator for a bit.The next afternoon I noticed that the solar charge controller has emitting a loud buzz, like an alert tone. The LED's on the charge controller appeared to be functioning correctly just the loud tone.
    Without the solar panels connected I still got the noise from the charge controller when connected to the batteries.
    The charge controller retailer had no information on what the problem could be and gladly replaced the charge controller no charge (pardon the pun).
    This brings me to my question: Do I need to put a properly sized diode between the charge controller and the batteries to prevent the on board charger from back feeding into the charge controller?
    Installing a Diode like that would prevent the charge controller from sensing battery voltage thus preventing the charge controller from working at all.

    What make and model in your charge controller?

    WWW

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    • #3
      Duh, I should have thought of that.
      The Charge controller I am using is: Strongway Digital Solar Charge Controller - 450 Watt/30 Amp Capacity.

      Comment


      • #4
        What is the VOC of your panels and how are they wired? What is the Max voltage input of the controller?

        WWW

        Comment


        • #5
          maybe your shore power charger overvoltaged the solar controller.. Do you have breakers or switches on the solar charge controller ?
          Isolate it when you use shore power. Use this sequence:
          Shut down - switch off PV, then Battery (the + wires to the controller)
          Start up - switch on the battery - wait for controller to boot up, then switch on PV and charging should start.
          Do not allow the PV to be engaged without the Battery voltage to the controller first, or you can fry it's brain
          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


          • #6
            To answer Mike90250: I currently have lots of fuses but no switches. Going to have to build a circuit breaker/switch box per your suggestion. Then it will be easy to shut down and disconnect.
            As to Wy_White_Wolf's question: The VOC for the panel is 22.7. The panels are connected in parallel to the controller.
            Following is the specifications from the manual.
            Rated voltage 12VDC Auto
            Max input power 450W
            Current
            Discharging 30A
            Charging 30A
            Overcharge protection 14.4V

            Comment


            • #7
              Sounds like you tripped the over-voltage protection. For the cost of the switch box, you might be better of just buying a better charge controller.
              CS6P-260P/SE3000 - http://tiny.cc/ed5ozx

              Comment


              • #8
                Originally posted by sensij View Post
                Sounds like you tripped the over-voltage protection. For the cost of the switch box, you might be better of just buying a better charge controller.
                Recommendation for a different charge controller?

                Comment


                • #9
                  Originally posted by dkrece View Post

                  Recommendation for a different charge controller?
                  Morningstar and Blue Sky make decent midrange charge controllers.

                  WWW

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                  • #10
                    Is the charge controller I have not correct for the panels being used, or ...?

                    Comment


                    • #11
                      Originally posted by dkrece View Post
                      Is the charge controller I have not correct for the panels being used, or ...?
                      The 14.4 V limit is much tighter than most, especially the way it seems to behave. If you are happy with PWM and don't want to jump to an mppt controller, something like the Renogy Wanderer (16 V over-voltage disconnect, 15 V over-voltage reconnect) would probably handle spikes from your generator much better than what you have. There are probably even less expensive viable options.
                      CS6P-260P/SE3000 - http://tiny.cc/ed5ozx

                      Comment


                      • #12
                        Originally posted by dkrece View Post
                        Is the charge controller I have not correct for the panels being used, or ...?
                        FWICS - It's cheap chinamart junk. There's very little true info on it and even the numbers they advertise don't add up. They claim it's 12/24 volt, 30 amp and 450 watts max. well 12 * 24 = 720 so one of them is wrong for it to be 450 watts. Never could find out what the max voltage input is. The 14.4 is where it shuts off on charging on the max voltage input.

                        WWW

                        Comment


                        • #13
                          Originally posted by Wy_White_Wolf View Post

                          FWICS - It's cheap chinamart junk. There's very little true info on it and even the numbers they advertise don't add up. They claim it's 12/24 volt, 30 amp and 450 watts max. well 12 * 24 = 720 so one of them is wrong for it to be 450 watts. Never could find out what the max voltage input is. The 14.4 is where it shuts off on charging on the max voltage input.

                          WWW
                          This project was a get it done situation, cost was not a consideration, I bought what was available from the local retailer. They have been good to me so far and it will be difficult for me to return the unit since they already replaced it, no questions asked. I will build a nice circuit breaker switch box (really need it anyway) and use the controller until it dies, then I will order a more robust unit.

                          Comment


                          • #14
                            Originally posted by Wy_White_Wolf View Post

                            FWICS - It's cheap chinamart junk. There's very little true info on it and even the numbers they advertise don't add up. They claim it's 12/24 volt, 30 amp and 450 watts max. well 12 * 24 = 720 so one of them is wrong for it to be 450 watts. Never could find out what the max voltage input is. The 14.4 is where it shuts off on charging on the max voltage input.

                            WWW
                            Strongway brand comes from Northern Tool + Equipment. It isn't listed as 24 V anywhere on their product page or in the documentation they offer, I'm not sure where you are seeing that.
                            CS6P-260P/SE3000 - http://tiny.cc/ed5ozx

                            Comment


                            • #15
                              Originally posted by Wy_White_Wolf View Post

                              FWICS - It's cheap chinamart junk. There's very little true info on it and even the numbers they advertise don't add up. They claim it's 12/24 volt, 30 amp and 450 watts max. well 12 * 24 = 720 so one of them is wrong for it to be 450 watts. Never could find out what the max voltage input is. The 14.4 is where it shuts off on charging on the max voltage input.

                              WWW
                              That CC is only rated for 12v batteries. But if you divide that 450 watts by the 14.4 max volts you get 31.25 amps which is about what a 30amp CC should allow.

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