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  • Questions and help needed on small solar project

    Hi this is my first post, I'm new to solar power I bought a 45 watt kit from a popular hardware store. not sure if I'm allowed to say it on here. Also purchased a deep cycle battery,
    but here is my problem the charge controller stops charging at 12v and my power inverter cuts off at 11.5 so that does not leave me much power for use.
    I thought I could fix this by adding another battery but most inverters I see are for 12v.
    So how do you guys have a multiple batteries?
    Thanks in advance


    Ok I bought a harbor freight kit which has 3 15 watt solar panels a thunderbolt magnum 4 amp 12 volt charge controller...
    a chicago electric 400watt power inverter.
    a everstart marine battery with 845 cranking amps and 122 amp hours @ 1 amp

  • #2
    Go ahead and tell us exactly what you bought Brand and model number and the specifications of each item.
    Not enough information in your post to determine anything. There is something amiss with the CC only charging to 12V but there may be adjustments on it to change that.
    Rich
    WWW.solarsaves.net

    NABCEP certified Technical Sales Professional

    http://www.solarpaneltalk.com/showth...Battery-Design

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

    www.gaisma.com

    Comment


    • #3
      Ok I bought a harbor freight kit which has 3 15 watt solar panels a thunderbolt magnum 4 amp 12 volt charge controller...
      a chicago electric 400watt power inverter.
      a everstart marine battery with 845 cranking amps and 122 amp hours @ 1 amp

      Comment


      • #4
        I couldn't find any documentation on the CC that relates to charging voltage.
        Best thing is to contact Harbor freight tech assistance.
        Rich
        WWW.solarsaves.net

        NABCEP certified Technical Sales Professional

        http://www.solarpaneltalk.com/showth...Battery-Design

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

        www.gaisma.com

        Comment


        • #5
          Originally posted by Naptown View Post
          I couldn't find any documentation on the CC that relates to charging voltage.
          Best thing is to contact Harbor freight tech assistance.
          well I'm considering upgrading so what type of charge controller is popular?
          and how do people use multiple batteries ?

          Comment


          • #6
            Originally posted by i.mikey View Post
            Ok I bought a harbor freight kit which has 3 15 watt solar panels
            Now we understand why you would not want to say what you bought. Of course we already knew that, but wanted to see if you had the guts to admit your mistake.
            MSEE, PE

            Comment


            • #7
              I don't see it as a mistake. I got a good price on it and it was a good way to get started.
              I knew when I bought it the charge controller was not great but the panels work great and I'm looking into
              upgrading at this point.

              Comment


              • #8
                Originally posted by i.mikey View Post
                I don't see it as a mistake. I got a good price on it and it was a good way to get started.
                I knew when I bought it the charge controller was not great but the panels work great and I'm looking into
                upgrading at this point.
                A upgrade would be to sell the HF stuff on Flea Bay, and get real panels and a good charge controller. YOu need a good 200 watt panel and a 20 amp charge controller to maintain your battery.
                MSEE, PE

                Comment


                • #9
                  I see the Harbor Freight set as a good starter set for people. It is a good starting point to learn the concepts of solar. No it's not very powerful, that's not the point. Telling people they need to spend $700 to $1000 on a starter kit is kind of rediculous. MaKing fun of someones starter set is rather uppity.

                  There is a company (I won't mention thier name out of respect for this forum's sponsor) that has a 50 watt Kit for people that are concidering the HF setup. It has a nice 50 Watt polycrystaline panel and a good chargre controller and cables. I thought that was an excelent idea because a lot of people are buying these small starter kits.

                  My 2cents, (about all it's worth also)
                  Green

                  Comment


                  • #10
                    Originally posted by green View Post
                    I see the Harbor Freight set as a good starter set for people. It is a good starting point to learn the concepts of solar. No it's not very powerful, that's not the point. Telling people they need to spend $700 to $1000 on a starter kit is kind of rediculous. MaKing fun of someones starter set is rather uppity.
                    Well you are missing a huge point. He is trying to use the HF kit to charge a 112 Amp hour battery. The HF kit can barely even charge up a 30 AH battery which it was designed for. So throwing more money into a bad idea is just silly. By the time he buys enough useless kits he will end up paying way more for inferior products and results. So is that what you want to encourage?
                    MSEE, PE

                    Comment


                    • #11
                      You're right

                      I did not mention the point that it wouldn't charge a 112 AH battery because that point had already been made. My point was that we all need to start somewhere. And look... his HF system already taught him an important lesson about battery sizing.

                      As far as what I want to encourage, I want to encourage people to learn as much as possible about renewable energies and conservation. I would also like to encourage people to encourage other people, if you know what I mean.

                      Peace,
                      Green

                      Comment


                      • #12
                        Originally posted by i.mikey View Post
                        Ok I bought a harbor freight kit which has 3 15 watt solar panels a thunderbolt magnum 4 amp 12 volt charge controller...
                        a chicago electric 400watt power inverter.
                        a everstart marine battery with 845 cranking amps and 122 amp hours @ 1 amp
                        Classic mistake of buying too large of a battery and too small of a panel like the other posts mentioned. But how would you know based on marketing and instructions that don't go into much detail on the usual C/20 minimum charge rate to help the consumer size the battery - never mind not knowing what their load requirements are.

                        Ok, your battery doesn't come with any listed 20-hour rate, only CCA and RC. Based on the RC I looked up for that battery, an *approximation* of the 20-hour rate for that marine battery. It is listed to have a 205ah RC, which can be converted like this:

                        RC * 0.6 = approximate 20 hour rate. The manufacturer of Everstarts, Exide, has conversion charts that bear out this approximation.

                        So, 205 * 0.6 = 123ah at a 20 hour rated conversion. WAAAY too big! 123 / 20 = 6.15amp minimum. You would need at least one more panel set to meet this, and real-world means yet ANOTHER set to do anything practical. Otherwise, your battery is not going to get charged properly, and will just die a slow death in a year or so. Oh, it will seem to work with the small stuff for awhile, but you'll see come this time next year.

                        So as pointed out before, you need to make that battery much smaller. And I'd try to use a deep-cycle battery that actually has a 20-hour rate listed for it. Not all batteries that have this rating are TRUE deep cycle, but they are better than the inexpensive dual-purpose types. "Marine" doesn't automatically make a good solar deep-cycle battery, even if they tout their trolling-motor prowess.

                        As for controllers - look into Morningstar and Steca. Both are pwm and have temperature compensation.

                        So you got burned like many (myself included when I first started out) - get a true deep cycle that is between the range of C/20 (largest) and C/8 (smallest) for flooded. For AGM, this would be C/20 to C/4. Compare this to the 3amps your kit is providing. Tip: While C/20 is the barest minimum, the smart money is to consider C/10 the minimum.

                        Without knowing about your solar insolation hours (real working hours, not just daylight), and load requirements, just be prepared to start all over. I would not advise scarfing up any more HF kits for now - just change the battery, change the controller, and have fun.

                        BTW, we aren't just being mean. There is a thread much like this in another popular solar power forum with much the same recommendations for exactly the same battery.

                        Comment


                        • #13
                          PNjunction, where are you coming up with a C/20 minimum charge rate for a FLA battery? That i snot enough to prevent Stratification. Needs to be up around C/12 to be able cause some light agitation to keep the electrolyte stirred up. Also since the battery has a CCA rating tells you it is a Cranking battery and will do poorly in any cycle application.
                          MSEE, PE

                          Comment


                          • #14
                            I found it on the NAWS solar forum and elsewhere - but to their credit, they did not say it was optimal.

                            Years ago I was struggling with experimenting with small panels / charger and a hybrid marine battery. (yeah, I know...) Everybody could tell me the voltage and maximum current rates, (even did the RC conversion to 20hour capacity) but could not find anything to differentiate between a "maintainer" and something that would really charge. I only thought it was just a matter of super long charge times, and didn't realize anything about overcoming internal resistance. Spent a LOT of time playing around with disappointing superficial surface charges at around C/40 rates. So finding that C/20 was a big eye-opener. Then again, I knew nothing of sulfation or stratification, so accepting a charge was my only consideration, not long term health.

                            To be honest, when I would say something like C/10 would be my personal minimum for FLA, it was only with limited solar-insolation hours in mind, thinking that most hobbiests would never get to the absorb stage at C/20 - even though it would actually charge.

                            BUT, as you have pointed out, a real-world minimum for FLA should be C/12. While many seem to have problems even getting to C/20, there seems to be no point in using it as a minimum reference if battery-health is jeopardized when you take into account sulphation AND stratification - something I didn't consider.

                            Accordingly, I'll be changing my tune to C/12 to C/8 as a general guideline for FLA rates. That puts even more pressure on the HF kits, but seems mandatory since a minimum of battery health has to taken into account as well.

                            Thanks for the challenge!

                            Comment


                            • #15
                              Originally posted by PNjunction View Post
                              ...
                              BUT, as you have pointed out, a real-world minimum for FLA should be C/12. While many seem to have problems even getting to C/20, there seems to be no point in using it as a minimum reference if battery-health is jeopardized when you take into account sulphation AND stratification - something I didn't consider.
                              I was mildly surprised to see, when reading a manufacturer's description of forklift-style batteries also usable for RE, that they offered as an accessory a pumped air introduction system designed to circulate the electrolyte and prevent stratification, even before the battery reached the gassing stage. So they take it quite seriously! I am not sure the exact charging current level is particularly important in preventing sulphation, as long as the battery is recharged promptly at the end of each discharge instead of being left at a low SOC for a day or more. That puts a lower limit on the wattage of the panels, but one which is scaled by the DOD rather than the full battery capacity.
                              But if the only thing which is preventing stratification is the charging rate, then that makes the minimum maximum rate (!) more critical. And that is specifically what Dereck cited in his statement about C/12.
                              SunnyBoy 3000 US, 18 BP Solar 175B panels.

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