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    Opinions on my 12V Circuit Diagram

    Hey Ant,

    Firstly, Thanks for setting this up. I'm a big fan of your site and you've really helped me out. This is my first post!
    I'm still pretty new to all of this and I'm a the point where I need to start considering my wiring before I go any further.
    I've knocked together this circuit diagram and would love any feedback. It may not have all of the info you'd need to give the best feedback, but anything glaringly obvious that I've missed would be great.

    Thanks

    https://photos.app.goo.gl/KP6HCBMQaykIJvdN2

    #2
    Have you thought about a b to b smart charger something like a ctek c250s or ring dsdc30 rather than the 16mm cables and heavy relay and separate solar controller.? How big is your alternator to have 200 amp relays? I do not think your split charge system actually charges as well although the solar may well compensate. What vehicle is it? Is it euro 6? does it have a smart alternator? It is hard work making connections to anything over 6mm wiring. You csnt really comment on cable sizes without knowing the run length.

    Comment


      #3
      Are your batteries 2 x 225Ah? You appear to never want to go to camp sites or at least not pay for hookup, what is your daily use? Do you drive every day? Camp all seasons? You have no music video or 12v tv. What is the big inverter for? you might do better with a slightly bigger inverter and a cheaper 240 volt A+ fridge?

      Comment


        #4
        the only thought I can add as you have had excellent feed back is in the event of a short the cables from the battery to a fuse should double insulated and away from any combustible material
        BuzznDave

        Comment


          #5
          Hi, The electrical regulations book, BS.7671 gives current carrying capacity for cables. 16mm copper is (depending on the way it's installed) a maximum of 87A, 10mm 65A and 4mm 37A. These are absolute maximum figures so, as the fuse only protects the cable, fuses should be somewhat smaller. Voltage drop should not be a problem over the short distances involved.

          Comment


            #6
            Originally posted by IMawle View Post
            Hey Ant,

            Firstly, Thanks for setting this up. I'm a big fan of your site and you've really helped me out. This is my first post!
            I'm still pretty new to all of this and I'm a the point where I need to start considering my wiring before I go any further.
            I've knocked together this circuit diagram and would love any feedback. It may not have all of the info you'd need to give the best feedback, but anything glaringly obvious that I've missed would be great.

            Thanks

            https://photos.app.goo.gl/KP6HCBMQaykIJvdN2
            Hi IMawle.
            Firstly it's Graham and Pauline you have to thank for the site, I just answer questions relating to Romahomes mainly if I think I have any useful information to share.
            Your wiring diagram seems pretty comprehensive, my only reservation is the use of two 6v batteries in series, I once worked on a yacht with batteries wired in series and you only need a cell on one battery to fail to significantly reduce the output voltage of the pair. I would use two 12v batteries wired in parallel to give a robust store for the energy you're able to produce from your solar panels and for any transformed 12v you need to run your mains outlet.
            Thanks
            Ant

            Comment


              #7
              I have to disagree about voltage drop not mattering. In this situation it may. when charging a leisure battery which is usually cooler and on a longer cable than the vb. The alternator ignores the leisure battery after about 80% charge because the hot vb with less lost volts is satisfied, so it reduces charge volts too soon. The leisure battery is then only partly charged and has a shorter life. This is why a b2b charger is better because it senses the leisure battery temperature and charge state and smart charges the leisure battery accordingly. Perhaps with an alternative charge source , solar, the battery will be topped of by that and it may not matter .
              As you say though the fuses are too big there.

              Comment


                #8
                OK so I assume you are a wild camper and like me have a van equipped for wilding (no hook-up). Why 6 volt batteries? 2 12v 110 amp hours would do the same. Do you need an MPPT solar controller - in my experience (4 years of solar power) a basic solar controller suffices.
                Your 300 Watts of Solar Panels will give on a good day somewhere around 20 amp at the best - Solar Panels are rated on Sunshine Portugal mid Summer.
                I guess everyone is intrigued what is the 1Kw Inverter for - although theoretically possible, I have a feeling that in practice this size of power demand will "cook" your batteries. 83 Amps - almost a cranking amperage -

                Jon
                Amor omnia vincit et nos cedamus amori
                https://smallromahome2oldies1largedog.blogspot.co.uk/

                Comment


                  #9
                  I would be wanting a few more USB points in strategic places to avoid trailing wires.
                  I
                  Reality is not what it seems

                  Comment


                    #10
                    2x 6 v in series 12 v but as ant says problematic 2x 12v in parallel.
                    BuzznDave

                    Comment


                      #11
                      Hey guys,

                      Thanks for all of the feedback. There are definitely some things to consider in there. I have purchased a lot of the components (though open to returns if they seem ridiculous) in the diagram and am looking for more of a technical review of the circuit diagram as it stands, as opposed to suggestions on the setup. Completely welcoming suggestions. Just want to make sure I don't set our home on fire in the process.

                      ----

                      Derekoak - I'm currently not convinced about the relay (hence why it's greyed out). A "friend" sold it to me (a bit of a rip off) and I'm not sure If I'll fit it yet. Ws going to see how we get on with the solar before deciding. I have a NOCO genius that plugs into the mains (when we do have access - Hoping to do the odd bit of house sitting as a break from the wilderness) for trickle charging and battery repair. I've tried to reference run length of cables where possible. Yes, batteries are 2x 6V 225Ah (Trojan T-105).

                      The vehicle is a 2.5l 05 Renault Master. It's pretty beefy. We won't drive every day and may stop for 4-5 days at a time.

                      I think we'll probably have music on a USB Bluetooth speaker and mobile phones and any video will be through one of 2 laptops (may get 12V chargers for these, or just use the inverter). We got a compressor fridge for £125 on eBay, it was a steal! Our daily usage will be minimal, we're looking for longer duration off-grid as opposed to high capacity.

                      Ant - Thanks. Ah, I see. I see what you're saying about the series batteries. I never really thought about that. They weren't crazy expensive for what they are. So hopefully they'll be OK. If I need to replace, I'll consider this method.

                      Steveharris - Thank you. Was your comment regarding the wire in reference to any particular 16mm run of cable. I've seen it used by a lot of people for the connection of batteries etc. Any fuse, in particular, you were referring to? I'm guessing the vehicle battery ones. I'm not even sure I'll go for the relay yet.

                      Kernowjon - Yep, we'll be wild for the most part. The batteries I got are leftover from a friends conversion. They were a good deal and are a good brand. As for the MPPT charger. I got it as part of a package with my 2x 150 Watt solar panels. The inverter will be for things like a travel hair dryer, blender, 2 laptops, hair clippers, camera charger, drill battery charger and I'm sure a few other things I can't think of at the moment. Do you think it's overkill? I only just ordered it. I was recommended at least 420Ah for a 1000W inverter.

                      jondxxx - You may be right. I might get a larger fuse box and spread a few about.

                      Comment


                        #12
                        Re split charge - I have a very simple system and it works - a simple 4 pin 60 amp relay - as in Headlight relay etc - because I hate "glowing" ignition lights the relay is activated from the sidelight circuit. I always drive with the sidelights on and so my battery 110 amp 12v is charging both from the altenator and via the solar panel. Never been a problem - I did once have a problem with a Smartcom that may have contributed to "killing" my old battery (it was over 3 years old) could be coincidence that both went at the same moment.
                        When it comes to electrics (despite or because of my City & Guilds) I always subscribe to the old fashioned maxim "KISS" - Keep It Simple Stupid!!!!
                        Jon
                        Amor omnia vincit et nos cedamus amori
                        https://smallromahome2oldies1largedog.blogspot.co.uk/

                        Comment


                          #13
                          I thimk jondxxx is right. You are stretching the batteries to run the inverter at full. I would have had smaller and been careful to not have too much on at a time but if you have it you are not going to push the batteries because you will not use it full on . Sounds like the max load is the hair dryer, i set up to use a tube connected to the hot air vents in the front. But my wife is willing to wash her hair then we drive until the engine is warm and then she dries her hair. My inverter is just 350w and we run a blender and bluetooth speaker charger occasionally.
                          i also have heard good things about trojans they are deep discharge and robust. If they go wrong then ant is right. Until then they are great.
                          There is no need for bigger relays than your alternator capacity. I doubt it is a smart alternator. Any 12v fridge that works is good for 125 my vitrifrigo was 600.
                          reduce the fuses to the wire capacity and you are good to go. I hate cigarette sockets they get bad connections and are clunky, just they are the standard. look at anderson power poles as an alternative 12 volt connector small solid higher rated.

                          Comment


                            #14
                            Re split charge - I have a very simple system and it works - a simple 4 pin 60 amp relay - as in Headlight relay etc - because I hate "glowing" ignition lights the relay is activated from the sidelight circuit. I always drive with the sidelights on and so my battery 110 amp 12v is charging both from the altenator and via the solar panel. Never been a problem - I did once have a problem with a Smartcom that may have contributed to "killing" my old battery (it was over 3 years old) could be coincidence that both went at the same moment.
                            When it comes to electrics (despite or because of my City & Guilds) I always subscribe to the old fashioned maxim "KISS" - Keep It Simple Stupid!!!!

                            BTW today I have driven about 26 miles - it is sunney the van has been standing for over an hour and a half Leisure battery voltage fluctuating 14.2 to 14.3v The load is a small compressor fridge.
                            Jon
                            Amor omnia vincit et nos cedamus amori
                            https://smallromahome2oldies1largedog.blogspot.co.uk/

                            Comment


                              #15
                              My preference if i was buying a van would be two 12v batteries. Not two 6v batteries.

                              Comment

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