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Solar Charger Help Please

Discussion in 'General Electronics Discussion' started by Heeran, Jul 25, 2013.

  1. Heeran

    Heeran

    64
    0
    Nov 13, 2012
    Hi
    Thanks For all the assistance before.
    I am trying to build an automatic solar charge control that can charge a 100Ah lead acid battery and I have a 135watt solar panel. I have searched the net and I have built numerous circuits but, they don't seem to work the way it supposed to work. I am from south Africa and I am not sure if the components are different resulting in this outcome. Could you please provide me with a circuit diagram as well as a list of components that I will require. I need the circuit to be as simple as possible but must be able to charge the battery and also not overcharge as well as be able to maintain a float charge when the battery is full. This circuit must have an input for the solar panel and an output for the battery and a LED to display charging and float but it is important that it does not need any adjustment. Just something that I can build and plug the input and output and let the circuit do the charging.
    Thanks
    I require another circuit but let me build this one then if you can maybe assist me with the other circuit.
    I thank you again for the help.
     
  2. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,156
    2,671
    Jan 21, 2010
    Firstly, I can assure you that components work the same in South Africa as they do in all other parts of the globe.

    Solar chargers combine two reasonably complex circuits. The first is a MPPT regulator, the second is a battery charger.

    For maximum power from the panels and maximum longevity from the batteries, you need both to be fairly sophisticated.

    Fortunately you can purchase them relatively cheaply.

    If you want to make your own, you need to determine how fancy and complex you want to be.

    "As simple as possible" might simply be placing a large shunt regulator across the solar panel output and then using a series diode before connecting it to the battery. Your shunt regulator needs to be capable of dissipating 135W, so it's going to need a large heatsink and will likely get hot (on a sunny day when the battery is charged).
     
  3. Heeran

    Heeran

    64
    0
    Nov 13, 2012
    Hi
    I understand what you mean. Can you maybe send me a circuit diagram as well as the list of components for a fully automatic solar charge control that requires no adjustments, just an input an and output. Are these charge control inputs universal, meaning I can place any wattage solar panel at the input as long as it is DC? .
    Can you also send me a circuit diagram and list of components of a 12 volt or lower motion sensor that has an adjustable timer. ( like the one we use on the outside to detect any movement an switch on the lights).
    Thanks
    Have a great day.
     
  4. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    Jan 21, 2010
    The controllers will have a power rating that you should not exceed (it relates to the panel wattage)

    What do you want to do? DO you want a solar outdoor light that comes on in the dark with movement?
     
  5. Heeran

    Heeran

    64
    0
    Nov 13, 2012
    The circuits are going to be two different circuits on their own. The solar control will only charge the battery via the pannel and the motion sensor with timer will switch on ligths but the sensor circuit must be 12v or lower to operate. Will the control circuit be able to handle any type and wattage of solar pannel as long as its a dc panel
     
  6. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    Jan 21, 2010
    Did you read the first sentence of my previous post?

    What experience do you have in constructing electronic projects?

    What is your budget?

    Are you doing this for experience, or to save money?
     
  7. Heeran

    Heeran

    64
    0
    Nov 13, 2012
    I do have a budget of 400 rand for purchase of components, the pannel i already have. I am not that good at building circuits but i built a few. I am building it to save electricity.
     
  8. Heeran

    Heeran

    64
    0
    Nov 13, 2012
    Hi, i have not received any feed back regarding the circuits. Please let me know if you currently busy working on it. Thanks
     
  9. davenn

    davenn Moderator

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    Sep 5, 2009
    probably because you have not given enough information

    have you bothered to google for solar charger/controller circuits.
    and considering your admission of not being good at electronics construction, this complex system is probably well out of your depth.
    visit some solar power company sites and have a look at what's available and for what price

    Dave
     
  10. Heeran

    Heeran

    64
    0
    Nov 13, 2012
    Hi
    I have done a lot of searching on the net for a MPPT solar charge circuit that can charge a 100Ah 12 volt deep cycle battery. I can find a circuit diagram. I can build the circuit as long as it requires not programing after being built. I have a 12 volt 135 watt dc solar panel for this circuit. All the reading I have done states a 15 or 20 amp 25volt MPPT charge controller would be perfect. I have tried google and other electronics circuit sites but cant find it. Please assist me if you can
     
  11. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,156
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    Jan 21, 2010
    MPPT chargers all use a microcontroller as far as I know .

    Also, I believe most MPPT chargers are buck topology, so they require the panel(s) to have a voltage higher than the battery.

    It seems your panel would be at most 12A, but do you have the specs for open circuit voltage and short circuit current?

    The open circuit voltage would probably have to be 18V (at least) for me to be happy it could be used to charge a 12V system.

    Also I don't suspect that $USD40 is going to be sufficient.

    Here is a cheap unit on eBay. That's within your budget, but I can't comment on the quality.

    Google of "mppt regulator schematic" if you want to see what's involved. I'm not sure I'd go with the you-tube examples though.

    Here is a non-mppt regulator. There's a number of problems:

    1) the 723 is a largely obsolete chip
    2) this circuit is designed for 7A (you need at least 15A)

    If you select a suitable mosfet (possibly several in parallel) and a suitable bank of resistors (I would recommend 1 ohm 150W). I would make the resistor out of four 1 ohm 50W resistors. But these would likely get close to blowing your budget right away...
     
  12. Heeran

    Heeran

    64
    0
    Nov 13, 2012
    Hi
    The solar panel has open circuit of 21.9 volts.
    I have attached a MPPT circuit that I have found on the net but would like to know if I can upgrade it to 15 amp or more and drop the current consumption of the circuit. If it can be done, how do I go about doing this change. This controller has a maximum of 10 amp and only handles a panel of 12volts 120watts or 24 volts 240watts. the current consumption is 200mA over a 24hr period. I google MPPT controller's and went to images on google and found the picture that I have attached. When you click on the picture and go onto that page, you get a details if the circuit. I cannot attach the complete file that I have downloaded. Please let me know whats your take on this circuit and can it be upgraded.
    Thanks
     

    Attached Files:

  13. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,156
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    Jan 21, 2010
    The mosfet is capable of the current and it's a switchmode device, so it's also possible that you would require only a moderate amount of heatsinking.

    That design requires a microcontroller. Do you also have access to the firmware?

    Does the firmware expect a certain maximum current?

    Can you program the microcontroller?

    Clearly this design is for a MUCH lower current (the output fuse is only 1.8A). It would need significant redesign to make it work at 15A.

    I would suggest that the mosfet, inductor, diode, and capacitors would need to be carefully considered. The sense resistor would also need to be adjusted.

    In this circuit, pretty much ALL of the magic happens in the PIC. And as an aside, I don't see that this has any temperature compensation, and nor does it have any means of disconnecting the load if the battery voltage drops too far.

    I'd also lay odds that you couldn't build it for $USD40 unless you already have a lot of the stuff you'll need.
     
  14. Heeran

    Heeran

    64
    0
    Nov 13, 2012
    hi, i dont have acesses to firmware and cannot program the controler. I require components that dont need programing, jst assembling onto the board. I do have alot of component already. The circuit i have sent to you say it is good for 10amps and. I got a separate circuit to discöect the battery from the circuit when the voltage drops bellow 11 volts. All this circuit has to do is charge the battery correctly and prevent overcharging to prevent any damage to the battery and allow it to last as long as it can.
     
  15. Heeran

    Heeran

    64
    0
    Nov 13, 2012
    This is the description that is attached to the image that I sent to you.

    Are you building the ultrasonic anti-fouling unit for your boat? You will need a solar panel and a charge controller to keep the batteries topped up. Or are you thinking of a large solar panel for your caravan or 4-wheel drive? Again, you will need a solar charge controller. This is the one to build.

    This charge controller is suitable for 12V panels up to 120W and 24V panels up to 240W. It incorporates Maximum Power Point Tracking (MPPT) and 3-stage battery charging. It works with any 12V panel from 40W up to 120W (3.3-10A) and can also be used with 24V panels in the 80W to 240W range, in conjunction with a 24V battery.

    Wouldn’t it be nice if you could just wire a solar panel (or panels) to a battery or two and leave it at that? Unfortunately, for all but the smallest panels, this is a very bad idea. The battery will be overcharged on sunny days and on cloudy days the battery may not charge at all, even though the panel is capable of harvesting energy. So there is no choice – you need a charge controller.

    This Charge Controller is suitable for charging Flooded Lead Acid, Gel-Cell (Sealed Lead Acid or SLA) and AGM (Absorbed Glass Mat) type batteries. Ideally, any battery used in a solar system should be a “deep discharge” type. Car batteries are not deep discharge types and are not suitable.

    Ultrasonic anti-fouling for boats

    We have already mentioned the Ultrasonic Anti-fouling unit for boats (SILICON CHIP, September & November 2010). This must run continuously to protect the boat hull from marine growth and for those without shore power, a solar panel and charge controller is the only solution. For this application we recommend, at minimum, a 12V 40W panel with a 12V 12Ah SLA battery.

    For continuous anti-fouling, the circuit draws an average of about 200mA. Over a 24-hour period this amounts to 4.8Ah or 60Wh per day from the 12V battery. This means that if a 40W panel generates full power for 1.5 hours or longer each day, this is enough for the anti-fouling unit to operate. However, if you are also concerned about automatic operation of bilge pumps etc, a 40W panel would be a good choice. The reason we have specified a larger panel and battery than strictly necessary is twofold.

    First, for a boat installation, you cannot orient the panel for best efficiency. If you are on a swing mooring, the boat’s heading will constantly change according to wind direction and even if it didn’t, you would still install the panel to result in minimum windage and this means that it must be installed horizontally. The same comment generally applies to a caravan installation. Second, you need a bigger panel to cope with sustained periods of bad weather when there is little sun.
    MPPT & charge optimisation

    Given that the solar panel is mounted horizontally, it is most important to collect as much energy as possible from it and this is where the Charge Controller’s MPPT (Maximum Power Point Tracking) comes in.

    As shown in Fig.1, for a typical solar panel exposed to full sunlight, the output ranges from maximum current when the output is shorted (Isc) to maximum voltage when the output is open circuit (Voc). For a typical 120W 12V panel, Isc is 7.14A and Voc is 21.8V. But the maximum power from a 120W panel is at 6.74A and 17.8V which is hardly a suitable match for a lead-acid battery.

    If we were to connect that 120W solar panel directly to the battery, the charge current would be about 7.1A at 12V (85.2W), 7.05A at 13V (91.7W) and 7A at 14.4V (101W), ie, much less than the 120W available from the solar panel at 17.8V.

    By contrast, MPPT keeps the solar panel current and voltage at the maximum power point while charging the battery, even though the battery voltage is lower than the solar panel voltage.

    This is achieved by an intelligent switchmode step-down voltage converter. To see how this works, refer to the block diagram of Fig.2 below. Current from the solar panel flows through diode D1 and Mosfet Q1. When Q1 is on, current (i1) flows through inductor L1 into capacitor C2 and the battery. This stores energy in the inductor’s magnetic field.

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    odWCzTh.jpgAt7z4tm.jpgybd5MVL.jpg

    kGNaxTu.jpgW9f5UHx.jpgEdll3Be.jpg
     
  16. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,156
    2,671
    Jan 21, 2010
    If this is a silicon chip project, can you tell me the month and year (and page number if you have it)?

    This design has a microcontroller, so if you build it you need the firmware (or an already programmed chip). Without this, it won't work.

    Silicon chip projects often provide a downloadable firmware or access to pre-programmed chips.

    I am concerned with the output fuse rating compared with the text you say goes with it.
     
  17. Heeran

    Heeran

    64
    0
    Nov 13, 2012
    hi, i dont have the page,year or month. I have googled firmware and it came up for apple computers, i have a toshiba computer with windows 7. What does this program do. How do we modify this circuit to use allready programed micro controlers. I have tried to search for more MPPT circuiys for the output that i require but nothing listed.
     
  18. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,156
    2,671
    Jan 21, 2010
    OK, it's issue 269, Feb 2011 (Here)

    I'll look it up and see what I an tell you.
     
  19. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,156
    2,671
    Jan 21, 2010
    Well, firstly, that circuit and that description don't match up.

    The real circuit is quite a bit different.

    Also there is a revised version in the March 2012 issue.

    If you want to build it you could purchase that issue (you can purchase it and view it on-line).

    Here are some of the bits they sell.

    If you purchase a copy of the magazine you can download some of them free of charge.

    The kit for this is available. $129 plus shipping. (I told you it would be expensive)
     
  20. Heeran

    Heeran

    64
    0
    Nov 13, 2012
    Hi
    I have checked the kit. But would that do what I need it to do. I do see know what you mean by expensive. I really want to build my own MPPT controller that can serve my requirements. It just a person achievement for me, hope you understand. Is there any other way that I would be able to achieve this.
     
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