For quite some time now, in ComoHacer.eu we are promoting renewable energies and the responsible use and reuse of materials, as an example of this we have the tutorial that we translated from the great Michael Davis on how to make a photovoltaic solar panel and a homemade wind turbine, in which, in the latter case, we add the design and manufacturing of a charge regulator or charge controller. Over time Mike discovered a new, much more efficient and cheaper design to do this and today we bring it here for you to enjoy.
As the cover of this article we have a simple diagram of the layout of a complete renewable energy system to obtain electricity from the wind and the sun. As we can see, the charge regulator plays a key role in this system, and not for nothing, as it is in charge of telling when the batteries should be charged and when the electricity generated should be dumped into the dummy load so as not to damage them. Let's see what we need to make our charge regulator:
Charge controller materials
We have them all in our official shop at the best price.
- IC1 - 5v voltage regulator (7805).
- IC2 - Integrated NE555.
- PB1 and PB2 - 2 pushbuttons SPST-NO.
- LED1 - 1 green LED.
- LED2 - 1 yellow LED.
- RLY1 - 40A Car Relay.
- D2 - Rectifier diode 1N4001.
- R1 and R2 - 2 variable resistors of 10kΩ.
- R3, R4 and R5 - 3 resistors of 1kΩ, 1/8w, 10%.
- R6 - 1 resistor of 330Ω, 1/8w, 10%.
- R7 - 1 resistor of 100Ω, 1/8w, 10%.
- Q1 - 2N2222 NPN transistor.
- Q2 - IRF540 MOSFET transistor.
- C1 - 1 capacitor 0.33μF, 35v, 10%.
- C2 - 1 capacitor 0.1μF, 35v, 10%.
Based on the diagram above, we can start to build the charge regulator as we like, using tools such as the following Eaglewhich has a free version, or OrCADor simply use a TEST PLATE to build our design on the fly. I say build it to our liking because the components that we have around the house may not have the same physiognomy and so they would not fit us correctly.
Anyway, a colleague of Mike's, Jason Markham, created a sketch for a printed plaque that I leave you below after having improved the quality a bit, as the image they leave us is very small and with little definition:
According to Mike, this redesign has been thought through from the ground up so that its parts are easily found in electronics shops and are as cheap as possible. The 555 integrated is the most famous of its kind, the 5v regulator is one of the most common on the market and all the resistors it uses are 1/8 watt, but they can be easily replaced by 1/4 watt resistors. The relay is by far the most expensive component in the installation, and this is because the current it can work at is too high for small installationsBut if you plan to increase it progressively, it is highly recommended. It is also very easy to find, here are the internal connections and their nomenclature so that you can see them easily:
Once we have the circuit assembled, we will have to calibrate it from the potentiometers by using the 11.9v minimum charge on batteries and 14.9v maximum charge. before throwing the energy into the dummy load. Remember that the dummy load only has to be used when we have a wind turbine in the circuit, if we only have solar panels, the dummy load can be left open.
The best way to make the adjustment is to use a variable power supply on the battery bank terminal in order to select the minimum and maximum voltage for charging the batteries. We put the power supply at 11.9v and measure with a multimeter on the test point 1 to adjust the variable resistor R1 until we get 1,667v and then put in the power supply at 14.9v and we measure in the test point 2by adjusting the variable resistor R2 to obtain 3,333v.
Once we have made the adjustment, we change the power supply. from 11.7v to 15.5v and we will have to listen to the relay making the change just when the required values are reached. The battery charge and dummy charge buttons can be used to change the state of the batteries when the batteries are in the correct state of charge. between the required values (11.9v and 14.9v). It should be noted that these values will be calibrated without a load connected, so in normal use, the values will be much more optimal to extend the life of the batteries.
Once we have finished making all the calibrations and checks that the circuit is working perfectly, we can put it all in one box in order to have it properly ordered. You can see that it has been included a fuse to the assembly plus all the external and internal connections required to make it much easier to use. In this case the box has a transparent lid, so Mike didn't find it necessary to drill any extra holes. to remove the LEDs indicators.
We can see the buttons for switching to the batteries for charging (Charge) and the button to throw energy to the dummy load (Dump). On the other side we have the connections necessary for the dummy load (Dump), the input from the solar panels/wind turbines (Inputup to 40A, remember), and the output to the battery bank (Battery), as well as their corresponding ground connections (GND).
It is important to bear in mind that when making the connections, the first thing to connect are the batteriesThis will avoid a possible failure due to the fact that the panels and wind turbines may be generating current at the time of connection. As mentioned above, if you plan to use a wind turbine in this charge regulator, it will be necessary to use the dummy loadThis will prevent the wind turbine from being damaged in very high winds as it will provide an electric brake to the motor and blades, just as the batteries do when they are being charged.
Another very important detail is that it is a charge regulator in which all inputs go to the same point, we will need to use a blocking diode in each of the systems (wind turbines and solar panels) to prevent them from feeding each other. This is highly necessary even if we have only one device operating, as if the blocking diodes are not installed, the systems could discharge the batteries as long as no power is being generated.
Here is a video that Mike recorded of the operation of the system with a single solar panel mounted and no dummy load connected, you can also see that the battery is fully charged, so if you select the load of the same, the charge regulator switches back to the dummy loadwhich in this particular case is an open circuit:
For the purists, the next step in the assembly would be to encapsulate it all in a portable or compact system and add an inverter to be able to connect household appliances, or to place a car cigarette lighter connector to 12vIt's a matter of letting your imagination run wild.
What about you, do you want to become self-sufficient with these renewable energy systems?
Buy - Components to make a mixed charge controller
More information - How to make a homemade wind turbine, How to make a homemade photovoltaic solar panel
Source - MDpub