The building of a charge controller.



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I had one of those weeks where I either couldn't work out in the garage because it was too late to make much noise, or I was looking after my daughter. So I spent a few late nights looking for a charge controller so that I don't fry my batteries by over charging them. That's when I came accross the website of a guy that had built his own. This was just what I needed, so I hatched a plan to build one.

For the time being I'm going to use the controller as it is, but I have some ideas to increase the capabilities of the charge controller and add some new features.

As I want to mill and drill the board with my CNC router, the best place for me to start was to design a layout in CAD. Once I had the design layed out, I exported the layers containing the traces and holes as DXF files. These could then be converted to gcode by importing directly into Mach3. The picture shows a test piece cut on an old board, hence the big hole in it. The test was just to get an idea of the depth and trace width I needed. The other picture shows the finished board. After I'd cut the final circuit board I noticed that I'd missed out a resistor and 4 holes for a header strip. I can manually drill the holes to add these components to the board, so all is not lost. I need to amend the CAD file for future use. I hope to make all the files available here once the board has been tested.

The main board is 3" square and will have cables attaching it to a few smaller boards for the LCD, control buttons, status LEDs and load switching circuit.

To get some practical programming experience using the PICAXE chip, I made a circuit to indicate wind speed from a small home made anemometer. The circuit will basically read pulses generated from a reed switch and magnet attached to the body of the anemometer. This is just a simple RPM counter, but will be calibrated to calculate wind speed in MPH. The anemometer assembly is almost finished. I'll put some picture up soon.

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The CAD layout.

The test run.

The final run.

Anemometer test circuit.