Procedure for constructing a solar charger for a 24V 3D printers (Cubify, Shapeoko, Rigidbot etc.)
- Connect six Robots Everywhere modular solar cells in a 3x2 configuration, so as to get 27 volt of nominal output. This is done by connecting 2 cells in parallel, repeating the process 3 times, and connecting the 3 pairs in series. If you cannot get our panels, a 9V panel will do.
- With a scalpel, carefully slice the printer's powersupply wire (from the powersupply to the printer, not from the powersupply to 110V) open, without disturbing the leads, for a length of 2 inches / 5 centimeters.
- If the + and - leads are coaxial: Move away the external lead so as to expose the internal insulator. At the center, slice it open lengthwise with the scalpel. Solder a small length of wire, color according to polarity, to the now-exposed wire. Insulate with tape. Solder another length of wire, color according to polarity, to the external conductor. Apply tape.
- If the + and - leads are parallel: At one end of the 5cm length, carefully open the insulation on the positive lead. Solder wire as above. Apply tape. At the other end of the 5cm length, repeat the process with the negative lead.
- Now you can inject 24VDC into the printer. The power supply's DC side capacitors and zener diodes will do the voltage regulation for you, as long as you keep the input voltage to reasonable levels.
- Connect two 12VDC batteries in series (connect one battery's + lead to the other's - lead; only do this for one lead, obviously!). Now you will have a "global" + lead, and a "global" - lead. To them, connect the solar panels, + to + and - to -. This last connection should use a long and thin wire (I recommend network cable internals) as you will need to move the solar panels.
- Connect two wires, colored according to polarity, to the "global" battery leads. Make sure the positive wire of this last pair is easy to connect and disconnect; or, if you have one, add a toggle switch (A house light switch will do). To the other end of the pair, connect the two short wires that you put on the powersupply, again according to polarity.
- If you have a voltmeter, put it in Volts mode, and connect it to the "global" battery leads. Voltages will fluctuate, but anything between 20 and 30 is normal. If less, do not try to print. If more, you have invented perpetual motion, because the panels don't give out that much.
- To balance the batteries, disconnect them from the circuit, connect them in parallel (+ to + and - to - both leads) and leave them alone for 30~60 minutes.
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