Intro: Using a Voltaic Solar Panel for an EL Wire Logo
Step 1: The Basics
The Voltaic Systems 6 Watt kit comes with their 6 Watt Panel and their V15 Rechargeable Battery, plus a variety of cables and connectors. The panel charges the battery, which functions like a typical external battery pack common these days with smartphones and mobile devices. The output of the battery is through a standard USB plug.
The EL Wire logo is powered by an inverter that runs off of (2) AA batteries. Since the inverter is necessary for the operation of the logo, it needs to be kept. But the batteries could be replaced by the power from the V15 Rechargeable Battery.
Step 2: Get Adjusted
Since the outputs of the 6 Watt Panel and the V15 Rechargeable Battery are 6 volts, and the input into the EL Wire inverter is 3 volts (2 AA batteries @ 1.5 volts each), it is necessary to convert the voltage.
The LM2596 DC-DC Buck Converter is the perfect solution here! It features a trim-pot adjustment for the output, 4.5-40 volt input, and 1.5-35 volt output. It is low-cost, which is ideal, and small form factor. In fact, after a little bit of investigation, I determined that, if I removed the batteries and part of the spring terminals, there was a perfect amount of room inside the EL Wire power pack for the LM2596!
Step 3: Start Wiring
Once the spring terminal of the battery pack was removed, there was a small hole in the base of the pack that happened to fit the wire perfectly. The wire, in this case, is a standard USB cable with a standard USB plug on one end (that will eventually plug into the V15 Rechargeable Battery.
Pull the wire through and trim back the outer insulation. You will need to separate out the woven jacket around the wires, as well as to trim off the foil shield around the wires. After that, separate out the (4) different wires.
Each wire has a function, and for our purposes, all we care about are the power wires - Red (+ voltage) and Black (Ground). You can ignore the Green and White wires. I chose to trim them off and get them out of my way.
Step 4: Solder and Adjust
The LM2596 board is clearly marked for + and - connections in and out. The red wire from the input is wired to + in, and the black wire from the input is wired to the - in. Another set of wires is connected to the + and - outputs.
Once all of the solder connections are made, a meter is connected to the output, and the trim pot on the LM2596 is adjusted until the output voltage on the meter measures 3.0 volts (to match the original AA batteries).
The output wires from the LM2596 were then soldered on to the inverter's circuit board, overlapping the original + and - inputs from the battery terminal.
Step 5: Setup the Solar!
Now it's time to feed the beast.
The 6 Watt Solar Panel was placed in the front window at Omaha Maker Group. It is behind a screen, for security. We would hate for our new Voltaic Systems panel to grow feet! Luckily, Voltaic Systems provides a long connection cable between the panel and the battery.
As soon as I plugged in the battery, the front LEDs lit up, showing that we were getting a good solid input from the panel. The front of the Makerspace gets direct sun for at least 6 hours a day.
The final step is to plug the USB plug from our newly-wired inverter directly into the V15 Rechargeable Battery.
Step 6: Finished!
With the 6 hours of direct sun, plus another 6+ hours of daylight, the Voltaic Systems 6 Watt panel gives the V15 Rechargeable Battery a good, solid charge everyday. This allows us to power our EL Wire Logo for around 4 hours each night, guiding our guests to our front door!