This is our robot battery charger

Step 1: ​Robot Battery Charger Step 1

Create 3D model using 3DS Max 2016 (or other 3D modeling software) Dimensions of port (space between two prongs is 1mm):

Step 2: ​Robot Battery Charger Step 2:

Convert file to STL (stereolitho) format and transport to 3D printer computer. Print the file on high infil setting (90-100%) and high detail in general. The printer may fill the 1mm gap between the prongs, so you can saw through the gap with a thin saw as the support plastic is not very difficult to cut through. Plug it in and out of the port a few times in order to smooth the process and then use a thin file in order to smooth out the inside if needed.

Step 3: ​Robot Battery Charger Step 3:

Use contact pads on the insides of the prongs in order to form the connection between the conductors when they are plugged in. Connect the back sides of the contact pads to wires (they often have a loop on the back to put wires through) to link them to the rest of the circuit later.

Step 4: USB Charging Circuit Step 1:

Get the spool of 22 gauge wire, cut into 4 pieces, each about 4 inches long. Feel free to cut longer for more reach on either end, ours are about 6-8 inches each.

Step 5: USB Charging Circuit Step 2:

Strip the wires at certain points. In order to strip them, it is nearly impossible to use a wire stripper due to how thin it is. We would recommend stripping them using the flat side of an xacto razor and scraping it off each side. Strip the insulation off the last centimeter or so of wire on each wire. Then, strip two centimeter long sections in the middle of two of the wires about an inch apart. On the other two wires, strip one section about 2 inches off the end.

Step 6: USB Charging Circuit Step 3:

In order to create the circuit, we would recommend taping the wires down on a piece of paper and taping the joints. This way you can edit the circuit easily and solder it later if you want to. Place the two wires with four stripped sections parallel to each other with 2-3 inches of space between them. Attach the resistors to each of the four stripped patches in the middle of these wires as shown in the diagram above. Attach the 75k resistor to the upper left, the 43.2k to the bottom left, and the two 49.9k resistors to the two right sections. Then, attach one of the remaining wires to the other side of the upper left 75k resistor, and the other wire to the 49.9k resistor in the upper right as shown above. Then, cross each of these wires over each other (without making contact on stripped sections) and wrap the stripped section in the middle around the resistor in the opposite corner. The wire starting at the 49.9k resistor in the upper right wraps around the 43.2k resistor. The wire starting at the 75k resistor in the upper left wraps around the 49.9k resistor in the bottom right. Both of these wires should then line up at the bottom of the circuit parallel to the other two wires next to them, as shown in the picture above.

Step 7: USB Charging Circuit Step 4:

If you want to, solder the joints together in order to make the circuit more stable and reliable.

Step 8: USB Charging Circuit Step 5:

Connect the output wires to the USB motherboard slot shown below. If you want to use both USB ports, attach another small wire onto the end of each wire and put them into the other side as well.

Add the solar panel and connect everything else:

Step 9:

Connect the two solar panel +/- wires to the +/- sides on the battery. Connect the +/- sides on the battery to the +/- input of the voltage regulator. Connect the +/- or +5V and GND wires at the top of the circuit and the +/- wires from the robot battery connector to the voltage regulator +/- output (set regulator to step down from 12V to 5V if needed).

Step 10: Graph

The graph was running for about an hour with a fan motor, amperage sensor, and voltage sensor wired in parallel, and the voltage stayed at a constant 1.5, and the amperage stayed around 1.25

Red line graph collects data on the voltage the solar panel was collecting Blue line graph collects data on the amperage of the solar panel There are jumps in the graph, which can most likely because of people walking in front of the solar panel and blocking the sunlight The graph is steady throughout most of the chart, but the dips in the graph could be because of passing clouds

Devices needed to collect data: High Current sensor Labquest 30-V Voltage Probe Alligator clamps

Step 11: Mobile Case Parameters:

The dimensions of the box are: 14in x 27in x 7in

Step 12: Mobile Case Step 1:

On one side of the 14in plywood plank cut a hole big enough for the handle to fit inside it, and seal any gaps with hot glue or strong tape.

Step 13: Mobile Case Step 2:

Make two more holes big enough for your wheels to fit in and drill anywhere needed to support the wheels

Step 14: Mobile Case Step 3:

On one side of the 27in plywood but two holes big enough for a usb to fit inside it, and another hole big enough for a female port to fit through

Step 15: Mobile Case Step 4:

Put all the parts of the boxes together with screws, and drill any other screw needed to hold both the handle and the wheels

<p>Cool charger design. Great intro project for robotics students.</p>

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