Solar Buoy Micro Mesh Node

Step 1: Solar Wiring & Enclosure Base Modification

Wire the integrated mini solar cell array to the input terminals of the MPPT charger module (square board). Drill a 1/4" hole through the bottom center of the clear buoy light cylinder. Pass an IPEX/U.FL to SMA female bulkhead pigtail (minimum 6" cable length with pre-applied heat shrink) through the base hole.

Secure the bulkhead with a toothed lockwasher and blue Threadlocker on the threads, applying clear silicone sealant inside and out to guarantee a weatherproof seal.

Figure 1: Mini solar array wired to the square MPPT charger module and round 1S BMS board. (Click image to enlarge)

Figure 2: SMA bulkhead connector installed through the 1/4" hole at the bottom of the acrylic cylinder with silicone sealant and hardware. (Click image to enlarge)

Step 2: Coaxial Strain Relief & Core Cushioning

Trim the original donor buoy foam block down to size and pierce a pass-through hole through its center. Route the pigtail cable up through the trimmed foam block.

Ensure the foam height is trimmed just tall enough to cushion the internal core assembly without placing a tight bend radius on the coaxial cable exiting the SMA connector base.

Figure 3: Pigtail passing vertically through the clear cylinder. (Click image to enlarge)

Figure 4: Top-down view showing the trimmed foam block cushioning the coaxial feedthrough. (Click image to enlarge)

Figure 5: Side profile of the foam block positioned at the base of the cylinder. (Click image to enlarge)

Step 3: Solar & Power Circuit Insulation

Connect the integrated single-cell battery through the round 1S BMS module for cell protection. Encapsulate both the BMS and MPPT boards in heatshrink tubing before final placement to prevent short circuits against adjacent components inside the compact tube.

Install an inline SPST slide switch on the hot leg of the battery output on the upper deck to act as a main power cutoff.

Step 4: Microcontroller Header Trimming & Logic Deck Isolation

Clip the bottom pins off the radio module board and trim a small portion off the Seeed Studio XIAO’s pre-attached header pins to allow the two boards to mate as flush as possible. Apply a layer of clear silicone over the clipped pin stubs on the bottom of the radio board to fully insulate the exposed metal and eliminate short risks.

Plug the two boards together tightly to minimize total vertical height inside the narrow cylinder. Snap the U.FL antenna connector onto the XIAO board, then anchor it with a dab of clear silicone sealant (or hot glue) to prevent vibration-induced disconnects.

Figure 6: Seeed Studio XIAO board plugged into the radio board with flexible PCB antenna attached. (Click image to enlarge)

Figure 7: Trimmed header pins allowing an ultra-compact, flush fit between boards. (Click image to enlarge)

Figure 8: Profile view of the completed logic stack before final assembly. (Click image to enlarge)

Step 5: Top Cap & Weatherproof Hanging Assembly

Drill a 1/4" hole through the apex of the clear threaded top cap. Install the stainless steel eyebolt using a washer, lockwasher, nut, and blue Threadlocker on the hardware threads.

Seal the eyebolt assembly thoroughly inside and out with clear silicone sealant. Re-lubricate and seal the main threads before closing up the housing.

Figure 9: Weatherproofed top cap assembly with stainless steel hanging loop. (Click image to enlarge)

Figure 10: Underside view of the top cap showing the secured hardware sealed with silicone. (Click image to enlarge)

Step 6: Enclosure Integration & Switch Placement

Slide the entire core stack into the clear cylinder, ensuring all components sit securely without pinching wires. Position the SPST power switch right at the top of the opening for easy access when the cap is unscrewed.

Figure 11: Core assembly inserted into housing, showing upper switch placement. (Click image to enlarge)

Figure 12: Top-down view showing the SPST switch and XIAO USB-C port easily accessible beneath the top cap. (Click image to enlarge)

Step 7: Flashing, Safety Checks & Final Deployment

Update Bootloader: Double-tap the reset button on the XIAO nRF52840 board to put it into bootloader mode, then drag and drop the .uf2 file from the Adafruit_nRF52_Bootloader_OTAFIX repository onto the mounted drive.

Flash Firmware: Flash the node with the ZephCore MeshCore port before final enclosure sealing.

Verify solar charging and radio transmission, screw on the top cap, and suspend the completed node via the stainless steel top loop.

Figure 13: The completed Solar Buoy Micro Mesh Node ready for field deployment. (Click image to enlarge)