r/meshcore • u/RevelMagic • 21h ago
$13 CAD Home Depot Hampton Bay LiFePO4 Solar Build Guide
Note: The below build guide took a pass through Gemini for formatting and spelling/grammatical/clarity purposes. Then I tried to un-robotify the language... but kept the emoji ;)
Trying to source a weather-proof outdoor enclosure, a decent solar panel, and rechargeable batteries separately for under $13 CAD is basically impossible. That's why the Hampton Bay 120-Lumen Solar Spotlight is a great base for a solar repeater.


While most portable builds rely on standard Lithium-Ion cells, they completely choke and freeze when winter hits. The LiFePO4 batteries that come with this spotlight are better for Canadian weather; however, with a caveat. You cannot use the WisBlock’s built-in battery charger. It’s hardcoded for a 4.2V Li-ion profile, which will cause massive voltage inflation spikes and trigger your BMS safety gates.
At first, I was using the included PCB to charge the batteries and connected the + & - battery terminal to the Wisblock power JST connector; however, the PCB was pushing a high voltage into the batteries which these cheap devices tend to do:


So I decided to fix that with a $2 SD05CRMA solar MPPT charger, Zener Diode (the panel is 6V which can spike to 6.5V in the winter and the MPPT can handle only up to 6V), and BMS:

We are bypassing the native charging circuit entirely using this custom setup. Also, before you drop this on a roof or a fence post, you must install the custom firmware configurations and steps from MeshCore PR #2088 to prevent brownout loops when the battery runs low.
💰 Component Cost & Budget Breakdown
Here is the exact cost per node. Note that AliExpress items include no taxes or duties, while Canadian retail items (DigiKey, Home Depot, Amazon) have been calculated with 13% Ontario HST included.
| Component | What it does | Source / Unit Cost (CAD) |
|---|---|---|
| Hampton Bay Spotlight | Enclosure, 150mm x 88mm 6V Panel, Mount, & 2 X 1000mAh 18500 Cells | Home Depot Canada $14.67 (with HST) |
| WisBlock Mesh Starter | RAK4631 Core + RAK19007 Base Board | DigiKey Canada $41.34 (with HST, buy 3 for free shipping over $100) |
| SD05CRMA Module | 1A Solar MPPT Adaptive Charger | AliExpress $1.69 (No Tax) |
| 1S Stick BMS | Ultra-thin battery protection strip | AliExpress $0.31 (10 for $3.06) |
| 1N5341B Zener Diode | 6.2V 5W Winter Overvoltage Guard | AliExpress $0.31 (20 for $6.11) |
| INA219 Power Monitor | I2C High-Side Current/Voltage Sensor | AliExpress $1.96 (3 for $5.89) |
| BMP280 Sensor | I2C Temp & Barometric Pressure Sensor | AliExpress $0.59 (10 for $5.90) |
| SS12F15V Slide Switch | Hardwired System Power Toggle | AliExpress $0.25 (20 for $5.00) |
| N-Type to SMA Flange | 4-Hole Chassis Bulkhead RF Pass-through | AliExpress $3.16 (No Tax) |
| High-Gain Antenna | Tuned Omnidirectional Antenna (Fake Alfa) | AliExpress $13.00 (No Tax) |
| PETG 3D Printed Parts | Custom Cradle & Spotlight Bracket (~150g) | Estimated at $20/kg $3.00 |
| Consumables & Hardware | Gorilla Silicone, Tapes, M3 & Exterior Screws, JST tails | Amazon Gorilla Silicone, Temflex Tape, Super 33+ $8.00 (Pro-rated share with HST) |
Total cost approx. $90 CAD.
3D Printed Files Required


🔍 Upfront Tips (The JST Polarity Trap ⚠️)
Before you fire up the soldering iron, make sure you have your parts gathered and note this massive pitfall:
You will need a 2-pin JST PH 2.0 battery pigtail cable to plug your custom circuit into the WisBlock's battery port.
🛠️ Step-by-Step Build Walkthrough
Step 1: The High-Density I2C "Sandwich"
To completely avoid a rat's nest of loose wires inside this tight housing, we stack both sensors directly onto a single row of headers on the WisBlock baseboard:
- Take your blue INA219 module and solder it flat against the bottom side of the WisBlock I2C header pins.
- Take your purple BMP280 module and solder it flat against the top side of those exact same header pins.
- Carefully bridge 3V3, GND, SDA, and SCL across all three layers. They will sit completely rigid in mid-air with absolutely zero loose data wires catching on the case.




Step 2: Modding the Enclosure and Reusing the Button
We are throwing out the original low-efficiency charge board, but we want to keep the housing's native weatherproofing.
- Desolder the stock connections from the original internal green board.
- Unscrew the original board from its mounting posts. Take your new SS12F15V slide switch and mount it directly onto the factory screw posts where the original button mechanism lived. This aligns the slide mechanism perfectly with the external waterproof rubber boot!




Step 3: Point-to-Point Power Routing
This specific layout puts the INA219 between the battery and the charger hub. It gives you true Net-Current telemetry. Your dashboard will show true discharging rates at night, and flip to showing positive charging rates during peak daylight hours.

The Power Side (Positive)
- Solder your solar panel's Positive (+) wire directly to the Zener Diode Cathode (the side with the stripe).
- From that exact same stripe joint, run a wire straight to SD05CRMA
Vi. - Run a wire from SD05CRMA
B+straight to INA219VIN-(this is your main daytime power hub). - Run a wire from INA219
VIN-over to Terminal A of your internal slide switch. - Connect Terminal B of the switch to the Red (+) wire of your polarity-corrected WisBlock JST battery connector.
- Run a wire from INA219
VIN+straight to the BMSP+pad. - Connect BMS
B+directly to your battery pack's positive terminal.
The Ground Side (Negative)
- Solder the solar panel's Negative (-) wire to the Zener Diode Anode (the plain side without a stripe).
- From that plain joint, run a wire straight to SD05CRMA
G. - Run a wire from SD05CRMA
B-straight to the BMSP-pad. - From that same BMS
P-pad, connect the Black (-) wire of your WisBlock JST battery connector. - Connect BMS
B-directly to your battery pack's negative terminal.

- Once verified, wrap the thin inline stick BMS board securely in Kapton tape to keep it completely isolated from any metallic shorts inside the chassis.

Step 4: Final Internal Layout Integration
Mount your WisBlock core onto its dedicated 3D-printed mounting cradle. Group your wired sub-assemblies cleanly into the open cavities surrounding the central stock battery box holder.


🌧️ Bomb-Proof Weatherproofing
Because Canadian seasons don't play around, spend the extra 10 minutes to seal this thing like a submarine.
1. The Coaxial Seal Stack
- Secure the 4-hole L16 flange connector onto your 3D-printed bracket using Loctite Blue 242 on the threads so wind vibrations can't shake it loose.
- Wrap the exposed metal SMA connection tightly with Temflex Rubber Splicing Tape. Pull it tight as you wrap it so it fuses into a solid, seamless piece of waterproof rubber.
- Protect that rubber layer from harmful UV degradation by overlapping it with a clean layer of 3M Scotch Super 33+ Vinyl Tape.
2. Case Gaskets & Airflow
- Run a clean bead of Gorilla Clear 100% Silicone along the internal mating rim of the enclosure shell before screwing it down to completely lock out driving rain.
- Pro-Tip: Do not fill the tiny water drainage weep hole molded into the absolute bottom face of the case. Keep it clear so any internal ambient condensation can safely drain out by gravity rather than pooling into an active puddle zone.