LiFePO4 + Solar 1W Repeater – Texas Heat Edition
This is an outdoor solar 1W MeshCore repeater built for hot, humid Texas weather. It uses a RAK 1W board, a LiFePO4 battery, an LFP-capable solar charger, a 5V regulator, a supercap-backed power rail, and sensors for power telemetry plus internal and external environmental conditions.
The goal is long unattended runtime in Texas heat and humidity, using LiFePO4 chemistry, temperature-protected charging, pressure equalization, drainage, and moisture control to keep the node reliable outdoors.
The external SHT45 temperature and humidity sensor sits in a sintered metal enclosure outside the box, while the BME680 monitors internal enclosure conditions.
The BLE antenna also makes service easier: we tested re-flashing at ~2.5 kbps from inside the house, even from a different floor, without opening the enclosure.
Telemetry
Telemetry is handled by a separate gate node running MeshCoreGate on a Heltec v4. The same approach can also be used on a Heltec V3 or a similar ESP32 LoRa + WiFi board.
The gate node polls repeaters over LoRa, then exposes the readings over local WiFi as a Prometheus-compatible HTTP endpoint. From there, the data can be pulled into Prometheus, Grafana, Home Assistant, or anything else that can scrape metrics.
For a cleaner telemetry setup, the repeater can also be flashed with this open MeshCore PR. It lets telemetry replies use direct low-power responses back to the gate node instead of flooding the public mesh, which also reduces impact on the solar node battery. The poll interval is once every 5 minutes.
Parts List
- LoRa board: RAK 1W / RAK3401, jumper set to external 5V
- Antenna: Fairview FM51OM1016 8dbi
- Battery: LiFePO4 26700 5000mAh
- Charger: Adafruit bq25185 solar charger, configured for LFP
- 5V regulator: Pololu S9V11F5
- Supercap: 15F KYOCERA AVX supercapacitor
- Current / voltage monitor: Adafruit INA3221
- Internal enclosure sensor: BME680
- External temp / humidity sensor: SHT45 in sintered enclosure
- RTC timer: Amazon module*
- Battery thermistor: NTCLE428E3103F524A
- BLE antenna: Amazon antenna*
- USB-C bulkhead: Amazon*
- Side switch: APEM
- Heatsink: Adafruit
- Enclosure: Amazon*
- Battery mounting: Amazon* + foam layer*
- Pressure valve: Amazon*
- Drain hole protection: rubber guard* + nylon filter*
- Solar panel: Voltaic 6V / 10W
The Adafruit INA3221 variant needs compatible I2C address handling; compile firmware with 0x40/0x41 support for INA3221.
5V Rail Filter
- 1x 1000uF organic cap: 16SVPF1000M
- 1x 100uF tantalum cap: 199D107X9010E6V1
- 1x 10uF ceramic cap: FG20X7R1H106KRT00
- 1x 0.1uF ceramic cap: K104K15X7RF53L2
- 1x ferrite bead: 28L0138-70R-10