Best Hardware for Fixed Repeaters
A fixed repeater node has one job: forward mesh packets reliably, indefinitely, with as little power consumption as possible. This page covers the hardware decisions that matter most for solar-powered or battery-backed repeater deployments.
The Core Decision: nRF52840 vs ESP32
For repeater use, the MCU platform is the single most important hardware choice. The nRF52840 (used in the RAK4631, T-Echo,RAK4631 and Station G2)T-Echo) consumes roughly 43 -orders 5xof magnitude less sleep power than the ESP32-S3 during sleep,S3, which is the state a repeater spends most of its time in. (Note: the Station G2 is an ESP32-S3 high-power base station, not an nRF52840 board - it is covered separately under base stations, not here.)
Power Draw Comparison by Board (Repeater Mode)
The figures below are estimates, not manufacturer-datasheet power tables. They assume a 5% active duty cycle and typical regulator/peripheral quiescent draw; real-world results vary with baseboard, firmware, mesh traffic, and radio settings. Datasheet anchor points are cited where available.
| Board | MCU | Active Current (mA) | Sleep Current (mA) | Avg Draw @ 1 tx/min (mA) | 18650 Runtime (hrs)* |
|---|---|---|---|---|---|
| RAK4631 (WisBlock) | nRF52840 | ~15 (RX; datasheet RX ~17, TX ~125 at 20 dBm) | 0. |
~2.5 (est.) | ~800+ (est.) |
| T-Echo | nRF52840 | ~18 (est.) | ~0.012 (est.; LILYGO publishes no power table) | ~3.0 (est.) | ~660 |
*18650 capacity assumed at 2500 mAh (a conservative, realistic usableusable-capacity capacity)planning figure; cells are commonly 2500-3500 mAh). Active time assumed at 5% duty cycle. Real-Runtime values are derived estimates, not datasheet specs - real-world results will vary based on mesh traffic, firmware version, and radio settings. (The Station G2 is omitted from this repeater table: it is an ESP32-S3 mains/PD-powered high-power base station, not a low-power solar-repeater candidate.)
Gold Standard: RAK4631 (RAK WisBlock)
The RAK4631 is the best board available for fixed repeater deployments. Its key advantages for repeater use:
82.0 µAdeepmodule sleep current (datasheet) - the radio and MCU together draw less than most voltage regulatorsleakleak; expect somewhat higher on a populated baseboard due to the baseboard regulator's quiescent current- Modular design - base board, core module, and optional IO modules are separate. The base board includes the battery management and charging circuit; you supply the battery.
- Industrial temperature range: -40°C to +85°C. (Standard ESP32 / ESP32-S3 parts are also rated -40°C
(vstoESP32's+85°C, so the MCU silicon is not the limiting factor; in practice the LiPo battery - typically rated ~0°C to +70°45°Ccommercialforrange)charging - sets the real-world thermal envelope for either platform.) - SX1262 radio with excellent receiver sensitivity: ~-137 dBm at
SF12/SF12 / 125 kHz bandwidth (the headline -148 dBm figure applies only at the narrowest bandwidth, not BW125) Crypto-gradeHardwarehardwarecryptographicsecurityacceleration viaARMthe Arm TrustZone CryptoCell-310 accelerator -relevantuseful for secure meshdeploymentsdeployments. (Note: this is a crypto accelerator, not Cortex-M33 TrustZone-M memory isolation; the nRF52840 is a Cortex-M4F.)- Excellent Meshtastic and MeshCore support - actively maintained firmware targets
RAK WisBlock Solar Repeater BOM
All prices below are approximate commodity / store prices as of 2026-06-08 and are volatile; verify against the RAK store and vendor listings before ordering. Present the total as an estimate range, not a fixed quote.
| Component | Part | Est. Cost (as of 2026-06-08) |
|---|---|---|
| Core module | RAK4631 (nRF52840 + SX1262) | ~$ |
| Base board | RAK19007 ($9.99) or RAK19003 (mini) | $ |
| Solar charge module | $8 - $15 | |
| LiPo battery | 3.7V 3000 - 5000 mAh flat pack | $8 - $15 |
| Solar panel | 5V 1W - 2W panel (60mm × 110mm |
$5 - $12 |
| Antenna | 915 MHz fiberglass or tuned whip | $8 - $25 |
| Enclosure | IP67 ABS box (100×68×50mm) | $6 - $12 (approximate commodity price) |
| Total | ~$ |
Alternative: T-Echo as a Repeater
The T-Echo makes an excellent fixed repeater when you want a complete ready-to-flash unit without assembly. It uses the same nRF52840 platform as the RAK4631 and achieves similar sleep power. Tradeoffs versus the WisBlock approach:
- The T-Echo includes a 1.54" e-paper display (useful for diagnostics; wastes a tiny amount of power even off)
- Battery capacity is limited to the small internal flat LiPo
that(thefitsbundledinsidecell-istypicallycommonly600cited-around1200~850mAh,mAh and is not user-removable; an optional ~2400 mAh expansion accessory exists), vs the large external packs usable withWisBlockWisBlock. Verify the bundled cell capacity against the current LILYGO listing. - GPS can be disabled in firmware to save the
~10 mAcurrent the Quectel L76K draws when active (~10 mA active; see the L76K datasheet) - important for pure repeater duty - The
rubberantennaduckuses a U.FL/IPEX connector (sources conflict on SMAantennavs U.FL - verify against your unit) and is easily replaced with a higher-gain antenna for elevated installs
Why Not Just Use an ESP32 Board?
ESP32 boards like the T-Beam Supreme are perfectly capable of repeater duty with AC power (plugged in). If you have mains power at the repeater site, the ESP32's higher power draw is irrelevant and its better WiFi connectivity can be useful for firmware OTA updates and gateway bridging. However:
- A solar system sized for an ESP32 repeater costs 3 - 4x more than one for a WisBlock, because the panel and battery must be larger
InForcloudyaconditionsgivenorsmallshorter winter days,panel/battery, an ESP32solarrepeaterwillisfailmorewherelikely to run out of charge in cloudy or short-day conditions than an nRF52840 system. (A properly sized ESP32 systemsurvivescan survive winter, and an undersized nRF52840 one can fail - the deciding variable is panel/battery sizing, not the MCU alone.)- The practical indoor/mains-powered exception: T-Beam Supreme repeaters work well in building deployments where power is available and WiFi/BLE features are useful
Antenna Recommendations for Fixed Repeaters
A fixed repeater benefits more from antenna quality than almost any other hardware upgrade. Typical improvements from the standard rubber duck to a quality fiberglass antenna range from +3 dB to +6 dB gain, which roughly doubles to quadruples effective range in ideal (free-space) conditions. In real-world obstructed paths (path-loss exponent ~2.7-4) the improvement is typically less.
| Antenna Type | Gain | Use Case | Notes |
|---|---|---|---|
| Rubber duck (included) | 1 - 2 dBi (nominal) | Basic testing only | Adequate for indoor, room-scale use |
| Tuned whip (λ/4 |
~ |
Outdoor mounted, no cable run | DIY option; cheap and |
| Fiberglass 3 dBi (e.g., Taoglas OMB. |
3 dBi | Pole-mounted outdoor repeater | Good all-around choice |
| Fiberglass 5 - 6 dBi collinear ( |
5 - 6 dBi | Hilltop / elevated repeater | Narrower vertical beam; best at elevation |
| Yagi directional (verify gain on datasheet) | 10 - 14 dBi | Point-to-point links | Only useful for specific directional paths |
FCC note: Antennas above 6 dBi gain require reducing conducted power dB-for-dB under FCC Part 15.247(b)(4) (subject to the fixed point-to-point provisions of 15.247(c)). Plan your link budget as EIRP = conducted power + antenna gain - feedline loss, and keep within the applicable limits for your operating authority.