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, and Station G2) consumes roughly 4 - 5x less power than the ESP32-S3 during sleep, which is the state a repeater spends most of its time in.

Power Draw Comparison by Board (Repeater Mode)

*18650 capacity assumed at 2500 mAh (realistic usable capacity). Active time assumed at 5% duty cycle. Real-world results will vary based on mesh traffic, firmware version, and radio settings.

Gold Standard: RAK4631 (RAK WisBlock)

The RAK4631 is the best board available for fixed repeater deployments. Its key advantages for repeater use:

• 8 µA deep sleep current - the radio and MCU together draw less than most voltage regulators leak
• 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 (vs ESP32's 0°C to +70°C commercial range)
• SX1262 radio with excellent receiver sensitivity: -137 dBm at SF12/125 kHz
• Crypto-grade hardware security via ARM TrustZone - relevant for secure mesh deployments
• Excellent Meshtastic and MeshCore support - actively maintained firmware targets

RAK WisBlock Solar Repeater BOM

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 display (useful for diagnostics; wastes a tiny amount of power even off)
• Battery capacity is limited to the flat LiPo that fits inside - typically 600 - 1200 mAh, vs the large external packs usable with WisBlock
• GPS can be disabled in firmware to save the ~10 mA the L76K draws when active - important for pure repeater duty
• The rubber duck SMA antenna 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
• In cloudy conditions or shorter winter days, an ESP32 solar repeater will fail where an nRF52840 system survives
• 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 conditions.