Mains Power for Permanent Installations
Mains Power for Permanent Installations
Where mains (AC grid) power is available, it is almost always preferable to solar for permanent installations. Mains power is reliable, provides essentially unlimited energy, eliminates battery degradation concerns, and simplifies the build significantly.
When to Use Mains Power
- Rooftop or building-mounted nodes where a power run is feasible
- Nodes at locations with existing power (communications towers, buildings, facilities)
- High-power nodes like the Station G2 (requires 15V PD
—- impractical with solar) - Room Server nodes that are expected to be always-on for message storage
Power Supply Requirements by Device
| Device | Input | Power Supply Needed |
|---|---|---|
| Heltec V3, V4 | 5V USB-C | Any 5V USB-C charger, minimum 1A |
| LilyGo T-Beam, T-Deck | 5V USB-C or Micro USB | Any 5V USB charger, minimum 1A |
| RAK WisBlock (RAK19007) | 5V USB or battery | 5V USB-A charger or 5V regulated supply |
| Station G2 | 15V USB-C PD | USB-C PD charger capable of 15V/2A (30W minimum) |
| Any node with LiPo | Battery + charger | Power the charger circuit; see device documentation |
Station G2 Power Requirements
The Station G2 requires 15V USB-C Power Delivery. This is a specific PD negotiation —- the charger must support 15V PD output, not just 5V. Compatible chargers include:
- Most 65W+ USB-C laptop chargers (verify 15V output in spec sheet)
- Anker 65W or 90W USB-C GaN chargers
- Any charger explicitly listing "15V/2A" or "15V/3A" in its PD output specs
A 5V USB charger plugged into the Station G2 will not provide enough power. The device may appear to power on but will behave erratically or fail to transmit at full power.
Battery Backup for Mains Installations
For mission-critical nodes on mains power, a battery backup (UPS function) maintains operation during power outages. Options:
- Small UPS: A compact DC UPS module (available from AliExpress for $
10–10 - $20) passes through 5V USB power and switches to battery automatically on outage. Battery runtime of a few hours is typical for small units. - Battery + charge controller: Keep a LiPo or 18650 connected to the
node’node's battery input. Most boards with JST battery connectors will charge the battery from USB and run from battery when USB power is removed—- providing automatic failover with no additional hardware. - Full UPS: For the Station G2 and other high-power nodes, a proper UPS with 15V PD output is required. These are less common but available from server hardware suppliers.
Weatherproofing Mains-Powered Outdoor Nodes
If the node is outdoors on mains power, weatherproofing requirements are the same as for solar nodes:
- Use an IP65+ enclosure
- Route mains wiring through appropriate weatherproof conduit
- Use a weatherproof outdoor power outlet or a sealed junction box for the power entry
- Keep the power supply (transformer/adapter) inside the weatherproof enclosure or in a separately housed waterproof enclosure
- If using a standard USB charger adapter, note that most USB chargers are not rated for outdoor use
—- enclose them in an additional weatherproof housing or use an industrial-rated outdoor power supply
Cable Run Considerations
For nodes mounted at height (rooftop, tower, pole), the cable run from power to the node may be significant. At 5V, voltage drop over long cables is a real concern:
| Cable Run | Cable Gauge | Voltage Drop at 500mA | Action |
|---|---|---|---|
| <5m | 24 AWG USB cable | Negligible | Standard USB cable fine |
| 22 AWG or better | 0. | Use thicker cable or boost supply voltage | |
| >15m | 18 AWG or higher, or 12V supply | Significant with 5V | Run 12V and use a 12V→5V DC-DC converter at the node |
For long cable runs, running 12V DC (lower current for same power, less voltage drop) and using a small buck converter at the node end is more efficient than running 5V USB over a long distance.
Lightning Protection for Mains-Powered Sites
Mains-powered outdoor nodes are vulnerable to both direct lightning strikes and power line surges. Protect with:
- A quality surge protector or transient voltage suppressor (TVS) on the mains input
- A DC-grounded lightning arrestor on the antenna feedline
- Ground the enclosure and mast to an earth ground rod
- Consider a whole-circuit surge protector at the breaker panel for critical sites