W4BOC-1 APRS digipeater/iGate goes permanent on Stone Mountain
Building on the results of the March 2026 county-wide APRS coverage drill, DeKalb ARES completed a permanent deployment of W4BOC-1 — the group's APRS digipeater and iGate — at the Stone Mountain summit. Operating on the national APRS frequency 144.390 MHz, it extends reliable automatic position reporting and short-messaging coverage across DeKalb County and beyond. The deployment also brought a substantial power-system upgrade benefiting every service on the Stone Mountain rack.
Power-system upgrade
The W4BOC-1 deployment was paired with a comprehensive overhaul of the backup power feeding the entire Stone Mountain communications rack — the 146.760 repeater, the VARA FM Winlink station, and the new APRS digipeater/iGate all share the same DC supply.
What’s in the rack now
- Battery: Ecoworthy 280 Ah LiFePO4 pack with an integrated JBD/Xiaoxiang Battery Management System (cell balancing, over-/ under-voltage, over-current, temperature protection)
- Charger: Victron Blue Smart IP22 12/30 (12 V, 30 A,
multi-stage with
STORAGEfloat-maintenance mode for batteries at full charge) - Topology: while mains is up, the charger feeds the load
directly — the battery sits in
STORAGEmode and only carries the load if mains drops. At a typical ~60 W combined draw across the three radios, the battery alone would run the rack for ~2 days off a full charge.
Live telemetry, publicly visible
Both the BMS and the charger are queried via Bluetooth LE by a small Windows app running on the rack PC. The app:
- Stores everything in a local time-series database (week-scale charts on a built-in web dashboard)
- Emails alerts when SoC drops below thresholds, mains is lost for more than 45 min, cells get out of balance, the charger errors, or temperature goes out of range
- Broadcasts APRS telemetry every few minutes, both via RF and APRS-IS, so the rack’s electrical health is visible on aprs.fi as a permanent record
You can see it live on the public station page:
→ aprs.fi/info/a/W4BOC-1 (Telemetry tab)
The five APRS telemetry channels published:
| Ch | Reading | Unit |
|---|---|---|
| 1 | Battery pack voltage (BMS) | V |
| 2 | Battery pack current — signed; +charging, −discharging | A |
| 3 | State of charge | % |
| 4 | Battery temperature | °C |
| 5 | Charger output current | A |
Plus eight binary “healthy” bits covering BMS charge/discharge FETs, mains presence, BMS heartbeat, BMS protections, charger error state, and SoC thresholds. A glance at the latest packet on aprs.fi tells you whether the rack is happy without needing remote-desktop access.
Why it matters
Three things this upgrade buys us beyond just “the lights stay on”:
- Single backup for the whole rack. Before, each radio had its own ad-hoc power arrangement. The new setup is one battery, one charger, one set of fused distribution rails — easier to maintain, easier to diagnose, easier to carry forward when individual radios are swapped.
- Operational visibility for everyone, not just the sysop. The APRS telemetry is publicly broadcast — any DKARES member can confirm the Stone Mountain rack is healthy in 10 seconds via aprs.fi. During an activation that’s the difference between guessing and knowing.
- Alerting that catches problems before they become outages. Email alerts on rapid SoC drop, prolonged mains loss, cell imbalance, and charger errors — so a developing problem (a failing charger, a single cell drifting) gets attention while there’s still time to act, not after the rack has gone dark.
The package — battery, charger, monitoring app, dashboard, alerting, APRS broadcast — runs unattended and self-restarts after power blips via Windows auto-login and a startup-folder launcher.