Keep Your Device Powered for the Whole Op

Why this matters

Every hardware op lives or dies on power. A Pi 4B at idle draws ~3W; with Wi-Fi attacks, ~7W. A 20,000 mAh USB battery (74 Wh) gives ~10 hours at full load. PoE++ delivers 60W indefinitely on PoE-capable switches. USB-PD from a wall charger is the holy grail: indefinite, drawn from infrastructure that's already there.

Demo

Op: 36 hours. Avg draw: 4W. Energy: 144 Wh. 20,000 mAh @ 5V = 100 Wh (short); 2× chained = 200 Wh (works with margin). Or: hide inside an always-powered device (UPS, printer) → unlimited.

Try it yourself

1. Measure idle and peak draw of your Pi with a USB power meter (~$10). Don't trust the datasheet.
2. Plan three ops: (a) 4h covert, (b) 36h overnight, (c) 30d unattended. Calculate battery + form factor.
3. Identify three 'always-on' power sources in a typical office. Note risks of each.
4. Build a 'kill on low battery' systemd unit that wipes ephemeral data when battery <15%.

References

• USB-PD 3.1 spec
• Pi power consumption table
• IEEE 802.3bt (PoE++)