Emergency Internet Go-Bag — Keep Wi-Fi Alive (Router + LTE/Starlink)
A compact, battery-powered comms kit for outages, shoots, events, and the apocalypse your router fantasizes about.
What You’re Building
Goal: Stable internet + Wi-Fi during power loss or in the wild. Prioritize DC efficiency for routers/APs/PoE; add a small inverter only if you must power AC-only gear (e.g., stock Starlink PSU).
- LTE/5G router or dual-WAN router
- Wi-Fi AP (PoE or DC barrel)
- Optional: Starlink (Standard or Mini)
24V 50Ah LiFePO₄ ≈ 1.28 kWh raw → ~1.15 kWh usable (90% DoD × 90% eff).
~18 W LTE AP ≈ 64 h; ~40–60 W Starlink ≈ 19–28 h (loads vary).
- Fuse near battery (+) and on each branch.
- Label AC IN vs AC OUT if you add an inverter.
- Dry, ventilated, upright. No house backfeed nonsense.
Parts (Tight List)
- Battery: 24V 50Ah LiFePO₄ (BMS inside) + strap
- DC buck: 24→12V, 20–30A adjustable (volt/amp display nice)
- 12V fuse block: Blade-style for branch circuits (5–15A)
- PoE: 48/52V PoE injector or PoE switch matching your AP
- Router: Dual-WAN (e.g., LTE + WAN), health-check failover
- Optional inverter: Pure-sine 300–600W for AC-only gear
- Hardware: 2 AWG (short runs) to main fuse, 8–12 AWG to buck, ring lugs, heat-shrink, glands
- Enclosure: Padded backpack or Pelican-style case, vents
Connectors: Anderson SB50 or Powerpole bus is tidy for field swaps.
PoE Power Map (for your AP/CPE)
| Standard | PSE Budget | PD Guaranteed | Notes |
|---|---|---|---|
| 802.3af (PoE) | 15.4 W | 12.95 W | 2-pair power |
| 802.3at (PoE+) | 30 W | 25.5 W | 2-pair power |
| 802.3bt (PoE++) | 60–90 W | ~51–71 W | 4-pair power |
Check your device label/datasheet to match injector/switch class.
Wiring (DC-First, Inverter Optional)
24V Batt + -> 40–60A main fuse -> 24→12V Buck (20–30A) -> 12V Fuse Block -> [Router, AP/PoE, USB-C PD]
24V Batt − -------------------------------------------------------------> Common − return
Optional AC path (if needed for Starlink Standard PSU):
24V Batt + -> 80–100A ANL/Class-T -> 300–600W Inverter -> Starlink PSU (AC)
24V Batt − ---------------------------------------------> Inverter −
- Fuse near battery: mount the main DC fuse as close as practicable to the battery positive.
- Branch fusing: 5–15A per 12V accessory; size to wire and device.
- Labeling: WAN1 (Starlink), WAN2 (LTE). Put your AP/PoE draw on a dedicated fused branch.
Build Steps (Condensed)
- Strap battery. Install main fuse at + battery, then run to buck input.
- Set buck to ~12.2–12.6 V under load. Feed a fused 12V block.
- Router/AP: power from 12V (barrel) or via a PoE injector/switch (48/52V).
- Optional inverter: wire via its own fuse if you must power AC gear.
- Dress, label, strain-relief. Close case; ensure vents/fans are clear.
Network Setup (Failover that Actually Fails Over)
- Dual-WAN: WAN1 = Starlink (or fiber), WAN2 = LTE/5G.
- Enable health checks (DNS pings or HTTP probes) and auto-failover.
- QoS: prioritize voice/streaming; rate-limit big updates on LTE.
- Optional: SSID “Go-Bag” and a hidden admin SSID with strong passphrases.
Record AP/Router login on a card in the lid. Keep SIM tool + spare nano-SIM.
Runtime Cheats
- LTE AP ~18 W → ~64 h
- Router + AP ~25 W → ~46 h
- Starlink Std 40–60 W → ~19–28 h
- Laptop charging + AP ~60–80 W → ~14–17 h
Assumes ~1.15 kWh usable (90% DoD × 90% eff). Actual varies.
Starlink Notes
- Standard/Actuated: ~50–75 W avg, ~20 W idle (official).
- Mini: ~20–40 W typical, USB-C PD supply (high-W PD required).
- Disable snow-melt & “performance” modes to save power.
Don’t Do This
- No unfused battery leads. Ever.
- No backfeeding buildings. Use only device outlets.
- No mystery PoE voltages: match 802.3 class or use the maker’s injector.
Go-Bag Quick Start (Stick Inside Lid)
24 V LiFePO₄ • DC-first • Optional inverter only if needed
Power Up
- Main fuse installed; case vents clear.
- Router/AP from 12V block (or PoE).
- If using Starlink PSU: turn inverter ON, then plug PSU.
Connect WAN
- Insert SIM for LTE.
- Starlink: place with sky view; wait link.
- Router health-check failover enabled.
Fast Runtime
- LTE AP ~18 W → ~64 h
- Starlink Std ~50 W → ~23 h
- Laptop + AP ~60 W → ~17 h
Save power: dim AP, disable snow-melt on Starlink, avoid inverter when possible.
Emergency
- Heat/odor/smoke: kill inverter (if used) → pull main power.
- Check fuses/lugs after cool-down.
QR: paste your docs link here.
Sources & References
- PoE Standards (power classes) — Cisco overview of IEEE 802.3af/at/bt (15.4W / 30W / 60–90W) and pair usage: Cisco: PoE power, data & control. Ubiquiti help center primer on PoE availability & modes: Ubiquiti: PoE modes and Intro to PoE.
- DC Over-Current & Fuse Placement — Blue Sea Systems on DC circuit protection and Class-T (high AIC) for inverters: Blue Sea: DC Circuit Protection, Class-T fuse category. ABYC E-11 excerpts on “as close as practicable” and the 40″/72″ sheath exceptions: Paneltronics E-11 excerpts (PDF).
- Starlink Power — Official support article with typical draw (Standard/Actuated 50–75 W avg; ~20 W idle; Mini 20–40 W): Starlink Support: Power specs.
Always follow the exact ratings and wiring diagrams in your device manuals. These references summarize widely used norms.