EMP + Rugged Wi-Fi Go Kit
Portable internet that eats blackouts for breakfast: 24 V LiFePO₄ core, LTE/5G failover, optional Starlink, EMP-aware shielding, and field-proof hardware.
Mission Profile
Battery: 24V 50Ah LiFePO₄ (≈1.28 kWh)
Outputs: 12V DC / 120V AC / USB-C PD / PoE
Runtime: 12–60h (load-dependent)
Hardened: Faraday liner + TVS/MOV
Case: IP54+ equipment case
Safety: Fuse near the battery, correct wire gauge, and never backfeed a building. Use listed components and follow your device manuals.
Parts to Buy (with Amperage Notes)
| Component | Spec | Amps / Fuse | Notes |
|---|---|---|---|
| LiFePO₄ Battery | 24 V 50 Ah (BMS inside) | Charge ≤ 0.5C → ≤25 A | Store 50–70% SOC; low-temp charge rules apply. |
| Pure-Sine Inverter | 300–600 W, 24 V input | DC ≈ 15–30 A @ 24 V | Only needed for AC loads (e.g., Starlink PSU). |
| 24→12 V Buck | Adjustable, 20–30 A | Fuse 40–60 A (input) | Feeds 12 V rail: router/AP/USB-C/PoE injector. |
| PoE Injector/Switch | 48–52 V PoE, ≥60 W | Fuse 5–10 A @ 12 V | For mesh AP or CPE that wants PoE. |
| USB-C PD Module | 12 V in → 60–100 W PD | Fuse 5–10 A | Laptop/phone top-ups without AC. |
| Dual-WAN Router | LTE/5G + WAN (Starlink) | Draw 8–20 W | Health checks + auto failover. |
| Battery Monitor (Shunt) | 200–300 A | All negatives after shunt | Shows amps in/out and SOC. |
| DC Protection | Class-T 125–200 A + 100–150 A DC breaker | Fuse near + battery | Main fuse then breaker to inverter leg. |
| Cables & Bars | 2 AWG battery leads; 6–10 AWG branches | 83 A peak capable | Per ampacity & voltage-drop charts. |
| EMP / Surge | Faraday bag/liner + TVS/MOV board | DC 24–36 V clamp | Bond liner to case ground lug. |
| Case & IO | Pelican-style case, vents, glands | Fans ~0.2–0.5 A ea | IP shroud over vents; SMA bulkheads if needed. |
Optional solar: 30–60 A MPPT, PV Voc ≤ controller limit, 2–4× “200 W 24 V-class” panels, 15 A string fuses when ≥2P.
Wiring Snapshot
24V Batt + -> Class-T 150–200A -> DC Breaker 100–150A -> Inverter + (AC loads)
24V Batt - -------------------------------------------------> Inverter -
24V Batt + -> 40–60A Fuse -> 24→12V Buck (20–30A) -> 12V Fuse Block -> [ Router | PoE | USB-C PD | Fans ]
24V Batt - -------------------------------------------------> Common Negative (post-shunt)
Battery Negative -> SHUNT -> Bus- (ALL negatives after the shunt)
Optional Solar:
PV Strings -> Combiner (15A/string if ≥2P) -> PV Disconnect -> MPPT PV+
MPPT BAT+ -> 60–80A fuse -> Bus+ ; MPPT BAT- -> Bus-
Label clearly: AC IN (charge), AC OUT (use), 12V OUT, Breaker, SOC display.
Build Steps
- Layout & Dry-Fit: Battery low & centered; inverter near exhaust vent; short 2 AWG runs.
- Cut IO: Drill for AC inlet/outlet, DC glands, fans, and SMA pass-throughs; deburr; fit gaskets.
- Main DC: Strap battery; Class-T fuse within ~8–10″ of +; DC breaker on inverter leg; shunt on battery −.
- Crimping: Use proper die (no hammer crimps). Heat-shrink lugs. Torque to spec.
- 12 V Rail: 24→12 V buck to blade fuse block; branch to router, PoE, USB-C PD, fans. Label fuses.
- Networking: Dual-WAN router (WAN1 Starlink, WAN2 LTE). Health check + failover. PoE to AP/CPE.
- EMP Layer: Faraday liner or copper mesh panel bonded to case ground; add TVS/MOV on DC bus.
- Program Limits: Inverter LVC ≈ 22–22.4 V; charge ≤ 0.5C; buck set 12.2–12.6 V under load.
- Pre-Power: Breaker OFF, continuity check Bus+ ↔ Bus−; verify polarity on inverter posts.
- Power-Up: Breaker ON → inverter ON; check idle draw; measure 12 V rail; test LTE first, then Starlink.
- Load Tests: 20–50 W (router) → add AP → add Starlink; log watts for your runtime card.
- Tidy & Label: Edge trim, cable dress, “AC IN vs AC OUT” labels, lid quick-start card attached.
Capacity & Runtime Estimator
Adjust loads & duty cycle; estimates account for inverter/buck efficiency and usable DoD.
Battery & Losses
Presets
Presets overwrite the table. Tweak values after.
| Device | Watt | Duty % | Qty | Avg W | |
|---|---|---|---|---|---|
Results
Total Average Load: 0 W
Usable Capacity: 0 Wh
Est. Runtime: 0 h 00 m
DC Current: 0 A @ 24 V
Tip: DC-only runs longer. AC inverter adds idle/surge overhead.
Solar MPPT Add-On (Optional)
Controller & Array
- MPPT: 24 V profile, 30–60 A, PV Voc max 100–150 V
- Strings: 2× “200 W 24 V” panels in series (Vmp ≈ 72 V) → efficient for MPPT
- Fusing: 15 A/string when ≥2 strings in parallel
- Connect order: Battery to MPPT first; PV last. Reverse to shut down.
Daily harvest ≈
PV_W × SunHours × 0.75 (e.g., 400 W × 4 h × 0.75 ≈ 1.2 kWh).Hookup
PV → Combiner (15A fuses) → PV Disconnect → MPPT PV+
MPPT BAT+ → 60–80A fuse → Bus+
MPPT BAT- → Bus-
Set Absorb ≈ 28.4–28.8 V; Float ≈ 27.0–27.6 V (or per battery manual)
EMP-Aware Hardening (Practical)
- Faraday layer: Use a tested Faraday bag or copper mesh liner bonded to a ground lug on the case; ensure lid continuity (conductive gasket or braid).
- Surge clamps: TVS diodes (e.g., 33–36 V working) across DC bus + MOVs; keep leads short.
- Cable hygiene: Route IO through glands; add ferrite clamps; avoid giant loop areas.
- Reality check: No portable kit is “EMP-proof”; aim for reasonable resilience, not invincibility.
Quick Start — Case Lid Card
Power Devices
- Flip Breaker ON.
- Press Inverter ON (if using AC).
- Router & AP are on 12 V rail (DC-only path = longer runtime).
- Plug AC loads (e.g., Starlink PSU) into AC OUT.
Charging
- Connect wall cord to AC IN.
- Charge current appears on shunt/inverter display.
- Unplug to stop charging.
WAN Failover
- WAN1: Starlink (AC)
- WAN2: LTE/5G
- Health checks enabled → auto swap
Fast Runtime
- Router 10 W → ~115 h
- AP 12 W → ~96 h
- Starlink 45 W → ~26 h
- Mixed ~95 W → ~12–13 h
Based on 1.28 kWh, 90% DoD, 90% efficiency. Real life varies.
Never backfeed a building. Keep dry & ventilated. Store 50–70% SOC.
Pre-Flight Checklist
Mechanical
- Battery strapped + padding
- Fans clear; filters clean
- Strain relief on all pass-throughs
Electrical
- Class-T fuse near battery +
- Shunt in negative; all returns post-shunt
- Polarity confirmed at inverter posts
Network
- WAN1 Starlink / WAN2 LTE set
- Health checks enabled
- SSID & password labeled
Sources & References
- OSHA — Portable Generator Safety (no backfeed). Link
- CPSC — Portable Generator Hazards (don’t backfeed). Link
- EC&M — NEC 702 Optional Standby overview (transfer equipment). Link
- Blue Sea — Class-T fuse specs & guidance. Link
- Blue Sea — Wire ampacity & voltage-drop charts (ABYC-based). Link
- Victron — SmartShunt/BMV manuals (all negatives after shunt). Link
- Victron — MPPT manuals (battery first; PV fusing). Link
- Battle Born / RELiON — LiFePO₄ charge setpoints (scale to 24 V). BB · RELiON
Always follow your specific device manuals; values here are typical.