Starlink 4 off-grid: compact router on PoE from a battery
A lean way to run a Starlink Standard 4 off-grid: power the small UTR-251 router with 57V PoE from a 48–57V injector fed straight off your battery — no wall brick, no inverter. Here's the wiring, the voltage window, and the parts.
This is an active build. The battery and charge profile below are the real settings running on the units we've set up; we'll add real-world power and performance numbers once it's logged some runtime. Check back for results.
The setup at a glance
Two small boxes do the work: a 48–57V PoE injector and Starlink's compact UTR-251 router. The dish rides the router's PoE. Because everything runs on DC, the battery feeds it directly.
How the power flows
The chain is short and all-DC:
Cyclone 51.2V LiFePO₄ battery → ING-G3 PoE injector (48–57V in) → 57V PoE up the Ethernet → UTR-251 router → dish.
The ING-G3 is a 150W, 4-pair gigabit PoE injector with surge protection. Its input range is 48–57 Vdc, which lands right on a working 51.2V LiFePO₄ bus (float ~53.5V) — so across the battery's normal range it takes the DC directly and injects a clean 57V PoE, no extra conversion.
1,2,3,6 / V− on 4,5,7,8.The voltage window & charge profile
Because a charge controller regulates this pack, the injector never sees the raw cell peak — it sees whatever the controller holds the bus at. On our units the Cyclone CYG-B51V-100A profile floats at 53.5V, absorbs to 56.0V, and won't climb past a 58.0V high-voltage shutdown, with a low-voltage disconnect at 45.0V. That keeps the bus inside the ING-G3's 48–57V input for essentially the whole cycle.
Cyclone CYG-B51V-100A — the charge settings we run
| Setting | Value |
|---|---|
| System voltage | 48 V |
| Float voltage | 53.5 V |
| Absorption / equalization | 56.0 V |
| High-voltage shutdown | 58.0 V |
| High-voltage warning | 57.9 V |
| Battery capacity | 100 Ah |
| Charge current | 5 A |
| Battery-on-discharge alarm | 51.0 V |
| Low-voltage warning | 47.0 V |
| LVD disconnect / reconnect | 45.0 / 47.2 V |
| Thermal compensation | Off |
That works out to about 3.34 V/cell float, 3.5 V/cell absorption, and 2.81 V/cell disconnect on a 16S LiFePO₄ pack — conservative and correct for the Cyclone 100Ah.
State of charge vs. resting voltage
Separate from the charge profile above, here's where a LiFePO₄ pack actually sits by charge level at rest (no load). Our window — 53.5V float down to the 45V disconnect, with a 47V low-voltage warning — keeps the 16S pack between roughly 90% and 10%, so it never deep-cycles. 12V (4S) and 24V (8S) columns are included for smaller packs.
| Charge | Per cell | 12V · 4S | 24V · 8S | 48V · 16S |
|---|---|---|---|---|
| 100% | 3.40V | 13.6V | 27.2V | 54.4V |
| 90% | 3.35V | 13.4V | 26.8V | 53.6V |
| 80% | 3.33V | 13.3V | 26.6V | 53.3V |
| 70% | 3.30V | 13.2V | 26.4V | 52.8V |
| 60% | 3.28V | 13.1V | 26.2V | 52.5V |
| 50% | 3.26V | 13.0V | 26.1V | 52.2V |
| 40% | 3.25V | 13.0V | 26.0V | 52.0V |
| 30% | 3.23V | 12.9V | 25.8V | 51.7V |
| 20% | 3.20V | 12.8V | 25.6V | 51.2V |
| 10% | 3.00V | 12.0V | 24.0V | 48.0V |
| Empty (cutoff) | ~2.50V | ~10.0V | ~20.0V | ~40.0V |
Approximate resting (no-load) voltages — LiFePO₄ is very flat through the middle, so trust your BMS percentage; values shift ~±0.05 V/cell by brand, temperature and load.
Mean Well SD-500L-48 DC-DC converter →
Wiring & polarity
Land the battery on the injector's DC input observing polarity, and fuse it on the battery side. The ING-G3 puts power on pairs 1,2,3,6 (V+) and 4,5,7,8 (V−) — standard 4-pair passive PoE — so use all-8-conductor cable rated for the run. Keep the PoE run within gigabit distance and use outdoor-rated cable with proper grounding/surge protection on a tower.
Networking: CGNAT, and put your own router in front
Powering the dish is only half the job — how you connect it matters just as much, especially on a shared or off-grid site. Two things change the moment you bring Starlink's feed into your own equipment.
You'll be on a CGNAT address by default
Plug the dish straight into your own router (instead of leaning on the Starlink router) and Starlink hands you a CGNAT (Carrier-Grade NAT) address. Your connection shares one public IP with many other subscribers, and your side gets a private-range address out of the 100.64.0.0/10 block — not a real public IP. It's fine for normal browsing, but it means no unsolicited inbound: you can't port-forward, host a server, or reach a camera/NVR from the outside without a workaround.
Always NAT your own devices behind your own router
Whether you keep the Starlink router or run a compact router like the UTR-251, don't hang all your gear directly on Starlink's network. Put your own router in front of your devices and let it NAT everything behind a single address:
- Privacy. The carrier side only ever sees one address — your router's — instead of every laptop, phone, camera and IoT gadget behind it.
- Security & control. Your router is a real firewall boundary — your own DHCP, DNS, VLANs and firewall rules, with your devices isolated from the Starlink side.
Frequently asked questions
Can you power a Starlink Standard 4 off-grid? +
Yes — feed a 48–57V PoE injector (like the ING-G3) straight off a 51.2V LiFePO₄ battery, and it powers the UTR-251 compact router and dish over 57V PoE. No inverter needed.
Why am I on a CGNAT address with Starlink? +
By default Starlink hands you a Carrier-Grade NAT address in the 100.64.0.0/10 range — you share one public IP, so no port-forwarding or inbound. Use Tailscale/WireGuard/ZeroTier, or Starlink's optional public-IP add-on, to reach the site.
How is the Standard 4 off-grid build different from the Gen 3? +
The Standard 4 uses the compact UTR-251 router on 57V PoE, so a 48–57V injector feeds it straight off the battery. The Gen 3 build (and the DC-converter route) is in the battery power guide.
How much battery do I need for a Standard 4 off-grid? +
Budget like any always-on dish — roughly 1–2 kWh/day depending on use and cold-weather heating. See power draw & battery sizing for the math.
Can I use this setup in an RV or while moving? +
For mobile use the Mini is the better fit — see Starlink 24/7 in an RV or van. The fixed-site PoE build here is aimed at towers and off-grid cabins.
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