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Starlink 4 Off-Grid: Powering the 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.

🔧 Live field build This is an active build — we're deploying this setup off-grid shortly. The specs below come straight off the equipment labels; we'll add real-world power and performance numbers once it's been running. 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.

Dish: Starlink Standard 4 Router: UTR-251 (57V PoE) Injector: ING-G3 (48–57V in) Source: 48V LiFePO₄
Starlink UTR-251 compact router label showing 9-24V input and dual 57V PoE inputs
The compact router (UTR-251). Printed inputs: 9–24V on the barrel, plus two 57V PoE ports. The 57V PoE is how we power it off-grid.

How the power flows

The chain is short and all-DC:

48V 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 48V LiFePO₄ bus (~54V) — so in most of the battery's range it takes the DC directly and injects a clean 57V PoE, no extra conversion.

ING-G3 PoE injector installed and wired to the DC plant
Installed on the plant — DC in on the studs, PoE out to the router.
ING-G3 PoE injector label: 150W 4-pair GigE, input 48-57 Vdc 3A
ING-G3 label. Input 48–57 Vdc, 150W, V+ on 1,2,3,6 / V− on 4,5,7,8.

The voltage window

A 16S "48V" LiFePO₄ pack swings from about 40V (cutoff) to 57.6V (full charge), floating around 54V in normal use. The ING-G3's 48–57V input covers almost all of that range directly.

⚠️ Watch the top of charge Full-charge at 57.6V is just above the injector's 57V input ceiling. It'll run, but if you want to stay fully in spec, put a wide-input DC-DC converter ahead of it and hold a steady voltage. A Mean Well SD-500L-48 (19–72V in, output adjustable 46–60V) set to ~56V does exactly that — it covers the whole battery range and hands the injector a clean, fixed feed.
Mean Well SD-500L-48 DC-DC converter →
Mean Well SD-500 series enclosed DC-DC converter
Mean Well SD-500-series DC-DC converter — set the SD-500L-48 output to ~56V and it feeds the injector a clean, in-spec voltage across the whole battery range.

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.

✅ Before you connect the dishMeter the injector's PoE output and confirm ~56–57V under load. Verify polarity twice — passive PoE has no negotiation to protect a miswire.

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