Eaton 5S550
Power outage? The Eaton 5S550 switches your NAS or router to battery instantly, with 8 outlets and zero fan noise in normal operation.
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Characteristics
- Power: 550VA / 330W
- Outlets: 8x NEMA 5-15R (4 battery-backed + 4 surge-only)
- Runtime: ≈12 min at half load, 1 min at full load
- Topology: Line-interactive, coax/data line protection
- 8 outlets, quiet operation, Eco-Control saves up to 30%
Detailed overview: Eaton 5S550 UPS
The Eaton 5S550 is an entry-level backup UPS built to protect a fixed piece of electronics, not to replace a solar inverter or an RV's 12V to 120V converter: it constantly monitors mains power and switches to battery the instant it detects an outage or a voltage sag. For a home fitted with residential solar, or an RV or boat running a Starlink dish, that is exactly what belongs between the wall outlet and a router, a modem or a small backup NAS: a few seconds of dropout is sometimes enough to knock a router offline at the worst possible moment. Eaton's Ellipse ECO line sold across Europe is not available in the US; the 5S550 is the brand's entry-level equivalent for home offices and small setups on this market.
With 550VA and 330W of continuous power, the 5S550 sits at the bottom of the 5S range, built for a single router, modem or standalone NAS. Its 8 NEMA 5-15R outlets split into 4 battery-backed plus surge protection, and 4 surge-protection-only, a generous outlet count for this power class. Line-interactive topology corrects minor sags and surges on the line without draining the battery, which preserves both its runtime and its lifespan, and coax plus data/modem line protection guards against surges riding in on those lines too.
The USB port and Eaton's Intelligent Power monitoring software let you schedule an automatic, clean shutdown of the NAS or server if an outage runs longer than the available runtime, about 12 minutes at half load and roughly 1 minute at full 330W load, avoiding any data corruption. Eco-Control can trim standby energy use by cutting power to secondary peripherals once the master device switches off, for savings Eaton rates at up to 30% compared with older-generation units.
The main thing to plan around is runtime at heavy load: at full 330W it drops to about a minute, so this unit buys enough time for a clean shutdown trigger rather than to keep a NAS running through a long outage. For a router, a modem or a standalone NAS, its outlet count and quiet operation make it a sensible, more than adequate entry point into Eaton's US lineup.
Comparison
When choosing a small UPS to protect a router or a backup NAS, the Eaton 5S550 is often compared to other entry-level models, in searches like "Eaton 5S550 vs APC Back-UPS". Here is how it stacks up against three alternatives: the Eaton 5S700, its more powerful sibling in the same US lineup; the APC Back-UPS BE600M1, a direct rival on budget; and the CyberPower CP550SLG, a step down in outlet count.
| Criterion | Eaton 5S550 | Eaton 5S700 | APC Back-UPS BE600M1 | CyberPower CP550SLG |
|---|---|---|---|---|
| Power | 550VA / 330W | 700VA / 420W | 600VA / 330W | 550VA / 330W |
| Outlets | 8x NEMA (4 battery-backed) | 8x NEMA (4 battery-backed) | 7 outlets (4 battery-backed) | 5 outlets (3 battery-backed) |
| Topology | Line-interactive | Line-interactive | Line-interactive | Line-interactive |
| Display / monitoring | USB software, no display | USB software, no display | No display | No display |
| Observed price | $156.99 | $163.99 | ≈ $80 | ≈ $60 |
Overall, the Eaton 5S550 stands out for its generous 8-outlet count and coax/data line protection at this price point, ahead of both the APC BE600M1 and the CyberPower CP550SLG on outlet count. The Eaton 5S700 remains the better pick if your router, modem and NAS combined draw close to 330W, for a similar price and more headroom.
Our tester's review: Dawid Lojewski
We set up the 5S550 under our router and a small backup NAS. Eaton does not sell its Ellipse ECO line in the US, so the 5S550 is what American buyers actually find, and it does the job well: fan noise is a non-issue in normal operation, which matters for a unit sitting in an occupied home office. During a deliberate outage test, the switch to battery was instant, with no reboot on either the router or the NAS. The 8 outlets, split 4 battery-backed and 4 surge-only, are generous for this power class and make it easy to keep secondary gear like a monitor or a printer on surge protection alone. Runtime at full 330W load is short, about 1 minute, plenty for a clean shutdown trigger but not for riding out a long outage; at half load it stretches to a more comfortable 12 minutes. For a router, a modem, or a small standalone NAS, this is a sensible, no-frills pick.
Frequently asked questions: Eaton 5S550 UPS
Eaton sells its Ellipse ECO line in Europe and the 5S line in the US; the two ranges do not overlap by name. The 5S550 is the closest US equivalent in power class, outlet type (NEMA 5-15R) and use case.
Eaton rates about 12 minutes of runtime at half load and roughly 1 minute at full 330W load, plenty of time for a router or modem that rarely draws more than 20 to 30W.
No, fan noise is not an issue in normal operation, which makes it a reasonable pick even for an occupied home office. It is not a fully passive design, but it stays discreet in day-to-day use.
Eco-Control automatically cuts power to secondary outlets once the device on the master outlet switches off, trimming standby consumption by up to 30% compared with older-generation Eaton UPS units.
The 8 NEMA 5-15R outlets split into 4 battery-backed plus surge protection (reserve these for the router, modem and NAS) and 4 surge-protection-only outlets for less critical devices like a monitor or printer.
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Published on 05/09/2026