Eaton 3S 700 (Gen 2)
Power cut? The Eaton 3S 700 Gen 2 switches your NAS or home lab to battery in an instant, with 8 outlets and 2 USB charging ports.
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Characteristics
- Power: 700 VA / 420 W
- Outlets: 8x BS (4 battery-backed + 4 surge-only)
- Runtime: ≈6 min at full load, 9 min at 50%
- Ports: 2x USB-A charging (2A) + USB software
- 8 outlets, silent, 2 USB charging ports included
Detailed overview: Eaton 3S 700 Gen 2 UPS
The Eaton 3S 700 (Gen 2) is a backup UPS built to protect a fixed piece of electronics, not to replace a solar inverter or a van's 12V to 230V converter: it constantly monitors mains power and switches to battery the instant it detects an outage or a surge. For a home fitted with residential solar, or a small home lab, that is exactly what belongs between the wall socket and a NAS, a network switch or a router: a few seconds of dropout is sometimes enough to corrupt a NAS mid write or drop an active SSH session.
With 700 VA and 420 W of continuous power, this 2nd generation gains two extra outlets over the previous model: its 8 BS outlets, split across 2 rows (4 battery-backed plus surge protection, 4 surge-protection-only), let you dedicate the most important sockets to the NAS, switch and router, and leave the rest of the peripherals on surge protection alone. Two USB-A charging ports (2A max) are built straight into the unit, handy for topping up a phone or a spare 4G dongle without tying up a mains socket.
The USB communication port and Eaton's included monitoring software (Windows, Mac and Linux compatible) let you schedule an automatic, clean shutdown of the NAS or server if an outage runs longer than the available runtime, about 6 minutes at full load and 9 minutes at half load, avoiding any data corruption. The sealed lead-acid battery is user-replaceable, typically after 3 to 5 years of use, and the unit includes surge protection for phone and network lines (RJ11/RJ45).
An Off-Line design (the most common at this price point), the 3S 700 does not actively regulate voltage the way a Line-Interactive model would, but stays highly responsive to a clean mains failure. For a home lab, a NAS or a router connected to a residential solar setup, its outlet count for the price makes it one of the most recommended picks in its class.
EAN: 3553340705038
Comparison
When choosing a UPS to protect a NAS or a home lab, the Eaton 3S 700 (Gen 2) is often compared to other models in the same power class, in searches like "Eaton 3S 700 vs APC Back-UPS" or "Eaton 3S vs CyberPower". Here is how it stacks up against three alternatives: the Eaton Ellipse ECO 650 USB IEC, its quieter but less equipped sibling already in our catalogue; the APC Back-UPS BX700U, a direct rival on power; and the CyberPower CP705EPFCLCD, pricier but fitted with an LCD display.
| Criterion | Eaton 3S 700 (Gen 2) | Eaton Ellipse ECO 650 USB IEC | APC Back-UPS BX700U | CyberPower CP705EPFCLCD |
|---|---|---|---|---|
| Power | 700 VA / 420 W | 650 VA / 400 W | 700 VA / 390 W | 705 VA / 405 W |
| Outlets | 8x BS (4 battery-backed) | 4x IEC C13 (3 battery-backed) | 6 outlets (3 battery-backed) | 6 outlets (4 battery-backed) |
| USB charging ports | 2x USB-A (2A) | None | 1x USB-A | None |
| Display / monitoring | USB software, no display | USB software, no display | No display | LCD + USB software |
| Observed price | £116.39 | £138.74 | ≈ £120 | ≈ £145 |
Overall, the Eaton 3S 700 (Gen 2) stands out for the best outlet count for the price in its class, with 8 sockets and 2 USB charging ports that neither the APC BX700U nor the Ellipse ECO 650 offer. The CyberPower CP705EPFCLCD keeps the edge on its LCD display, a genuine plus for tracking load at a glance, but at a noticeably higher price for near-identical power.
Related video
Video: Eaton 3S 700VA IEC sockets UPS - Published on 25/04/2017
Our tester's review: Dawid Lojewski
Fitted under our home network rack, the 3S 700 Gen 2 keeps a NAS, switch and router running through short outages without a hitch. The 8 outlets, split across 2 rows, make it much easier to fit several bulky power bricks side by side without them fighting for space, a real step up from the previous generation's 6 sockets. During a deliberate power cut test under load, the switch to battery was instant, with no NAS reboot and no dropped connection. The 2 USB-A ports are handy for topping up a phone or a spare 4G dongle straight off the unit. Once installed on the NAS, the monitoring software correctly triggered a clean shutdown a few minutes into the outage. One honest downside: at full 420 W load, runtime drops to around 6 minutes, just enough for a clean shutdown rather than riding out a long outage. For a small home lab, a hard combination of outlet count and price to beat.
Frequently asked questions: Eaton 3S 700 Gen 2 UPS
The 2nd generation gains two extra outlets (8 instead of 6, split across 2 rows) and 2 built-in USB-A charging ports, both absent on the first generation. Power output stays the same at 700 VA / 420 W.
Eaton rates about 6 minutes of runtime at full load (420 W) and 9 minutes at half load (210 W), enough for the USB monitoring software to trigger a clean NAS shutdown before the battery runs out.
Yes, the 3S 700 runs silently in normal mains operation. There is no active fan on this model, unlike some more powerful units in Eaton's range.
Yes, the sealed lead-acid battery is designed to be user-replaceable without special tools, typically after 3 to 5 years depending on use. Eaton sells compatible replacement battery packs.
4 outlets are battery-backed plus surge-protected (reserve these for the NAS, router and switch), and 4 are surge-protection-only, for less critical devices like a monitor or a printer.
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Published on 05/09/2026