VA and watts are two ratings, and the smaller one is the real one · review

UGREEN NASync US3000, 120 W constant, 0 s switchover review

A 120 W UPS designed around network storage, switching to battery in a stated zero seconds, with an application that shuts the NAS down automatically and restarts it.

By Jean-Benoit Buisson

The bottom line A purpose-built UPS whose value is the software rather than the battery: automatic shutdown, standby and restart for a NAS. It claims a zero-second switchover without naming the topology that would explain it, and publishes no runtime at all.

A 120 W UPS built for one job and one maker’s hardware.

The job

A network storage device that must not lose a write. The application detects the failure, shuts the NAS down cleanly, holds it in standby and restarts it when the mains returns. That sequence is the product; the battery is the means.

Zero seconds

Claimed in the first bullet. A genuinely uninterrupted output implies an online topology — the load always fed from the inverter, with no switch to make. The listing claims the outcome and never names the architecture, which is the half that would make it checkable.

The narrowing

120 W constant, matched to UGREEN NAS voltage requirements. That is a deliberate limitation rather than an oversight, and it means the unit is bought as part of one maker’s system rather than as a general UPS.

The blanks

No VA rating. No runtime. No outlet list. No battery replaceability. For a UPS, a runtime is the second question after the switchover, and it is not answered.

Availability

German, French, Italian and Spanish Amazon stores quoted about 110 € when this page was compiled.

American and British Amazon stores carry it too, priced in their own currency, which the euro range above deliberately omits.

These figures are what Keepa reported on the day this page was last updated. Availability and pricing move without notice.

Prices quoted in this text were read on 16 September 2026. The live price is at the top of the page.

What it gets right, and what it leaves out

Strengths

Automatic NAS shutdown and restart, which is what a UPS for storage is actually for
A zero-second switchover is claimed, which is the strongest transfer figure in this family
A nine-stage protection system filtering lightning and mains fluctuations

Compromises

Matched specifically to UGREEN NAS units, which narrows it considerably
No VA rating, no runtime and no outlet list
A zero-second switchover implies an online topology, which the listing never states

Specifications

VA	Nowhere in the listing — only a watt figure is published
Watt ratings	120 W constant output, matched to UGREEN NAS requirements, third bullet
Topology	Nowhere in the listing
Waveform	Nowhere in the listing
Transfer time	0 seconds, first bullet — the only UPS here to claim an uninterrupted switchover
Runtime	Nowhere in the listing
Outlets	Nowhere in the listing
Software	UGREEN application for status, battery and protection monitoring, with automatic NAS shutdown, standby on failure and restart, second bullet
Battery replaceability	Nowhere in the listing
Amazon reference	B0DDC9ZK8R (same reference on 6 Amazon marketplaces)
EAN	6941876246151

Questions owners ask about this one

What does zero seconds imply?

An online topology, where the load is always fed from the inverter and the mains only charges the battery — so there is no switch to make. The listing claims the result without naming the topology, and the two normally go together.

Why is automatic shutdown the point?

Because a NAS that loses power mid-write can corrupt data, and a UPS that keeps it alive for ten minutes only helps if something tells the NAS to stop cleanly. The application doing that automatically is what distinguishes this from a general-purpose UPS.