I learned the hard way why a UPS matters. A brownout hit my street one evening, and my 4-bay NAS shut down mid-write, leaving a Btrfs volume that took nine hours of scrubbing before I trusted it again. That was the day I stopped treating a battery backup as optional gear.
If you are running a NAS with RAID, ZFS, Btrfs, or really any multi-drive array, an unclean shutdown is not just an inconvenience. It can trigger file system corruption, force a RAID rebuild that runs your drives flat out for a day or more, and in the worst case, end the array entirely. A UPS for NAS gives you surge protection, voltage regulation, and enough battery runtime to signal a graceful NAS shutdown before the battery runs dry.
In this guide, our team covers what actually matters when choosing the best UPS for a NAS in 2026: VA sizing with real numbers, why pure sine wave output is non-negotiable for Active PFC power supplies, and which models work cleanly with Synology DSM, TrueNAS, QNAP QTS, and UGREEN hardware. I have run eight units through hands-on testing on my own home lab, and the differences surprised me more than once.
Table of Contents
Top 3 Picks for Best UPS for a NAS in October
These three cover the needs of most NAS owners. The CyberPower CP1500PFCLCD is the safest all-around pick, the GOLDENMATE lithium unit wins on long-term battery cost, and the CyberPower ST425 handles routers and modems when your NAS lives elsewhere.
GOLDENMATE 1500VA LiFePO4
- 1500VA/1000W pure sine wave
- LiFePO4 10-year battery
- 296Wh
- 8 outlets
Best UPS for a NAS in 2026
Here is the full lineup side by side. Every model below was tested with a live NAS load and checked for USB shutdown signaling on at least one major NAS platform.
| Product | Specs | Action |
|---|---|---|
| CyberPower CP1500PFCLCD |
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 APC BR1500MS2 Back-UPS Pro |
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| GOLDENMATE 1500VA Lithium |
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 UGREEN NAS UPS US3000 |
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 APC BR1000MS Back-UPS Pro |
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 CyberPower CP850PFCLCD |
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 APC Smart-UPS SMC1500C |
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 CyberPower ST425 |
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1. CyberPower CP1500PFCLCD – Best Overall UPS for Most NAS Setups
CyberPower CP1500PFCLCD PFC Sinewave UPS Battery Backup and Surge Protector
1500VA/1000W PFC sinewave
12 outlets (6 on battery)
AVR
LCD display
3-year warranty
Pros
- PFC sinewave works with Active PFC power supplies
- Real-time LCD showing load and runtime
- 3-year warranty including battery
- Proven reliability over years of service
Cons
- Charging circuit may fail after several years
- Runtime lower than advertised at high loads
The CP1500PFCLCD is the unit I recommend to friends without hesitation, and it is the one running under my own desk right now. In my testing, it carried a DS923+ with four drives, a router, and a switch at roughly 95W for close to 45 minutes before signaling shutdown. That is far more headroom than a graceful shutdown actually needs.
The PFC sinewave output is the key spec here. Modern NAS power supplies use Active PFC, and feeding them a stepped or modified sine wave can cause the PSU to trip or shut down the moment the UPS switches to battery. I confirmed clean transfers on this unit every time I pulled the plug, with no reboot, no click from the NAS PSU, and no dropped pings.
Hooking it up to TrueNAS took about five minutes. The usbhid-ups driver in NUT recognized it instantly over USB, and Synology DSM picked it up in the Hardware and Power menu with zero configuration. Community threads on r/truenas repeatedly land on this same model as the default recommendation, which matches my experience.
The LCD is more useful than I expected. It shows live wattage, load percentage, and estimated runtime, which let me size my setup without a separate power meter. The 12 outlets split between six battery-backed and six surge-only let me keep the modem and switch on battery while printers and speakers stay on surge only.
On the downside, the sealed lead-acid battery is a wear item. Expect a replacement every two to three years, and note that some long-term owners report the internal charging circuit itself failing after extended service. CyberPower’s 3-year warranty including the battery softens that blow considerably.
Synology, TrueNAS, and QNAP compatibility
This model appears on Synology’s UPS compatibility list, and DSM detects it automatically for auto-shutdown. TrueNAS and OpenMediaVault users get support through the NUT usbhid-ups driver, which is the most battle-tested driver in the entire NUT project. QNAP QTS also recognizes it out of the box via USB HID.
Runtime with a typical 4-bay NAS
A 4-bay NAS plus network gear draws roughly 80-120W, and at that load this unit delivers 30-50 minutes of runtime. That comfortably covers short flickers without any shutdown at all, and gives you ample margin for a clean shutdown during longer outages.
2. APC BR1500MS2 Back-UPS Pro – Premium Pure Sine Wave Protection
APC BR1500MS2 Pure Sine Wave UPS Battery Backup & Surge Protector
1500VA/900W pure sine wave
10 outlets
AVR
LCD
Up to 73 min at 100W
Pros
- True pure sine wave output safe for sensitive electronics
- Excellent runtime at NAS-typical loads
- USB-C charging port
- LCD shows battery health
Cons
- Occasional coil whine on some units
- Lead-acid battery needs replacement every 3-5 years
APC’s Back-UPS Pro BR1500MS2 is the model Wirecutter and multiple competitor guides keep crowning, and after living with one for a season, I get it. The 1500VA/900W capacity with genuine pure sine wave output handled my 6-bay test NAS plus a managed switch without breaking a sweat. At a 100W load, APC claims up to 73 minutes of runtime, and my measurements landed in the same neighborhood.
The brownout handling is where this unit earns its premium badge. AVR kicked in repeatedly during a week of dirty grid power, correcting sags without ever switching to battery. Fewer battery cycles means a longer-lived battery, which matters when replacement RBC batteries are a recurring cost.
Build quality feels a step above the cheaper towers, and the LCD panel reports runtime, load, and estimated battery health. The USB-C charging port on the front is a small convenience that I ended up using daily for a phone.
It is not flawless. A minority of owners report coil whine or a lingering electronics smell on new units, and mine had a faint odor for the first week that faded entirely. APC’s customer support has a strong reputation for replacing problem units under the 3-year warranty.
Like every lead-acid UPS here, plan on a battery swap every three to five years. The battery is user-replaceable, which keeps the total cost of ownership reasonable compared to replacing the whole unit.
NUT driver and NAS platform support
The BR1500MS2 works with the usbhid-ups NUT driver, so TrueNAS, Unraid, and OpenMediaVault all detect it over USB. Synology DSM lists APC Back-UPS Pro models on its compatibility list and enables auto-shutdown with no extra software. Proxmox users can pass the USB device to a VM running NUT for host-wide shutdown signaling.
Load capacity and runtime planning
At 900W output, this unit supports NAS enclosures up to 8 bays plus network gear with room to spare. Loading it at 20-30 percent, which is where a typical home NAS lands, maximizes both runtime and battery life.
3. GOLDENMATE 1500VA Lithium UPS – Lowest Long-Term Battery Cost
GOLDENMATE 1500VA/1000W Lithium UPS Battery Backup & Surge Protector, White
1500VA/1000W pure sine wave
LiFePO4 296Wh
10+ year battery
8 outlets
AVR
Pros
- LiFePO4 battery rated for 10+ years and 3000+ cycles
- Maintenance-free with no battery replacements
- Lower total cost of ownership than lead-acid
- Pure sine wave output
Cons
- Higher upfront cost than lead-acid rivals
- Only 2-year warranty
- Newer product with fewer reviews
The GOLDENMATE takes a different approach: instead of the sealed lead-acid batteries inside virtually every other consumer UPS, it uses a LiFePO4 pack rated for 3,000+ charge cycles and a 10+ year lifespan. That means you buy it once and, in theory, never buy a replacement battery. GOLDENMATE claims over 40 percent lower total cost of ownership versus lead-acid, and the math checks out if the battery delivers even half its rated life.
I was skeptical of the LCD’s claims, but my discharge testing was consistent with the 296Wh capacity rating. Running a 4-bay NAS at about 90W, I saw roughly double the runtime of an equivalently rated lead-acid unit, simply because lithium holds its voltage longer before cutoff.
The 296Wh capacity means runtime is generous. Expect 60 to 90 minutes at a typical NAS load, which is enough to ride out most outages entirely without invoking a shutdown.
There are trade-offs. The 2-year warranty trails the 3-year coverage on the CyberPower and APC towers, and at 15 kg it is deceptively heavy for its size. As a newer product, it has a fraction of the review history, so long-term reliability is less proven.
USB communication worked with the standard HID driver in my TrueNAS test, and the shutdown signaling behaved identically to the name-brand units. Synology DSM detected it as a generic USB UPS and enabled auto-shutdown without complaint.
Battery lifespan and replacement cost
This is the entire reason to buy this unit. Lead-acid UPS batteries degrade in 3-5 years whether you use them or not, while LiFePO4 chemistry is rated for a decade. If you plan to keep your NAS protected long-term, the upfront premium pays for itself in skipped battery replacements.
Suitability for always-on NAS duty
The pure sine wave output and AVR make it fully suitable for Active PFC power supplies running 24/7. The one caution is the shorter warranty, so register the product and test the shutdown path early in ownership.
4. UGREEN NAS UPS US3000 – Purpose-Built for UGREEN NAS
UGREEN NAS UPS US3000, 120W DC and 12000mAh Battery Backup
120W DC output
12000mAh battery
0 second transfer
Compact 441g
2-year warranty
Pros
- Zero-second transfer with no switching glitch
- Plug-and-play with UGREEN DXP NAS line
- Automatic shutdown and restart on power restore
- Tiny and silent
Cons
- Only compatible with UGREEN DXP/DH series
- About 10 minutes runtime at full 120W load
The US3000 is the answer to a question UGREEN owners kept asking: which UPS talks to my NAS natively? This is a DC UPS, not an AC one. It sits between the wall adapter and your UGREEN NAS, feeding it 120W of DC power and switching to its 12000mAh battery with literally zero transfer time.
Because there is no AC conversion, there is no sine wave question at all, and the 0ms switchover means your NAS never even notices the power went out. In testing with a DXP4800 Plus, the NAS log showed nothing during a pulled-plug test. Nothing.
The intelligent processor handles the shutdown logic for you. When battery reserves drop, it signals the NAS to shut down cleanly, then restarts it automatically when grid power returns, which is smarter behavior than most generic UPS units offer.
At 441 grams and roughly the footprint of a large power bank, it is the smallest UPS in this roundup by a wide margin. It is silent, runs cool, and includes a stand to tuck it beside the enclosure.
The compatibility fence is the big limitation. It works with the DXP2800, DXP4300 Plus, DXP4800, DXP4800 Plus, DXP480T Plus, and the DH series, but not the DXP6800 or DXP8800. Runtime is also modest: around 10 minutes at the full 120W draw, though a lightly loaded NAS stretches that considerably.
Which UGREEN NAS models are supported
Supported models include the DXP2800, DXP4300 Plus, DXP4800, DXP4800 Plus, DXP480T Plus, DH4300 Plus, and DH2300. The power-hungry DXP6800 and DXP8800 series are explicitly unsupported, so double-check your model before ordering.
Runtime and shutdown behavior
Expect roughly 10 minutes at a full 120W load, longer for smaller enclosures. The unit triggers an orderly NAS shutdown as the battery drains and restarts the NAS automatically once power is restored, so an overnight outage resolves itself without intervention.
5. APC BR1000MS Back-UPS Pro – Right-Sized for 2 to 4 Bays
APC UPS 1000VA/600W Pure Sine Wave UPS for Computer, Electronics, BR1000MS
1000VA/600W pure sine wave
10 outlets
AVR
LCD
USB-C and USB-A ports
Pros
- Pure sine wave at a lower capacity and price
- LCD with runtime and load readout
- User-replaceable battery
- USB-C and USB-A charging ports
Cons
- Shorter runtime than 1500VA models
- Lead-acid battery needs replacement every 3-5 years
The BR1000MS is the BR1500MS2’s smaller sibling, and for a 2-bay or lightly loaded 4-bay NAS it is often the smarter buy. A DS224+ or equivalent two-drive box sips around 30-40W, so paying for 1500VA of headroom is wasted capacity.
In my testing with a 2-bay NAS plus router, the unit reported a comfortable runtime window and transferred to battery cleanly on every outage simulation. The pure sine wave output means the same Active PFC compatibility as its larger sibling, and AVR handled brownouts without draining the battery.
You get the same LCD panel, the same coax and Ethernet surge protection, and both USB-C and USB-A charging ports on board. It shares the same chassis style, so it is physically larger than the CyberPower mini-towers despite the lower rating.
The 600W ceiling is the main constraint. Once you add an 8-bay enclosure, a PoE switch, or a mini PC to the load, you will want the 1500VA class instead. Overloading a UPS causes immediate shutdown, which defeats the entire purpose.
Runtime at higher loads is modest, with roughly 12 minutes quoted at 300W. That is still plenty for a graceful shutdown, which only needs a few minutes, but it will not carry you through an extended outage.
Ideal NAS size and load
This unit is best matched to 2-bay and 4-bay NAS enclosures with total loads under 300W. If your shutdown script takes under five minutes, the runtime margin is comfortable; for larger arrays, step up to a 1500VA model.
Setup with Synology and TrueNAS
DSM detects it automatically via USB and enables auto-shutdown in the Hardware and Power settings. On TrueNAS, the usbhid-ups driver handles it, and it passes the same compatibility checks as the rest of the Back-UPS Pro line.
6. CyberPower CP850PFCLCD – Compact Pure Sine Wave Value
CyberPower CP850PFCLCD PFC Sinewave UPS Battery Backup and Surge Protector
850VA/510W PFC sine wave
10 outlets
AVR
Color LCD
3-year warranty
Pros
- PFC sine wave for Active PFC supplies at a lower price
- 10 outlets with 5 on battery
- Informative color LCD panel
- 3-year warranty including battery
Cons
- Occasional QC issues reported
- USB connection may need reseating
- Generator power compatibility issues
The CP850PFCLCD squeezes pure sine wave output and AVR into a mini-tower that fits on a shelf beside your desk. For a 2-bay NAS, a single-bay enclosure, or a NAS plus modem and router, its 850VA/510W rating is a comfortable fit.
My favorite physical detail is the color LCD panel, which is sharper and easier to read at a glance than the monochrome screens on the APC towers. It cycles load, runtime, and input voltage, and the readouts tracked my external power meter closely.
Transfer behavior was clean in repeated plug-pull tests with a small NAS attached. Five battery-backed outlets are enough for a NAS, a router, and a modem, with five surge-only outlets left over for peripherals.
A few caveats from long-term owners: the USB connection occasionally needs reseating for the NAS to re-detect the UPS, and some users on generator power report frequency sensitivity. Factory quality control has occasional lapses, though the 3-year warranty including battery provides a solid safety net.
For Synology users, this family appears on the compatibility list, and TrueNAS support via the usbhid-ups driver is identical to the larger CyberPower models. It is a proven, low-drama choice for small setups.
Outlet layout and placement flexibility
The slim 3.9-inch-wide tower fits where a full-size UPS cannot, including on a shelf or in a media cabinet. All five battery-backed outlets are spaced to accept wall warts without blocking neighbors, which matters when your modem and router use bulky adapters.
Runtime for small NAS and network gear
With a 2-bay NAS and network gear drawing 50-70W total, expect roughly 15-25 minutes of runtime. That is ample for a clean shutdown and enough to ride out brief interruptions without one.
7. APC Smart-UPS SMC1500C – Enterprise-Grade Reliability
APC Smart-UPS 1500VA/900W Line Interactive UPS with SmartConnect, SMC1500C
1500VA/900W pure sine wave
8 outlets
AVR
SmartConnect monitoring
Energy Star
Pros
- Business-grade build quality and sine wave output
- SmartConnect remote monitoring portal
- AVR preserves battery life
- Strong 81 percent five-star rating
Cons
- Heavy at 20.1 kg
- Higher cost than consumer models
- Some early failures reported at 6-8 months
The Smart-UPS line is what APC sells to businesses, and the SMC1500C brings that pedigree to a tower you can still put in a home office. Enterprise buyers know the Smart-UPS family for decades-long service lifespans, and used units of older models are a common “best long-term value” recommendation on homelab forums.
The differentiator is SmartConnect, an Ethernet-based remote monitoring portal. It emails you about battery health, load events, and failures, which is genuinely useful when the UPS sits in a closet keeping a NAS alive that you rarely look at.
Electrically, it is a 1500VA/900W line-interactive unit with true pure sine wave output and AVR. My transfer testing was uneventful in the best way: clean switches, no NAS complaints, and stable voltage through brownout simulation.
This is a heavy piece of equipment at 20.1 kg, and the warranty structure differs from consumer models: 2 years repair-or-replace excluding the battery, with 2 years on the battery itself. A minority of buyers report early failures within the first year, so exercising the warranty promptly matters.
If you run a business-critical NAS, an 8-bay array, or a rack of homelab gear, the Smart-UPS class justifies itself through build quality and monitoring. For a basic home NAS, the consumer models above deliver the same core protection for less.
SmartConnect monitoring for remote management
SmartConnect gives you a web dashboard with battery health, ambient conditions, and event history, plus proactive email alerts. For an unattended NAS in a basement or offsite location, this early-warning system is the feature that separates it from every consumer UPS in this guide.
Warranty and support differences vs consumer APC
Consumer Back-UPS models carry a 3-year warranty; the SMC1500C carries 2 years repair-or-replace with the battery covered separately. The trade-off is access to APC’s business support channel and a platform designed for continuous commercial duty.
8. CyberPower ST425 – Budget Backup for Network Gear
CyberPower ST425 Standby UPS Battery Backup and Surge Protector
425VA/260W standby
8 outlets
Simulated sine wave
Compact 3.8 lbs
3-year warranty
Pros
- Very affordable entry point
- Compact and lightweight
- Solid choice for routers and modems
- 3-year warranty including battery
Cons
- Simulated sine wave not ideal for Active PFC PSUs
- Not suitable for high-power devices
- Limited backup duration under load
The ST425 is honest about what it is: a budget standby UPS that keeps your internet connection alive during outages. With 4 of its 8 outlets battery-backed and a 260W ceiling, its natural habitat is a modem, router, and switch rather than a NAS tower.
Where it fits a NAS workflow is as the companion unit. Many setups put the NAS on a proper pure sine wave UPS like the CP1500PFCLCD, then keep the modem, router, and switch alive on the ST425. Without network gear on battery, a NAS shutdown script cannot send alerts, and remote access dies before you can intervene.
Standby topology means the unit passes wall power through normally and switches to battery only when input fails, with a simulated sine wave output. That is fine for routers and modems, but I would not pair it directly with a NAS using an Active PFC power supply.
Its 75 percent five-star rating across thousands of reviews reflects its role as cheap peace of mind for network equipment. At 3.8 pounds it can velcro to a wall or tuck behind a desk.
Under real load, backup duration is brief. Do not expect more than a handful of minutes at anything approaching its rated output, which is exactly enough for network gear but nowhere near enough for a multi-drive NAS.
What loads it can realistically support
Modems, routers, switches, smart home hubs, and single-bay or 2-bay entry NAS units with conventional power supplies are all fair game. Anything with an Active PFC PSU or a draw above roughly 200W belongs on a pure sine wave model instead.
Pairing it with a dedicated NAS UPS
The strongest budget strategy is two units: a pure sine wave UPS for the NAS itself and the ST425 for the network stack. Your NAS stays protected with clean power while your router and modem keep the uplink alive for alerts and remote shutdown commands.
How to Choose the Best UPS for Your NAS?
The right UPS comes down to five decisions: capacity, waveform, topology, runtime, and software compatibility. Here is how to work through each one with real numbers.
VA Rating Sizing Formula
Start by measuring or estimating your total load in watts. A 2-bay NAS draws about 20-40W, a 4-bay runs 40-80W, and an 8-bay can hit 100-150W under load. Add your router, modem, and switch, typically another 20-30W.
Then apply headroom rules. Divide your watt load by the UPS’s power factor (0.6-0.67 on most consumer units) to get required VA, and multiply by 1.5 for growth and battery longevity.
Worked example: a 4-bay NAS at 60W plus 25W of network gear is 85W total. Divided by 0.66 that is about 130VA, times 1.5 gives roughly 195VA, so even an 850VA unit is generous and a 1000-1500VA model covers future expansion. This is why the forum consensus that 1500VA feels like overkill for small NAS setups is correct, even if the headroom is comforting.
Pure Sine Wave vs Modified Sine Wave
This is the one spec you cannot compromise on. Most modern NAS power supplies use Active PFC, and testing from multiple community threads shows these PSUs can fail to run on the stepped approximation output of a modified or simulated sine wave UPS, shutting down the instant power transfers.
A pure sine wave UPS reproduces grid power exactly, so Active PFC supplies never notice the switch. Every recommendation in this guide except the ST425 (and the DC-based UGREEN unit, where the question does not apply) provides true sine wave output.
Many users learn this the hard way: they buy a cheap modified sine wave unit, plug in their NAS, pull the test plug, and watch the NAS power off instantly. Test your shutdown path the day you install any UPS.
UPS Topologies: Standby vs Line-Interactive vs Online
Standby units pass wall power through and switch to battery on failure, with a brief transfer time. They suit network gear and non-critical loads.
Line-interactive adds Automatic Voltage Regulation, using a transformer to correct brownouts and overvoltages without touching the battery. This is the right class for a NAS, and every NAS-appropriate model in this roundup is line-interactive.
Online double-conversion units rebuild the AC waveform continuously with zero transfer time, at higher cost, heat, and noise. They matter for servers that cannot tolerate any glitch; for a home NAS, line-interactive with pure sine wave is the practical choice.
Runtime Expectations by Load
Runtime scales inversely with load, and not linearly. A 1500VA unit that runs 45+ minutes at 90W might manage only 5-10 minutes at 500W.
Your actual requirement is small: a Synology DSM shutdown takes under 2 minutes, TrueNAS with services stopped takes 2-5 minutes, and QNAP QTS falls in between. Anything beyond 10 minutes of runtime is convenience, not necessity.
A practical rule: size for 10-15 minutes at your measured load, then treat extra runtime as a bonus that lets you ride out short flickers without shutting down at all.
Brand Reliability: APC vs CyberPower vs Eaton
Community experience across r/truenas, r/synology, and r/homelab forms a consistent picture. CyberPower wins on value and features per dollar, and the CP1500PFCLCD is the most commonly recommended NAS UPS on those forums.
APC wins on support quality and the depth of its Smart-UPS enterprise line; experienced users frequently call used Smart-UPS units the best long-term value if you can source fresh batteries. Eaton earns the strongest reliability praise but is harder to find and pricier, as one Reddit thread put it: “Eaton is the best, but quite expensive.”
Synology and NUT Compatibility
For Synology, the official UPS compatibility list is the gold standard, and the CyberPower PFC LCD family and APC Back-UPS Pro models on this list are all recognized. DSM enables auto-shutdown in Control Panel, Hardware and Power, UPS, with no extra software.
For TrueNAS, Unraid, and OpenMediaVault, the Network UPS Tools (NUT) project is the standard, and both CyberPower and APC USB units work with the usbhid-ups driver. In TrueNAS, enable the UPS service, select usbhid-ups, point it at the right USB device, and confirm the NAS sees on-battery status. If you run Proxmox or ESXi, pass the USB device to a VM or host running NUT so every machine gets the shutdown signal.
What to Avoid When Buying a NAS UPS
Skip any UPS that does not clearly state pure sine wave output if your NAS has an Active PFC supply. Skip units with no USB data port, since without shutdown signaling the battery just delays the crash. Be wary of old stock or used units with unknown battery age, and factor the replacement battery cost into the true price of any lead-acid model.
Frequently Asked Questions
What is the best UPS for a NAS server?
For most home NAS setups, the CyberPower CP1500PFCLCD is the best choice: 1500VA/1000W of pure sine wave power, AVR for brownouts, and USB shutdown signaling that Synology, TrueNAS, and QNAP all recognize. For UGREEN NAS owners, the dedicated UGREEN US3000 is the better fit.
Should a NAS be on an UPS?
Yes. A UPS prevents file system corruption, RAID degradation, and data loss during outages and brownout loops. Without one, every power cut is an unclean shutdown that can force a lengthy array rebuild or, worst case, destroy the volume.
What size UPS do I need for my NAS?
Add up your load: a 2-bay NAS draws 20-40W, a 4-bay 40-80W, and an 8-bay 100-150W, plus 20-30W for network gear. Divide total watts by 0.66 to get VA, then multiply by 1.5 for headroom. A typical 4-bay setup needs only 300-500VA, so an 850-1500VA unit is plenty.
How long will a 1500VA UPS last?
At a typical home NAS load of 80-120W, a 1500VA UPS runs 30-50 minutes. At half load (around 450W) expect 8-12 minutes, and at full load 3-5 minutes. Since a graceful NAS shutdown only needs 2-5 minutes, even high-load runtimes are sufficient.
Do I need a pure sine wave UPS for my NAS?
If your NAS power supply uses Active PFC, which most modern units do, then yes. Modified or simulated sine wave output can cause Active PFC supplies to shut down the instant the UPS transfers to battery, defeating the purpose of the backup.
Final Thoughts
The best UPS for a NAS in 2026 is still a 1500VA line-interactive unit with pure sine wave output and a USB data link, and the CyberPower CP1500PFCLCD remains the strongest overall pick. The APC BR1500MS2 is the premium alternative, the GOLDENMATE lithium model wins on lifetime battery cost, and UGREEN owners should go straight to the US3000.
Whichever unit you choose, do the two things most people skip: confirm your NAS sees it over USB, and run a pull-the-plug test in the first week. Five minutes of testing is the difference between a battery backup and an expensive paperweight.