About this UPS
The CyberPower ST900U is a 900VA / 500W standby UPS from CyberPower's professional power-protection range. Engineered for reliable battery backup, voltage regulation, and surge protection in home office, business, and IT environments, backed by the full CyberPower manufacturer warranty.
Specifications
| Output Capacity (VA) | 900 VA |
| Output Power (Watts) | 500 W |
| Topology | Standby |
| Output Waveform | Simulated Sine Wave |
| Output Voltage | 120 VAC |
| Input Plug | NEMA 5-15P |
| Outlets | 12 × NEMA 5-15R |
| Form Factor | Compact |
| Connectivity | USB |
| Warranty | 3 Years Limited |
| Weight | 3.49 kg (7.7 lb) |
| UPC | 649532621521 |
| Manufacturer Part Number | ST900U |
Technical specifications
Setup checklist: after you receive your UPS →
How long it'll keep your equipment up.
Manufacturer-specified runtime at typical loads. Real-world figures depend on battery age, ambient temperature, and load profile.
Compare with alternatives
The ST900U side by side with UPS from other makers.
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Xtreme Power Conversion
Xtreme Power A60-850 850 VA / 500 W Standby UPS, 120 V
Compared with ST900U Spec ST900U Xtreme Power Capacity 900 VA / 500 W 850 VA / 500 W Topology Standby Standby Form Tower Tower Input plug NEMA 5-15P NEMA 5-15P Outlets 6 × NEMA 5-15R, 6 × NEMA 5-15R (6 on battery) 5 × NEMA 5-15R, 5 × NEMA 5-15R (5 on battery) Runtime, half load 8 min 6 min Differences
- 5 battery-backed outlets instead of 6
- Lower VA rating: 850 VA instead of 900 VA
$219.81 -
Xtreme Power Conversion
Xtreme Power S71-1000 1000 VA / 600 W Line-Interactive UPS, 120 V
Compared with ST900U Spec ST900U Xtreme Power Capacity 900 VA / 500 W 1000 VA / 600 W Topology Standby Line-Interactive Form Tower Tower Input plug NEMA 5-15P NEMA 5-15P Outlets 6 × NEMA 5-15R, 6 × NEMA 5-15R (6 on battery) 6 × NEMA 5-15R Runtime, half load 8 min 2 min Differences
- Line-interactive, a step up from standby
- Larger unit: 600 W instead of 500 W
$362.40 -
Xtreme Power Conversion
Xtreme Power T91-700 700 VA / 700 W Online UPS, 120 V
Compared with ST900U Spec ST900U Xtreme Power Capacity 900 VA / 500 W 700 VA / 700 W Topology Standby Online Double-Conversion Form Tower Tower Input plug NEMA 5-15P NEMA 5-15P Outlets 6 × NEMA 5-15R, 6 × NEMA 5-15R (6 on battery) 6 × NEMA 5-15R Runtime, half load 8 min 16 min Differences
- Lower VA rating: 700 VA instead of 900 VA
- Online double-conversion, a step up from standby
- Larger unit: 700 W instead of 500 W
$958.94
Check outlets and the runtime your load needs before ordering. Questions? Call 438-881-3363 or ask for a quote.
Replacement batteries that fit this exact UPS
A line-interactive UPS typically needs new batteries every 3 to 5 years. Matching replacement cartridges are listed by UPS model; confirm the exact model before ordering.
Questions before you buy
How do I know this UPS will run my equipment?
Add up the wattage draw of every device you'll plug in (servers, switches, monitors). The UPS's wattage rating (not VA) is the number that matters. Aim for the UPS to run at 60 to 70% of capacity at full load: this gives headroom for inrush current and a meaningful runtime margin. Email us your equipment list; we'll respond within one business day with sizing guidance.
What's covered by the warranty, and how long does it last?
New units carry the warranty coverage stated by the manufacturer; see the product listing or manufacturer documentation for the applicable terms. Refurbished units are covered by the 1-year UPSPLUSBATTERY warranty handled in Canada.
Can I extend runtime beyond what's shown above?
Many Smart-UPS-class models accept an external battery pack (XBP) connected to the rear battery port. If this UPS shows "Extended Runtime Capable: Yes" in the spec grid above, an XBP is supported. Compatible XBPs and the runtime gain they deliver vary by model; contact us if you don't see the right XBP in our catalogue.