P91-1.5kLi vs Vertiv Liebert PSI5-1500RT120LIN
Both are 1500 VA / 1350 W, 120V lithium UPS in a 2U rack/tower chassis about 16 inches deep. The Vertiv PSI5-1500RT120LIN is line-interactive. The Xtreme Power P91-1.5kLi is online double-conversion, lighter, with two more outlets, faster recharge, operation to 50 °C, a battery rated for up to 15 years and a 6-year warranty.
What the P91-1.5kLi brings
Zero transfer time and continuously regulated output, against line-interactive AVR on the PSI5.
Eight NEMA 5-15R against six, including a controllable bank.
25.6 lbs against 28.3 lbs, in the same 2U.
About 1.5 hours to 90%, against about 2 hours.
Runs in hot closets and edge rooms; the PSI5 is rated to 40 °C.
LiFePO₄ rated for up to 15 years, against 8 to 10 years.
Electronics and lithium battery (USA and Canada), against 5 years. Reduced to 2 years at 40–50 °C; 2 years depot repair elsewhere.
About 8 minutes at full load and 17 at half load, in line with the PSI5.
Qualifies for U.S. government, education and public-sector procurement as standard.
P91-1.5kLi vs PSI5-1500RT120LIN
| Feature | Xtreme P91-1.5kLi | Vertiv PSI5-1500RT120LIN |
|---|---|---|
| Topology | Online double-conversion | Line-interactive with AVR |
| Output capacity | 1500 VA / 1350 W | 1500 VA / 1350 W |
| Rack space | 2U | 2U |
| Depth | 15.1″ rack (16.1″ with bezel) | 16.2″ |
| Weight | 25.6 lbs | 28.3 lbs |
| Runtime at full load | 8 min at 1350 W | 7.5 min at 1350 W |
| Runtime at half load | About 17 min at 675 W | 17.7 min at 675 W |
| Recharge | About 1.5 h to 90% | About 2 h |
| Battery | LiFePO₄ (LFP), hot-swappable | Lithium-ion, hot-swappable |
| Battery life rating | Up to 15 years | 8–10 years |
| Operating temperature | 0–50 °C (derated above 40 °C) | 0–40 °C |
| Outlets | 8 × 5-15R (one controllable bank) | 6 × 5-15R (3 programmable) |
| Input cord | 6 ft, 5-15P | 10 ft, 5-15P |
| Network card | Optional Web/SNMP | Included |
| Warranty | 6-year full (electronics and battery) | 5-year advance replacement |
| TAA compliant | Yes, standard | Confirm per part number |
Where the PSI5 leads: a network card included in the box, a longer 10 ft input cord, three individually programmable outlets, and advance-replacement warranty service. Runtime is about equal.
Vertiv and Liebert are trademarks of Vertiv Group Corp., referenced here for factual comparison only. Vertiv figures are from Vertiv’s published data and distributor listings, checked October 2026; verify current specifications before purchase. The P91-1.5kLi depth is rack-mounting depth.
Compare the P91-1.5kLi with Eaton, Vertiv and APC →Choosing between them
Choose the P91-1.5kLi for servers, storage, network gear and generator-backed sites that need online double conversion, for warm rooms up to 50 °C, for the longest battery life and warranty, for more outlets, and for TAA procurement. Choose the PSI5-1500RT120LIN where line-interactive protection is enough and a network card in the box matters.
Need more runtime? See the P91-2kLi 2000 VA comparison. Need 1U? See the J90 1U online lithium UPS.
P91-1.5kLi vs PSI5-1500RT120LIN: frequently asked questions
What is the difference between the P91-1.5kLi and the Vertiv PSI5-1500RT120LIN?
Why does online double conversion matter?
How does runtime compare?
How do they compare on depth and weight?
How long do the batteries last?
Is the P91-1.5kLi TAA compliant?
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