The Advantages of Using Lithium-Ion Batteries in Single-Phase UPS Applications for Edge Data Centers

Overview

The paper first lists the weaknesses of VRLA: string failure risk, a 3-5 year life, temperature sensitivity and weight. A 2013 Ponemon study attributed 55% of unplanned outages and one third of UPS failures to VRLA battery failure. VRLA needs about 25°C room temperature for a 3-5 year life, each 15°C rise halves useful life, and end of life is defined at 80% capacity.

On the Li-ion side, UPS chemistries are LFP, LMO and NMC (or LMO/NMC blends). Li-ion has an 8-10 year design life and is still at about 93% capacity when VRLA reaches 80%; it is about 60% lighter, up to 70% smaller and operates at 30°C without life loss. Li-ion rack systems recharge to 90% in under 2 hours versus over 4 hours for VRLA, with up to 24 hours for a full VRLA recharge.

The cost comparison is the paper's decision point: Li-ion's initial cost is 1.75-2.25 times VRLA, yet the 10-year TCO for a 1500 VA UPS is $1,000 against $1,700, a 41% saving, with payback within five years. The saving comes from avoiding battery replacements at remote sites. The document focuses on small single-phase UPSs and does not cover large three-phase systems.

Key points

1. 2013 Ponemon study: 55% of unplanned outages and one third of UPS failures attributed to VRLA battery failure.
2. VRLA needs ~25°C room temperature for a 3-5 year life; each 15°C increase halves useful life; end of life is at 80% capacity.
3. UPS Li-ion chemistries are LFP, LMO and NMC (or LMO/NMC blends).
4. Li-ion: 8-10 year design life (still ~93% capacity when VRLA reaches 80%), ~60% lighter, up to 70% smaller, operates at 30°C without life loss.
5. Li-ion rack systems recharge to 90% in under 2 h versus over 4 h for VRLA (up to 24 h for full recharge).
6. Initial Li-ion cost is 1.75-2.25x VRLA.
7. 10-year TCO for a 1500 VA UPS is $1,000 vs $1,700 (41% saving), with payback within five years.

Using it in design

• For edge and closet designs, default the single-phase UPS battery to Li-ion where room temperature is uncontrolled, and show replacement cycles in lifecycle cost (VRLA 3-5 y, Li-ion 8-10 y).
• Give the catalogue battery design life, recharge time to 90% and maximum ambient without derating.
• Warn when VRLA is placed in spaces above 25°C.
• Include travel and labour cost per replacement for remote sites in TCO.

Who should read it

IT and facilities managers choosing single-phase UPS batteries for many branch and edge sites.

Related standards

• IEC 62040-1
• IEC 62619
• UL 1973

Publication details

Authors

Vertiv

Publisher

Vertiv

Year

2023

Document number

SL-70595

Document language

English

Source type

Manufacturer

Access

Free to read

Licence

Copyright retained; citation only — the publisher’s terms apply to the original document

Citation