Battery Technology for Single Phase UPS Systems: VRLA vs. Li-ion

Overview

The paper applies the VRLA versus Li-ion comparison made for three-phase UPSs to the single-phase UPSs used in edge rooms and racks. The core finding is that over a 10-year period Li-ion reduces total cost of ownership, because VRLA packs need replacement roughly every 4 years. Because edge rooms often have no maintenance staff on site, less frequent battery replacement is also an operational advantage, and in such sites it can be a sufficient reason on its own.

The figures rest on a 1.5 kVA single-phase UPS example: 10-year TCO is 53% lower for Li-ion than for VRLA. Service life at 25°C is 4 years for VRLA and 10 years for Li-ion. The VRLA service life range is 3-6 years, while Li-ion exceeds 10 years according to accelerated testing. This difference makes a decision in favour of Li-ion easier where a short runtime is adequate, although the runtime actually required should still be verified.

On runtime the example difference is small: at 25°C a 1.5 kVA unit gives 22 minutes with VRLA and 19 minutes with Li-ion. Li-ion therefore trades slightly shorter runtime for far longer life and lower cost. The paper also notes that battery management systems give better visibility of state of health, and it summarises safety advances in cell chemistry. A limit is that the results apply to the 1.5 kVA example, and ratios may differ at other sizes.

Key points

1. 10-year TCO for a 1.5 kVA single-phase UPS: Li-ion is 53% lower than VRLA.
2. Service life at 25°C: VRLA 4 years vs Li-ion 10 years.
3. Example runtime at 25°C: 22 minutes (VRLA) vs 19 minutes (Li-ion) for 1.5 kVA.
4. VRLA service life range is 3-6 years; Li-ion exceeds 10 years in accelerated testing.
5. VRLA packs need replacement roughly every 4 years.
6. Battery management systems improve state-of-health visibility.

Using it in design

• Prefer Li-ion with a 10-year life as the default for edge and rack UPS.
• Include VRLA battery refresh at years 4 and 8 in the TCO calculation.
• Use this comparison in the edge-site template.

Who should read it

Designers and IT managers selecting UPSs for edge rooms and racks.

Related standards

• IEC 62040-1
• UL 1778
• UL 9540A

Publication details

Authors

Victor Avelar; Martin Zacho

Publisher

Schneider Electric

Year

2017

Document number

WP 266

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