IEEE Std 485-2020 PDF

Full title and description

IEEE Std 485™-2020 — IEEE Recommended Practice for Sizing Lead‑Acid Batteries for Stationary Applications. This recommended practice gives methods to define dc loads and to size lead‑acid battery strings (vented and VRLA) to supply those loads in stationary float (standby) service; it includes cell selection considerations, sizing worksheets, temperature correction factors, aging factors and worked examples. Installation, maintenance, qualification and testing procedures, charger sizing, and battery chemistries other than lead‑acid are outside its scope.

Abstract

Methods for defining the dc load and for sizing a lead‑acid battery to supply that load for stationary battery applications in float (standby) service are described. The document provides guidance on duty‑cycle definition, load classification (continuous, non‑continuous, momentary), selection factors for vented and valve‑regulated lead‑acid cells, cell‑sizing calculations and worksheets, and recommended design margins (aging factors and temperature corrections). Design of the dc system, charger sizing, installation, maintenance and testing practices are explicitly excluded.

General information

• Status: Approved / Active — IEEE Recommended Practice (IEEE Std 485™‑2020), revision of IEEE Std 485‑2010.
• Publication date: Published 5 June 2020; approved 6 May 2020.
• Publisher: The Institute of Electrical and Electronics Engineers (IEEE).
• ICS / categories: Electrical engineering — Galvanic cells and batteries; commonly aligned with ICS 29.220.20 (acid secondary cells and batteries).
• Edition / version: 2020 edition (revision of the 2010 edition).
• Number of pages: 69 pages (published PDF length).

Scope

This recommended practice addresses methods to: define and classify the dc duty cycle; calculate required battery capacity and number of cells/strings for stationary float (standby) applications; account for temperature and aging effects; and select appropriate vented or valve‑regulated lead‑acid (VRLA) cells. It provides worksheets and worked examples for cell sizing. The scope excludes detailed installation, maintenance and test procedures, charger design and sizing, and guidance for non‑lead‑acid battery chemistries.

Key topics and requirements

• Duty‑cycle definition and load classification (continuous, non‑continuous, momentary) for accurate sizing.
• Methods to convert power profiles to equivalent discharge currents and to account for voltage decline during discharge.
• Cell selection considerations for vented and VRLA lead‑acid cells, including plate design and manufacturer data review.
• Recommended aging (capacity degradation) and initial capacity factors (typical guidance: design for a capacity margin such as an aging factor ~1.25, with exceptions noted).
• Temperature correction factors and their application to rated capacities and sizing calculations.
• Worked sizing worksheets, charts and example calculations to determine number of cells, cell size, and parallel strings when required.
• Explicit exclusions: charger sizing, installation/maintenance/test procedures, and other battery chemistries.

Typical use and users

Primary users are power and system engineers, telecom and utility engineers, UPS and data‑center designers, battery specifiers, manufacturers and consulting engineers responsible for standby power systems. It is used to size stationary lead‑acid battery systems for telecommunications, utility substation DC supplies, emergency power systems, and other float/standby applications where predictable, long‑term float performance is required.

Related standards

Relevant IEEE and international documents often referenced alongside IEEE Std 485‑2020 include: IEEE Std 450 (vented lead‑acid battery maintenance and test guidance), IEEE Std 484 and 1187/1188 (installation and application guidance for lead‑acid batteries and VRLA), IEEE Std 1013 (sizing for PV stand‑alone systems) and IEC stationary battery standards such as IEC 60896 and IEC 61056. Project design documents (e.g., facility design manuals) commonly cross‑reference these standards.

Keywords

lead‑acid batteries, battery sizing, sizing worksheets, battery duty cycle, float service, VRLA, vented lead‑acid (VLA), rated capacity, aging factor, temperature correction, stationary applications.

FAQ

Q: What is this standard?

A: IEEE Std 485™‑2020 is a recommended practice that provides methods and guidance for sizing lead‑acid batteries (vented and VRLA) for stationary float (standby) applications.

Q: What does it cover?

A: It covers defining the dc duty cycle, converting power/load profiles to discharge currents, selecting cell sizes and numbers of cells/strings, applying temperature and aging correction factors, and using worksheets and examples to calculate required battery capacity. It does not cover charger sizing, installation, routine maintenance procedures or non‑lead‑acid chemistries.

Q: Who typically uses it?

A: Power systems engineers, telecom and utility designers, UPS and data‑center designers, battery manufacturers and technical consultants specifying or verifying stationary lead‑acid battery systems.

Q: Is it current or superseded?

A: The 2020 edition is the current revision (approved 6 May 2020, published 5 June 2020) and replaces IEEE Std 485‑2010. Users should check IEEE Standards Association resources for any errata or later revisions.

Q: Is it part of a series?

A: It is part of the suite of IEEE battery standards and recommended practices addressing stationary batteries (installation, maintenance, testing and application), and is commonly used in conjunction with related IEEE and IEC standards for battery installation and testing.

Q: What are the key keywords?

A: battery duty cycle, lead‑acid, VRLA, vented battery, sizing, rated capacity, float service, aging factor, temperature correction.