ABM Technology and Battery Testing in Eaton UPS Products

Overview

VRLA batteries marketed with a 10-year design life are replaced every 4-5 years on average in UPS service and can be about 30% of UPS cost. ABM addresses this with a three-stage cycle: charge, float with an automatic battery test, and a long rest with the charger off and open-circuit voltage monitored.

Charge mode uses constant voltage at float level with current above 0.1C, up to a 100-hour limit, then 48 h of float with an automatic battery test after 24 h. Rest mode turns the charger off for about 28 days; charging restarts after an outage longer than 15 s, low open-circuit voltage, timer expiry or battery replacement.

The battery test discharges at about 15% load for up to 6 minutes then at 50% load for 45 s, and compares voltage to a load-dependent end-of-life threshold. On day 27 of rest, a 15-minute battery still provides all but about 30 seconds of its runtime. Calculated service life at 25 C increases by about six years versus float charging.

The paper presents accelerated-life and long-term test evidence, and states when to disable the scheme: with wet-cell batteries.

Key points

1. VRLA batteries marketed with a 10-year design life are replaced every 4-5 years on average in UPS service and can be about 30% of UPS cost.
2. Charge mode: constant voltage at float level, current above 0.1C, up to 100 hours; then 48 h float with an automatic test after 24 h.
3. Rest mode turns the charger off for about 28 days; an outage over 15 s, low open-circuit voltage, timer expiry or battery replacement restarts charging.
4. The test discharges at ~15% load for up to 6 minutes then 50% load for 45 s against a load-dependent end-of-life threshold.
5. On day 27 of rest a 15-minute battery still gives all but about 30 seconds of runtime.
6. Calculated service life at 25 C rises by about six years versus float charging.

Using it in design

• Add charging method (float, opportunistic/ABM, Li-ion BMS) and automatic battery test capability to the battery/UPS catalogue.
• Default the VRLA replacement interval to 4-5 years unless managed charging is specified.
• Warn if opportunistic charging is applied to flooded or wet-cell batteries.
• Include a 2-3% runtime derating at the end of the rest period in the autonomy margin.

Who should read it

UPS designers and facility operators planning VRLA battery life and maintenance.

Related standards

• IEEE 1188
• IEC 60896-21

Publication details

Authors

Eaton

Publisher

Eaton

Year

2018

Document number

WP09-18 (AP162001EN)

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