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Werk #18749: UPS Capacity: warn/crit thresholds are now evaluated while the UPS is on mains

Component Checks & agents
Title UPS Capacity: warn/crit thresholds are now evaluated while the UPS is on mains
Date May 22, 2026
Level Trivial Change
Class Bug Fix
Compatibility Compatible - no manual interaction needed
Checkmk versions & editions
3.0.0b1
Not yet released
Checkmk Community, Checkmk Pro, Checkmk Ultimate, Checkmk Cloud, Checkmk Ultimate MT
2.5.0p6 Checkmk Community, Checkmk Pro, Checkmk Ultimate, Checkmk Cloud, Checkmk Ultimate MT

Previously, the warning and critical thresholds configured via the UPS Capacity rule for the battery capacity (percent) were silently ignored whenever the UPS was running on mains power. They were only evaluated while the UPS was on battery, which is the situation in which they were least useful: a battery that fails to fully charge while on mains went unnoticed.

With this fix, the configured thresholds are evaluated in all operational states. A UPS with a degraded battery sitting on mains at e.g. 90% will now go WARN/CRIT against the default (95, 90) thresholds, surfacing a problem that was being masked before.

If you relied on the previous silent behavior, either delete the UPS Capacity rule for the affected hosts or relax the configured thresholds.

The analogous suppression for the time-on-battery metric is not affected: that one only ignores the value when the device reports 0 as an "invalid" sentinel on mains, which is the correct behavior.

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