UPS battery cell impedance rise vs baseline that triggers investigation under the battery-maintenance program
~20% (early screening trigger)estimate
| Value kind | estimate — Interpret this value according to its displayed kind, scope, source, and as-of date. |
|---|---|
| Scope | A screening trigger, not a universal threshold: the acceptance limit depends on battery chemistry and construction, the measurement method and instrument, the commissioning baseline and cell temperature, and the OEM's published limits. Practice varies: about 20% over the commissioning baseline is a common early screen, while some tester guidance treats a 50-100% change as serious. A repeatable rise opens an investigation and the prescribed capacity or condition assessment. |
| Caveat | Impedance does not measure remaining capacity and does not establish that a cell will open at the next transfer. Replacement follows the approved battery-maintenance program (IEEE 450/1188-class capacity testing for lead-acid, or the OEM protocol). |
| As of | 2026-10 |
| Source | Megger stationary-battery testing guidance and tester-vendor guidance for the ~20% screen; method (baseline trending, then capacity testing) per IEEE Std 1188 (VRLA) and IEEE Std 450 (vented) |
| Review | checking…review by 2027-10-01 · standard cadence |
| Recorded changes | last 2026-10-16 · 3 revisions tracked |
| Claim id | ups-battery-cell-impedance-rise-vs-baseline |
Where the guide uses it
← Full numbers register — every date-stamped figure in the guide, with revision history.