Engineering guide
Built-in UPS battery tests and runtime calibration
Most three-phase UPS can test their own batteries. A short battery test (about 10% of runtime on a Galaxy VS) catches blown fuses and weak blocks; a runtime calibration discharges to the low-battery warning to correct the runtime estimate; and on some models a SPoT mode test discharges the batteries at a set power without a load bank. Each one spends battery life, so schedule them on purpose.
Key facts
- Galaxy VS battery test: Uses about 10% of total runtime capacity
- Battery test schedule: Weekly up to once a year
- Battery test prerequisites: Batteries over 50% charged, over 4 minutes of runtime
- Runtime calibration: Discharges to the low DC warning level
- Calibration load window: At least 10% load, varying no more than 20%
- Galaxy VL SPoT mode: Discharge test without a load bank, 0 to 100% output power
Three tests, three different questions
| Test | What it does | What it proves |
|---|---|---|
| Battery test | Short discharge, about 10% of total runtime capacity (Galaxy VS) | No blown fuse, no weak block |
| Runtime calibration | Transfers to battery and discharges to the low DC warning level | The real capacity, so the runtime estimate is corrected |
| Battery SPoT mode (Galaxy VL) | Discharge at an output power set from 0 to 100%, without a load bank | Runtime at your operating load |
None of them replaces a full load-bank test of the power train; they answer the battery question only.
Battery test: frequent and light
On the Galaxy VS, the battery test checks for blown fuses and weak batteries and uses about 10% of the runtime. It needs the batteries above 50% charged and more than 4 minutes of runtime available, and it can be scheduled from weekly to once a year. If the utility drops or a critical alarm appears, the test aborts and the UPS returns to normal operation.
Eaton's 93PM works the same idea into its charger: Advanced Battery Management keeps the batteries charged and tests them periodically by transferring to battery mode while monitoring voltage, with a series of tests 24 hours into the float period.
Runtime calibration: deep and occasional
Calibration discharges the batteries to the low DC warning level and uses the elapsed time and load to recalculate capacity. Schneider recommends it at start-up, when batteries are replaced, and when the battery solution changes. The load must be at least 10% and must not move more than 20% during the test.
The cost is real: during calibration the batteries are too low to carry the load through an outage, runtime stays short until recharge, and repeated testing or calibration can affect battery service life. Run it in a quiet period with the generator available.
SPoT mode: a discharge test without a load bank
The Galaxy VL manual describes Battery SPoT mode, which performs a battery discharge test without the need for a load bank, at an output power you set between 0 and 100%. The load is not supported by the UPS during the test, so it is run with the load shut down or on an alternative supply, and the feature has to be enabled by Schneider Electric services during start-up.
Turning results into a plan
A failed battery test or a calibration that shows less runtime than designed is the trigger to measure each block and plan the string. Compare the measured runtime with your target using a UPS runtime calculator, then book the work with a crew that replaces three-phase battery strings on site. Battery age is the other half of the answer; see how long three-phase UPS batteries last.
Related pages
Common questions
How much battery does a Galaxy VS battery test use?
About 10% of the total runtime capacity. With 10 minutes of runtime, the test runs for about 1 minute.
When should a runtime calibration be done?
Schneider recommends it at start-up, when batteries are replaced, and when the battery solution changes.
Is a runtime calibration risky?
During the test the batteries are discharged to the low DC warning level and cannot carry the load through an outage, and repeated calibrations can affect battery life.
Can a UPS test its batteries without a load bank?
The Galaxy VL Battery SPoT mode does a discharge test without a load bank, at an output power you set, but the UPS does not support the load during the test.
Does the Eaton 93PM test its own batteries?
Yes. Advanced Battery Management tests the batteries periodically by transferring to battery mode and monitoring voltage, including a series of tests 24 hours into the float period.
Sources, checked October 4, 2026:
- Schneider Electric, Galaxy VS UPS Operation, 990-5910G (5/2025), pp. 17, 53, 54
- Schneider Electric, Galaxy VL UPS Operation, 990-91379H (3/2026), p. 62
- Eaton 93PM-L 20-60 kW (208V) UPS Installation and Operation Manual, P-164000711 Rev 12, p. 4 (PDF 16)
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