CASE-008 · Teaching Example
UPS Battery Runtime
How long does the UPS model run the 900 W teaching load on the stated battery budget?
Teaching example—not a real installation.
01
Teaching inputs
Fixed values from the versioned calculation fixture.
- Same fixture as CASE-004
- TC-018, not a second measured site
- Load
- 900 W at power factor 0.9, quantity 1
- Margin
- 20%
- Battery
- 48 V, 100 Ah, state of charge 1 to 0.2, health 1
- Efficiency / idle
- 0.9 / 0 W
02
Calculation path
Each transformation stays visible.
- 1
Keep the sizing result visible
Runtime does not replace the watt and volt-ampere requirement. The margin is applied once.
900 × 1.2 = 1080 W; 1080 / 0.9 = 1200 VA - 2
Store energy without multiplying efficiency
The UPS contract puts efficiency on the battery-side power, not inside the watt-hours.
E = 48 × 100 × 0.8 × 1 = 3840 Wh - 3
Divide by battery-side power
The AC load is divided by efficiency. Idle power is zero.
1000 W = 900 / 0.9; runtime = 3840 / 1000 = 3.84 h
03 · Result
The modeled outcome.
Teaching example—not a real installation. Results apply only to the stated fixture inputs.
| Measure | Calculated value | Interpretation |
|---|---|---|
| Sizing, unchanged from CASE-004 | 1080 W | 1200 VA |
| Usable energy | 3840 Wh | Efficiency is not inside this term |
| Runtime | 3.84 hours | 3840 / 1000 |
Teaching Example: 3.84 hours uses the UPS formula. The battery-runtime calculator would multiply efficiency into the energy instead, so it is not this result.
04
Boundaries & sources
What the result does—and does not—support.
- Constant voltage and constant load. No Peukert effect, chemistry, temperature or BMS limit.
- No manufacturer runtime curve is claimed. SRC-010 has a null URL on the calculation record.
- Do not treat 3.84 hours as the 12 V, 100 W, 8.64 hour battery-runtime fixture.
Method references
PowerEngineerLab internal method · model 1.0.0 · dataset user-input-v1
Same inputs as CASE-004 SRC-010 project calculation model (URL null on the calculation record)Continue exploring