Lesson 09 / 12 · Opening balances
Track energy before the outage
Why does the 50 kWh case last longer when it can charge first?
Predict before you run
Write down your prediction, then change only the input below. In the interactive lesson, compare the starting case with the challenge and export a worksheet to retain your reasoning.
| Input | Starting value | Challenge value |
|---|---|---|
| Battery charging power | 100 kW | 0 kW |
Reported quantity: s elapsed. The live control accepts 0–100 kW.
Worked answer Link to this answer
The battery starts at 50 kWh. Before the 300 s outage it gains 7.9166… kWh at 100 kW charging power. Depletion is at 478.2675 s; with charging disabled it is at 453.9 s.
| Configuration | Battery charging power | Result (s elapsed) |
|---|---|---|
| Starting case | 100 kW | 478.2675 |
| Challenge | 0 kW | 453.9 |
Calculated from the same inputs as the interactive lesson. Display rounded to six decimal places; full decimal strings, inputs and energy records are in the downloadable result record. Elapsed seconds start at simulation time zero; ride-through starts at the outage.
Reproduce the configuration
| IT demand / simulated duration | 1000 kW / 1800 s |
|---|---|
| Opening battery / energy capacity | 50 kWh / 100 kWh |
| Charging power limit | 100 kW |
| Charge / discharge efficiency | 0.95 / 0.9 |
| Distribution efficiency | 0.95 |
| Generator start delay | 30 s |
Scheduled events
- 300 s: utility — asset down
- 300 s: generator — asset down
- 900 s: utility — asset up
- 900 s: generator — asset up
The browser lesson applies its configuration to the generator_failure preset. Open it above, run the starting case, switch to the challenge, and use “Verify against Python” to compare complete results. Use the worksheet export to keep the prediction, completed inputs and answer together.
Sources and verification
- Lesson definitions and input transformations
- Native Python default/challenge checks
- Electrical continuity contract
- Three reference cases, equations and versioned source records
Cite this lesson
Mohammad Rezwan Khan. “Track energy before the outage.” Datacenter Twin Lab, engine 2.0.1. https://khanlab.co.technology/learn/precharge/
Documentation source: 4878472c4d6c166c3dbd81aee292a0a56e89ffff. For a numerical claim, also retain the completed inputs and the result record; the live lesson can be changed by its controls.
Original material by Mohammad Rezwan Khan, engine 2.0.1. Synthetic teaching cases; no facility calibration or independent external reproduction has been established. Annual PUE planning and outage continuity are different calculations. Full scope and evidence.