ENERGY DETECTIVE / CASE FILE 02

Full Battery, Cold Kettle

The lights work. The kettle does not.

The cabin has plenty of stored energy, but the kettle refuses to heat while the background equipment keeps running. Investigate power limits without confusing watts with watt-hours.

Your missionDeliver 75 Wh of kettle heating within five minutes while retaining 100 W background service.

Not started

No progress yet. Choose a prediction to begin.

START / PREDICT

What went wrong?

Choose an initial idea. It will not be graded or count against you.

The simultaneous AC request exceeds the inverter continuous ratingThe battery has too little stored energyA motor startup surge caused a real inverter trip Not sure yet — I want to investigate

No prediction saved yet.

01 / SURVEY THE SCENE

Something doesn't add up.

Inspect the equipment. Each object reveals a clue and its measurement boundary.

Current experiment readings — battery energy availableRun an experiment to inspect battery energy.

Run an experiment to see the equipment states.

Scene is illustrative, not a wiring diagram. All clues are also available as the ordered buttons above.

Original system evidence notebook 0 / 5

Select any clue to inspect its reading.

No evidence collected yet.

02 / TEST THE THEORY

Run a controlled experiment.

Run the original system, then change one authored parameter set. Every experiment starts again from its documented initial conditions.

Choose your intervention

Select a change to see which settings will be different.

Service

Battery left

Unserved AC

Original energy compared with the selected test. Exact results remain available in the table below.

Replay speed Inspect a moment

Choose a moment to inspect.

See the actual energy ledger and intervals

Starting battery Wh = remaining Wh + delivered AC Wh + conversion loss Wh + overhead Wh. Unserved AC is not withdrawn from the battery.

Each model interval, including exact cutoff boundaries
Elapsed	Requested AC Wh	Served AC Wh	Unserved AC Wh	Battery remaining Wh

03 / EXPLAIN

Close the case with evidence.

Your conclusion must refer to a recorded experiment and evidence you uncovered.

Cause you want to defend Experiment supporting my explanation

This is your claimed supporting test. Inspecting a different experiment will not change it.

Collect evidence and test an effective repair before closing the case.

Investigation tools

Need a hint?

Hint 1 is available.

Model and measurement methodology

Read more: LiFePO4 battery-bank sizing

Classroom activity sheet

All Detective cases

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What this investigation teaches

Energy stored in Wh is different from continuous output power in W. This teaching model reserves background load and rejects the entire oversized kettle request.

Try the reasoning outside the game

Deliver 75 Wh of kettle heating within five minutes while retaining 100 W background service. Compare watts (instantaneous power) and watt-hours (energy accumulated over time), remembering to include the measurement boundary and all stated losses.

Learn more in our LiFePO4 battery-bank sizing guide. The values in this case are fictional teaching presets, not installation recommendations.