ENERGY DETECTIVE / CASE FILE 01

The Overnight Drain

The refrigerator went silent before sunrise.

A cabin battery was charged at sunset, but the refrigerator went quiet before sunrise. Equipment notes and equipment readings seem to disagree. Investigate where the energy went.

Your missionKeep the refrigerator running for the full 18:00–06:00 night.

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 battery budget omitted inverter overheadThe battery was not charged at sunsetThe refrigerator secretly used more than its stated AC demand 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 Unserved AC is not withdrawn from the battery.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: Inverter idle consumption

Classroom activity sheet

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What this investigation teaches

Small continuous losses accumulate. Inverter overhead is battery-side draw, separate from conversion efficiency.

Try the reasoning outside the game

Keep the refrigerator running for the full 18:00–06:00 night. 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 Inverter idle consumption guide. The values in this case are fictional teaching presets, not installation recommendations.